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Kalantari N, Sepidarkish M, Ghaffari S, Rostami-Mansoor S. Does vitamin D reduce the mortality rate of Plasmodium infection?: a systematic review and meta-analysis. Malar J 2023; 22:173. [PMID: 37277818 DOI: 10.1186/s12936-023-04612-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 05/30/2023] [Indexed: 06/07/2023] Open
Abstract
BACKGROUND Vitamin D supplementation is recommended as an effective adjunct to counteract malaria pathogenesis, but the evidence on this point is limited and controversial. This systematic review and meta-analysis aimed to investigate the effect of vitamin D administration on the survival rate of Plasmodium-infected animals in experimentally-induced malaria on days 6 and 10 post-infection. METHODS Five electronic databases were searched up to 20 December 2021. The pooled risks ratio (RR) and associated 95% confidence interval were estimated using the Restricted-maximum likelihood (REML) random-effects model. Heterogeneity was assessed by Cochran's Q test and I2 value. Sub-group analyses were used to identify the sources of heterogeneity for several variables, such as type of vitamin D, type of intervention, and dose of vitamin D. RESULTS Out of 248 articles found in the electronic database, six were eligible for inclusion in the meta-analysis. The current study found that the pooled random effect of risks ratio favored a statistically significant effect of vitamin D administration on survival rate in infected mice on day 6 post Plasmodium infection (RR = 1.08, 95%CI 1.03, 1.15, p < 0.99; I2 = 0%). It also found that vitamin D administration significantly affected the survival rate on day 10 post-infection (RR = 1.94, 95%CI 1.39, 2.71, p < 0.001; I2 = 69.02%). Subgroup analyses demonstrated a significant pooled RRs of the positive effect of vitamin D administration for cholecalciferol (RR = 3.11, 95%CI 2.41, 4.03, p < 0.001; I2 = 0%), doses higher than 50 µg/kg (RR = 3.37, 95%CI 2.55, 4.27, p < 0.001; I2 = 0%), and oral administration (RR = 3.01, 95%CI 2.37, 3.82, p < 0.001; I2 = 0%). CONCLUSION This systematic review and meta-analysis showed that vitamin D administration positively affects the survival rate in Plasmodium-infected mice. Since, the mouse model may not accurately reproduce the clinical and pathological features of human malaria, future research should investigate the impact of vitamin D in human malaria.
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Affiliation(s)
- Narges Kalantari
- Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Mahdi Sepidarkish
- Department of Biostatistics and Epidemiology, School of Public Health, Babol University of Medical Sciences, Babol, Iran
| | - Salman Ghaffari
- Department of Mycology and Parasitology, School of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Sahar Rostami-Mansoor
- Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran.
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Plasmodium falciparum Merozoite Surface Proteins Polymorphisms and Treatment Outcomes among Patients with Uncomplicated Malaria in Mwanza, Tanzania. J Trop Med 2022; 2022:5089143. [DOI: 10.1155/2022/5089143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/26/2022] [Accepted: 10/20/2022] [Indexed: 11/25/2022] Open
Abstract
Background. The severity of malaria infection depends on the host, parasite and environmental factors. Merozoite surface protein (msp) diversity determines transmission dynamics, P. falciparum immunity evasion, and pathogenesis or virulence. There is limited updated information on P. falciparum msp polymorphisms and their impact on artemether-lumefantrine treatment outcomes in Tanzania. Therefore, this study is aimed at examining msp genetic diversity and multiplicity of infection (MOI) among P. falciparum malaria patients. The influence of MOI on peripheral parasite clearance and adequate clinical and parasitological response (ACPR) was also assessed. Methods. Parasite DNA was extracted from dried blood spots according to the manufacture’s protocol. Primary and nested PCR were performed. The PCR products for both the block 2 region of msp1 and the block 3 regions of msp2 genes and their specific allelic families were visualized on a 2.5% agarose gel. Results. The majority of the isolates, 58/102 (58.8%) for msp1 and 69/115 (60.1%) for msp2, harboured more than one parasite genotypes. For the msp1 gene, K1 was the predominant allele observed (75.64%), whereas RO33 occurred at the lowest frequency (43.6%). For the msp2 gene, the 3D7 allele was observed at a higher frequency (81.7%) than the FC27 allele (76.9%). The MOIs were 2.44 for msp1 and 2.27 for msp2 (
). A significant correlation between age and multiplicity of infection (MOI) for msp1 or MOI for msp2 was not established in this study (rho = 0.074,
and rho = −0.129,
, respectively). Similarly, there was no positive correlation between parasite density at day 1 and MOI for both msp1 (rho = 0.113,
) and msp2 (rho = 0.043,
). The association between MOI and ACPR was not observed for either msp1 or mps2 (
and 0.296, respectively). Conclusions. This study reports high polyclonal infections, MOI and allelic frequencies for both msp1 and msp2. There was a lack of correlation between MOI and ACPR. However, a borderline significant correlation was observed between day 2 parasitaemia and MOI.
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Agonhossou R, Akoton R, Lagnika H, Djihinto OY, Sovegnon PM, Saizonou HD, Ntoumi F, Wondji CS, Borrmann S, Adegnika AA, Djogbénou LS. P. falciparum msp1 and msp2 genetic diversity in P. falciparum single and mixed infection with P. malariae among the asymptomatic population in Southern Benin. Parasitol Int 2022; 89:102590. [PMID: 35472441 DOI: 10.1016/j.parint.2022.102590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 04/17/2022] [Accepted: 04/19/2022] [Indexed: 10/18/2022]
Abstract
Plasmodium falciparum and Plasmodium malariae infections are prevalent in malaria-endemic countries. However, very little is known about their interactions especially the effect of P. malariae on P. falciparum genetic diversity. This study aimed to assess P. falciparum genetic diversity in P. falciparum and mixed infection P. falciparum/P. malariae isolates among the asymptomatic populations in Southern Benin. Two hundred and fifty blood samples (125 of P. falciparum and 125 P. falciparum/P. malariae isolates) were analysed by a nested PCR amplification of msp1 and msp2 genes. The R033 allelic family was the most represented for the msp1 gene in mono and mixed infection isolates (99.2% vs 86.4%), while the K1 family had the lowest frequency (38.3% vs 20.4%). However, with the msp2 gene, the two allelic families displayed similar frequencies in P. falciparum isolates while the 3D7 allelic family was more represented in P. falciparum/P. malariae isolates (88.7%). Polyclonal infections were also lower (62.9%) in P. falciparum/P. malariae isolates (p < 0.05). Overall, 96 individual alleles were identified (47 for msp1 and 49 for msp2) in P. falciparum isolates while a total of 50 individual alleles were identified (23 for msp1 and 27 for msp2) in P. falciparum/P. malariae isolates. The Multiplicity of Infection (MOI) was lower in P. falciparum/P. malariae isolates (p < 0.05). This study revealed a lower genetic diversity of P. falciparum in P. falciparum/P. malariae isolates using msp1 and msp2 genes among the asymptomatic population in Southern Benin.
