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Monteiro W, Karl S, Kuehn A, Almeida A, White M, Vitor-Silva S, Melo G, Brito-Sousa JD, Baia-da-Silva DC, Silva-Neto AV, Sampaio V, Bassat Q, Felger I, Mueller I, Lacerda M. Prevalence and force of Plasmodium vivax blood-stage infection and associated clinical malaria burden in the Brazilian Amazon. Mem Inst Oswaldo Cruz 2022; 117:e210330. [PMID: 35766676 PMCID: PMC9239689 DOI: 10.1590/0074-02760210330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/16/2022] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Understanding the epidemiology of malaria through the molecular force of the blood-stage infection of Plasmodium vivax (molFOB) may provide a detailed assessment of malaria transmission. OBJECTIVES In this study, we investigated risk factors and spatial-temporal patterns of incidence of Plasmodium infection and clinical malaria episodes in three peri-urban communities of Manaus, Western Brazilian Amazon. METHODS Monthly samples were collected in a cohort of 1,274 individuals between April 2013 and March 2014. DNA samples were subject to Plasmodium species. molFOB was calculated by counting the number of genotypes observed on each visit, which had not been present in the preceding two visits and adjusting these counts by the respective times-at-risk. FINDINGS Respectively, 77.8% and 97.2% of the population remained free of P. vivax and P. falciparum infection. Expected heterozygosity for P. vivax was 0.69 for MSP1_F3 and 0.86 for MS2. Multiplicity of infection in P. vivax was close to the value of 1. The season was associated with P. vivax positivity [adjusted hazard ratio (aHR) 2.6 (1.9-5.7)] and clinical disease [aHR 10.6 (2.4-47.2)]. P. falciparum infection was associated with previous malarial episodes [HR 9.7 (4.5-20.9)]. Subjects who reported possession of a bed net [incidence rate ratio (IRR) 1.6 (1.2-2.2)] or previous malaria episodes [IRR 3.0 (2.0-4.5)] were found to have significantly higher P. vivax molFOB. MAIN CONCLUSIONS Overall, P. vivax infection prevailed in the area and infections were mostly observed as monoclonal. Previous malaria episodes were associated with significantly higher P. vivax molFOB.
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Abebaw A, Aschale Y, Kebede T, Hailu A. The prevalence of symptomatic and asymptomatic malaria and its associated factors in Debre Elias district communities, Northwest Ethiopia. Malar J 2022; 21:167. [PMID: 35659661 PMCID: PMC9166605 DOI: 10.1186/s12936-022-04194-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 05/21/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is a major cause of morbidity and mortality worldwide. According to the World Health Organization 2021 malaria report, it is considered to be endemic in 85 countries and territories. Malaria elimination programmes have also faced many challenges, such as widespread asymptomatic carriers in endemic regions, and they should be considered in malaria-control programmes in endemic areas for successful transmission interruption. This study aimed to assess the prevalence of symptomatic and asymptomatic malaria infections, and associated factors in Debre Elias district communities, Northwest Ethiopia from May to Jun 2018. METHODS A community-based cross-sectional study was conducted among selected kebeles in Debre Elias district, Amhara region, North-western Ethiopia. Multi-stage sampling technique was carried out to select representative households. A total of 440 randomly selected households were included, of which one individual per household was sampled for laboratory examination. Malaria prevalence was determined by light microscopy of stained blood films and using CareStart™ Malaria HRP2/pLDH (Pf/Pv) Combo rapid diagnostic test (RDT). A structured questionnaire was employed to collect socio-demographic data and associated risk factors. Data entry and analysis were carried out using Epi data 3.1 and SPSS version 23 software, respectively. The association between dependent and independent variables was explored by using bivariate and multivariate logistic regression analyses. Statistically significant association was declared at P-value of < 0.05. RESULTS A total of 440 (333 asymptomatic and 107 symptomatic) individuals were included in this study. The overall prevalence of malaria was 5% with the majority (59.1%) of infections caused by Plasmodium falciparum. Among asymptomatic participants, 4.8% (n = 16, 95% CI = 2.6-7.3) and 4.2% (n = 14, 95% CI = 2.1-6.5) were diagnosed and confirmed by RDT and light microscopy respectively. Similarly, the prevalence of malaria among 107 symptomatic individuals was 7.5% (n = 8, 95% CI = 2.8-12.6) by either RDT or light microscopy. Utilization of insecticide-treated net (ITN), availability of ITN, house with eave, previous history of malaria infection, and family history of malaria infection were significantly associated with malaria infection (P < 0.05). CONCLUSION In this study, the prevalence of asymptomatic and symptomatic malaria was moderate. Screening of both symptomatic and asymptomatic malaria in the community is very important to scale up intervention programmes.
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Affiliation(s)
- Abtie Abebaw
- Department of Medical Laboratory Science, College of Health Sciences, Debre Markos University, P.O. Box: 269, Debre Markos, Ethiopia.
| | - Yibeltal Aschale
- Department of Medical Laboratory Science, College of Health Sciences, Debre Markos University, P.O. Box: 269, Debre Markos, Ethiopia
| | - Tadesse Kebede
- Department of Microbiology, Immunology and Parasitology, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology and Parasitology, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Futagbi G, Otu PS, Abdul-Rahman M, Aidoo EK, Lo AC, Gyan BA, Afrane YA, Amoah LE. Association of TNF-Alpha, MBL2, NOS2, and G6PD with Malaria Outcomes in People in Southern Ghana. Genet Res (Camb) 2022; 2022:6686406. [PMID: 35291755 PMCID: PMC8901335 DOI: 10.1155/2022/6686406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/11/2022] [Accepted: 02/10/2022] [Indexed: 11/17/2022] Open
Abstract
Background One major issue that has set back the gains of the numerous malaria control interventions that national malaria control programs have implemented is asymptomatic malaria. Certain host genetic factors are known to influence symptomatic malaria; however, not much is known about how host genetics influences the acquisition of asymptomatic malaria. Methods Genomic DNA was extracted from whole blood collected from 60 symptomatic and 149 nonfebrile (asymptomatic, N = 109, and uninfected, N = 40) volunteers aged between 2 and 69 years from a high (Obom) and a low (Asutsuare) malaria transmission setting in Southern Ghana. Restriction fragment length polymorphism (RFLP) was used to determine polymorphisms at the MBL2 54, TNF-α 308, NOS2 954, and G6PD 202/376 gene loci. Results Polymorphisms at the MBL2 54 and TNF-α 308 loci were significantly different amongst the three categories of volunteers in both Asutsuare (p = 0.006) and Obom (p=0.05). In Asutsuare, a low malaria transmission area, the allele G has significantly higher odds (3.15) of supporting asymptomatic malaria as against symptomatic malaria. There were significantly higher odds of TNF-α genotype GA being associated with symptomatic malaria as against asymptomatic malaria in both sites, Obom (p=0.027) and Asutsuare (p=0.027). The allele B of the G6PD gene was more prevalent in symptomatic rather than asymptomatic parasite-infected individuals in both Obom (p=0.001) and Asutsuare (p=0.003). Conclusion Individuals in Southern Ghana carrying the TNF-α 308 GA genotype are more likely to exhibit symptoms of malaria when infected with the malaria parasite as opposed to harboring an asymptomatic infection. Also, the B allele of the G6PD gene is likely to prevent a P. falciparum-infected person from exhibiting symptoms and thereby promote asymptomatic parasite carriage.
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Affiliation(s)
- Godfred Futagbi
- Department of Animal Biology and Conservation Science, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Paulina S Otu
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Mubarak Abdul-Rahman
- Department of Pathology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Ebenezer K Aidoo
- Department of Medical Laboratory, Accra Technical University, Accra, Ghana
| | - Aminata C Lo
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Ben A Gyan
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, University of Ghana Medical School, University of Ghana, Accra, Ghana
| | - Linda E Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
- West Africa Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
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Asymptomatic Plasmodium vivax malaria in the Brazilian Amazon: Submicroscopic parasitemic blood infects Nyssorhynchus darlingi. PLoS Negl Trop Dis 2021; 15:e0009077. [PMID: 34714821 PMCID: PMC8555776 DOI: 10.1371/journal.pntd.0009077] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 08/30/2021] [Indexed: 11/19/2022] Open
Abstract
Individuals with asymptomatic infection due to Plasmodium vivax are posited to be important reservoirs of malaria transmission in endemic regions. Here we studied a cohort of P. vivax malaria patients in a suburban area in the Brazilian Amazon. Overall 1,120 individuals were screened for P. vivax infection and 108 (9.6%) had parasitemia detected by qPCR but not by microscopy. Asymptomatic individuals had higher levels of antibodies against P. vivax and similar hematological and biochemical parameters compared to uninfected controls. Blood from asymptomatic individuals with very low parasitemia transmitted P. vivax to the main local vector, Nyssorhynchus darlingi. Lower mosquito infectivity rates were observed when blood from asymptomatic individuals was used in the membrane feeding assay. While blood from symptomatic patients infected 43.4% (199/458) of the mosquitoes, blood from asymptomatic infected 2.5% (43/1,719). However, several asymptomatic individuals maintained parasitemia for several weeks indicating their potential role as an infectious reservoir. These results suggest that asymptomatic individuals are an important source of malaria parasites and Science and Technology for Vaccines granted by Conselho Nacional de may contribute to the transmission of P. vivax in low-endemicity areas of malaria.
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Nundu SS, Culleton R, Simpson SV, Arima H, Muyembe JJ, Mita T, Ahuka S, Yamamoto T. Malaria parasite species composition of Plasmodium infections among asymptomatic and symptomatic school-age children in rural and urban areas of Kinshasa, Democratic Republic of Congo. Malar J 2021; 20:389. [PMID: 34600558 PMCID: PMC8487491 DOI: 10.1186/s12936-021-03919-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Malaria remains a major public health concern in the Democratic Republic of Congo (DRC), and school-age children are relatively neglected in malaria prevalence surveys and may constitute a significant reservoir of transmission. This study aimed to understand the burden of malaria infections in school-age children in Kinshasa/DRC. METHODS A total of 634 (427 asymptomatic and 207 symptomatic) blood samples collected from school-age children aged 6 to 14 years were analysed by microscopy, RDT and Nested-PCR. RESULTS The overall prevalence of Plasmodium spp. by microscopy, RDT and PCR was 33%, 42% and 62% among asymptomatic children and 59%, 64% and 95% in symptomatic children, respectively. The prevalence of Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale spp. by PCR was 58%, 20% and 11% among asymptomatic and 93%, 13% and 16% in symptomatic children, respectively. Among P. ovale spp., P. ovale curtisi, P. ovale wallikeri and mixed P. ovale curtisi + P. ovale wallikeri accounted for 75%, 24% and 1% of infections, respectively. All Plasmodium species infections were significantly more prevalent in the rural area compared to the urban area in asymptomatic infections (p < 0.001). Living in a rural as opposed to an urban area was associated with a five-fold greater risk of asymptomatic malaria parasite carriage (p < 0.001). Amongst asymptomatic malaria parasite carriers, 43% and 16% of children harboured mixed Plasmodium with P. falciparum infections in the rural and the urban areas, respectively, whereas in symptomatic malaria infections, it was 22% and 26%, respectively. Few children carried single infections of P. malariae (2.2%) and P. ovale spp. (1.9%). CONCLUSION School-age children are at significant risk from both asymptomatic and symptomatic malaria infections. Continuous systematic screening and treatment of school-age children in high-transmission settings is needed.
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Affiliation(s)
- Sabin S Nundu
- Department of International Health and Medical Anthropology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Nagasaki University, Nagasaki, Japan
- Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of Congo
| | - Richard Culleton
- Division of Molecular Parasitology, Proteo-Science Center, Ehime University, Ehime, Japan.
| | - Shirley V Simpson
- Department of International Health and Medical Anthropology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Nagasaki University, Nagasaki, Japan
| | - Hiroaki Arima
- Department of International Health and Medical Anthropology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Jean-Jacques Muyembe
- Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of Congo
| | - Toshihiro Mita
- Department of Tropical Medicine and Parasitology, Faculty of Medicine, Juntendo University, Tokyo, Japan
| | - Steve Ahuka
- Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of Congo
| | - Taro Yamamoto
- Department of International Health and Medical Anthropology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Nagasaki University, Nagasaki, Japan
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Mensah BA, Myers-Hansen JL, Obeng Amoako E, Opoku M, Abuaku BK, Ghansah A. Prevalence and risk factors associated with asymptomatic malaria among school children: repeated cross-sectional surveys of school children in two ecological zones in Ghana. BMC Public Health 2021; 21:1697. [PMID: 34535112 PMCID: PMC8447720 DOI: 10.1186/s12889-021-11714-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 08/29/2021] [Indexed: 11/27/2022] Open
Abstract
Background Asymptomatic Plasmodium infections significantly drive malaria transmission and impact control and elimination strategies, but are largely uncharacterized. We investigated the prevalence and risk factors of asymptomatic malaria infections to inform malaria control strategies in Ghana. Method Five cross-sectional surveys were conducted at the end of the peak transmission season (August–September) on 4892 school children aged between 6 and 14 years in two distinct ecological settings in Ghana between 2013 and 2017. The study sites were Begoro (forest ecology) and Cape Coast (coastal ecology). The children were screened for malaria parasites by microscopic examination of Giemsa-stained thin and thick blood films. Hemoglobin levels were measured using the Hemocue HB analyzer. In addition, height was measured and the height-for-age z-scores estimated from the reference population defined by WHO to determine children who were stunted. Proportions of categorical and means of continuous variables were compared using Chi-square test and Student’s t-test respectively, and multivariable logistic regression was done to assess risk factors associated with asymptomatic infections. Results The overall prevalence of asymptomatic malaria in the school children was higher in Begoro compared to Cape Coast (27% (95% CI: 17, 24%) vs. 24% (95% CI: 17, 24%), p value = 0.04). The study recorded three species of Plasmodium (Plasmodia falciparum, malariae, and ovale) in both sites. Plasmodium falciparum was the predominant species, accounting for about 85% of infections in both study sites. The asymptomatic school children were more likely to be anaemic (OR = 2.01, p value< 0.001) and stunted in growth (OR = 1.46, p value< 0.001). Males carried more asymptomatic infection than females (OR = 1.18, p value = 0.015). School children aged 12–14 years had more asymptomatic infections than those aged 6–8 years (OR = 1.28, p value = 0.005). Conclusion There is a considerable burden of asymptomatic malaria in the two regions of Ghana, which is associated with males, older children, anaemia, and stunted growth in children, and may have implications for malaria control and elimination strategies in Ghana.
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Affiliation(s)
- B A Mensah
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - J L Myers-Hansen
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.,Department of Parasitology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - E Obeng Amoako
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - M Opoku
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.,Department of Parasitology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - B K Abuaku
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - A Ghansah
- Department of Epidemiology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana. .,Department of Parasitology, College of Health Sciences, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
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Roberds A, Ferraro E, Luckhart S, Stewart VA. HIV-1 Impact on Malaria Transmission: A Complex and Relevant Global Health Concern. Front Cell Infect Microbiol 2021; 11:656938. [PMID: 33912477 PMCID: PMC8071860 DOI: 10.3389/fcimb.2021.656938] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/18/2021] [Indexed: 02/05/2023] Open
Abstract
Malaria/HIV-1 co-infection has become a significant public health problem in the tropics where there is geographical overlap of the two diseases. It is well described that co-infection impacts clinical progression of both diseases; however, less is known about the impact of co-infection on disease transmission. Malaria transmission is dependent upon multiple critical factors, one of which is the presence and viability of the sexual-stage gametocyte. In this review, we summarize evidence surrounding gametocyte production in Plasmodium falciparum and the development factors and the consequential impact that HIV-1 has on malaria parasite transmission. Epidemiological and clinical evidence surrounding anemia, immune dysregulation, and chemotherapy as it pertains to co-infection and gametocyte transmission are reviewed. We discuss significant gaps in understanding that are often due to the biological complexities of both diseases as well as the lack of entomological data necessary to define transmission success. In particular, we highlight special epidemiological populations, such as co-infected asymptomatic gametocyte carriers, and the unique role these populations have in a future focused on malaria elimination and eradication.
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Affiliation(s)
- Ashleigh Roberds
- Department of Preventive Medicine and Biostatistics, Division of Tropical Public Health, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Emily Ferraro
- Department of Preventive Medicine and Biostatistics, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Shirley Luckhart
- Department of Entomology, Plant Pathology and Nematology, Department of Biological Sciences, College of Agricultural and Life Sciences, University of Idaho, Moscow, ID, United States
| | - V Ann Stewart
- Department of Preventive Medicine and Biostatistics, Division of Tropical Public Health, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
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Auburn S, Cheng Q, Marfurt J, Price RN. The changing epidemiology of Plasmodium vivax: Insights from conventional and novel surveillance tools. PLoS Med 2021; 18:e1003560. [PMID: 33891580 PMCID: PMC8064506 DOI: 10.1371/journal.pmed.1003560] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Sarah Auburn and co-authors discuss the unique biology and epidemiology of P. vivax and current evidence on conventional and new approaches to surveillance.
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Affiliation(s)
- Sarah Auburn
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Qin Cheng
- Department of Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
- The Australian Defence Force Malaria and Infectious Disease Institute Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jutta Marfurt
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia
| | - Ric N. Price
- Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
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Genotyping cognate Plasmodium falciparum in humans and mosquitoes to estimate onward transmission of asymptomatic infections. Nat Commun 2021; 12:909. [PMID: 33568678 PMCID: PMC7875998 DOI: 10.1038/s41467-021-21269-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 01/15/2021] [Indexed: 01/30/2023] Open
Abstract
Malaria control may be enhanced by targeting reservoirs of Plasmodium falciparum transmission. One putative reservoir is asymptomatic malaria infections and the scale of their contribution to transmission in natural settings is not known. We assess the contribution of asymptomatic malaria to onward transmission using a 14-month longitudinal cohort of 239 participants in a high transmission site in Western Kenya. We identify P. falciparum in asymptomatically- and symptomatically-infected participants and naturally-fed mosquitoes from their households, genotype all parasites using deep sequencing of the parasite genes pfama1 and pfcsp, and use haplotypes to infer participant-to-mosquito transmission through a probabilistic model. In 1,242 infections (1,039 in people and 203 in mosquitoes), we observe 229 (pfcsp) and 348 (pfama1) unique parasite haplotypes. Using these to link human and mosquito infections, compared with symptomatic infections, asymptomatic infections more than double the odds of transmission to a mosquito among people with both infection types (Odds Ratio: 2.56; 95% Confidence Interval (CI): 1.36-4.81) and among all participants (OR 2.66; 95% CI: 2.05-3.47). Overall, 94.6% (95% CI: 93.1-95.8%) of mosquito infections likely resulted from asymptomatic infections. In high transmission areas, asymptomatic infections are the major contributor to mosquito infections and may be targeted as a component of transmission reduction.
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Frimpong A, Amponsah J, Adjokatseh AS, Agyemang D, Bentum-Ennin L, Ofori EA, Kyei-Baafour E, Akyea-Mensah K, Adu B, Mensah GI, Amoah LE, Kusi KA. Asymptomatic Malaria Infection Is Maintained by a Balanced Pro- and Anti-inflammatory Response. Front Microbiol 2020; 11:559255. [PMID: 33281757 PMCID: PMC7705202 DOI: 10.3389/fmicb.2020.559255] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Accepted: 10/19/2020] [Indexed: 01/12/2023] Open
Abstract
Background Pro- and anti-inflammatory cytokines are important mediators of immunity and are associated with malaria disease outcomes. However, their role in the establishment of asymptomatic infections, which may precede the development of clinical symptoms, is not as well-understood. Methods We determined the association of pro and anti-inflammatory cytokines and other immune effector molecules with the development of asymptomatic malaria. We measured and compared the plasma levels of pro-inflammatory mediators including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin (IL)-6, IL-12p70, IL-17A, and granzyme B, the anti-inflammatory cytokine IL-4 and the regulatory cytokine IL-10 from children with asymptomatic malaria infections (either microscopic or submicroscopic) and uninfected controls using Luminex. Results We show that individuals with microscopic asymptomatic malaria had significantly increased levels of TNF-α and IL-6 compared to uninfected controls. Children with either microscopic or submicroscopic asymptomatic malaria exhibited higher levels of IFN-γ, IL-17A, and IL-4 compared to uninfected controls. The levels of most of the pro and anti-inflammatory cytokines were comparable between children with microscopic and submicroscopic infections. The ratio of IFN-γ/IL-10, TNF-α/IL-10, IL-6/IL-10 as well as IFN-γ/IL-4 and IL-6/IL-4 did not differ significantly between the groups. Additionally, using a principal component analysis, the cytokines measured could not distinguish amongst the three study populations. This may imply that neither microscopic nor submicroscopic asymptomatic infections were polarized toward a pro-inflammatory or anti-inflammatory response. Conclusion The data show that asymptomatic malaria infections result in increased plasma levels of both pro and anti-inflammatory cytokines relative to uninfected persons. The balance between pro- and anti-inflammatory cytokines are, however, largely maintained and this may in part, explain the lack of clinical symptoms. This is consistent with the generally accepted observation that clinical symptoms develop as a result of immunopathology involving dysregulation of inflammatory mediator balance in favor of pro-inflammatory mediators.
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Affiliation(s)
- Augustina Frimpong
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana.,Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana.,African Institute for Mathematical Sciences, Accra, Ghana
| | - Jones Amponsah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Abigail Sena Adjokatseh
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Dorothy Agyemang
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Lutterodt Bentum-Ennin
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Ebenezer Addo Ofori
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana.,Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Eric Kyei-Baafour
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Kwadwo Akyea-Mensah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Bright Adu
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Gloria Ivy Mensah
- Department of Bacteriology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Linda Eva Amoah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana.,Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Kwadwo Asamoah Kusi
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana.,Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana.,Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
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11
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Profiles of Plasmodium falciparum infections detected by microscopy through the first year of life in Kintampo a high transmission area of Ghana. PLoS One 2020; 15:e0240814. [PMID: 33075074 PMCID: PMC7571695 DOI: 10.1371/journal.pone.0240814] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 10/02/2020] [Indexed: 11/24/2022] Open
Abstract
Although malaria mortality among children under five years of age is high, the characteristics of their infection patterns are not well described. The aim of this study was to examine the longitudinal sequence pattern of Plasmodium falciparum infections in the first year of life within a birth cohort in Kintampo, Ghana (N = 1855). Infants were monitored at home with monthly sampling and also at the clinic for any febrile illness between 2008 and 2011. Light microscopy was performed on monthly scheduled visits and febrile ill visits over twelve months of follow-ups (n = 19231). Microscopy-positive visits accompanied with or without symptoms were rare during the first five months of life but were common from six to twelve months of age. Among 1264 infants with microscopy data over a minimum of eight monthly visits and also throughout in sick visits, some were microscopy negative (36%), and others positive: only-symptomatic (35%), alternating (22%) and only-asymptomatic (7%). The median age of microscopic infection was seven months for the alternating group and eight months for both the only-symptomatic and only-asymptomatic groups. The alternating group had the highest cumulative incidence of microscopic infections, the lowest age at first infection and 87 different infection patterns. Parasite densities detected by microscopy were significantly higher for symptomatic versus asymptomatic infection. We conclude that infants in malaria endemic areas experience diverse infection profiles throughout their first year of life. Further investigations should include submicroscopic reservoir and may shed more light on the factors that determine susceptibility to malaria during infancy.
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Large Variations in Malaria Parasite Carriage by Afebrile School Children Living in Nearby Communities in the Central Region of Ghana. J Trop Med 2020; 2020:4125109. [PMID: 33029151 PMCID: PMC7528039 DOI: 10.1155/2020/4125109] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 06/25/2020] [Accepted: 09/03/2020] [Indexed: 02/08/2023] Open
Abstract
Background Indicators of successful malaria control interventions include a reduction in the prevalence and densities of malaria parasites contained in both symptomatic and asymptomatic infections as well as a reduction in malaria transmission. Individuals harboring malaria parasites in asymptomatic infections serve as reservoirs for malaria transmission. This study determined the prevalence of asymptomatic malaria parasite carriage in afebrile children attending six different schools in two districts, the Cape Coast Metropolitan Assembly (CCMA) and the Komenda Edina Eguafo Abirem (KEEA) of the Central Region of Ghana. Methods This cross sectional study recruited afebrile children aged between 3 and 15 years old from six randomly selected schools in the Central Region of Ghana. Finger-pricked blood was collected and used to prepare thick and thin blood smears as well as spot a strip of filter paper (Whatman #3). Nested PCR was used to identify Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale, and Plasmodium vivax in DNA extracted from the filter paper spots. The multiplicity of P. falciparum infection was determined using merozoite surface protein 2 genotyping. Results Out of the 528 children sampled, PCR identified 27.1% to harbor Plasmodium parasites in asymptomatic infections, whilst microscopy identified malaria parasites in 10.6% of the children. The overall PCR estimated prevalence of P. falciparum and P. malariae was 26.6% and 1.3%, respectively, with no P. ovale or P. vivax identified by PCR or microscopy. The RDT positivity rate ranged from 55.8% in Simiw to 4.5% in Kuful. Children from the Simiw Basic School accounted for 87.5% of all the asymptomatic infections. The multiplicity of P. falciparum infection was predominantly monoclonal and biclonal. Conclusions The low prevalence of asymptomatic malaria parasite carriage by the children living in the Cape Coast Metropolis suggests that the malaria control interventions in place in CCMA are highly effective and that additional malaria control interventions are required for the KEEA district to reduce the prevalence of asymptomatic malaria parasite carriers. No molecular evidence of P. ovale and P. vivax was identified in the afebrile children sampled from the selected schools.
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Okyere B, Owusu-Ofori A, Ansong D, Buxton R, Benson S, Osei-Akoto A, Owiredu EW, Adjei C, Xorse Amuzu E, Marfo Boaheng J, Dickerson T. Point prevalence of asymptomatic Plasmodium infection and the comparison of microscopy, rapid diagnostic test and nested PCR for the diagnosis of asymptomatic malaria among children under 5 years in Ghana. PLoS One 2020; 15:e0232874. [PMID: 32716936 PMCID: PMC7384639 DOI: 10.1371/journal.pone.0232874] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 04/23/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Plasmodium infection among children is a serious public health problem. Asymptomatic malaria infection among humans serves as a significant reservoir for transmitting Plasmodium to uninfected Anopheles mosquitoes, fueling malaria endemicity and asymptomatic malaria may progress to clinical malaria. Therefore, prompt and accurate diagnosis of malaria infection is crucial for the management and control of malaria, especially in endemic areas. This study assessed the point prevalence of asymptomatic malaria infection and evaluated the performance of malaria Rapid Diagnostic Tests (RDT), light microscopy and nested PCR (nPCR) for the diagnosis of asymptomatic malaria infection in a paediatric population in the Atwima Nwabiagya North district, Ghana. METHODS This cross-sectional study enrolled 500 asymptomatic children aged ≤ 5 years. After consent was obtained from a parent, blood samples were collected from each participant to assess for Plasmodium infection based on histidine rich protein-2 (pfHRP-2)-based malaria RDT, light microscopy and nPCR. RESULTS The point prevalence of asymptomatic malaria by microscopy, RDT, and nPCR were 116/500 (23.2%), 156/500 (31.2%), and 184/500 (36.8%), respectively. Using nPCR as the reference, RDT presented with a perfect sensitivity (100.0%), specificity (100.0%), accuracy (100.0%), and reliability (100.0%) in detecting asymptomatic P. falciparum infection. Likewise, microscopy presented with an excellent specificity and high accuracy in detecting both P. falciparum (100.0%; 85.6%) and P. malariae (100.0%; 100.0%). However, the sensitivity (56.4%) and reliability (56.4%) of microscopy was low for both P. falciparum. CONCLUSION The findings of this study indicate a high point prevalence of asymptomatic Plasmodium infection among children in Atwima Nwabiagya North district, Ghana. In the absence of the more sensitive PCR, pfHRP-2-based malaria RDT provides substantial diagnostic sensitivity, specificity, accuracy and reliability and is superior to microscopy.
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Affiliation(s)
- Bismark Okyere
- Department of Clinical Microbiology, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Alex Owusu-Ofori
- Department of Clinical Microbiology, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Daniel Ansong
- Department of Child Health, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Rebecca Buxton
- Medical Laboratory Science Division, Department of Pathology, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Scott Benson
- Division of Public Health, Department of Family and Preventive Medicine, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
| | - Alex Osei-Akoto
- Department of Child Health, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Eddie-Williams Owiredu
- Department of Molecular Medicine, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Collins Adjei
- Department of Clinical Microbiology, School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Evans Xorse Amuzu
- Research and Development Unit, Komfo Anokye Teaching Hospital, Kumasi, Ghana
| | | | - Ty Dickerson
- Division of Pediatric Inpatient Medicine, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
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Corder RM, Ferreira MU, Gomes MGM. Modelling the epidemiology of residual Plasmodium vivax malaria in a heterogeneous host population: A case study in the Amazon Basin. PLoS Comput Biol 2020; 16:e1007377. [PMID: 32168349 PMCID: PMC7108741 DOI: 10.1371/journal.pcbi.1007377] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2019] [Revised: 03/31/2020] [Accepted: 01/29/2020] [Indexed: 02/07/2023] Open
Abstract
The overall malaria burden in the Americas has decreased dramatically over the past two decades, but residual transmission pockets persist across the Amazon Basin, where Plasmodium vivax is the predominant infecting species. Current elimination efforts require a better quantitative understanding of malaria transmission dynamics for planning, monitoring, and evaluating interventions at the community level. This can be achieved with mathematical models that properly account for risk heterogeneity in communities approaching elimination, where few individuals disproportionately contribute to overall malaria prevalence, morbidity, and onwards transmission. Here we analyse demographic information combined with routinely collected malaria morbidity data from the town of Mâncio Lima, the main urban transmission hotspot of Brazil. We estimate the proportion of high-risk subjects in the host population by fitting compartmental susceptible-infected-susceptible (SIS) transmission models simultaneously to age-stratified vivax malaria incidence densities and the frequency distribution of P. vivax malaria attacks experienced by each individual over 12 months. Simulations with the best-fitting SIS model indicate that 20% of the hosts contribute 86% of the overall vivax malaria burden. Despite the low overall force of infection typically found in the Amazon, about one order of magnitude lower than that in rural Africa, high-risk individuals gradually develop clinical immunity following repeated infections and eventually constitute a substantial infectious reservoir comprised of asymptomatic parasite carriers that is overlooked by routine surveillance but likely fuels onwards malaria transmission. High-risk individuals therefore represent a priority target for more intensive and effective interventions that may not be readily delivered to the entire community.
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Affiliation(s)
- Rodrigo M. Corder
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
- * E-mail: (RMC); (MGMG)
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - M. Gabriela M. Gomes
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
- CIBIO-InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, and CMUP, Centro de Matemática da Universidade do Porto, Porto, Portugal
- * E-mail: (RMC); (MGMG)
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15
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Ome-Kaius M, Kattenberg JH, Zaloumis S, Siba M, Kiniboro B, Jally S, Razook Z, Mantila D, Sui D, Ginny J, Rosanas-Urgell A, Karl S, Obadia T, Barry A, Rogerson SJ, Laman M, Tisch D, Felger I, Kazura JW, Mueller I, Robinson LJ. Differential impact of malaria control interventions on P. falciparum and P. vivax infections in young Papua New Guinean children. BMC Med 2019; 17:220. [PMID: 31813381 PMCID: PMC6900859 DOI: 10.1186/s12916-019-1456-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION As malaria transmission declines, understanding the differential impact of intensified control on Plasmodium falciparum relative to Plasmodium vivax and identifying key drivers of ongoing transmission is essential to guide future interventions. METHODS Three longitudinal child cohorts were conducted in Papua New Guinea before (2006/2007), during (2008) and after scale-up of control interventions (2013). In each cohort, children aged 1-5 years were actively monitored for infection and illness. Incidence of malaria episodes, molecular force of blood-stage infections (molFOB) and population-averaged prevalence of infections were compared across the cohorts to investigate the impact of intensified control in young children and the key risk factors for malaria infection and illness in 2013. RESULTS Between 2006 and 2008, P. falciparum infection prevalence, molFOB, and clinical malaria episodes reduced by 47%, 59% and 69%, respectively, and a further 49%, 29% and 75% from 2008 to 2013 (prevalence 41.6% to 22.1% to 11.2%; molFOB: 3.4 to 1.4 to 1.0 clones/child/year; clinical episodes incidence rate (IR) 2.6 to 0.8 to IR 0.2 episodes/child/year). P. vivax clinical episodes declined at rates comparable to P. falciparum between 2006, 2008 and 2013 (IR 2.5 to 1.1 to 0.2), while P. vivax molFOB (2006, 9.8; 2008, 12.1) and prevalence (2006, 59.6%; 2008, 65.0%) remained high in 2008. However, in 2013, P. vivax molFOB (1.2) and prevalence (19.7%) had also substantially declined. In 2013, 89% of P. falciparum and 93% of P. vivax infections were asymptomatic, 62% and 47%, respectively, were sub-microscopic. Area of residence was the major determinant of malaria infection and illness. CONCLUSION Intensified vector control and routine case management had a differential impact on rates of P. falciparum and P. vivax infections but not clinical malaria episodes in young children. This suggests comparable reductions in new mosquito-derived infections but a delayed impact on P. vivax relapsing infections due to a previously acquired reservoir of hypnozoites. This demonstrates the need to strengthen implementation of P. vivax radical cure to maximise impact of control in co-endemic areas. The high heterogeneity of malaria in 2013 highlights the importance of surveillance and targeted interventions to accelerate towards elimination.