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Affiliation(s)
- Romuald Agonhossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin.
| | - Romaric Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin
| | - Hamirath Lagnika
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Oswald Y Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Pierre M Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Helga D Saizonou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin
| | - Francine Ntoumi
- Fondation Congolaise pour la Recherche Médicale (FCRM), Brazzaville, Congo; Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany
| | - Charles S Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; Department of Parasitology and Medical Entomology, Centre for Research in Infectious Diseases (CRID), Yaoundé, Centre Region, 237, Cameroon
| | - Steffen Borrmann
- Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Tübingen, Germany
| | - Ayola A Adegnika
- Fondation Pour la Recherche Scientifique (FORS), ISBA, BP 88, Cotonou, Bénin; Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon; Institute for Tropical Medicine (ITM), University of Tübingen, Tübingen, Germany; Eberhard Karls Universität Tübingen, Tübingen, Germany; German Center for Infection Research (DZIF), Tübingen, Germany
| | - Luc S Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, 01BP 526, Cotonou, Benin; Institut Régional de Santé Publique/Université d'Abomey-Calavi, BP 384 Ouidah, Bénin
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Lagnika HO, Moussiliou A, Agonhossou R, Sovegnon P, Djihinto OY, Medjigbodo AA, Djossou L, Amoah LE, Ogouyemi-Hounto A, Djogbenou LS. Plasmodium falciparum msp1 and msp2 genetic diversity in parasites isolated from symptomatic and asymptomatic malaria subjects in the South of Benin. Parasitol Res 2022; 121:167-175. [PMID: 34993632 DOI: 10.1007/s00436-021-07399-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 11/29/2021] [Indexed: 10/19/2022]
Abstract
Symptomatic and asymptomatic malaria patients are considered as the reservoirs of human Plasmodium. In the present study, we have evaluated the Plasmodium falciparum merozoite surface protein-1 (Pfmsp1) and protein-2 (Pfmsp2) genetic diversity among the symptomatic and asymptomatic malaria infection from health facilities in Cotonou, Benin Republic. A cross-sectional study recruited 158 individuals, including 77 from the asymptomatic and 81 from the symptomatic groups. The parasites were genotyped using Nested Polymerase Chain Reaction. Samples identified as Plasmodium falciparum were genotyped for their genetic diversity. No significant difference was observed in the overall multiplicity of infection (MOI) between the asymptomatic and symptomatic groups. In the symptomatic group, the overall frequency of K1, MAD20, and RO33 allelic family was more predominant (98.5%) followed by 3D7 (87.3%) and FC27 (83.1%). However, in asymptomatic group, the K1 alleles were the most prevalent (100%) followed by FC27 (89.9%), 3D7 (76.8%), MAD20 (60.5%), and RO33 (35.5%). The frequency of multiple allelic types (K1+MAD20+RO33) at the Pfmsp1 loci in the symptomatic infections was significantly higher when compared to that of the asymptomatic ones (97% vs. 34%, p < 0.05), whereas no difference was observed in the frequency of multiple allelic types (3D7 and FC27) at the Pfmsp2 loci between the two groups. The high presence of msp1 multiple infections in the symptomatic group compared to asymptomatic ones suggests an association between the genetic diversity and the onset of malaria symptoms. These data can provide valuable information in the development of a vaccine that could reduce the symptomatic disease.
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Affiliation(s)
- Hamirath Odée Lagnika
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Azizath Moussiliou
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Romuald Agonhossou
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Pierre Sovegnon
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Oswald Yédjinnavênan Djihinto
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Adandé Assogba Medjigbodo
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Laurette Djossou
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin
| | - Linda Eva Amoah
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | | | - Luc Salako Djogbenou
- Tropical Infectious Diseases Research Centre, University of Abomey-Calavi, 01BP 526, Cotonou, Benin.
- Laboratory of Infectious Vector-Borne Diseases, Regional Institute of Public Health/University of Abomey-Calavi, BP 384, Ouidah, Benin.
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Mohammed H, Assefa A, Chernet M, Wuletaw Y, Commons RJ. Genetic polymorphisms of Plasmodium falciparum isolates from Melka-Werer, North East Ethiopia based on the merozoite surface protein-2 (msp-2) gene as a molecular marker. Malar J 2021; 20:85. [PMID: 33579293 PMCID: PMC7881608 DOI: 10.1186/s12936-021-03625-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 02/04/2021] [Indexed: 11/21/2022] Open
Abstract
Background The characterization of parasite populations circulating in malaria endemic areas is necessary to evaluate the success of ongoing interventions and malaria control strategies. This study was designed to investigate the genetic diversity of Plasmodium falciparum isolates from the semi-arid area in North East Ethiopia, using the highly polymorphic merozoite surface protein-2 (msp2) gene as a molecular marker. Methods Dried blood spot isolates were collected from patients with P. falciparum infection between September 2014 and January 2015 from Melka-Werer, North East Ethiopia. Parasite DNA was extracted and genotyped using allele-specific nested polymerase chain reactions for msp2. Results 52 isolates were collected with msp2 identified in 41 (78.8%) isolates. Allele typing of the msp2 gene detected the 3D7/IC allelic family in 54% and FC27 allelic family in 46%. A total of 14 different msp2 genotypes were detected including 6 belonging to the 3D7/IC family and 8 to the FC27 family. Forty percent of isolates had multiple genotypes and the overall mean multiplicity of infections (MOI) was 1.2 (95%CI 0.96–1.42). The heterozygosity index was 0.50 for the msp2 locus. There was no difference in MOI between age groups. A negative correlation between parasite density and multiplicity of infection was found (p = 0.02). Conclusion Plasmodium falciparum isolates from the semi-arid area of North East Ethiopia are mainly monoclonal with low MOI and limited genetic diversity in the study population.
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Affiliation(s)
- Hussein Mohammed
- Malaria, Neglected Tropical Diseases Research Team, Bacterial, Parasitic, Zoonotic Diseases Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia.
| | - Ashenafi Assefa
- Malaria, Neglected Tropical Diseases Research Team, Bacterial, Parasitic, Zoonotic Diseases Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Melkie Chernet
- Malaria, Neglected Tropical Diseases Research Team, Bacterial, Parasitic, Zoonotic Diseases Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Yonas Wuletaw
- Malaria, Neglected Tropical Diseases Research Team, Bacterial, Parasitic, Zoonotic Diseases Research Directorate, Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Robert J Commons
- Global Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Australia.,Internal Medicine Services, Ballarat Health Services, Ballarat, Australia
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Oboh MA, Ndiaye T, Diongue K, Ndiaye YD, Sy M, Deme AB, Diallo MA, Yade MS, Volkman SK, Badiane AS, Amambua-Ngwa A, Ndiaye D. Allelic diversity of MSP1 and MSP2 repeat loci correlate with levels of malaria endemicity in Senegal and Nigerian populations. Malar J 2021; 20:38. [PMID: 33436004 PMCID: PMC7805152 DOI: 10.1186/s12936-020-03563-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/20/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Characterizing the genetic diversity of malaria parasite populations in different endemic settings (from low to high) could be helpful in determining the effectiveness of malaria interventions. This study compared Plasmodium falciparum parasite population diversity from two sites with low (pre-elimination) and high transmission in Senegal and Nigeria, respectively. METHODS Parasite genomic DNA was extracted from 187 dried blood spot collected from confirmed uncomplicated P. falciparum malaria infected patients in Senegal (94) and Nigeria (93). Allelic polymorphism at merozoite surface protein 1 (msp1) and merozoite surface protein- 2 (msp2) genes were assessed by nested PCR. RESULTS The most frequent msp1 and msp2 allelic families are the K1 and IC3D7 allelotypes in both Senegal and Nigeria. Multiplicity of infection (MOI) of greater that 1 and thus complex infections was common in both study sites in Senegal (Thies:1.51/2.53; Kedougou:2.2/2.0 for msp1/2) than in Nigeria (Gbagada: 1.39/1.96; Oredo: 1.35/1.75]). The heterozygosity of msp1 gene was higher in P. falciparum isolates from Senegal (Thies: 0.62; Kedougou: 0.53) than isolates from Nigeria (Gbagada: 0.55; Oredo: 0.50). In Senegal, K1 alleles was associated with heavy than with moderate parasite density. Meanwhile, equal proportions of K1 were observed in both heavy and moderate infection types in Nigeria. The IC3D7 subtype allele of the msp2 family was the most frequent in heavily parasitaemic individuals from both countries than in the moderately infected participants. CONCLUSION The unexpectedly low genetic diversity of infections high endemic Nigerian setting compared to the low endemic settings in Senegal is suggestive of possible epidemic outbreak in Nigeria.