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Affiliation(s)
- Maria Ome-Kaius
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.,Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Johanna Helena Kattenberg
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.,Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.,Institute of Tropical Medicine, Antwerp, Belgium
| | - Sophie Zaloumis
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Matthew Siba
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Benson Kiniboro
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Shadrach Jally
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Zahra Razook
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Daisy Mantila
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Desmond Sui
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | - Jason Ginny
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | | | - Stephan Karl
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea.,Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | | | - Alyssa Barry
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia
| | - Stephen J Rogerson
- Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Moses Laman
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea
| | | | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | | | - Ivo Mueller
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia.,Institut Pasteur, Paris, France
| | - Leanne J Robinson
- Papua New Guinea Institute of Medical Research, Madang, Papua New Guinea. .,Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia. .,Department of Medical Biology, University of Melbourne, Melbourne, Australia. .,Burnet Institute, Melbourne, Australia.
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16
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Abukari Z, Okonu R, Nyarko SB, Lo AC, Dieng CC, Salifu SP, Gyan BA, Lo E, Amoah LE. The Diversity, Multiplicity of Infection and Population Structure of P. falciparum Parasites Circulating in Asymptomatic Carriers Living in High and Low Malaria Transmission Settings of Ghana. Genes (Basel) 2019; 10:genes10060434. [PMID: 31181699 PMCID: PMC6628376 DOI: 10.3390/genes10060434] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 05/31/2019] [Accepted: 06/03/2019] [Indexed: 11/24/2022] Open
Abstract
Background: Diversity in Plasmodium falciparum poses a major threat to malaria control and elimination interventions. This study utilized 12 polymorphic microsatellite (MS) markers and the Msp2 marker to examine diversity, multiplicity of infection (MOI) as well as the population structure of parasites circulating in two sites separated by about 92 km and with varying malaria transmission intensities within the Greater Accra Region of Ghana. Methods: The diversity and MOI of P. falciparum parasites in 160 non-symptomatic volunteers living in Obom (high malaria transmission intensity) and Asutsuare (low malaria transmission intensity) aged between 8 and 60 years was determined using Msp2 genotyping and microsatellite analysis. Results: The prevalence of asymptomatic P. falciparum carriers as well as the parasite density of infections was significantly higher in Obom than in Asutsuare. Samples from Asutsuare and Obom were 100% and 65% clonal, respectively, by Msp2 genotyping but decreased to 50% and 5%, respectively, when determined by MS analysis. The genetic composition of parasites from Obom and Asutsuare were highly distinct, with parasites from Obom being more diverse than those from Asutsuare. Conclusion: Plasmodium falciparum parasites circulating in Obom are genetically more diverse and distinct from those circulating in Asutsuare. The MOI in samples from both Obom and Asutsuare increased when assessed by MS analysis relative to MSP2 genotyping. The TA40 and TA87 loci are useful markers for estimating MOI in high and low parasite prevalence settings.
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Affiliation(s)
- Zakaria Abukari
- Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - Ruth Okonu
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - Samuel B Nyarko
- School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana.
| | - Aminata C Lo
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
- Department of Parasitology, University Cheikh Anta Diop, Dakar, Senegal.
| | - Cheikh C Dieng
- Department of Biological Sciences, University of North Carolina at Charlotte, NC 28223, USA.
| | - Samson P Salifu
- Department of Biochemistry and Biotechnology, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Ben A Gyan
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - Eugenia Lo
- Department of Biological Sciences, University of North Carolina at Charlotte, NC 28223, USA.
| | - Linda E Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
- West Africa Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana.
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Jiram AI, Ooi CH, Rubio JM, Hisam S, Karnan G, Sukor NM, Artic MM, Ismail NP, Alias NW. Evidence of asymptomatic submicroscopic malaria in low transmission areas in Belaga district, Kapit division, Sarawak, Malaysia. Malar J 2019; 18:156. [PMID: 31046769 PMCID: PMC6498596 DOI: 10.1186/s12936-019-2786-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/22/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Malaysia has declared its aim to eliminate malaria with a goal of achieving zero local transmission by the year 2020. However, targeting the human reservoir of infection, including those with asymptomatic infection is required to achieve malaria elimination. Diagnosing asymptomatic malaria is not as straightforward due to the obvious lack of clinical manifestations and often subpatent level of parasites. Accurate diagnosis of malaria is important for providing realistic estimates of malaria burden and preventing misinformed interventions. Low levels of parasitaemia acts as silent reservoir of transmission thus remains infectious to susceptible mosquito vectors. Hence, the aim of this study is to investigate the prevalence of asymptomatic submicroscopic malaria (SMM) in the District of Belaga, Sarawak. METHODS In 2013, a total of 1744 dried blood spots (DBS) were obtained from residents of 8 longhouses who appeared healthy. Subsequently, 251 venous blood samples were collected from residents of 2 localities in 2014 based on the highest number of submicroscopic cases from prior findings. Thin and thick blood films were prepared from blood obtained from all participants in this study. Microscopic examination were carried out on all samples and a nested and nested multiplex PCR were performed on samples collected in 2013 and 2014 respectively. RESULTS No malaria parasites were detected in all the Giemsa-stained blood films. However, of the 1744 samples, 29 (1.7%) were positive for Plasmodium vivax by PCR. Additionally, of the 251 samples, the most prevalent mono-infection detected by PCR was Plasmodium falciparum 50 (20%), followed by P. vivax 39 (16%), P. knowlesi 9 (4%), and mixed infections 20 (8%). CONCLUSIONS This research findings conclude evidence of Plasmodium by PCR, among samples previously undetectable by routine blood film microscopic examination, in local ethnic minority who are clinically healthy. SMM in Belaga district is attributed not only to P. vivax, but also to P. falciparum and P. knowlesi. In complementing efforts of programme managers, there is a need to increase surveillance for SMM nationwide to estimate the degree of SMM that warrant measures to block new transmission of malaria.
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Affiliation(s)
- Adela Ida Jiram
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia.
| | - Choo Huck Ooi
- Vector Borne Diseases Section, Sarawak Health Department, Ministry of Health Malaysia, Diplomatik Road, Off Bako Road, Petra Jaya, 93050, Kuching, Sarawak, Malaysia
| | - José Miguel Rubio
- Malaria & Emerging Parasitic Diseases Laboratory, Parasitology Department, National Centre of Microbiology, Instituto de Salud Carlos III (ISCIII), Carretera de Majadahonda - Pozuelo, km. 2,200, Majadahonda, 28220, Madrid, Spain
| | - Shamilah Hisam
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Govindarajoo Karnan
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Nurnadiah Mohd Sukor
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Mohd Mafie Artic
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Nor Parina Ismail
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
| | - Nor Wahida Alias
- Parasitology Unit, Infectious Diseases Research Centre, Institute for Medical Research, Ministry of Health Malaysia, Jalan Pahang, 50588, Kuala Lumpur, Malaysia
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18
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Amaral LC, Robortella DR, Guimarães LFF, Limongi JE, Fontes CJF, Pereira DB, de Brito CFA, Kano FS, de Sousa TN, Carvalho LH. Ribosomal and non-ribosomal PCR targets for the detection of low-density and mixed malaria infections. Malar J 2019; 18:154. [PMID: 31039781 PMCID: PMC6492410 DOI: 10.1186/s12936-019-2781-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 04/13/2019] [Indexed: 01/01/2023] Open
Abstract
Background The unexpected high proportion of submicroscopic malaria infections in areas with low transmission intensity challenges the control and elimination of malaria in the Americas. The current PCR-based assays present limitations as most protocols still rely on amplification of few-copies target gene. Here, the hypothesis was that amplification of different plasmodial targets—ribosomal (18S rRNA) and non-ribosomal multi-copy sequences (Pvr47 for Plasmodium vivax and Pfr364 for Plasmodium falciparum)—could increase the chances of detecting submicroscopic malaria infection. Methods A non-ribosomal real-time PCR assay targeting Pvr47/Pfr364 (NR-qPCR) was established and compared with three additional PCR protocols, two of them based on 18S rRNA gene amplification (Nested-PCR and R-qPCR) and one based on Pvr47/Pfr364 targets (NR-cPCR). The limit of detection of each PCR protocol, at single and artificial mixed P. vivax/P. falciparum infections, was determined by end-point titration curves. Field samples from clinical (n = 110) and subclinical (n = 324) malaria infections were used to evaluate the impact of using multiple molecular targets to detect malaria infections. Results The results demonstrated that an association of ribosomal and non-ribosomal targets did not increase sensitivity to detect submicroscopic malaria infections. Despite of that, artificial mixed-malaria infections demonstrated that the NR-qPCR was the most sensitive protocol to detect low-levels of P. vivax/P. falciparum co-infections. Field studies confirmed that submicroscopic malaria represented a large proportion (up to 77%) of infections among asymptomatic Amazonian residents, with a high proportion of infections (~ 20%) identified only by the NR-qPCR. Conclusions This study presents a new species-specific non-ribosomal PCR assay with potential to identify low-density P. vivax and P. falciparum infections. As the majority of subclinical infections was caused by P. vivax, the commonest form of malaria in the Amazon area, future studies should investigate the potential of Pvr47/Pfr364 to detect mixed-malaria infections in the field. Electronic supplementary material The online version of this article (10.1186/s12936-019-2781-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lara Cotta Amaral
- Instituto René Rachou, Fundação Oswaldo Cruz, FIOCRUZ-MINAS, Belo Horizonte, MG, Brazil
| | - Daniela Rocha Robortella
- Instituto René Rachou, Fundação Oswaldo Cruz, FIOCRUZ-MINAS, Belo Horizonte, MG, Brazil.,Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
| | | | | | | | - Dhelio Batista Pereira
- Centro de Pesquisas em Medicina Tropical de Rondônia (CEPEM), Porto Velho, Rondônia, Brazil
| | | | - Flora Satiko Kano
- Instituto René Rachou, Fundação Oswaldo Cruz, FIOCRUZ-MINAS, Belo Horizonte, MG, Brazil
| | - Taís Nóbrega de Sousa
- Instituto René Rachou, Fundação Oswaldo Cruz, FIOCRUZ-MINAS, Belo Horizonte, MG, Brazil.
| | - Luzia Helena Carvalho
- Instituto René Rachou, Fundação Oswaldo Cruz, FIOCRUZ-MINAS, Belo Horizonte, MG, Brazil. .,Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil.
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Chaumeau V, Kajeechiwa L, Fustec B, Landier J, Naw Nyo S, Nay Hsel S, Phatharakokordbun P, Kittiphanakun P, Nosten S, Thwin MM, Win Tun S, Wiladphaingern J, Cottrell G, Parker DM, Minh MC, Kwansomboon N, Metaane S, Montazeau C, Kunjanwong K, Sawasdichai S, Andolina C, Ling C, Haohankhunnatham W, Christiensen P, Wanyatip S, Konghahong K, Cerqueira D, Imwong M, Dondorp AM, Chareonviriyaphap T, White NJ, Nosten FH, Corbel V. Contribution of Asymptomatic Plasmodium Infections to the Transmission of Malaria in Kayin State, Myanmar. J Infect Dis 2019; 219:1499-1509. [PMID: 30500927 PMCID: PMC6467188 DOI: 10.1093/infdis/jiy686] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/27/2018] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The objective of mass antimalarial drug administration (MDA) is to eliminate malaria rapidly by eliminating the asymptomatic malaria parasite reservoirs and interrupting transmission. In the Greater Mekong Subregion, where artemisinin-resistant Plasmodium falciparum is now widespread, MDA has been proposed as an elimination accelerator, but the contribution of asymptomatic infections to malaria transmission has been questioned. The impact of MDA on entomological indices has not been characterized previously. METHODS MDA was conducted in 4 villages in Kayin State (Myanmar). Malaria mosquito vectors were captured 3 months before, during, and 3 months after MDA, and their Plasmodium infections were detected by polymerase chain reaction (PCR) analysis. The relationship between the entomological inoculation rate, the malaria prevalence in humans determined by ultrasensitive PCR, and MDA was characterized by generalized estimating equation regression. RESULTS Asymptomatic P. falciparum and Plasmodium vivax infections were cleared by MDA. The P. vivax entomological inoculation rate was reduced by 12.5-fold (95% confidence interval [CI], 1.6-100-fold), but the reservoir of asymptomatic P. vivax infections was reconstituted within 3 months, presumably because of relapses. This was coincident with a 5.3-fold (95% CI, 4.8-6.0-fold) increase in the vector infection rate. CONCLUSION Asymptomatic infections are a major source of malaria transmission in Southeast Asia.
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Affiliation(s)
- Victor Chaumeau
- Centre hospitalier universitaire de Montpellier, Montpellier
- UMR 224 “Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle,” Institut de Recherche pour le Développement, Montpellier
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Ladda Kajeechiwa
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Bénédicte Fustec
- UMR 224 “Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle,” Institut de Recherche pour le Développement, Montpellier
| | - Jordi Landier
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
- Institut de Recherches pour le Développement, Aix Marseille Univ, INSERM, SESSTIM, Marseille
| | - Saw Naw Nyo
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Saw Nay Hsel
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Phabele Phatharakokordbun
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Prapan Kittiphanakun
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Suphak Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - May Myo Thwin
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Saw Win Tun
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Jacher Wiladphaingern
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Gilles Cottrell
- UMR 216 “Mère et enfant face aux infections tropicales,” Institut de Recherche pour le Développement, Université Paris Descartes, Paris, France
| | - Daniel M Parker
- Department of Population Health and Disease Prevention, University of California, Irvine
| | - Myo Chit Minh
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Nittpha Kwansomboon
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Selma Metaane
- UMR 224 “Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle,” Institut de Recherche pour le Développement, Montpellier
| | - Céline Montazeau
- UMR 224 “Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle,” Institut de Recherche pour le Développement, Montpellier
| | - Kitti Kunjanwong
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Sunisa Sawasdichai
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Chiara Andolina
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Clare Ling
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Warat Haohankhunnatham
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Peter Christiensen
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Sunaree Wanyatip
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Kamonchanok Konghahong
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
| | - Dominique Cerqueira
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University
| | - Arjen M Dondorp
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University
| | | | - Nicholas J White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, United Kingdom
| | - Vincent Corbel
- UMR 224 “Maladies Infectieuses et Vecteurs, Ecologie, Génétique, Evolution et Contrôle,” Institut de Recherche pour le Développement, Montpellier
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20
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Feged-Rivadeneira A, Ángel A, González-Casabianca F, Rivera C. Malaria intensity in Colombia by regions and populations. PLoS One 2018; 13:e0203673. [PMID: 30208075 PMCID: PMC6135511 DOI: 10.1371/journal.pone.0203673] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 08/26/2018] [Indexed: 12/15/2022] Open
Abstract
Determining the distribution of disease prevalence among heterogeneous populations at the national scale is fundamental for epidemiology and public health. Here, we use a combination of methods (spatial scan statistic, topological data analysis and epidemic profile) to study measurable differences in malaria intensity by regions and populations of Colombia. This study explores three main questions: What are the regions of Colombia where malaria is epidemic? What are the regions and populations in Colombia where malaria is endemic? What associations exist between epidemic outbreaks between regions in Colombia? Plasmodium falciparum is most prevalent in the Pacific Coast, some regions of the Amazon Basin, and some regions of the Magdalena Basin. Plasmodium vivax is the most prevalent parasite in Colombia, particularly in the Northern Amazon Basin, the Caribbean, and municipalities of Sucre, Antioquia and Cordoba. We find an acute peak of malarial infection at 25 years of age. Indigenous and Afrocolombian populations experience endemic malaria (with household transmission). We find that Plasmodium vivax decreased in the most important hotspots, often with moderate urbanization rate, and was re-introduced to locations with moderate but sustained deforestation. Infection by Plasmodium falciparum, on the other hand, steadily increased in incidence in locations where it was introduced in the 2009-2010 generalized epidemic. Our findings suggest that Colombia is entering an unstable transmission state, where rapid decreases in one location of the country are interconnected with rapid increases in other parts of the country.
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Affiliation(s)
- Alejandro Feged-Rivadeneira
- Department of Anthropology, Stanford University, Stanford, CA, United States of America
- Department of Urban Management and Design, Universidad del Rosario, Bogotá, Colombia
- * E-mail:
| | - Andrés Ángel
- Department of Mathematics, Universidad de los Andes, Bogotá, Colombia
- Department of Mathematics and Statistics, Universidad del Norte, Barranquilla, Colombia
| | | | - Camilo Rivera
- Walmartlabs, Sunnyvale, CA, United States of America
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21
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Mooney JP, Barry A, Gonçalves BP, Tiono AB, Awandu SS, Grignard L, Drakeley CJ, Bottomley C, Bousema T, Riley EM. Haemolysis and haem oxygenase-1 induction during persistent "asymptomatic" malaria infection in Burkinabé children. Malar J 2018; 17:253. [PMID: 29980206 PMCID: PMC6035425 DOI: 10.1186/s12936-018-2402-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/03/2018] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The haemolysis associated with clinical episodes of malaria results in the liberation of haem, which activates the enzyme haem oxygenase-1 (HO-1). HO-1 has been shown to reduce neutrophil function and increase susceptibility to invasive bacterial disease. However, the majority of community-associated malaria infections are subclinical, often termed "asymptomatic" and the consequences of low-grade haemolysis during subclinical malaria infection are unknown. STUDY DESIGN AND RESULTS As part of an ongoing study of subclinical malaria in Burkina Faso, 23 children with subclinical Plasmodium falciparum infections (determined by qPCR) were compared with 21 village-matched uninfected control children. Infected children showed evidence of persistent haemolysis over 35 days, with raised plasma haem and HO-1 concentrations. Concentrations of IL-10, which can also directly activate HO-1, were also higher in infected children compared to uninfected children. Regression analysis revealed that HO-1 was associated with haemolysis, but not with parasite density, anaemia or IL-10 concentration. CONCLUSIONS This study reveals that subclinical P. falciparum malaria infection is associated with sustained haemolysis and the induction of HO-1. Given the association between HO-1, neutrophil dysfunction and increased risk of Salmonella bacteraemia, prolonged HO-1 induction may explain epidemiological associations and geographic overlap between malaria and invasive bacterial disease. Further studies are needed to understand the consequences of persistent subclinical malaria infection, low-grade haemolysis and raised HO-1 on immune cell function and risk of comorbidities.
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Affiliation(s)
- Jason P Mooney
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK. .,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK.
| | - Aissata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Université de Ouagadougou, Ouagadougou, Burkina Faso
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Université de Ouagadougou, Ouagadougou, Burkina Faso
| | - Shehu S Awandu
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris J Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Christian Bottomley
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Eleanor M Riley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.,The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
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22
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Zhao Y, Zeng J, Zhao Y, Liu Q, He Y, Zhang J, Yang Z, Fan Q, Wang Q, Cui L, Cao Y. Risk factors for asymptomatic malaria infections from seasonal cross-sectional surveys along the China-Myanmar border. Malar J 2018; 17:247. [PMID: 29973194 PMCID: PMC6032786 DOI: 10.1186/s12936-018-2398-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 06/22/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Border malaria, a shared phenomenon in the Greater Mekong Sub-region of Southeast Asia, is a major obstacle for regional malaria elimination. Along the China-Myanmar border, an additional problem arose as a result of the settlement of internally displaced people (IDP) in the border region. Since asymptomatic malaria significantly impacts transmission dynamics, assessment of the prevalence, dynamics and risk factors of asymptomatic malaria infections is necessary. METHODS Cross-sectional surveys were carried out in 3 seasons (March and April, July and November) and 2 sites (villages and IDP camps) in 2015. A total of 1680 finger-prick blood samples were collected and used for parasite detection by microscopy and nested RT-PCR (nRT-PCR). Logistic regression models were used to explore the risk factors associated with asymptomatic malaria at individual and household levels. RESULTS The prevalence of asymptomatic Plasmodium infections was 23.3% by nRT-PCR, significantly higher than that detected by microscopy (1.5%). The proportions of Plasmodium vivax, Plasmodium falciparum and mixed-species infections were 89.6, 8.1 and 2.3%, respectively. Asymptomatic infections showed obvious seasonality with higher prevalence in the rainy season. Logistic regression analysis identified males and school children (≤ 15 years) as the high-risk populations. Vector-based interventions, including bed net and indoor residual spray, were found to have significant impacts on asymptomatic Plasmodium infections, with non-users of these measures carrying much higher risks of infection. In addition, individuals living in poorly constructed households or farther away from clinics were more prone to asymptomatic infections. CONCLUSIONS Sub-microscopic Plasmodium infections were highly prevalent in the border human populations from IDP camps and surrounding villages. Both individual- and household-level risk factors were identified, which provides useful information for identifying the high-priority populations to implement targeted malaria control.
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Affiliation(s)
- Yan Zhao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Jie Zeng
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Yonghong Zhao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Qingyang Liu
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Yang He
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China
| | - Jiaqi Zhang
- Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Zhaoqing Yang
- Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Qinghui Wang
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China.
| | - Liwang Cui
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China. .,Department of Entomology, Pennsylvania State University, University Park, State College, PA, 16802, USA.
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, 110122, Liaoning, China.
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23
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Froeschl G, Saathoff E, Kroidl I, Berens-Riha N, Clowes P, Maboko L, Assisya W, Mwalongo W, Gerhardt M, Ntinginya EN, Hoelscher M. Reduction of malaria prevalence after introduction of artemisinin-combination-therapy in Mbeya Region, Tanzania: results from a cohort study with 6773 participants. Malar J 2018; 17:245. [PMID: 29940968 PMCID: PMC6019526 DOI: 10.1186/s12936-018-2389-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 06/13/2018] [Indexed: 11/10/2022] Open
Abstract
Background A marked decline in malaria morbidity and mortality has been reported after the introduction of artemisinin-based combination therapy (ACT) in high malaria prevalence countries in Africa. Data on the impact of ACT and on the prevalence of malaria has so far been scarce for Southwest Tanzania. Methods Between 2005 and 2011, a large general population cohort in the Mbeya Region in the south-west of Tanzania has been surveyed within the EMINI-study (Evaluation and Monitoring of the Impact of New Interventions). Participants were examined once per year, including rapid diagnostic testing for malaria. ACT was introduced in the region according to national guidelines in the time period 2006/2007, replacing sulfadoxine/pyrimethamine as first-line therapy. In four study sites, 6773 individuals who participated in the first two of three consecutive survey visits in the period from 2006 to 2009 were included in this analysis. The prevalence of Plasmodium infection prior to and after the introduction of ACT was compared by logistic regression, with consideration of climatic variability, age, sex, socio-economic status and bed net use as potential confounders. Results A significant reduction over time in the prevalence of Plasmodium falciparum infection from 2.5 to 0.3% was shown across the four study sites. The decline was not explained by other factors included in the analysis, therefore, the decline over time most likely reflects the impact of introduction of ACT in the study area. Conclusions The longitudinal study showed a significant and relevant decline in the prevalence of P. falciparum infection after introduction of ACT, which could not be explained by potential confounders. The data suggests that artemisinin-based combinations are not only an effective instrument for reduction of immediate morbidity and mortality, but also for reduction of transmission rates.
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Affiliation(s)
- Guenter Froeschl
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany. .,German Center for Infection Research (DZIF), Partner Site Munich, Leopoldstr. 5, 80802, Munich, Germany.
| | - Elmar Saathoff
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, Leopoldstr. 5, 80802, Munich, Germany
| | - Inge Kroidl
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, Leopoldstr. 5, 80802, Munich, Germany
| | - Nicole Berens-Riha
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, Leopoldstr. 5, 80802, Munich, Germany
| | - Petra Clowes
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany.,National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Leonard Maboko
- National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Weston Assisya
- National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Wolfram Mwalongo
- National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Martina Gerhardt
- National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Elias Nyanda Ntinginya
- National Institute of Medical Research-Mbeya Medical Research Centre, P.O. Box 2410, Hospital Hill Road, Mbeya, Tanzania
| | - Michael Hoelscher
- Division of Infectious Diseases and Tropical Medicine, University Hospital, LMU Munich, Leopoldstr. 5, 80802, Munich, Germany.,German Center for Infection Research (DZIF), Partner Site Munich, Leopoldstr. 5, 80802, Munich, Germany
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24
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Martins-Campos KM, Kuehn A, Almeida A, Duarte APM, Sampaio VS, Rodriguez ÍC, da Silva SGM, Ríos-Velásquez CM, Lima JBP, Pimenta PFP, Bassat Q, Müller I, Lacerda M, Monteiro WM, Barbosa Guerra MDGV. Infection of Anopheles aquasalis from symptomatic and asymptomatic Plasmodium vivax infections in Manaus, western Brazilian Amazon. Parasit Vectors 2018; 11:288. [PMID: 29728152 PMCID: PMC5935932 DOI: 10.1186/s13071-018-2749-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 02/26/2018] [Indexed: 12/22/2022] Open
Abstract
Background Asymptomatic individuals are one of the major challenges for malaria elimination programs in endemic areas. In the absence of clinical symptoms and with a lower parasite density they constitute silent reservoirs considered important for maintaining transmission of human malaria. Studies from Brazil have shown that infected individuals may carry these parasites for long periods. Results Patients were selected from three periurban endemic areas of the city of Manaus, in the western Brazilian Amazon. Symptomatic and asymptomatic patients with positive thick blood smear and quantitative real-time PCR (qPCR) positive for Plasmodium vivax were invited to participate in the study. A standardised pvs25 gene amplification by qPCR was used for P. vivax gametocytes detection. Anopheles aquasalis were fed using membrane feeding assays (MFA) containing blood from malaria patients. Parasitemia of 42 symptomatic and 25 asymptomatic individuals was determined by microscopic examination of blood smears and qPCR. Parasitemia density and gametocyte density were assessed as determinants of infection rates and oocysts densities. A strong correlation between gametocyte densities (microscopy and molecular techniques) and mosquito infectivity (P < 0.001) and oocysts median numbers (P < 0.05) was found in both groups. The ability to infect mosquitoes was higher in the symptomatic group (41%), but infectivity in the asymptomatic group was also seen (1.42%). Conclusions Although their infectivity to mosquitoes is relatively low, given the high prevalence of P. vivax asymptomatic carriers they are likely to play and important role in malaria transmission in the city of Manaus. The role of asymptomatic infections therefore needs to be considered in future malaria elimination programs in Brazil. Electronic supplementary material The online version of this article (10.1186/s13071-018-2749-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Keillen M Martins-Campos
- Programa de Pós Graduação em Medicina Tropical, Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Brazil.,Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Andrea Kuehn
- Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.,ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Anne Almeida
- Programa de Pós Graduação em Medicina Tropical, Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Brazil.,Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Ana Paula M Duarte
- Programa de Pós Graduação em Medicina Tropical, Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Brazil.,Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | | | - Íria C Rodriguez
- Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Sara G M da Silva
- Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | | | | | - Paulo Filemon Paolucci Pimenta
- Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.,Centro de Pesquisas René Rachou, Fiocruz, Belo Horizonte, Brazil
| | - Quique Bassat
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Ivo Müller
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.,Walter and Eliza Hall Institute, Parkville, Australia
| | - Marcus Lacerda
- Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.,Instituto de Pesquisas Leônidas & Maria Deane, Fiocruz, Manaus, Brazil
| | - Wuelton M Monteiro
- Programa de Pós Graduação em Medicina Tropical, Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Brazil.,Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil
| | - Maria das Graças V Barbosa Guerra
- Programa de Pós Graduação em Medicina Tropical, Escola Superior de Ciências da Saúde, Universidade do Estado do Amazonas, Manaus, Brazil. .,Departamento de Ensino e Pesquisa, Fundação de Medicina Tropical Dr. Heitor Vieira Dourado, Manaus, Brazil.
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25
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Gbalégba CGN, Ba H, Silué KD, Ba O, Tia E, Chouaibou M, Tian-Bi NTY, Yapi GY, Koné B, Utzinger J, Koudou BG. Distribution of Plasmodium spp. infection in asymptomatic carriers in perennial and low seasonal malaria transmission settings in West Africa. Infect Dis Poverty 2018; 7:39. [PMID: 29690913 PMCID: PMC5926534 DOI: 10.1186/s40249-018-0412-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2017] [Accepted: 03/24/2018] [Indexed: 11/24/2022] Open
Abstract
Background Since 2000, substantial progress has been made in reducing malaria worldwide. However, some countries in West Africa remain a hotspot for malaria with all age groups at risk. Asymptomatic carriers of Plasmodium spp. are important sources of infections for malaria vectors and thus contribute to the anchoring of the disease in favourable eco-epidemiological settings. The objective of this study was to assess the asymptomatic malaria case rates in Korhogo and Kaedi, two urban areas in northern Côte d’Ivoire and southern Mauritania, respectively. Methods Cross-sectional surveys were carried out during the rainy season in 2014 and the dry season in 2015 in both settings. During each season, 728 households were randomly selected and a household-based questionnaire was implemented to collect demographic and epidemiological data, including of malaria preventive methods used in communities. Finger-prick blood samples were obtained for biological examination using microscopy and rapid diagnostic tests (RDTs). Results Overall, 2672 households and 15 858 consenting participants were surveyed. Plasmodium spp. infection was confirmed in 12.4% (n = 832) and 0.3% (n = 22) of the assessed individuals in Korhogo and Kaedi, respectively. In Korhogo, the prevalence of asymptomatic malaria was 10.5% (95% CI: 9.7–11.2) as determined by microscopy and 9.3% (95% CI: 8.6–10.0%) when assessed by RDT. In Kaedi, asymptomatic malaria prevalence was 0.2% (95% CI: 0.1–0.4%) according to microscopy, while all RDTs performed were negative (n = 8372). In Korhogo, asymptomatic malaria infection was significantly associated with age and season, with higher risk within the 5–14 years-old, and during the rainy season. In Kaedi, the risk of asymptomatic malaria infection was associated with season only (higher during the dry season; crude OR (cOR): 6.37, 95% CI: 1.87–21.63). P. falciparum was the predominant species identified in both study sites representing 99.2% (n = 825) in Korhogo and 59.1% (n = 13) in Kaedi. Gametocytes were observed only in Korhogo and only during the rainy season at 1.3% (95% CI: 0.7–2.4%). Conclusions Our findings show a low prevalence of clinical malaria episodes with a significant proportion of asymptomatic carriers in both urban areas. National policies for malaria infections are focused on treatment of symptomatic cases. Malaria control strategies should be designed for monitoring and managing malaria infections in asymptomatic carriers. Additional measures, including indoor residual spraying, effective use of long-lasting insecticidal nets is strongly needed to reduce the number of Plasmodium spp. infections in Korhogo and Kaedi. Electronic supplementary material The online version of this article (10.1186/s40249-018-0412-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Constant G N Gbalégba
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 B.P. 801, Abidjan, 02, Côte d'Ivoire. .,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire.
| | - Hampâté Ba
- Laboratoire de Parasitologie - Mycologie, Institut National de Recherches en Santé Publique , B.P. 695, Nouakchott, Mauritania
| | - Kigbafori D Silué
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire.,Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 B.P. 582, Abidjan, 22, Côte d'Ivoire
| | - Ousmane Ba
- Laboratoire de Parasitologie - Mycologie, Institut National de Recherches en Santé Publique , B.P. 695, Nouakchott, Mauritania
| | - Emmanuel Tia
- Centre d'Entomologie Médicale et Vétérinaire, Université Alassane Ouattara, 27 B.P. 529, Abidjan, 27, Côte d'Ivoire
| | - Mouhamadou Chouaibou
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire
| | - Nathan T Y Tian-Bi
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire.,Unité de Formation et de Recherche Biosciences, Université Félix Houphouët-Boigny, 22 B.P. 582, Abidjan, 22, Côte d'Ivoire
| | - Grégoire Y Yapi
- Centre d'Entomologie Médicale et Vétérinaire, Université Alassane Ouattara, 27 B.P. 529, Abidjan, 27, Côte d'Ivoire
| | - Brama Koné
- Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire.,Université Péléforo Gon Coulibaly, B.P. 1328, Korhogo, Côte d'Ivoire
| | - Jürg Utzinger
- Swiss Tropical and Public Health Institute , P.O. Box, CH- 4002, Basel, Switzerland.,University of Basel, P.O. Box, CH-4003, Basel, Switzerland
| | - Benjamin G Koudou
- Unité de Formation et de Recherche Sciences de la Nature, Université Nangui Abrogoua, 02 B.P. 801, Abidjan, 02, Côte d'Ivoire.,Centre Suisse de Recherches Scientifiques en Côte d'Ivoire , 01 B.P. 1303, Abidjan, 01, Côte d'Ivoire.,Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine , Pembroke Place, Liverpool, L3 5QA, UK
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Almeida ACG, Kuehn A, Castro AJM, Vitor-Silva S, Figueiredo EFG, Brasil LW, Brito MAM, Sampaio VS, Bassat Q, Felger I, Tadei WP, Monteiro WM, Mueller I, Lacerda MVG. High proportions of asymptomatic and submicroscopic Plasmodium vivax infections in a peri-urban area of low transmission in the Brazilian Amazon. Parasit Vectors 2018; 11:194. [PMID: 29558985 PMCID: PMC5859403 DOI: 10.1186/s13071-018-2787-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 03/07/2018] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Population-based studies conducted in Latin America have shown a high proportion of asymptomatic and submicroscopic malarial infections. Considering efforts aiming at regional elimination, it is important to investigate the role of this asymptomatic reservoir in malaria transmission in peri-urban areas. This study aimed to estimate the prevalence of Plasmodium spp. and gametocyte burden on symptomatic and asymptomatic infections in the Brazilian Amazon. RESULTS Two cross-sectional household surveys (CS) were conducted including all inhabitants in a peri-urban area of Manaus, western Amazonas State, Brazil. Malaria parasites were detected by light microscopy (LM) and qPCR. Sexual stages of Plasmodium spp. were detected by LM and RT-qPCR. A total of 4083 participants were enrolled during the two surveys. In CS1, the prevalence of Plasmodium vivax infections was 4.3% (86/2010) by qPCR and 1.6% (32/2010) by LM. Fifty percent (43/86) of P. vivax infected individuals (qPCR) carried P. vivax gametocytes. In CS2, 3.4% (70/2073) of participants had qPCR-detectable P. vivax infections, of which 42.9% (30/70) of infections were gametocyte positive. The P. vivax parasite density was associated with gametocyte carriage (P < 0.001). Sixty-seven percent of P. vivax infected individuals and 53.4% of P. vivax gametocyte carriers were asymptomatic. CONCLUSIONS This study confirms a substantial proportion of asymptomatic and submicroscopic P. vivax infections in the study area. Most asymptomatic individuals carried gametocytes and presented low asexual parasitemia. This reservoir actively contributes to malaria transmission in the Brazilian Amazon, underscoring a need to implement more efficient control and elimination strategies.