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Affiliation(s)
- Mary A Oboh
- Medical Research Council Unit, the Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia.
| | - Tolla Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal.
| | - Khadim Diongue
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Yaye D Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mouhamad Sy
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Awa B Deme
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mamadou A Diallo
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mamadou S Yade
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Sarah K Volkman
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
| | - Aida S Badiane
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, the Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Daouda Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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Kumari P, Sinha S, Gahtori R, Yadav CP, Pradhan MM, Rahi M, Pande V, Anvikar AR. Prevalence of Asymptomatic Malaria Parasitemia in Odisha, India: A Challenge to Malaria Elimination. Am J Trop Med Hyg 2020; 103:1510-1516. [PMID: 32783792 DOI: 10.4269/ajtmh.20-0018] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The prevalence of malaria in India is decreasing, but it remains a major concern for public health administration. The role of submicroscopic malaria and asymptomatic malaria parasitemia and their persistence is being explored. A cross-sectional survey was conducted in the Kandhamal district of Odisha (India) during May-June 2017. Blood samples were collected from 1897 individuals for screening of asymptomatic parasitemia. Samples were screened using rapid diagnostic tests (RDTs) and examined microscopically for Plasmodium species. Approximately 30% of randomly selected samples (n = 586) were analyzed using real-time PCR (qPCR), and the genetic diversity of Plasmodium falciparum was analyzed. The prevalence of Plasmodium species among asymptomatic individuals detected using qPCR was 18%, which was significantly higher than that detected by microscopy examination (5.5%) or RDT (7.3%). Of these, 37% had submicroscopic malaria. The species-specific prevalence among asymptomatic malaria-positive cases for P. falciparum, Plasmodium vivax, and mixed infection (P. falciparum and P. vivax) by qPCR was 57%, 29%, and 14%, respectively. The multiplicity of infection was 1.6 and 1.2 for the merozoite surface protein-1 gene (msp1) and (msp2), respectively. Expected heterozygosity was 0.64 and 0.47 for msp1 and msp2, respectively. A significant proportion of the study population, 105/586 (18%), was found to be a reservoir for malaria infection, and identification of this group will help in the development of elimination strategies.
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Affiliation(s)
- Preeti Kumari
- Kumaun University, Nainital, India.,ICMR - National Institute of Malaria Research, New Delhi, India
| | - Swati Sinha
- Kumaun University, Nainital, India.,ICMR - National Institute of Malaria Research, New Delhi, India
| | - Renuka Gahtori
- Kumaun University, Nainital, India.,ICMR - National Institute of Malaria Research, New Delhi, India
| | | | | | - Manju Rahi
- Indian Council of Medical Research, New Delhi, India
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Ndiaye T, Sy M, Gaye A, Siddle KJ, Park DJ, Bei AK, Deme AB, Mbaye A, Dieye B, Ndiaye YD, Ndiaye IM, Diallo MA, Diongue K, Volkman SK, Badiane AS, Ndiaye D. Molecular epidemiology of Plasmodium falciparum by multiplexed amplicon deep sequencing in Senegal. Malar J 2020; 19:403. [PMID: 33172455 PMCID: PMC7654156 DOI: 10.1186/s12936-020-03471-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/30/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Molecular epidemiology can provide important information regarding the genetic diversity and transmission of Plasmodium falciparum, which can assist in designing and monitoring elimination efforts. However, malaria molecular epidemiology including understanding the genetic diversity of the parasite and performing molecular surveillance of transmission has been poorly documented in Senegal. Next Generation Sequencing (NGS) offers a practical, fast and high-throughput approach to understand malaria population genetics. This study aims to unravel the population structure of P. falciparum and to estimate the allelic diversity, multiplicity of infection (MOI), and evolutionary patterns of the malaria parasite using the NGS platform. METHODS Multiplex amplicon deep sequencing of merozoite surface protein 1 (PfMSP1) and merozoite surface protein 2 (PfMSP2) in fifty-three P. falciparum isolates from two epidemiologically different areas in the South and North of Senegal, was carried out. RESULTS A total of 76 Pfmsp1 and 116 Pfmsp2 clones were identified and 135 different alleles were found, 56 and 79 belonged to the pfmsp1 and pfmsp2 genes, respectively. K1 and IC3D7 allelic families were most predominant in both sites. The local haplotype diversity (Hd) and nucleotide diversity (π) were higher in the South than in the North for both genes. For pfmsp1, a high positive Tajima's D (TD) value was observed in the South (D = 2.0453) while negative TD value was recorded in the North (D = - 1.46045) and F-Statistic (Fst) was 0.19505. For pfmsp2, non-directional selection was found with a highly positive TD test in both areas and Fst was 0.02111. The mean MOI for both genes was 3.07 and 1.76 for the South and the North, respectively, with a statistically significant difference between areas (p = 0.001). CONCLUSION This study revealed a high genetic diversity of pfmsp1 and pfmsp2 genes and low genetic differentiation in P. falciparum population in Senegal. The MOI means were significantly different between the Southern and Northern areas. Findings also showed that multiplexed amplicon deep sequencing is a useful technique to investigate genetic diversity and molecular epidemiology of P. falciparum infections.
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Affiliation(s)
- Tolla Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal.
| | - Mouhamad Sy
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Amy Gaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | | | - Daniel J Park
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Amy K Bei
- Yale School of Public Health, 60 College Street, New Haven, CT, 06510, USA
| | - Awa B Deme
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Aminata Mbaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Baba Dieye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Yaye Die Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Ibrahima Mbaye Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Mamadou Alpha Diallo
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Khadim Diongue
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Sarah K Volkman
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Immunology and Infectious Diseases, Harvard University, Cambridge, MA, USA
| | - Aida Sadikh Badiane
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Daouda Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard University, Cambridge, MA, USA
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9
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Sondo P, Derra K, Rouamba T, Nakanabo Diallo S, Taconet P, Kazienga A, Ilboudo H, Tahita MC, Valéa I, Sorgho H, Lefèvre T, Tinto H. Determinants of Plasmodium falciparum multiplicity of infection and genetic diversity in Burkina Faso. Parasit Vectors 2020; 13:427. [PMID: 32819420 PMCID: PMC7441709 DOI: 10.1186/s13071-020-04302-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 08/10/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Investigating malaria transmission dynamics is essential to inform policy decision making. Whether multiplicity of infection (MOI) dynamic from individual infections could be a reliable malaria metric in high transmission settings with marked variation in seasons of malaria transmission has been poorly assessed. This study aimed at investigating factors driving Plasmodium falciparum MOI and genetic diversity in a hyperendemic area of Burkina Faso. METHODS Blood samples collected from a pharmacovigilance trial were used for polymerase chain reaction genotyping of the merozoite surface proteins 1 and 2. MOI was defined as the number of distinct parasite genotypes co-existing within a particular infection. Monthly rainfall data were obtained from satellite data of the Global Precipitation Measurement Database while monthly malaria incidence aggregated data were extracted from District Health Information Software 2 medical data of the Center-West health regional direction. RESULTS In the study area, infected people harboured an average of 2.732 (± 0.056) different parasite genotypes. A significant correlation between the monthly MOI and the monthly malaria incidence was observed, suggesting that MOI could be a good predictor of transmission intensity. A strong effect of season on MOI was observed, with infected patients harbouring higher number of parasite genotypes during the rainy season as compared to the dry season. There was a negative relationship between MOI and host age. In addition, MOI decreased with increasing parasite densities, suggesting that there was a within-host competition among co-infecting genetically distinct P. falciparum variants. Each allelic family of the msp1 and msp2 genes was present all year round with no significant monthly fluctuation. CONCLUSIONS In high malaria endemic settings with marked variation in seasons of malaria transmission, MOI represents an appropriate malaria metric which provides useful information about the longitudinal changes in malaria transmission in a given area. Besides transmission season, patient age and parasite density are important factors to consider for better understanding of variations in MOI. All allelic families of msp1 and msp2 genes were found in both dry and rainy season. The approach offers the opportunity of translating genotyping data into relevant epidemiological information for malaria control.
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Affiliation(s)
- Paul Sondo
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso.
| | - Karim Derra
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Toussaint Rouamba
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Seydou Nakanabo Diallo
- Institut National de Santé Publique/Centre Muraz de Bobo-Dioulasso, Bobo-Dioulasso, Burkina Faso
| | - Paul Taconet
- Centre de Recherche en Écologie et Évolution de la Santé (CREES), Montpellier, France
| | - Adama Kazienga
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hamidou Ilboudo
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Marc Christian Tahita
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Innocent Valéa
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
| | - Thierry Lefèvre
- Centre de Recherche en Écologie et Évolution de la Santé (CREES), Montpellier, France.,Laboratoire Mixte International sur les Vecteurs (LAMIVECT), Bobo-Dioulasso, Burkina Faso.,Institut de Recherche pour le Développement (IRD), Centre National pour la Recherche Scientifique (CNRS), Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Université de Montpellier, Montpellier, France
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé/Clinical Research Unit of Nanoro (IRSS-URCN), Nanoro, Burkina Faso
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10
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Roh ME, Tessema SK, Murphy M, Nhlabathi N, Mkhonta N, Vilakati S, Ntshalintshali N, Saini M, Maphalala G, Chen A, Wilheim J, Prach L, Gosling R, Kunene S, S Hsiang M, Greenhouse B. High Genetic Diversity of Plasmodium falciparum in the Low-Transmission Setting of the Kingdom of Eswatini. J Infect Dis 2020; 220:1346-1354. [PMID: 31190073 PMCID: PMC6743842 DOI: 10.1093/infdis/jiz305] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 06/12/2019] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND To better understand transmission dynamics, we characterized Plasmodium falciparum genetic diversity in Eswatini, where transmission is low and sustained by importation. METHODS Twenty-six P. falciparum microsatellites were genotyped in 66% of confirmed cases (2014-2016; N = 582). Population and within-host diversity were used to characterize differences between imported and locally acquired infections. Logistic regression was used to assess the added value of diversity metrics to classify imported and local infections beyond epidemiology data alone. RESULTS Parasite population in Eswatini was highly diverse (expected heterozygosity [HE] = 0.75) and complex: 67% polyclonal infections, mean multiplicity of infection (MOI) 2.2, and mean within-host infection fixation index (FWS) 0.84. Imported cases had comparable diversity to local cases but exhibited higher MOI (2.4 vs 2.0; P = .004) and lower mean FWS (0.82 vs 0.85; P = .03). Addition of MOI and FWS to multivariate analyses did not increase discrimination between imported and local infections. CONCLUSIONS In contrast to the common perception that P. falciparum diversity declines with decreasing transmission intensity, Eswatini isolates exhibited high parasite diversity consistent with high rates of malaria importation and limited local transmission. Estimates of malaria transmission intensity from genetic data need to consider the effect of importation, especially as countries near elimination.
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Affiliation(s)
- Michelle E Roh
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco.,Department of Epidemiology and Biostatistics, University of California, San Francisco
| | - Sofonias K Tessema
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco
| | - Maxwell Murphy
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco
| | | | | | | | | | - Manik Saini
- Clinton Health Access Initiative, Mbabane, Eswatini
| | | | - Anna Chen
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco
| | - Jordan Wilheim
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco
| | - Lisa Prach
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco
| | - Roly Gosling
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco.,Department of Epidemiology and Biostatistics, University of California, San Francisco
| | | | - Michelle S Hsiang
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco.,Department of Pediatrics, University of California, San Francisco.,Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas
| | - Bryan Greenhouse
- Division of HIV, Infectious Diseases, and Global Medicine, Department of Medicine, University of California, San Francisco.,Chan Zuckerberg Biohub, San Francisco, California
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11
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Impact of an Irrigation Dam on the Transmission and Diversity of Plasmodium falciparum in a Seasonal Malaria Transmission Area of Northern Ghana. J Trop Med 2020; 2020:1386587. [PMID: 32308690 PMCID: PMC7155757 DOI: 10.1155/2020/1386587] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 02/14/2020] [Indexed: 01/13/2023] Open
Abstract
Water bodies such as dams are known to alter the local transmission patterns of a number of infectious diseases, especially those transmitted by insects and other arthropod vectors. The impact of an irrigation dam on submicroscopic asexual parasite carriage in individuals living in a seasonal malaria transmission area of northern Ghana was investigated. A total of 288 archived DNA samples from two cross-sectional surveys in two communities in the Bongo District of Northern Ghana were analysed. Parasite density was determined by light microscopy and PCR, and parasite diversity was assessed by genotyping of the polymorphic Plasmodium falciparum msp2 block-3 region. Submicroscopic parasitaemia was estimated as the proportional difference between positive samples identified by PCR and microscopy. Dry season submicroscopic parasite prevalence was significantly higher (71.0%, p=0.013) at the dam site compared with the nondam site (49.2%). Similarly, wet season submicroscopic parasite prevalence was significantly higher at the dam site (54.5%, p=0.008) compared with the nondam site (33.0%). There was no difference in parasite density between sites in the dry season (p=0.90) and in the wet season (p=0.85). Multiplicity of infection (MOI) based on PCR data was significantly higher at the dam site compared with the nondam site during the dry season (p < 0.0001) but similar between sites during the wet season. MOI at the nondam site was significantly higher in the wet season than in the dry season (2.49, 1.26, p < 0.0001) but similar between seasons at the dam site. Multivariate analysis showed higher odds of carrying submicroscopic parasites at the dam site in both dry season (OR = 7.46, 95% CI = 3.07–18.15) and in wet season (OR = 1.73, 95% CI = 1.04–2.86). The study findings suggest that large water bodies impact year-round carriage of submicroscopic parasites and sustain Plasmodium transmission.
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12
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Kimenyi KM, Wamae K, Ochola-Oyier LI. Understanding P. falciparum Asymptomatic Infections: A Proposition for a Transcriptomic Approach. Front Immunol 2019; 10:2398. [PMID: 31681289 PMCID: PMC6803459 DOI: 10.3389/fimmu.2019.02398] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 09/25/2019] [Indexed: 12/11/2022] Open
Abstract
Malaria is still a significant public health burden in the tropics. Infection with malaria causing parasites results in a wide range of clinical disease presentations, from severe to uncomplicated or mild, and in the poorly understood asymptomatic infections. The complexity of asymptomatic infections is due to the intricate interplay between factors derived from the human host, parasite, and environment. Asymptomatic infections often go undetected and provide a silent natural reservoir that sustains malaria transmission. This creates a major obstacle for malaria control and elimination efforts. Numerous studies have tried to characterize asymptomatic infections, unanimously revealing that host immunity is the underlying factor in the maintenance of these infections and in the risk of developing febrile malaria infections. An in-depth understanding of how host immunity and parasite factors interact to cause malaria disease tolerance is thus required. This review primarily focuses on understanding anti-inflammatory and pro-inflammatory responses to asymptomatic infections in malaria endemic areas, to present the view that it is potentially the shift in host immunity toward an anti-inflammatory profile that maintains asymptomatic infections after multiple exposures to malaria. Conversely, symptomatic infections are skewed toward a pro-inflammatory immune profile. Moreover, we propose that these infections can be better interrogated using next generation sequencing technologies, in particular RNA sequencing (RNA-seq), to investigate the immune system using the transcriptome sampled during a clearly defined asymptomatic infection.