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Affiliation(s)
- Anne C G Almeida
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil. .,Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil.
| | - Andrea Kuehn
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Carrer del Rosselló, 132, 08036, Barcelona, Spain
| | - Arthur J M Castro
- Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil.,Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, N. 2.936, Petrópolis, Manaus, CEP: 69067-375, Brazil
| | - Sheila Vitor-Silva
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil
| | - Erick F G Figueiredo
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil
| | - Larissa W Brasil
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil
| | - Marcelo A M Brito
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil.,Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil
| | - Vanderson S Sampaio
- Fundação de Vigilância em Saúde do Amazonas, Sala de Análise de Situação em Saúde, Av. Torquato Tapajós, N. 6132, Colônia Santo Antonio, Manaus, CEP:69093-018, Brazil
| | - Quique Bassat
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Carrer del Rosselló, 132, 08036, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça (CISM), Rua 12, Cambeve, Vila de Manhiça, CP 1929, Maputo, Mozambique.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys, 23 08010, Barcelona, Spain
| | - Ingrid Felger
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4051, Basel, Switzerland.,University of Basel, Petersplatz 1, 4001, Basel, Switzerland
| | - Wanderli P Tadei
- Instituto Nacional de Pesquisas da Amazônia (INPA), Av. André Araújo, N. 2.936, Petrópolis, Manaus, CEP: 69067-375, Brazil
| | - Wuelton M Monteiro
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil. .,Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil.
| | - Ivo Mueller
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Carrer del Rosselló, 132, 08036, Barcelona, Spain.,Walter and Eliza Hall Institute, Parkville, Australia
| | - Marcus V G Lacerda
- Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD), Av. Pedro Teixeira, N.25, Dom Pedro, Manaus, Amazonas, CEP: 69040-000, Brazil.,Universidade do Estado do Amazonas (UEA), Av. Djalma Batista, N. 3578, Flores, Manaus, Amazonas, CEP: 69005-010, Brazil.,Instituto de Pesquisas Leônidas e Maria Deane (ILMD), Manaus, Brazil
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de Alencar FEC, Malafronte RDS, Cerutti Junior C, Natal Fernandes L, Buery JC, Fux B, Rezende HR, Duarte AMRDC, Medeiros-Sousa AR, Miranda AE. Assessment of asymptomatic Plasmodium spp. infection by detection of parasite DNA in residents of an extra-Amazonian region of Brazil. Malar J 2018. [PMID: 29540186 PMCID: PMC5853114 DOI: 10.1186/s12936-018-2263-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Background The hypotheses put forward to explain the malaria transmission cycle in extra-Amazonian Brazil, an area of very low malaria incidence, are based on either a zoonotic scenario involving simian malaria, or a scenario in which asymptomatic carriers play an important role. Objectives To determine the incidence of asymptomatic infection by detecting Plasmodium spp. DNA and its role in residual malaria transmission in a non-Amazonian region of Brazil. Methods Upon the report of the first malaria case in 2010 in the Atlantic Forest region of the state of Espírito Santo, inhabitants within a 2 km radius were invited to participate in a follow-up study. After providing signed informed consent forms, inhabitants filled out a questionnaire and gave blood samples for PCR, and thick and thin smears. Follow-up visits were performed every 3 months over a 21 month period, when new samples were collected and information was updated. Results Ninety-two individuals were initially included for follow-up. At the first collection, all of them were clearly asymptomatic. One individual was positive for Plasmodium vivax, one for Plasmodium malariae and one for both P. vivax and P. malariae, corresponding to a prevalence of 3.4% (2.3% for each species). During follow-up, four new PCR-positive cases (two for each species) were recorded, corresponding to an incidence of 2.5 infections per 100 person-years or 1.25 infections per 100 person-years for each species. A mathematical transmission model was applied, using a low frequency of human carriers and the vector density in the region, and calculated based on previous studies in the same locality whose results were subjected to a linear regression. This analysis suggests that the transmission chain is unlikely to be based solely on human carriers, regardless of whether they are symptomatic or not. Conclusion The low incidence of cases and the low frequency of asymptomatic malaria carriers investigated make it unlikely that the transmission chain in the region is based solely on human hosts, as cases are isolated one from another by hundreds of kilometers and frequently by long periods of time, reinforcing instead the hypothesis of zoonotic transmission. Electronic supplementary material The online version of this article (10.1186/s12936-018-2263-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Filomena E C de Alencar
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
| | | | - Crispim Cerutti Junior
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Lícia Natal Fernandes
- Protozoology Laboratory, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Julyana Cerqueira Buery
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Blima Fux
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Helder Ricas Rezende
- Entomology and Malacology Unit, Espírito Santo State Department of Health (SESA), Vitória, Brazil
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Pizzitutti F, Pan W, Feingold B, Zaitchik B, Álvarez CA, Mena CF. Out of the net: An agent-based model to study human movements influence on local-scale malaria transmission. PLoS One 2018; 13:e0193493. [PMID: 29509795 PMCID: PMC5839546 DOI: 10.1371/journal.pone.0193493] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 02/12/2018] [Indexed: 01/08/2023] Open
Abstract
Though malaria control initiatives have markedly reduced malaria prevalence in recent decades, global eradication is far from actuality. Recent studies show that environmental and social heterogeneities in low-transmission settings have an increased weight in shaping malaria micro-epidemiology. New integrated and more localized control strategies should be developed and tested. Here we present a set of agent-based models designed to study the influence of local scale human movements on local scale malaria transmission in a typical Amazon environment, where malaria is transmission is low and strongly connected with seasonal riverine flooding. The agent-based simulations show that the overall malaria incidence is essentially not influenced by local scale human movements. In contrast, the locations of malaria high risk spatial hotspots heavily depend on human movements because simulated malaria hotspots are mainly centered on farms, were laborers work during the day. The agent-based models are then used to test the effectiveness of two different malaria control strategies both designed to reduce local scale malaria incidence by targeting hotspots. The first control scenario consists in treat against mosquito bites people that, during the simulation, enter at least once inside hotspots revealed considering the actual sites where human individuals were infected. The second scenario involves the treatment of people entering in hotspots calculated assuming that the infection sites of every infected individual is located in the household where the individual lives. Simulations show that both considered scenarios perform better in controlling malaria than a randomized treatment, although targeting household hotspots shows slightly better performance.
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Affiliation(s)
- Francesco Pizzitutti
- Universidad San Francisco de Quito, Instituto de Geografía, Quito, Ecuador
- Duke University, Duke global Health Institute, Durham, NC, United States of America
| | - William Pan
- Duke University, Duke global Health Institute, Durham, NC, United States of America
| | - Beth Feingold
- SUNY-Albany, School of Public Health, Rensselaer, Albany, NY, United States of America
| | - Ben Zaitchik
- Johns Hopkins University, Morton K. Blaustein Department of Earth & Planetary Sciences, Baltimore, MD, United States of America
| | | | - Carlos F. Mena
- Universidad San Francisco de Quito, Instituto de Geografía, Quito, Ecuador
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Martin TCS, Vinetz JM. Asymptomatic Plasmodium vivax parasitaemia in the low-transmission setting: the role for a population-based transmission-blocking vaccine for malaria elimination. Malar J 2018; 17:89. [PMID: 29466991 PMCID: PMC5822557 DOI: 10.1186/s12936-018-2243-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 02/17/2018] [Indexed: 12/21/2022] Open
Abstract
Plasmodium vivax remains an important cause of morbidity and mortality across the Americas, Horn of Africa, East and South East Asia. Control of transmission has been hampered by emergence of chloroquine resistance and several intrinsic characteristics of infection including asymptomatic carriage, challenges with diagnosis, difficulty eradicating the carrier state and early gametocyte appearance. Complex human-parasite-vector immunological interactions may facilitate onward infection of mosquitoes. Given these challenges, new therapies are being explored including the development of transmission to mosquito blocking vaccines. Herein, the case supporting the need for transmission-blocking vaccines to augment control of P. vivax parasite transmission and explore factors that are limiting eradication efforts is discussed.
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Affiliation(s)
- Thomas C S Martin
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Joseph M Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, USA.
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Arwati H, Yotopranoto S, Rohmah EA, Syafruddin D. Submicroscopic malaria cases play role in local transmission in Trenggalek district, East Java Province, Indonesia. Malar J 2018; 17:2. [PMID: 29301534 PMCID: PMC5755365 DOI: 10.1186/s12936-017-2147-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 12/19/2017] [Indexed: 12/24/2022] Open
Abstract
Background Trenggalek district is a hypoendemic malaria area with mainly imported cases brought by migrant workers from islands outside Java. During malaria surveillance in 2015, no malaria cases were found microscopically, but some cases were positive by PCR. Therefore, a study was conducted to prove that local malaria transmission still occur. Methods The adult villagers were invited to the house of the head of this village to be screened for malaria using aseptic venipuncture of 1 mL blood upon informed consent. Thin and thick blood films as well as blood spots on filter paper were made for each subject. The blood films were stained with Giemsa and the blood spots were used to extract DNA for polymerase chain reaction (PCR) amplification to determine the malaria infection. In addition, the history of malaria infection and travel to malaria endemic areas were recorded. Entomologic survey to detect the existence of anopheline vector was also conducted. Results Of the total 64 subjects that participated in the survey, no malaria parasites were found through microscopic examination of the blood films. The PCR analysis found six positive cases (two Plasmodium falciparum, one Plasmodium vivax and two mixed infection of both species), and two of them had no history of malaria and have never travelled to malaria endemic area. Entomologic survey using human bait trap detected the existence of Anopheles indefinitus that was found to be positive for P. vivax by PCR. Conclusions The results indicated that although we did not find any microscopically slide positive cases, six PCR positive subjects were found. The fact that 2 of the 6 malaria positive subjects have never travelled to malaria endemic area together with the existence of the vector confirm the occurence of local transmission of malaria in the area.
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Affiliation(s)
- Heny Arwati
- Department of Parasitology, Faculty of Medicine, Universitas Airlangga, Campus A, Jalan Prof. Moestopo No. 47, Surabaya, 60131, Indonesia.
| | - Subagyo Yotopranoto
- Department of Parasitology, Faculty of Medicine, Universitas Airlangga, Campus A, Jalan Prof. Moestopo No. 47, Surabaya, 60131, Indonesia
| | - Etik Ainun Rohmah
- Entomology Study Group, Institute of Tropical Diseases, Universitas Airlangga, Campus C, Jalan Ir. Soekarno, Surabaya, 60115, Indonesia
| | - Din Syafruddin
- Eijkman Institute for Molecular Biology, JalanDiponegoro 69, Jakarta, 10430, Indonesia.,Department of Parasitology, Faculty of Medicine, Hasanuddin University, Makassar, JalanPerintisKemerdekaan Km 10, Makassar, 90245, Indonesia
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Cabral FJ, Vianna LG, Medeiros MM, Carlos BC, Martha RD, Silva NM, Silva LHPD, Stabeli RG, Wunderlich G. Immunoproteomics of Plasmodium falciparum-infected red blood cell membrane fractions. Mem Inst Oswaldo Cruz 2017; 112:850-856. [PMID: 29211247 PMCID: PMC5719555 DOI: 10.1590/0074-02760170041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Accepted: 06/30/2017] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND The surface of infected red blood cells (iRBCs) has been widely investigated
because of the molecular complexity and pathogenesis mechanisms involved.
Asymptomatic individuals are important in the field because they can
perpetuate transmission as natural reservoirs and present a challenge for
diagnosing malaria because of their low levels of circulating parasites.
Recent studies of iRBC antibody recognition have shown that responses are
quantitatively similar in symptomatic and asymptomatic infections, but no
studies have characterised the plasmodial proteins targeted by this
response. OBJECTIVES Our main objective was to identify Plasmodium falciparum
proteins associated with iRBC ghosts recognised by antibodies in the sera of
symptomatic and asymptomatic individuals in the Brazilian Amazon. METHODS We collected symptomatic and asymptomatic sera from patients residing in the
Brazilian Amazon and P. falciparum iRBC ghosts to identify
the proteins involved in natural antibody recognition by 2D-electrophoresis,
western blotting, and high- resolution mass spectrometry. FINDINGS 2D gel-based immunoproteome analysis using symptomatic and asymptomatic sera
identified 11 proteins with at least one unique peptide, such as chaperones
HSP70-1 and HSP70-x, which likely are components of the secretion
machinery/PTEX translocon. PfEMP1 is involved in antigenic variation in
symptomatic infections and we found putative membrane proteins whose
functions are unknown. MAIN FINDINGS Our results suggest a potential role of old and new proteins, such as
antigenic variation proteins, iRBC remodelling, and membrane proteins, with
no assigned functions related to the immune response against P.
falciparum, providing insights into the pathogenesis,
erythrocyte remodelling, and secretion machinery important for alternative
diagnosis and/or malaria therapy.
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Affiliation(s)
- Fernanda J Cabral
- Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Biologia Animal, Campinas, SP, Brasil.,Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | | | - Marcia M Medeiros
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil.,Universidade Nova de Lisboa, Instituto de Higiene e Medicina Tropical, Lisboa, Portugal
| | - Bianca Cechetto Carlos
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
| | | | - Nadia Maria Silva
- Universidade Estadual de Campinas, Instituto de Biologia, Departamento de Biologia Animal, Campinas, SP, Brasil
| | | | | | - Gerhard Wunderlich
- Universidade de São Paulo, Instituto de Ciências Biomédicas, Departamento de Parasitologia, São Paulo, SP, Brasil
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Miller RH, Hathaway NJ, Kharabora O, Mwandagalirwa K, Tshefu A, Meshnick SR, Taylor SM, Juliano JJ, Stewart VA, Bailey JA. A deep sequencing approach to estimate Plasmodium falciparum complexity of infection (COI) and explore apical membrane antigen 1 diversity. Malar J 2017; 16:490. [PMID: 29246158 PMCID: PMC5732508 DOI: 10.1186/s12936-017-2137-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 12/06/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Humans living in regions with high falciparum malaria transmission intensity harbour multi-strain infections comprised of several genetically distinct malaria haplotypes. The number of distinct malaria parasite haplotypes identified from an infected human host at a given time is referred to as the complexity of infection (COI). In this study, an amplicon-based deep sequencing method targeting the Plasmodium falciparum apical membrane antigen 1 (pfama1) was utilized to (1) investigate the relationship between P. falciparum prevalence and COI, (2) to explore the population genetic structure of P. falciparum parasites from malaria asymptomatic individuals participating in the 2007 Demographic and Health Survey (DHS) in the Democratic Republic of Congo (DRC), and (3) to explore selection pressures on geospatially divergent parasite populations by comparing AMA1 amino acid frequencies in the DRC and Mali. RESULTS A total of 900 P. falciparum infections across 11 DRC provinces were examined. Deep sequencing of both individuals, for COI analysis, and pools of individuals, to examine population structure, identified 77 unique pfama1 haplotypes. The majority of individual infections (64.5%) contained polyclonal (COI > 1) malaria infections based on the presence of genetically distinct pfama1 haplotypes. A minimal correlation between COI and malaria prevalence as determined by sensitive real-time PCR was identified. Population genetic analyses revealed extensive haplotype diversity, the vast majority of which was shared across the sites. AMA1 amino acid frequencies were similar between parasite populations in the DRC and Mali. CONCLUSIONS Amplicon-based deep sequencing is a useful tool for the detection of multi-strain infections that can aid in the understanding of antigen heterogeneity of potential malaria vaccine candidates, population genetics of malaria parasites, and factors that influence complex, polyclonal malaria infections. While AMA1 and other diverse markers under balancing selection may perform well for understanding COI, they may offer little geographic or temporal discrimination between parasite populations.