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Affiliation(s)
- Kelvin M Kimenyi
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya.,Centre for Biotechnology and Bioinformatics, University of Nairobi, Nairobi, Kenya
| | - Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya
| | - Lynette Isabella Ochola-Oyier
- KEMRI-Wellcome Trust Research Programme, CGMRC, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
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13
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Tawe L, Menegon M, Ramatlho P, Muthoga CW, Mutukwa N, Vurayai M, Bothudile W, Motshoge T, L'Episcopia M, Mosweunyane T, Kasvosve I, Severini C, Paganotti GM. Molecular Surveillance of Plasmodium falciparum Drug Resistance Markers in Clinical Samples from Botswana. Am J Trop Med Hyg 2019; 99:1499-1503. [PMID: 30350774 DOI: 10.4269/ajtmh.18-0440] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Drug-resistant Plasmodium falciparum is a major threat to global malaria control and elimination efforts. In Botswana, a southern African country approaching malaria elimination, P. falciparum molecular data are not available. Parasites were assessed through pollymerase chain reaction (PCR) for confirmation of positive rapid diagnostic tests, multiplicity of infection (MOI), and drug resistance markers among isolates from clinical uncomplicated malaria cases collected at health facilities. Of 211 dried blood spot samples selected for the study, 186 (88.2%) were PCR positive for P. falciparum. The mean MOI based on MSP1 genotyping was 2.3 and was not associated with age. A high prevalence of wild-type parasites for pfcrt and pfmdr1 was found, with a haplotype frequency (K76/N86) of 88.8% and 17.7% of the isolates having two copies of the pfmdr1 gene. For pfATPase6, all the parasites carried the wild-type S769 allele. Sequencing showed no evidence of non-synonymous mutations associated with reduced artemisinin derivative sensitivity in the P. falciparum k13 gene. In conclusion, we found that P. falciparum parasites in Botswana were mostly wild type for the drug resistance markers evaluated. Yet, there was a high rate of a molecular marker associated to reduced sensitivity to lumefantrine. Our results indicate the need for systematic drug efficacy surveillance to complement malaria elimination efforts.
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Affiliation(s)
- Leabaneng Tawe
- Sub-Saharan African Network for TB/HIV Research Excellence (SANTHE) at Botswana-Harvard Partnership, Gaborone, Botswana.,Botswana-University of Pennsylvania Partnership, Gaborone, Botswana.,Department of Medical Laboratory Sciences, University of Botswana, Gaborone, Botswana
| | - Michela Menegon
- Department of Infectious Diseases, Istituto Superiore di Sanita', Rome, Italy
| | - Pleasure Ramatlho
- Department of Biological Sciences, University of Botswana, Gaborone, Botswana
| | | | - Naledi Mutukwa
- Department of Pathology, University of Botswana, Gaborone, Botswana
| | - Moses Vurayai
- National Health Laboratory, Department of Microbiology, Gaborone, Botswana
| | - Wame Bothudile
- Department of Medical Laboratory Sciences, University of Botswana, Gaborone, Botswana
| | - Thato Motshoge
- Department of Biological Sciences, University of Botswana, Gaborone, Botswana
| | | | | | - Ishmael Kasvosve
- Department of Medical Laboratory Sciences, University of Botswana, Gaborone, Botswana
| | - Carlo Severini
- Department of Infectious Diseases, Istituto Superiore di Sanita', Rome, Italy
| | - Giacomo M Paganotti
- Department of Biomedical Sciences, University of Botswana, Gaborone, Botswana.,Botswana-University of Pennsylvania Partnership, Gaborone, Botswana.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
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14
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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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15
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Low genetic diversity and complexity of submicroscopic Plasmodium falciparum infections among febrile patients in low transmission areas in Senegal. PLoS One 2019; 14:e0215755. [PMID: 31022221 PMCID: PMC6483351 DOI: 10.1371/journal.pone.0215755] [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: 11/19/2018] [Accepted: 04/08/2019] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION Submicroscopic Plasmodium infections are common in malaria endemic countries, but very little studies have been done in Senegal. This study investigates the genetic diversity and complexity of submicroscopic P. falciparum infections among febrile patients in low transmission areas in Senegal. MATERIALS AND METHODS Hundred and fifty blood samples were collected from febrile individuals living in Dielmo and Ndiop (Senegal) between August 2014 and January 2015, tested for microscopic and sub-microscopic P. falciparum infections and characterized for their genetic diversity and complexity of infections using msp-1 and msp-2 genotyping. RESULTS Submicroscopic P. falciparum infections were 19.6% and 25% in Dielmo and Ndiop, respectively. K1 and 3D7 were the predominant msp-1 and msp-2 allelic types with respective frequencies of 67.36% and 67.10% in microscopic isolates and 58.24% and 78% in submicroscopic ones. Frequencies of msp-1 allelic types were statistically comparable between the studied groups (p>0.05), and were respectively 93.54% vs 87.5% for K1, 60% vs 54.83% for MAD20 and 41.93% vs 22.5% for RO33 while frequencies of msp-2 allelic types were significantly highest in the microscopy group for FC27 (41.93% vs 10%, Fisher's Exact Test, p = 0.001) and 3D7 (61.29% vs 32.5%, Fisher's Exact Test, p = 0.02). Multiplicities of infection were lowest in submicroscopic P. falciparum isolates. CONCLUSIONS The study revealed a high submicroscopic P. falciparum carriage among patients in the study areas, and that submicroscopic P. falciparum isolates had a lower genetic diversity and complexity of malaria infections.
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16
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Deku JG, Lokpo SY, Kye-Amoah KK, Orish VN, Ussher FA, Esson J, Aduko RA, Dakorah MP, Osei-Yeboah J. Malaria Burden and Trend Among Clients Seeking Healthcare in the Western Region: A 4-Year Retrospective Study at the Sefwi-Wiawso Municipal Hospital, Ghana. Open Microbiol J 2018. [DOI: 10.2174/1874285801812010404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Background:
Malaria cases continue to rise despite sustained efforts directed at eliminating the burden among Ghanaians. This study was aimed at describing the spectrum of malaria burden in a four-year (2013-2016) retrospective review among clients seeking care at the Sefwi-Wiawso Municipal Hospital in the Western Region of Ghana.
Materials and Methods:
The study analyzed secondary data extracted on 32,629 patients who were referred to the Laboratory for malaria testing from January 2013 to December 2016. Socio-demographic data included age and gender, department of test requisition and malaria results were obtained from the archived Daily Malaria Logbook records. Approval for the study was granted by the authorities of the Sefwi-Wiawso Municipal Hospital.
Results:
The overall confirmed malaria case was 8629 (26.5%), among under five 1,384 (58.7%), pregnant women 4451 (20.3%) and 14.1% among asymptomatic population. Significant gender disparity in the confirmation of suspected malaria cases was observed with males recording higher rate (45.8%) than females (36.7%). The peak of the malaria epidemic was observed in the wet season (195 cases per month), compared to the dry season (133 cases per month).
Conclusion:
Cases of malaria is increasing with high rates among vulnerable groups in the Western Region. There is the need to intensify efforts to reduce the burden in the study area especially among vulnerable groups.