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Affiliation(s)
- Robin H Miller
- Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD, USA
| | - Nicholas J Hathaway
- Program in Bioinformatics and Integrative Biology, University of Massachusetts School of Medicine, 55 Lake Avenue North, Worcester, MA, USA
| | - Oksana Kharabora
- University of North Carolina School of Medicine, 101 Manning Drive, Chapel Hill, NC, USA
| | - Kashamuka Mwandagalirwa
- Ecole de Santé Publique, Université de Kinshasa, Commune de Lemba, P.O Box 11850, Kinshasa, Democratic Republic of Congo
| | - Antoinette Tshefu
- Ecole de Santé Publique, Université de Kinshasa, Commune de Lemba, P.O Box 11850, Kinshasa, Democratic Republic of Congo
| | - Steven R Meshnick
- University of North Carolina School of Medicine, 101 Manning Drive, Chapel Hill, NC, USA
| | - Steve M Taylor
- Division of Infectious Diseases and Duke Global Health Institute, Duke University Medical Center, 303 Research Drive, Durham, NC, USA
| | - Jonathan J Juliano
- University of North Carolina School of Medicine, 101 Manning Drive, Chapel Hill, NC, USA
| | - V Ann Stewart
- Uniformed Services University, 4301 Jones Bridge Road, Bethesda, MD, USA
| | - Jeffrey A Bailey
- Program in Bioinformatics and Integrative Biology, University of Massachusetts School of Medicine, 55 Lake Avenue North, Worcester, MA, USA.
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de Alencar FEC, Malafronte RDS, Cerutti C, Natal Fernandes L, Buery JC, Fux B, Rezende HR, Miranda AE. Reassessment of asymptomatic carriers of Plasmodium spp. in an endemic area with a very low incidence of malaria in extra-Amazonian Brazil. Malar J 2017; 16:452. [PMID: 29121963 PMCID: PMC5679383 DOI: 10.1186/s12936-017-2103-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 11/02/2017] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Regions with residual transmission are potential obstacles to the elimination of malaria. It is, therefore, essential to understand the factors associated with the maintenance of endemic malaria in these areas. The objective was to investigate whether the status of asymptomatic carriers of Plasmodium spp. DNA is maintained in the long term in an extra-Amazonian region of Brazil with low incidence, residual malaria transmission. METHODS Asymptomatic carriers of Plasmodium DNA detected in a survey carried out between 2001 and 2004 were reassessed between 2010 and 2011 using questionnaires, PCR and thick and thin blood smear tests three times at 3-month intervals. RESULTS Of the 48 carriers detected between 2001 and 2004, 37 were located. Of these, only two had positive PCR results and, as in the first survey, Plasmodium malariae DNA was detected. CONCLUSION The findings suggest that untreated dwellers from this extra-Amazonian region, who initially harbour malaria parasites, may become negative without ever developing apparent symptoms of the disease. Although the possibility of re-infection cannot be ruled out, the finding of two individuals harbouring P. malariae, both in the first and in the second survey, may be compatible with a long-term carrier state for this parasite. Since most clinical cases of malaria in the region are a consequence of infection by Plasmodium vivax, the epidemiological impact of such long-term carriage would be limited.
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Affiliation(s)
- Filomena E C de Alencar
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil.
| | | | - Crispim Cerutti
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Lícia Natal Fernandes
- Protozoology Laboratory, Institute of Tropical Medicine, University of São Paulo, São Paulo, Brazil
| | - Julyana Cerqueira Buery
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Blima Fux
- Graduate Programme in Infectious Diseases, Federal University of Espírito Santo, Vitória, Brazil
| | - Helder Ricas Rezende
- Entomology and Malacology Unit, Espírito Santo State Department of Health (SESA), Vitória, Brazil
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Zainabadi K, Adams M, Han ZY, Lwin HW, Han KT, Ouattara A, Thura S, Plowe CV, Nyunt MM. A novel method for extracting nucleic acids from dried blood spots for ultrasensitive detection of low-density Plasmodium falciparum and Plasmodium vivax infections. Malar J 2017; 16:377. [PMID: 28923054 PMCID: PMC5604154 DOI: 10.1186/s12936-017-2025-3] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 09/07/2017] [Indexed: 11/10/2022] Open
Abstract
Background Greater Mekong Subregion countries are committed to eliminating Plasmodium falciparum malaria by 2025. Current elimination interventions target infections at parasite densities that can be detected by standard microscopy or rapid diagnostic tests (RDTs). More sensitive detection methods have been developed to detect lower density “asymptomatic” infections that may represent an important transmission reservoir. These ultrasensitive polymerase chain reaction (usPCR) tests have been used to identify target populations for mass drug administration (MDA). To date, malaria usPCR tests have used either venous or capillary blood sampling, which entails complex sample collection, processing and shipping requirements. An ultrasensitive method performed on standard dried blood spots (DBS) would greatly facilitate the molecular surveillance studies needed for targeting elimination interventions. Methods A highly sensitive method for detecting Plasmodium falciparum and P. vivax 18S ribosomal RNA from DBS was developed by empirically optimizing nucleic acid extraction conditions. The limit of detection (LoD) was determined using spiked DBS samples that were dried and stored under simulated field conditions. Further, to assess its utility for routine molecular surveillance, two cross-sectional surveys were performed in Myanmar during the wet and dry seasons. Results The lower LoD of the DBS-based ultrasensitive assay was 20 parasites/mL for DBS collected on Whatman 3MM filter paper and 23 parasites/mL for Whatman 903 Protein Saver cards—equivalent to 1 parasite per 50 µL DBS. This is about 5000-fold more sensitive than standard RDTs and similar to the LoD of ≤16–22 parasites/mL reported for other ultrasensitive methods based on whole blood. In two cross-sectional surveys in Myanmar, nearly identical prevalence estimates were obtained from contemporaneous DBS samples and capillary blood samples collected during the wet and dry season. Conclusions The DBS-based ultrasensitive method described in this study shows equal sensitivity as previously described methods based on whole blood, both in its limit of detection and prevalence estimates in two field surveys. The reduced cost and complexity of this method will allow for the scale-up of surveillance studies to target MDA and other malaria elimination interventions, and help lead to a better understanding of the epidemiology of low-density malaria infections. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-2025-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kayvan Zainabadi
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Matthew Adams
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Zay Yar Han
- Department of Medical Research, Ministry of Health and Sports, Yangon, Myanmar
| | - Hnin Wai Lwin
- Department of Medical Research, Ministry of Health and Sports, Yangon, Myanmar
| | - Kay Thwe Han
- Department of Medical Research, Ministry of Health and Sports, Yangon, Myanmar
| | - Amed Ouattara
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Si Thura
- Community Partners International, Yangon, Myanmar
| | - Christopher V Plowe
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, USA
| | - Myaing M Nyunt
- Division of Malaria Research, Institute for Global Health, University of Maryland School of Medicine, Baltimore, USA.
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Abstract
Plasmodium vivax is the second most prevalent cause of malaria worldwide and the leading cause of malaria outside of Africa. Although infections are seldom fatal clinical disease can be debilitating and imposes significant health and economic impacts on affected populations. Estimates of transmission and prevalence intensity can be problematic because many episodes of vivax originate from hypnozoite stages in the liver that have remained dormant from previous infections by an unknown mechanism. Lack of treatment options to clear hypnozoites and the ability to infect mosquitoes before disease symptoms present represent major challenges for control and eradication of vivax malaria. Compounding these challenges is the unique biology of P. vivax and limited progress in development of experimental research tools, thereby hindering development of new drugs and vaccines. Renewed emphasis on vivax malaria research is beginning to make progress in overcoming some of these challenges.
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Affiliation(s)
- John H Adams
- Center for Global Health and Infectious Diseases, Department of Global Health, University of South Florida, Tampa, Florida 33612
| | - Ivo Mueller
- Population Health & Immunity Division, Walter & Eliza Hall Institute, Parkville, Victoria 3052, Australia
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Das S, Jang IK, Barney B, Peck R, Rek JC, Arinaitwe E, Adrama H, Murphy M, Imwong M, Ling CL, Proux S, Haohankhunnatham W, Rist M, Seilie AM, Hanron A, Daza G, Chang M, Nakamura T, Kalnoky M, Labarre P, Murphy SC, McCarthy JS, Nosten F, Greenhouse B, Allauzen S, Domingo GJ. Performance of a High-Sensitivity Rapid Diagnostic Test for Plasmodium falciparum Malaria in Asymptomatic Individuals from Uganda and Myanmar and Naive Human Challenge Infections. Am J Trop Med Hyg 2017; 97:1540-1550. [PMID: 28820709 PMCID: PMC5817764 DOI: 10.4269/ajtmh.17-0245] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sensitive field-deployable diagnostic tests can assist malaria programs in achieving elimination. The performance of a new Alere™ Malaria Ag P.f Ultra Sensitive rapid diagnostic test (uRDT) was compared with the currently available SD Bioline Malaria Ag P.f RDT in blood specimens from asymptomatic individuals in Nagongera, Uganda, and in a Karen Village, Myanmar, representative of high- and low-transmission areas, respectively, as well as in pretreatment specimens from study participants from four Plasmodium falciparum-induced blood-stage malaria (IBSM) studies. A quantitative reverse transcription PCR (qRT-PCR) and a highly sensitive enzyme-linked immunosorbent assay (ELISA) test for histidine-rich protein II (HRP2) were used as reference assays. The uRDT showed a greater than 10-fold lower limit of detection for HRP2 compared with the RDT. The sensitivity of the uRDT was 84% and 44% against qRT-PCR in Uganda and Myanmar, respectively, and that of the RDT was 62% and 0% for the same two sites. The specificities of the uRDT were 92% and 99.8% against qRT-PCR for Uganda and Myanmar, respectively, and 99% and 99.8% against the HRP2 reference ELISA. The RDT had specificities of 95% and 100% against qRT-PCR for Uganda and Myanmar, respectively, and 96% and 100% against the HRP2 reference ELISA. The uRDT detected new infections in IBSM study participants 1.5 days sooner than the RDT. The uRDT has the same workflow as currently available RDTs, but improved performance characteristics to identify asymptomatic malaria infections. The uRDT may be a useful tool for malaria elimination strategies.
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Affiliation(s)
- Smita Das
- Diagnostics Program, PATH, Seattle, Washington
| | | | | | - Roger Peck
- Diagnostics Program, PATH, Seattle, Washington
| | - John C Rek
- Infectious Disease Research Collaboration, Kampala, Uganda
| | | | - Harriet Adrama
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Maxwell Murphy
- University of California San Francisco, San Francisco, California
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Clare L Ling
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Stephane Proux
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Warat Haohankhunnatham
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Melissa Rist
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Annette M Seilie
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Amelia Hanron
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Glenda Daza
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | - Ming Chang
- Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | | | | | | | - Sean C Murphy
- Center for Emerging and Re-emerging Infectious Diseases, University of Washington, Seattle, Washington.,Department of Microbiology, University of Washington, Seattle, Washington.,Department of Laboratory Medicine, University of Washington, Seattle, Washington
| | | | - Francois Nosten
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.,Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Bryan Greenhouse
- University of California San Francisco, San Francisco, California
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Effects of liver-stage clearance by Primaquine on gametocyte carriage of Plasmodium vivax and P. falciparum. PLoS Negl Trop Dis 2017; 11:e0005753. [PMID: 28732068 PMCID: PMC5540608 DOI: 10.1371/journal.pntd.0005753] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 08/02/2017] [Accepted: 06/27/2017] [Indexed: 01/08/2023] Open
Abstract
Background Primaquine (PQ) is the only currently licensed antimalarial that prevents Plasmodium vivax (Pv) relapses. It also clears mature P. falciparum (Pf) gametocytes, thereby reducing post-treatment transmission. Randomized PQ treatment in a treatment-to-reinfection cohort in Papua New Guinean children permitted the study of Pv and Pf gametocyte carriage after radical cure and to investigate the contribution of Pv relapses. Methods Children received radical cure with Chloroquine, Artemether-Lumefantrine plus either PQ or placebo. Blood samples were subsequently collected in 2-to 4-weekly intervals over 8 months. Gametocytes were detected by quantitative reverse transcription-PCR targeting pvs25 and pfs25. Results PQ treatment reduced the incidence of Pv gametocytes by 73%, which was comparable to the effect of PQ on incidence of blood-stage infections. 92% of Pv and 79% of Pf gametocyte-positive infections were asymptomatic. Pv and to a lesser extent Pf gametocyte positivity and density were associated with high blood-stage parasite densities. Multivariate analysis revealed that the odds of gametocytes were significantly reduced in mixed-species infections compared to single-species infections for both species (ORPv = 0.39 [95% CI 0.25–0.62], ORPf = 0.33 [95% CI 0.18–0.60], p<0.001). No difference between the PQ and placebo treatment arms was observed in density of Pv gametocytes or in the proportion of Pv infections that carried gametocytes. First infections after blood-stage and placebo treatment, likely caused by a relapsing hypnozoite, were equally likely to carry gametocytes than first infections after PQ treatment, likely caused by an infective mosquito bite. Conclusion Pv relapses and new infections are associated with similar levels of gametocytaemia. Relapses thus contribute considerably to the Pv reservoir highlighting the importance of effective anti-hypnozoite treatment for efficient control of Pv. Trial registration ClinicalTrials.gov NCT02143934 Plasmodium vivax (Pv) mainly affects Asia, Central and South America as well as Ethiopia. In Papua New Guinea (PNG) Pv prevalence is among the highest worldwide. The biggest challenge for the control of Pv infections is the formation of dormant liver stages, which have the ability to relapse and cause disease even after successful clearance of asexual stages in the blood circulation. Primaquine is the only licensed drug that is able to prevent Pv relapses. A randomized treatment-to-reinfection cohort in Papua New Guinean children permitted permitted the study of Pv and P. falciparum gametocyte carriage after radical cure with Primaquine and to investigate the contribution of Pv relapses to transmission. We found that most gametocyte carriers in this study were detected in asymptomatic infections and that relapses and new infections are associated with similar Pv gametocyte production. These are strong arguments emphasizing the importance of sensitive detection and early treatment of asymptomatic and submicroscopic Plasmodium spp. infections and of anti-hypnozoite treatment for an effective control of Pv.