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17
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Lamptey H, Ofori MF, Kusi KA, Adu B, Owusu-Yeboa E, Kyei-Baafour E, Arku AT, Bosomprah S, Alifrangis M, Quakyi IA. The prevalence of submicroscopic Plasmodium falciparum gametocyte carriage and multiplicity of infection in children, pregnant women and adults in a low malaria transmission area in Southern Ghana. Malar J 2018; 17:331. [PMID: 30223841 PMCID: PMC6142636 DOI: 10.1186/s12936-018-2479-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 09/10/2018] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND The gametocyte stage of Plasmodium falciparum is considered an important target for disrupting malaria transmission. Indications are that various demographic groups, such as children and pregnant women may differ in risk of harbouring gametocytes, which may be crucial for targeted control. In this study, the relationship between the prevalence and multiplicity of P. falciparum, asexual parasite infections and gametocytaemia was assessed in three different demographic groups in an area of southern Ghana with low malaria endemicity. Levels of antibody responses to Pfs230 were also assessed as a proxy for the presence of gametocytes. METHODS The study involved multiple cross-sectional sampling of children (N = 184, aged 2-15 years), male and non-pregnant female adults (N = 154, aged 16-65 years) and pregnant women (N = 125, aged 18-45 years) from Asutsuare in the Shai Osudoku District of Greater Accra Region in Ghana. Asexual parasitaemia was detected by microscopy and PCR, and gametocytaemia was assessed by Pfs25-real time PCR. Multiclonal P. falciparum infections were estimated by msp2 genotyping and an indirect ELISA was used to measure plasma IgG antibodies to Pfs230 antigen. RESULTS Overall, children and pregnant women had higher prevalence of submicroscopic gametocytes (39.5% and 29.7%, respectively) compared to adults (17.4%). Multiplicity of infection observed amongst children (3.1) and pregnant women (3.9) were found to be significantly higher (P = 0.006) compared with adults (2.7). Risk of gametocyte carriage was higher in individuals infected with P. falciparum having both Pfmsp2 3D7 and FC27 parasite types (OR = 5.92, 95% CI 1.56-22.54, P = 0.009) compared with those infected with only 3D7 or FC27 parasite types. In agreement with the parasite prevalence data, anti-Pfs230 antibody levels were lower in gametocyte positive adults (β = - 0.57, 95% CI - 0.81, - 0.34, P < 0.001) compared to children. CONCLUSIONS These findings suggest that children and pregnant women are particularly important as P. falciparum submicroscopic gametocyte reservoirs and represent important focus groups for control interventions. The number of clones increased in individuals carrying gametocytes compared to those who did not carry gametocytes. The higher anti-gametocyte antibody levels in children suggests recent exposure and may be a marker of gametocyte carriage.
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Affiliation(s)
- Helena Lamptey
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana.
| | - Michael Fokuo Ofori
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Kwadwo Asamoah Kusi
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Bright Adu
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Eunice Owusu-Yeboa
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Eric Kyei-Baafour
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Andrea Twumwaa Arku
- Immunology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Samuel Bosomprah
- Department of Biostatistics, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Michael Alifrangis
- Centre for Medical Parasitology, Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
- Department of Infectious Disease, National University Hospital (Rigshospitalet), Copenhagen, Denmark
| | - Isabella A Quakyi
- Department of Biological, Environmental and Occupational Health Sciences, School of Public Health, College of Health Sciences, University of Ghana, Legon, Ghana
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18
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Seasonal variations in Plasmodium falciparum genetic diversity and multiplicity of infection in asymptomatic children living in southern Ghana. BMC Infect Dis 2018; 18:432. [PMID: 30157794 PMCID: PMC6114730 DOI: 10.1186/s12879-018-3350-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 08/21/2018] [Indexed: 11/11/2022] Open
Abstract
Background Genetic diversity in Plasmodium falciparum (P. falciparum) parasites is a major hurdle to the control of malaria. This study monitored changes in the genetic diversity and the multiplicity of P. falciparum parasite infection in asymptomatic children living in southern Ghana at 3 month intervals between April 2015 and January 2016. Methods Filter paper blood spots (DBS) were collected quarterly from children living in Obom, a community with perennial malaria transmission and Abura, a community with seasonal malaria transmission. Genomic DNA was extracted from the DBS and used in polymerase chain reaction (PCR)-based genotyping of the merozoite surface protein 1 (msp 1) and merozoite surface protein 2 (msp 2) genes. Results Out of a total of 787 samples that were collected from the two study sites, 59.2% (466/787) tested positive for P. falciparum. The msp 1 and msp 2 genes were successfully amplified from 73.8% (344/466) and 82.5% (385/466) of the P. falciparum positive samples respectively. The geometric mean MOI in Abura ranged between 1.17 (95% CI: 1.08–1.28) and 1.48 (95% CI: 1.36–1.60) and was significantly lower (p < 0.01, Dunn’s multiple comparison test) than that determined in Obom, where the geometric mean MOI ranged between 1.82 (95% CI: 1.58–2.08) and 2.50 (95% CI: 2.33–2.678) over the study period. Whilst the msp 1 R033:MAD20:KI allelic family ratio was dynamic, the msp 2 3D7:FC27 allelic family ratio remained relatively stable across the changing seasons in both sites. Conclusions This study shows that seasonal variations in parasite diversity in these communities can be better estimated by msp 1 rather than msp 2 due to the constantly changing relative intra allelic frequencies observed in msp 1 and the fact that the dominance of any msp 2 allele was dependent on the transmission setting but not on the season as opposed to the dominance of any msp 1 allele, which was dependent on both the season and the transmission setting. Electronic supplementary material The online version of this article (10.1186/s12879-018-3350-z) contains supplementary material, which is available to authorized users.
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Huang B, Tuo F, Liang Y, Wu W, Wu G, Huang S, Zhong Q, Su XZ, Zhang H, Li M, Bacar A, Abdallah KS, Mliva AMSA, Wang Q, Yang Z, Zheng S, Xu Q, Song J, Deng C. Temporal changes in genetic diversity of msp-1, msp-2, and msp-3 in Plasmodium falciparum isolates from Grande Comore Island after introduction of ACT. Malar J 2018; 17:83. [PMID: 29458365 PMCID: PMC5819244 DOI: 10.1186/s12936-018-2227-3] [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: 10/10/2017] [Accepted: 02/08/2018] [Indexed: 11/26/2022] Open
Abstract
Background Malaria is still one of the serious public health problems in Grande Comore Island, although the number of annual cases has been greatly reduced in recent years. A better understanding of malaria parasite population diversity and transmission dynamics is critical for assessing the effectiveness of malaria control measures. The objective of this study is to investigate temporal changes in genetic diversity of Plasmodium falciparum populations and multiplicity of infection (MOI) in Grande Comore 10 years after introduction of ACT. Methods A total of 232 P. falciparum clinical isolates were collected from the Grande Comore Island during two sampling periods (118 for 2006‒2007 group, and 114 for 2013‒2016 group). Parasite isolates were characterized for genetic diversity and complexity of infection by genotyping polymorphic regions in merozoite surface protein gene 1 (msp-1), msp-2, and msp-3 using nested PCR and DNA sequencing. Results Three msp-1 alleles (K1, MAD20, and RO33), two msp-2 alleles (FC27 and 3D7), and two msp-3 alleles (K1 and 3D7) were detected in parasites of both sampling periods. The RO33 allele of msp-1 (84.8%), 3D7 allele of msp-2 (90.8%), and K1 allele of msp-3 (66.7%) were the predominant allelic types in isolates from 2006–2007 group. In contrast, the RO33 allele of msp-1 (63.4%), FC27 allele of msp-2 (91.1%), and 3D7 allele of msp-3 (53.5%) were the most prevalent among isolates from the 2013–2016 group. Compared with the 2006‒2007 group, polyclonal infection rates of msp-1 (from 76.7 to 29.1%, P < 0.01) and msp-2 (from 62.4 to 28.3%, P < 0.01) allelic types were significantly decreased in those from 2013‒2016 group. Similarly, the MOIs for both msp-1 and msp-2 were higher in P. falciparum isolates in the 2006–2007 group than those in 2013–2016 group (MOI = 3.11 vs 1.63 for msp-1; MOI = 2.75 vs 1.35 for msp-2). DNA sequencing analyses also revealed reduced numbers of distinct sequence variants in the three genes from 2006‒2007 to 2013‒2016: msp-1, from 32 to 23 (about 28% decline); msp-2 from 29 to 21 (about 28% decline), and msp-3 from 11 to 3 (about 72% decline). Conclusions The present data showed dramatic reduction in genetic diversity and MOI among Grande Comore P. falciparum populations over the course of the study, suggesting a trend of decreasing malaria transmission intensity and genetic diversity in Grande Comore Island. These data provide valuable information for surveillance of P. falciparum infection and for assessing the appropriateness of the current malarial control strategies in the endemic area.
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Affiliation(s)
- Bo Huang
- Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, Guangdong, People's Republic of China.,Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Fei Tuo
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Yuan Liang
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Wanting Wu
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Guangchao Wu
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Shiguang Huang
- School of Stomatology, Jinan University, Guangzhou, 510632, Guangdong, People's Republic of China
| | - Qirun Zhong
- Artepharm, Co., Ltd, Guangzhou, 510405, Guangdong, People's Republic of China
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Hongying Zhang
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Mingqiang Li
- Artepharm, Co., Ltd, Guangzhou, 510405, Guangdong, People's Republic of China
| | - Affane Bacar
- National Malaria Control Programme, BP 500, Moroni, Comoros
| | | | | | - Qi Wang
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Zhaoli Yang
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Shaoqin Zheng
- Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China
| | - Qin Xu
- Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, Guangdong, People's Republic of China
| | - Jianping Song
- Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, Guangdong, People's Republic of China. .,Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China.
| | - Changsheng Deng
- Institute of Tropical Medicine, Guangzhou University of Chinese Medicine, Guangzhou, 510006, Guangdong, People's Republic of China. .,Science and Technology Park, Guangzhou University of Chinese Medicine, Guangzhou, 510445, Guangdong, People's Republic of China.
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20
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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: 33] [Impact Index Per Article: 4.7] [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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21
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Kusi KA, Manu EA, Manful Gwira T, Kyei-Baafour E, Dickson EK, Amponsah JA, Remarque EJ, Faber BW, Kocken CHM, Dodoo D, Gyan BA, Awandare GA, Atuguba F, Oduro AR, Koram KA. Variations in the quality of malaria-specific antibodies with transmission intensity in a seasonal malaria transmission area of Northern Ghana. PLoS One 2017; 12:e0185303. [PMID: 28945794 PMCID: PMC5612719 DOI: 10.1371/journal.pone.0185303] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Accepted: 09/11/2017] [Indexed: 02/07/2023] Open
Abstract
Introduction Plasmodium falciparum induced antibodies are key components of anti-malarial immunity in malaria endemic areas, but their antigen targets can be polymorphic. Induction of a high proportion of strain-specific antibodies will limit the recognition of a broad diversity of parasite strains by these responses. There are indications that circulating parasite diversity varies with malaria transmission intensity, and this may affect the specificity of elicited anti-malarial antibodies. This study therefore assessed the effect of varying malaria transmission patterns on the specificity of elicited antibody responses and to identify possible antibody correlates of naturally acquired immunity to malaria in children in an area of Ghana with seasonal malaria transmission. Methods This retrospective study utilized plasma samples collected longitudinally at six time points from children aged one to five years. Multiplex assays were used to measure antibody levels against four P. falciparum AMA 1 variants (from the 3D7, FVO, HB3 and CAMP parasite strains) and the 3D7 variant of the EBA 175 region II antigen and the levels compared between symptomatic and asymptomatic children. The relative proportions of cross-reactive and strain-specific antibodies against the four AMA 1 variants per sampling time point were assessed by Bland-Altman plots. The levels of antibodies against allelic AMA1 variants, measured by singleplex and multiplex luminex assays, were also compared. Results The data show that increased transmission intensity is associated with higher levels of cross-reactive antibody responses, most likely a result of a greater proportion of multiple parasite clone infections during the high transmission period. Anti-AMA1 antibodies were however associated with a history of infection rather than protection in this age group. Conclusion The data contribute to understanding the underlying mechanism of the acquisition of strain-transcending antibody immunity following repeated exposure to diverse parasite strains.
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Affiliation(s)
- Kwadwo A. Kusi
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- * E-mail:
| | - Emmanuel A. Manu
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Theresa Manful Gwira
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Eric Kyei-Baafour
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Emmanuel K. Dickson
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Jones A. Amponsah
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Edmond J. Remarque
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Bart W. Faber
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Clemens H. M. Kocken
- Department of Parasitology, Biomedical Primate Research Centre, Rijswijk, The Netherlands
| | - Daniel Dodoo
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Ben A. Gyan
- Department of Immunology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
| | - Gordon A. Awandare
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
| | - Frank Atuguba
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Abraham R. Oduro
- Navrongo Health Research Centre, Ghana Health Service, Navrongo, Ghana
| | - Kwadwo A. Koram
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Ghana
- Department of Epidemiology, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Legon, Ghana
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22
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Amoah LE, Nuvor SV, Obboh EK, Acquah FK, Asare K, Singh SK, Boampong JN, Theisen M, Williamson KC. Natural antibody responses to Plasmodium falciparum MSP3 and GLURP(R0) antigens are associated with low parasite densities in malaria patients living in the Central Region of Ghana. Parasit Vectors 2017; 10:395. [PMID: 28835262 PMCID: PMC5569498 DOI: 10.1186/s13071-017-2338-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/16/2017] [Indexed: 12/20/2022] Open
Abstract
Background Plasmodium falciparum genetic diversity and multiplicity of infection (MOI) are parasite features that have been suggested to influence the acquisition of protective immunity against malaria. This study sought to assess the relationship between MOI and parasite density (PD) in malaria patients living in the Central Region of Ghana and to determine whether naturally occurring antibody levels against P. falciparum GLURP (PF3D7_1035300) and MSP3 (PF3D7_1035400) antigens are associated with decreased parasite load. Methods Dried filter paper blood blots were obtained from children and adults diagnosed with uncomplicated P. falciparum malaria. Microscopy was used to estimate P. falciparum parasite density and polymerase chain reaction (PCR) amplification of the polymorphic regions of msp1 (PF3D7_0930300) and msp2 (PF3D7_0206800) was used for parasite genotyping and MOI determination. ELISA was used to measure the serum IgG concentration of R0 fragment of GLURP (GLURP(R0)) and MSP3 antibodies. Results All 115 samples were positive for P. falciparum by PCR using either the msp1 or msp2 genotyping primer sets. The most prevalent msp1 and msp2 alleles were KI and 3D7, respectively. The geometric mean (GM) for MOI determined by both msp1 and msp2 genotyping was 1.3 for the entire population and was generally higher in children than in adults. Seropositivity was estimated at 67 and 63% for GLURP(R0) and MSP3 antibodies, respectively, and antibody titers were negatively correlated with parasite density. Conclusions The negative correlation between naturally occurring GLURP(R0) and MSP3 antibody levels and parasite density observed in this study suggest that augmenting the antibody response with the GMZ2 vaccine could enhance protection in the Central Region of Ghana. Electronic supplementary material The online version of this article (doi:10.1186/s13071-017-2338-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- L E Amoah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
| | - S V Nuvor
- Department of Microbiology and Immunology, School of Medical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - E K Obboh
- School of Medical Sciences University of Cape Coast, Cape Coast, Ghana
| | - F K Acquah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - K Asare
- Department of Biomedical Sciences University of Cape Coast, Cape Coast, Ghana
| | - S K Singh
- Department for Congenital disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - J N Boampong
- Department of Biomedical Sciences University of Cape Coast, Cape Coast, Ghana
| | - M Theisen
- Department for Congenital disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology, Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark.,Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - K C Williamson
- Loyola University Chicago, Chicago, IL, USA.,Uniform Services University of the Health Sciences, Bethesda, MD, USA
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23
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Botwe AK, Asante KP, Adjei G, Assafuah S, Dosoo D, Owusu-Agyei S. Dynamics in multiplicity of Plasmodium falciparum infection among children with asymptomatic malaria in central Ghana. BMC Genet 2017; 18:67. [PMID: 28716086 PMCID: PMC5514501 DOI: 10.1186/s12863-017-0536-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 07/11/2017] [Indexed: 12/18/2022] Open
Abstract
Background The determinants of malaria parasite virulence is not entirely known, but the outcome of malaria infection (asymptomatic or symptomatic) has been associated with carriage of distinct parasite genotypes. Alleles considered important for erythrocyte invasion and selected as candidate targets for malaria vaccine development are increasingly being shown to have distinct characteristics in infection outcomes. Any unique/distinct patterns or alleles linked to infection outcome should be reproducible for a given malaria-cohort regardless of location, time or intervention. This study compared merozoite surface protein 2 (MSP2) genotypes from children with asymptomatic malaria at same geographical location, from two time periods. Results As the prevalence and incidence of malaria (measured for other studies) significantly reduced between 2004 (time point one) and 2009 (time point two), MSP2 multiplicity of infections (MOI) also reduced significantly from 2.3 at time point (TP) one to 1.9 at TP two. IC/3D7 genotypes out-numbered FC27 genotypes at both time points. At TP2 however, FC27 allele diversity was more than the IC/3D7 allele diversity. A decrease in the IC/3D7:FC27 genotype proportions from 2:1 at TP1 to 1:1 at TP2, seemed to be driven mainly by a decrease in carriage of IC/3D7 alleles. MOI was higher in the dry season than in the subsequent wet season, but the decrease was not significant at TP2. Conclusion MSP2 MOI was higher in the dry season than in the subsequent wet season, while the carriage of IC/3D7 alleles decreased over this time period. It may be that decreases in transmission are related specifically to the IC/3D7 allelic family. The influence of transmission on MSP2 allele diversity needs to be clearly deciphered in studies which should include the use of sensitive methods for the detection of polymorphic parasite markers for both symptomatic and asymptomatic malaria. Such studies will enable better understanding of associations between allelic variants, MOI, transmission, malaria infection and disease.