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Rovira-Vallbona E, Contreras-Mancilla JJ, Ramirez R, Guzmán-Guzmán M, Carrasco-Escobar G, Llanos-Cuentas A, Vinetz JM, Gamboa D, Rosanas-Urgell A. Predominance of asymptomatic and sub-microscopic infections characterizes the Plasmodium gametocyte reservoir in the Peruvian Amazon. PLoS Negl Trop Dis 2017; 11:e0005674. [PMID: 28671944 PMCID: PMC5510906 DOI: 10.1371/journal.pntd.0005674] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 07/14/2017] [Accepted: 05/31/2017] [Indexed: 11/18/2022] Open
Abstract
Malaria transmission requires that Anopheles mosquitoes ingest Plasmodium gametocyte stages circulating in the human bloodstream. In the context of malaria elimination, understanding the epidemiology of gametocytes relative to all Plasmodium infections and the contribution of asymptomatic and sub-microscopic parasite carriers to the gametocyte reservoir is necessary, especially in low endemic settings with predominance of P.vivax. A 13-month longitudinal study was conducted in two communities (n = 1935 individuals) of Loreto Department, Peru, with five active screenings for Plasmodium infections and gametocyte stages by quantitative real-time PCR (qPCR) and reverse transcription (RT)-qPCR, respectively. Parasite prevalence by qPCR was 7.2% for P.vivax (n = 520/7235; range by survey 6.0%-8.1%) and 3.2% for P.falciparum (n = 235/7235; range by survey 0.4%-7.7%). Sub-microscopic infections accounted for 73.5% of P.vivax (range by survey 60%-89%) and almost the totality of P.falciparum cases. Gametocytes were found in 28.4% P.vivax infections (range by survey 18.7%-34.1%), with a peak of 61.5% in one community at the start of the transmission season. About 59.8% of all P.vivax gametocyte carriers were asymptomatic and 31.9% were sub-microscopic. Age patterns for gametocyte prevalence paralleled asexual stage infections and peaked among >15–25 year old individuals. Asexual parasite density was found to be the strongest predictor for P.vivax gametocyte presence in longitudinal multivariate analysis (odds ratio 2.33 [95% confidence interval 1.96, 2.78]; P<0.001). Despite significant differences in seasonality patterns and P.vivax prevalence found at the local scale, sub-microscopic and asymptomatic infections predominate and contribute significantly to the gametocyte reservoir in different communities of the Peruvian Amazon. Control and elimination campaigns need sensitive tools to detect all infections that escape routine malaria surveillance, which may contribute to maintain transmission in the region. Malaria elimination, i.e. the complete interruption of parasite transmission in a region, is in the agenda of health authorities in countries that achieved substantial reduction of the disease burden in the past decade. However, our understanding of transmission epidemiology for low transmission areas where Plasmodium vivax is endemic, like the Amazon basin, is still limited. In this study, we describe the prevalence and risk factors for carrying the parasite stages that are transmitted to the mosquito vectors, named gametocytes, in 1935 individuals from two communities of the Peruvian Amazon that were regularly screened during 1 year. We report that malaria infections with no clinical symptoms and those with parasite levels below microscopy detection threshold, account for two thirds of all P.vivax infections with gametocytes, and that the highest infection rate is found among young adults. In addition, almost the totality of P.falciparum infections detected was sub-microscopic. Because all these infections escape current malaria surveillance systems -based on passive case detection and/or microscopy diagnosis-, new approaches are necessary to target all infections in order to eliminate the malaria transmission reservoir in Peru.
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Affiliation(s)
- Eduard Rovira-Vallbona
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- * E-mail:
| | | | - Roberson Ramirez
- Laboratorio Satelite Iquitos UPCH-UCSD, Universidad Peruana Cayetano Heredia, Loreto, Peru
| | - Mitchel Guzmán-Guzmán
- Laboratorio Satelite Iquitos UPCH-UCSD, Universidad Peruana Cayetano Heredia, Loreto, Peru
| | - Gabriel Carrasco-Escobar
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Alejandro Llanos-Cuentas
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Joseph M. Vinetz
- Department of Medicine, University of California San Diego, San Diego, California, United States of America
| | - Dionicia Gamboa
- Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru
- Departamento de Ciencias Celulares y Moleculares, Facultad de Ciencias y Filosofia, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Anna Rosanas-Urgell
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
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Samuels AM, Awino N, Odongo W, Abong'o B, Gimnig J, Otieno K, Shi YP, Were V, Allen DR, Were F, Sang T, Obor D, Williamson J, Hamel MJ, Patrick Kachur S, Slutsker L, Lindblade KA, Kariuki S, Desai M. Community-based intermittent mass testing and treatment for malaria in an area of high transmission intensity, western Kenya: study design and methodology for a cluster randomized controlled trial. Malar J 2017; 16:240. [PMID: 28592250 PMCID: PMC5463392 DOI: 10.1186/s12936-017-1883-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 05/29/2017] [Indexed: 01/13/2023] Open
Abstract
Most human Plasmodium infections in western Kenya are asymptomatic and are believed to contribute importantly to malaria transmission. Elimination of asymptomatic infections requires active treatment approaches, such as mass testing and treatment (MTaT) or mass drug administration (MDA), as infected persons do not seek care for their infection. Evaluations of community-based approaches that are designed to reduce malaria transmission require careful attention to study design to ensure that important effects can be measured accurately. This manuscript describes the study design and methodology of a cluster-randomized controlled trial to evaluate a MTaT approach for malaria transmission reduction in an area of high malaria transmission. Ten health facilities in western Kenya were purposively selected for inclusion. The communities within 3 km of each health facility were divided into three clusters of approximately equal population size. Two clusters around each health facility were randomly assigned to the control arm, and one to the intervention arm. Three times per year for 2 years, after the long and short rains, and again before the long rains, teams of community health volunteers visited every household within the intervention arm, tested all consenting individuals with malaria rapid diagnostic tests, and treated all positive individuals with an effective anti-malarial. The effect of mass testing and treatment on malaria transmission was measured through population-based longitudinal cohorts, outpatient visits for clinical malaria, periodic population-based cross-sectional surveys, and entomological indices.
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Affiliation(s)
- Aaron M Samuels
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA. .,Centers for Disease Control and Prevention, Kisian Campus, Off Busia Road, P O Box 1578, Kisumu, 40100, Kenya.
| | - Nobert Awino
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Wycliffe Odongo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Benard Abong'o
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Gimnig
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Kephas Otieno
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Ya Ping Shi
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Vincent Were
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Denise Roth Allen
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Florence Were
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Tony Sang
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - David Obor
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Williamson
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Mary J Hamel
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - S Patrick Kachur
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Laurence Slutsker
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Kim A Lindblade
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
| | - Simon Kariuki
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Meghna Desai
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA
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Zaw MT, Thant M, Hlaing TM, Aung NZ, Thu M, Phumchuea K, Phusri K, Saeseu T, Yorsaeng R, Nguitragool W, Felger I, Kaewkungwal J, Cui L, Sattabongkot J. Asymptomatic and sub-microscopic malaria infection in Kayah State, eastern Myanmar. Malar J 2017; 16:138. [PMID: 28376883 PMCID: PMC5381021 DOI: 10.1186/s12936-017-1789-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 03/22/2017] [Indexed: 11/10/2022] Open
Abstract
Background Myanmar has the heaviest burden of
malaria in the Greater Mekong Sub-region. Asymptomatic Plasmodium spp. infections are common in this region and may represent an important reservoir of transmission that must be targeted for malaria elimination. Methods A mass blood survey was conducted among 485 individuals from six villages in Kayah State, an area of endemic but low transmission malaria in eastern Myanmar. Malaria infection was screened by rapid diagnostic test (RDT), light microscopy and real-time polymerase chain reaction (PCR), and its association with demographic factors was explored. Results The prevalence of asymptomatic Plasmodium spp. infection was 2.3% (11/485) by real-time PCR. Plasmodium vivax accounted for 72.7% (8/11) and Plasmodium falciparum for 27.3% (3/11) of infections. Men were at greater risk of infection by Plasmodium spp. than women. Individuals who worked as farmers or wood and bamboo cutters had an increased risk of infection. Conclusion A combination of RDT, light microscopy and PCR diagnostics were used to identify asymptomatic malaria infection, providing additional information on asymptomatic cases in addition to the routine statistics on symptomatic cases, so as to determine the true burden of disease in the area. Such information and risk factors can improve malaria risk stratification and guide decision-makers towards better design and delivery of targeted interventions in small villages, representative of Kayah State.
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Affiliation(s)
- Myo Thiha Zaw
- Defence Services Medical Research Centre (DSMRC), Nay Pyi Taw, Myanmar.,Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Myo Thant
- Defence Services Medical Research Centre (DSMRC), Nay Pyi Taw, Myanmar
| | - Tin Maung Hlaing
- Defence Services Medical Research Centre (DSMRC), Nay Pyi Taw, Myanmar
| | - Naing Zin Aung
- Defence Services Medical Research Centre (DSMRC), Nay Pyi Taw, Myanmar.,Loikaw Military Hospital, Loikaw, Kayah, Myanmar
| | - Min Thu
- Loikaw Military Hospital, Loikaw, Kayah, Myanmar
| | - Kanit Phumchuea
- Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kanokwan Phusri
- Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Teerawat Saeseu
- Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ritthideach Yorsaeng
- Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Ingrid Felger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical & Public Health Institute, Basel, Switzerland
| | - Jaranit Kaewkungwal
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Liwang Cui
- Department of Entomology, The Pennsylvania State University, 501 ASI Building, University Park, PA, 16801, USA.
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit (MVRU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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Pacheco MA, González R, Brochero HL. [Anopheles darlingi (Diptera: Culicidae) Rood 1926: Morphometric variations in wings and legs of populations from Colombia]. BIOMEDICA : REVISTA DEL INSTITUTO NACIONAL DE SALUD 2017; 37:124-134. [PMID: 29161484 DOI: 10.7705/biomedica.v37i0.3492] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 07/27/2017] [Accepted: 05/19/2017] [Indexed: 06/07/2023]
Abstract
INTRODUCTION Natural populations of Anopheles darlingi, the main malaria vector in Colombia, have shown phenotypic variations in some of their diagnostic characters. OBJECTIVE To characterize morphometric variations in wing spot patterns and diagnostic characters of the hind leg of adult females of An. darlingi collected in areas where malaria is endemic. MATERIALS AND METHODS Patterns of the costal vein spots of wild females of An. darling populations collected in the departments of Chocó, Guaviare, Meta and Vichada were analyzed using linear and morphometric approaches. The second tarsomere of the hind leg of females was characterized by linear morphometric analysis. RESULTS We found 19 patterns of spots in the costal vein; patterns I (n=118/240, 49%) and VI (n=66, 28%) were the most frequent. The proportion of the basal dark area of hind tarsomere II and the length of hind tarsomere II (DSIII2/Ta-III2) constituted a robust diagnostic character as it represented 89% (n=213/240) of the total specimens studied. Significant differences were found in the wing shape (F=1.65, df =50, p<0.001) and the wing size (F=3.37, df=5, p=0.005) among populations from different locations. The smallest centroid size (2.64 mm) was found in populations from Chocó. CONCLUSIONS We registered 11 new wing spot patterns in the costal vein and the dominance of the patterns I and VI for populations of An. darlingi from Colombia. We confirmed DSIII2/TaIII2 ratio as a robust diagnostic character for the taxonomy of this species. We found differences between the size and shape of the wings of An. darlingi populations in accordance to their geographical distribution, which constitute important bionomic aspects for this malaria vector.
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Affiliation(s)
- Miguel Alfonso Pacheco
- Facultad de Ciencias Agrarias, Universidad Nacional de Colombia, Bogotá, D.C., Colombia.
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43
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Sumbele IUN, Nkemnji GB, Kimbi HK. Soil-transmitted helminths and plasmodium falciparum malaria among individuals living in different agroecosystems in two rural communities in the mount Cameroon area: a cross-sectional study. Infect Dis Poverty 2017; 6:67. [PMID: 28302147 PMCID: PMC5353792 DOI: 10.1186/s40249-017-0266-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 02/17/2017] [Indexed: 11/30/2022] Open
Abstract
Background Soil-transmitted helminths (STHs) and Plasmodium falciparum infections remain public health problems in Cameroon. A cross-sectional study was carried out in the Mount Cameroon area to determine the prevalence and intensity of STHs and P. falciparum infections in individuals living in different agroecosystems; to assess the influence of these infections on haematological parameters; and to identify the risk factors associated with STH infections. Methods STH and malaria parasites were detected using the Kato-Katz method and Giemsa staining of blood films, respectively. Complete blood count values were obtained using an automatic haematology analyser. Soil samples were analysed using the sucrose floatation sedimentation method. Categorical and continuous variables were compared as required and logistic regression models were used to assess the risk factors for STH infections and anaemia. Results Of the 450 participants examined, STHs, P. falciparum and mixed co-infections were detected in 14.0, 33.3 and 5.6% of participants, respectively. Significantly higher prevalences of Ascaris (18.8%) and Trichuris (7.9%) infections were observed in participants from tea plantation areas compared to those from banana and palm plantation areas, with similar trends in egg density. P. falciparum prevalence and parasite density were comparable between the different agroecosystems. The overall prevalence of anaemia was 64.2%. The prevalence of haematological manifestations such as moderate (48.0%) and severe (8.0%) anaemia, leucopenia (26.9%) and microcytosis (30.8%) was significantly higher among Plasmodium-STH co-infected participants. Soil samples from plantations showed the highest prevalences of STH eggs compared to soil samples from areas around pit toilets and public water taps. Living in a tea plantation area (OR = 3.07), age (AOR = 1.49) and lack of access to potable water (OR = 2.25) were identified as risk factors for STH infections, while the age groups 15–25 years (OR = 2.928) and 26–35 years (OR = 2.832), and being female (OR = 2.671) were significant risk factors for anaemia. Conclusions STHs, malaria and anaemia are still of public health concern in plantation communities. Co-infections negatively influence haematological parameters. The tea farming agroecosystem, age and lack of access to potable water were identified as significant risk factors for STH infections. Trial registration Not applicable. Electronic supplementary material The online version of this article (doi:10.1186/s40249-017-0266-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Helen Kuokuo Kimbi
- Department of Zoology and Animal Physiology, University of Buea, Buea, Cameroon.,Department of Medical Laboratory Sciences, University of Bamenda, Bamenda, Cameroon
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Howes RE, Battle KE, Mendis KN, Smith DL, Cibulskis RE, Baird JK, Hay SI. Global Epidemiology of Plasmodium vivax. Am J Trop Med Hyg 2016; 95:15-34. [PMID: 27402513 PMCID: PMC5198891 DOI: 10.4269/ajtmh.16-0141] [Citation(s) in RCA: 253] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 04/19/2016] [Indexed: 01/09/2023] Open
Abstract
Plasmodium vivax is the most widespread human malaria, putting 2.5 billion people at risk of infection. Its unique biological and epidemiological characteristics pose challenges to control strategies that have been principally targeted against Plasmodium falciparum Unlike P. falciparum, P. vivax infections have typically low blood-stage parasitemia with gametocytes emerging before illness manifests, and dormant liver stages causing relapses. These traits affect both its geographic distribution and transmission patterns. Asymptomatic infections, high-risk groups, and resulting case burdens are described in this review. Despite relatively low prevalence measurements and parasitemia levels, along with high proportions of asymptomatic cases, this parasite is not benign. Plasmodium vivax can be associated with severe and even fatal illness. Spreading resistance to chloroquine against the acute attack, and the operational inadequacy of primaquine against the multiple attacks of relapse, exacerbates the risk of poor outcomes among the tens of millions suffering from infection each year. Without strategies accounting for these P. vivax-specific characteristics, progress toward elimination of endemic malaria transmission will be substantially impeded.
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Affiliation(s)
- Rosalind E. Howes
- Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio
| | - Katherine E. Battle
- Spatial Ecology and Epidemiology Group, Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Kamini N. Mendis
- Global Malaria Program, World Health Organization, Geneva, Switzerland
| | - David L. Smith
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland
- Sanaria Institute for Global Health and Tropical Medicine, Rockville, Maryland
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington
| | | | - J. Kevin Baird
- Eijkman-Oxford Clinical Research Unit, Jakarta, Indonesia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Simon I. Hay
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, United Kingdom
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Fontoura PS, Finco BF, Lima NF, de Carvalho JF, Vinetz JM, Castro MC, Ferreira MU. Reactive Case Detection for Plasmodium vivax Malaria Elimination in Rural Amazonia. PLoS Negl Trop Dis 2016; 10:e0005221. [PMID: 27941968 PMCID: PMC5179126 DOI: 10.1371/journal.pntd.0005221] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/22/2016] [Accepted: 12/01/2016] [Indexed: 12/31/2022] Open
Abstract
Background Malaria burden in Brazil has reached its lowest levels in 35 years and Plasmodium vivax now accounts for 84% of cases countrywide. Targeting residual malaria transmission entrenched in the Amazon is the next major challenge for ongoing elimination efforts. Better strategies are urgently needed to address the vast reservoir of asymptomatic P. vivax carriers in this and other areas approaching malaria elimination. Methods We evaluated a reactive case detection (RCD) strategy tailored for P. vivax transmission in farming settlements in the Amazon Basin of Brazil. Over six months, 41 cases detected by passive surveillance triggered four rounds of RCD (0, 30, 60, and 180 days after index case enrollment), using microscopy- and quantitative real-time polymerase chain reaction (qPCR)-based diagnosis, comprising subjects sharing the household (HH) with the index case (n = 163), those living in the 5 nearest HHs within 3 km (n = 878), and individuals from 5 randomly chosen control HHs located > 5 km away from index cases (n = 841). Correlates of infection were identified with mixed-effects logistic regression models. Molecular genotyping was used to infer local parasite transmission networks. Principal findings/Conclusions Subjects in index and neighbor HHs were significantly more likely to be parasitemic than control HH members, after adjusting for potential confounders, and together harbored > 90% of the P. vivax biomass in study subjects. Clustering patterns were temporally stable. Four rounds of microscopy-based RCD would identify only 49.5% of the infections diagnosed by qPCR, but 76.8% of the total parasite biomass circulating in the proximity of index HHs. However, control HHs accounted for 27.6% of qPCR-positive samples, 92.6% of them from asymptomatic carriers beyond the reach of RCD. Molecular genotyping revealed high P. vivax diversity, consistent with complex transmission networks and multiple sources of infection within clusters, potentially complicating malaria elimination efforts. Addressing the vast reservoir of asymptomatic Plasmodium vivax carriers clustered in hard-to-reach rural communities is a major challenge faced by countries approaching malaria elimination across Latin America and Asia. Routine surveillance targets subjects presenting with fever or reporting recent fever, but overlooks asymptomatic infections that might be otherwise detected by periodic mass blood surveys of the entire population at risk. Here we show that subjects living in close proximity to malaria cases detected by routine passive surveillance are much more likely to carry both symptomatic and asymptomatic infections than randomly selected inhabitants in the same farming settlements in the Amazon Basin of Brazil. Four rounds of microscopy-based screening for malaria parasites targeted at these high-risk subjects would identify 49.5% of the parasite carriers (who together harbored 76.8% of the total P. vivax biomass circulating in the proximity of index cases) detected by a more sensitive molecular method. Whether subpatent and asymptomatic carriers outside the identified clusters of symptomatic infections, beyond the reach of our screening, represent a significant parasite reservoir remains undetermined. The extensive genetic diversity found in local P. vivax populations suggests that multiple sources of infection fuel ongoing residual transmission within malaria clusters, further complicating current elimination efforts.
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Affiliation(s)
- Pablo S. Fontoura
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Bruna F. Finco
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Nathália F. Lima
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Jaques F. de Carvalho
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
| | - Joseph M. Vinetz
- Division of Infectious Diseases, Department of Medicine, University of California San Diego, La Jolla, CA, United States of America
- Alexander von Humboldt Institute of Tropical Medicine and Faculty of Sciences, Department of Cellular and Molecular Sciences, Laboratory of Research and Development, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Márcia C. Castro
- Department of Global Health and Population, Harvard T. H. Chan School of Public Health, Boston, MA, United States of America
| | - Marcelo U. Ferreira
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil
- * E-mail:
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Sifft KC, Geus D, Mukampunga C, Mugisha JC, Habarugira F, Fraundorfer K, Bayingana C, Ndoli J, Umulisa I, Karema C, von Samson-Himmelstjerna G, Aebischer T, Martus P, Sendegeya A, Gahutu JB, Mockenhaupt FP. Asymptomatic only at first sight: malaria infection among schoolchildren in highland Rwanda. Malar J 2016; 15:553. [PMID: 27842542 PMCID: PMC5109732 DOI: 10.1186/s12936-016-1606-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 11/07/2016] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium infection and malaria in school children are increasingly recognized as a relevant public health problem, but data on actual prevalence and health consequences are insufficient. The present study from highland southern Rwanda aimed at estimating infection prevalence among children attending school, at identifying associated factors and at assessing the clinical consequences of these infections. Methods In a survey including 12 schools in the Huye district of Rwanda, 1089 children aged 6–10 years were clinically and anthropometrically examined, malaria parasites were diagnosed by microscopy and PCR, haemoglobin concentrations were measured, and socio-economic and behavioural parameters as well as medical histories were obtained. Results Upon examination, the vast majority of children was asymptomatic (fever 2.7%). Plasmodium infection was detected in 22.4% (Plasmodium falciparum, 18.8%); 41% of these were submicroscopic. Independent predictors of infection included low altitude, higher age, preceding antimalarial treatment, and absence of electricity or a bicycle in the household. Plasmodium infection was associated with anaemia (mean haemoglobin difference of −1.2 g/dL; 95% CI, −0.8 to −1.5 g/dL), fever, underweight, clinically assessed malnutrition and histories of fever, tiredness, weakness, poor appetite, abdominal pain, and vomiting. With the exception of underweight, these conditions were also increased at submicroscopic infection. Conclusion Malaria infection is frequent among children attending school in southern highland Rwanda. Although seemingly asymptomatic in the vast majority of cases, infection is associated with a number of non-specific symptoms in the children´s histories, in addition to the impact on anaemia. This argues for improved malaria surveillance and control activities among school children.
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Affiliation(s)
- Kevin C Sifft
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Berlin, Germany
| | - Dominik Geus
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Berlin, Germany
| | - Caritas Mukampunga
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Jean Claude Mugisha
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Felix Habarugira
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Kira Fraundorfer
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Claude Bayingana
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Jules Ndoli
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Irenee Umulisa
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Corine Karema
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Toni Aebischer
- Mycotic and Parasitic Agents and Mycobacteria, Department of Infectious Diseases, Robert Koch-Institute, Berlin, Germany
| | - Peter Martus
- Institute for Clinical Epidemiology and Applied Biometry, University Hospital, Tuebingen, Germany
| | - Augustin Sendegeya
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Jean Bosco Gahutu
- University Teaching Hospital of Butare, University of Rwanda, Butare, Rwanda
| | - Frank P Mockenhaupt
- Institute of Tropical Medicine and International Health, Charité-University Medicine Berlin, Berlin, Germany.
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Utilizing direct skin feeding assays for development of vaccines that interrupt malaria transmission: A systematic review of methods and case study. Vaccine 2016; 34:5863-5870. [PMID: 27789147 DOI: 10.1016/j.vaccine.2016.10.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/23/2016] [Accepted: 10/11/2016] [Indexed: 01/29/2023]
Abstract
Shifting the malaria priorities from a paradigm of control and elimination to a goal of global eradication calls for renewed attention to the interruption of malaria transmission. Sustained progress toward eradication will require both improved understanding of infectious reservoirs and efficient development of novel transmission-blocking interventions, such as rapidly acting and highly efficacious therapeutics and vaccines. Here, we review the direct skin feeding assay (DSF), which has been proposed as a valuable tool for measuring the in natura transmission of malaria parasites from human hosts to mosquito vectors across heterogeneous populations. To capture the methodological breadth of this assay's use, we first systematically review and qualitatively synthesize previously published investigations using DSFs to study malaria transmission in humans. Then, using a recent Phase 1 trial in Mali of the Pfs25H-EPA/Alhydrogel® vaccine candidate (NCT01867463) designed to interrupt Plasmodium falciparum transmission as a case study, we describe the potential opportunities and current limitations of utilizing the endpoints measured by DSF in making early clinical decisions for individually randomized transmission-interrupting intervention candidates. Using simulations based on the data collected in the clinical trial, we demonstrate that the capacity of the DSF to serve as an evaluative tool is limited by the statistical power constraints of the "effective sample size" (i.e. the number of subjects that are capable of transmitting at the time of feeding). Altogether, our findings suggest DSFs have great potential utility for assessing the public health impacts of emerging antimalarial tools, but additional research is needed to address issues of scalability and to establish correlation with community-wide clinical endpoints as well as complementary in vitro measures, such as standard membrane feeding assays.
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Okebe J, Bousema T, Affara M, Di Tanna GL, Dabira E, Gaye A, Sanya-Isijola F, Badji H, Correa S, Nwakanma D, Van Geertruyden JP, Drakeley C, D'Alessandro U. The Gametocytocidal Efficacy of Different Single Doses of Primaquine with Dihydroartemisinin-piperaquine in Asymptomatic Parasite Carriers in The Gambia: A Randomized Controlled Trial. EBioMedicine 2016; 13:348-355. [PMID: 27825738 PMCID: PMC5264436 DOI: 10.1016/j.ebiom.2016.10.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/14/2016] [Accepted: 10/19/2016] [Indexed: 11/23/2022] Open
Abstract
Background Asymptomatic low-density gametocyte carriers represent the majority of malaria-infected individuals. However, the impact of recommended treatment with single low dose of primaquine and an artemisinin-based combination therapy to reduce transmission in this group is unknown. Methods This was a four-arm, open label, randomized controlled trial comparing the effect of dihydroartemisinin-piperaquine (DHAP) alone or combined with single dose of primaquine (PQ) at 0.20 mg/kg, 0.40 mg/kg, or 0.75 mg/kg on Plasmodium falciparum gametocytaemia, infectiousness to mosquitoes and hemoglobin change in asymptomatic, malaria-infected, glucose-6-phosphate dehydrogenase (G6PD) normal individuals. Randomization was done using a computer-generated sequence of uneven block sizes with codes concealed in sequentially numbered opaque envelopes. The primary endpoint was the prevalence of P. falciparum gametocytemia at day 7 of follow-up determined by quantitative nucleic acid sequence based assay and analysis was by intention to treat. The trial has been concluded (registration number: NCT01838902; https://clinicaltrials.gov/ct2/show/NCT01838902). Results A total of 694 asymptomatic, malaria-infected individuals were enrolled. Gametocyte prevalence at day 7 was 37.0% (54/146; 95% CI 29.2–45.4), 19.0% (27/142; 95% CI 12.9–26.4), 17.2% (25/145; 95% CI 11.0–23.5) and 10.6% (15/141; 95% CI 6.1–16.9) in the DHAP alone, 0.20 mg/kg, 0.40 mg/kg, and 0.75 mg/kg PQ arms, respectively. The main adverse events reported include headache (130/471, 27.6%), cough (73/471, 15.5%), history of fever (61/471, 13.0%) and abdominal pain (57/471, 12.1%). There were five serious adverse events however, none was related to the interventions. Interpretation A single course of PQ significantly reduces gametocyte carriage in malaria-infected asymptomatic, G6PD-normal individuals without increasing the risk of clinical anemia. The limited number of successful mosquito infections suggests that post-treatment transmission potential in this asymptomatic population is low. Treatment with primaquine and an artemisinin-based combination therapy is part of malaria elimination strategies. Its slow uptake, despite specific recommendations highlights the need for evidence on primaquine's efficacy and safety. About 50% of asymptomatic P. falciparum-infected individuals carry gametocytes detectable by sensitive molecular methods. Primaquine reduced gametocyte prevalence at day 7 and carriage time in the study population at all doses tested.
Adding a single dose (0.75 mg/kg) of primaquine to the treatment of uncomplicated falciparum malaria was recommended in 2010 on the basis of weak evidence. Primaquine, at doses as low as 0.20 mg/kg, can reduce substantially gametocyte carriage in asymptomatic, malaria-infected individuals, representing the majority of the human reservoir of infection. Post-treatment transmission potential is low with artemisinin-based combination alone or with the 0.20 mg/kg dose but may occur despite reductions in gametocyte carriage.
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Affiliation(s)
- Joseph Okebe
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia; Epidemiology for Global Health Institute, Faculty of Medicine & Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - Teun Bousema
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Muna Affara
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Gian Luca Di Tanna
- Pragmatic Clinical Trials Unit, Centre for Primary Care and Public Health, Queen Mary University of London, United Kingdom.
| | - Edgard Dabira
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Abdoulaye Gaye
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Frank Sanya-Isijola
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Henry Badji
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Simon Correa
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Davis Nwakanma
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Jean-Pierre Van Geertruyden
- Epidemiology for Global Health Institute, Faculty of Medicine & Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
| | - Umberto D'Alessandro
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia; Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.
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Lennon SE, Miranda A, Henao J, Vallejo AF, Perez J, Alvarez A, Arévalo-Herrera M, Herrera S. Malaria elimination challenges in Mesoamerica: evidence of submicroscopic malaria reservoirs in Guatemala. Malar J 2016; 15:441. [PMID: 27577992 PMCID: PMC5006524 DOI: 10.1186/s12936-016-1500-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 08/20/2016] [Indexed: 11/23/2022] Open
Abstract
Background Even though malaria incidence has decreased substantially in Guatemala since 2000, Guatemala remains one of the countries with the highest malaria transmission in Mesoamerica. Guatemala is committed to eliminating malaria as part of the initiative ‘Elimination of Malaria in Mesoamerica and the Island of Hispaniola’ (EMMIE); however, it is still in the control phase. During the past decade, the government strengthened malaria control activities including mass distribution of long-lasting insecticide-impregnated bed nets, early diagnosis and prompt treatment. This study aimed to determine the prevalence of malaria, including gametocytes, in three areas of Guatemala using active case detection (ACD) and quantitative polymerase chain reaction (qPCR). Methods Cross-sectional surveys were conducted in three departments with varying transmission intensities: Escuintla, Alta Verapaz and Zacapa. Blood samples from 706 volunteers were screened for malaria using microscopy and qPCR which was also used to determine the prevalence of gametocytes among infected individuals. Results were collected and analysed using REDCap and R Project, respectively. Results Malaria was diagnosed by microscopy in only 2.8 % (4/141) of the volunteers from Escuintla. By contrast, qPCR detected a prevalence of 7.1 % (10/141) in the same volunteers, 8.4 % (36/429) in Alta Verapaz, and 5.9 % (8/136) in Zacapa. Overall, 7.6 % (54/706) of the screened individuals were positive, with an average parasitaemia level of 40.2 parasites/μL (range 1–1133 parasites/μL) and 27.8 % carried mature gametocytes. Fifty-seven percent (31/54) of qPCR positive volunteers were asymptomatic and out of the 42.6 % of symptomatic individuals, only one had a positive microscopy result. Conclusions This study found a considerable number of asymptomatic P. vivax infections that were mostly submicroscopic, of which, approximately one-quarter harboured mature gametocytes. This pattern is likely to contribute to maintaining transmission across the region. Robust surveillance systems, molecular diagnostic tests and tailored malaria detection activities for each endemic site may prove to be imperative in accelerating malaria elimination in Guatemala and possibly across all of Mesoamerica. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1500-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Adolfo Miranda
- Centro Nacional de Epidemiología (CNE), Guatemala City, Guatemala
| | - Juliana Henao
- Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia
| | - Andres F Vallejo
- Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia
| | - Julianh Perez
- Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia
| | - Alvaro Alvarez
- Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia
| | - Myriam Arévalo-Herrera
- Caucaseco Scientific Research Center (CSRC)/Centro Latino Americano de Investigación en Malaria (CLAIM), Cali, Colombia.,Facultad de Salud, Universidad del Valle, Cali, Colombia
| | - Sócrates Herrera
- Malaria Vaccine and Drug Development Center (MVDC), Cali, Colombia. .,Caucaseco Scientific Research Center (CSRC)/Centro Latino Americano de Investigación en Malaria (CLAIM), Cali, Colombia.
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50
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Hamze H, Charchuk R, Jean Paul MK, Claude KM, Léon M, Hawkes MT. Lack of household clustering of malaria in a complex humanitarian emergency: implications for active case detection. Pathog Glob Health 2016; 110:223-227. [PMID: 27560094 DOI: 10.1080/20477724.2016.1220730] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND Malaria contributes to elevated morbidity and mortality in populations displaced by conflict in tropical zones. In an attempt to reduce malaria transmission in an internally displaced persons (IDP) camp in eastern Democratic Republic of Congo (DRC), we tested a strategy of active case detection of household contacts of malaria cases. METHODS Prospective community-based survey. RESULTS From a convenience sample of 100 febrile patients under 5 years of age from the IDP camp presenting to a nearby clinic for management of a fever episode, 19 cases of uncomplicated malaria and 81 controls with non-malarial febrile illness (NFMI) were diagnosed. We engaged community health workers in the IDP camp to screen their household contacts for malaria using rapid diagnostic tests. We detected 29 cases of malaria through this active case-finding procedure. Household contacts of children with uncomplicated malaria were no more likely to have positive Plasmodium falciparum antigenemia than controls with NFMI (OR 0.89, 95% CI 0.33 to 2.4, p = 1.0), suggesting that malaria cases did not cluster at the household level. However, household contacts reporting mild symptoms at the time of community survey (headache, myalgia) had a higher odds of malaria than asymptomatic individuals (OR 14 (95% CI 4.2-48), p ≤ 0.001 and 18 (95% CI 5.9-54), p ≤ 0.001, respectively). CONCLUSION Screening household contacts of malaria cases was not an efficient case-finding strategy in a Congolese IDP camp. Symptom-based screening may be a simpler and cost-effective method to identify individuals at increased risk of malaria for targeted screening and treatment in an IDP camp.
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Affiliation(s)
- Hasan Hamze
- a School of Public Health , University of Alberta , Edmonton , Canada
| | - Rhianna Charchuk
- a School of Public Health , University of Alberta , Edmonton , Canada
| | | | - Kasereka Masumbuko Claude
- c Department of Surgery , Université Catholique du Graben , Butembo , Democratic Republic of the Congo
| | - Mashukano Léon
- d Médecins d'Afrique , Goma , Democratic Republic of the Congo
| | - Michael T Hawkes
- a School of Public Health , University of Alberta , Edmonton , Canada.,e Department of Pediatrics , University of Alberta , Edmonton , Canada.,f Department of Medical Microbiology and Immunology , University of Alberta , Edmonton , Canada
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