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Affiliation(s)
- Akua Kyerewaa Botwe
- Ghana Health Service. Health Research Unit, Kintampo Health Research Centre. MOH/GHS, P.O.Box 200, College of Health Street, Kintampo, Brong Ahafo, Ghana. .,Department of Medicine, Solna, Karolinska Institutet, Stockholm, 17176, Sverige, Sweden.
| | - Kwaku Poku Asante
- Ghana Health Service. Health Research Unit, Kintampo Health Research Centre. MOH/GHS, P.O.Box 200, College of Health Street, Kintampo, Brong Ahafo, Ghana
| | - George Adjei
- Ghana Health Service. Health Research Unit, Kintampo Health Research Centre. MOH/GHS, P.O.Box 200, College of Health Street, Kintampo, Brong Ahafo, Ghana
| | - Samuel Assafuah
- Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - David Dosoo
- Ghana Health Service. Health Research Unit, Kintampo Health Research Centre. MOH/GHS, P.O.Box 200, College of Health Street, Kintampo, Brong Ahafo, Ghana
| | - Seth Owusu-Agyei
- Ghana Health Service. Health Research Unit, Kintampo Health Research Centre. MOH/GHS, P.O.Box 200, College of Health Street, Kintampo, Brong Ahafo, Ghana
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24
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Niang M, Thiam LG, Loucoubar C, Sow A, Sadio BD, Diallo M, Sall AA, Toure-Balde A. Spatio-temporal analysis of the genetic diversity and complexity of Plasmodium falciparum infections in Kedougou, southeastern Senegal. Parasit Vectors 2017; 10:33. [PMID: 28103905 PMCID: PMC5244544 DOI: 10.1186/s13071-017-1976-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 01/10/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic analyses of the malaria parasite population and its temporal and spatial dynamics could provide an assessment of the effectiveness of disease control strategies. The genetic diversity of Plasmodium falciparum has been poorly documented in Senegal, and limited data are available from the Kedougou Region. This study examines the spatial and temporal variation of the genetic diversity and complexity of P. falciparum infections in acute febrile patients in Kedougou, southeastern Senegal. A total of 263 sera from patients presenting with acute febrile illness and attending Kedougou health facilities between July 2009 and July 2013 were obtained from a collection established as part of arbovirus surveillance in Kedougou. Samples identified as P. falciparum by nested PCR were characterized for their genetic diversity and complexity using msp-1 and msp-2 polymorphic markers. RESULTS Samples containing only P. falciparum accounted for 60.83% (160/263) of the examined samples. All three msp-1 allelic families (K1, MAD20 and RO33) and two msp-2 allelic families (FC27 and 3D7) were detected in all villages investigated over the 5-year collection period. The average genotype per allelic family was comparable between villages. Frequencies of msp-1 and msp-2 allelic types showed no correlation with age (Fisher's exact test, P = 0.59) or gender (Fisher's exact test, P = 0.973), and were similarly distributed throughout the 5-year sampling period (Fisher's exact test, P = 0.412) and across villages (Fisher's exact test, P = 0.866). Mean multiplicity of infection (MOI) for both msp-1 and msp-2 was highest in Kedougou village (2.25 and 2.21, respectively) and among younger patients aged ≤ 15 years (2.12 and 2.00, respectively). The mean MOI was highest in 2009 and decreased progressively onward. CONCLUSION Characterization of the genetic diversity and complexity of P. falciparum infections in Kedougou revealed no spatio-temporal variation in the genetic diversity of P. falciparum isolates. However, mean MOI varied with time of sera collection and decreased over the course of the study (July 2009 to July 2013). This suggests a slow progressive decrease of malaria transmission intensity in Kedougou Region despite the limited impact of preventive and control measures implemented by the National Malaria Control Programme on malaria morbidity and mortality.
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Affiliation(s)
- Makhtar Niang
- Institut Pasteur Dakar, Immunology Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal.
| | - Laty G Thiam
- Institut Pasteur Dakar, Immunology Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal.,Department of Animal Biology, Cheikh Anta Diop University of Dakar, Dakar, Senegal
| | - Cheikh Loucoubar
- Institut Pasteur Dakar, Biostatistics, Bioinformatics and Modeling Group, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Abdourahmane Sow
- Institut Pasteur Dakar, Arbovirus and Viral Hemorrhagic Fevers Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Bacary D Sadio
- Institut Pasteur Dakar, Arbovirus and Viral Hemorrhagic Fevers Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Mawlouth Diallo
- Institut Pasteur Dakar, Medical Entomology Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Amadou A Sall
- Institut Pasteur Dakar, Arbovirus and Viral Hemorrhagic Fevers Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal
| | - Aissatou Toure-Balde
- Institut Pasteur Dakar, Immunology Unit, 36 Avenue Pasteur, BP 220, Dakar, Senegal
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25
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Chang HH, Worby CJ, Yeka A, Nankabirwa J, Kamya MR, Staedke SG, Dorsey G, Murphy M, Neafsey DE, Jeffreys AE, Hubbart C, Rockett KA, Amato R, Kwiatkowski DP, Buckee CO, Greenhouse B. THE REAL McCOIL: A method for the concurrent estimation of the complexity of infection and SNP allele frequency for malaria parasites. PLoS Comput Biol 2017; 13:e1005348. [PMID: 28125584 PMCID: PMC5300274 DOI: 10.1371/journal.pcbi.1005348] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 02/09/2017] [Accepted: 01/05/2017] [Indexed: 12/24/2022] Open
Abstract
As many malaria-endemic countries move towards elimination of Plasmodium falciparum, the most virulent human malaria parasite, effective tools for monitoring malaria epidemiology are urgent priorities. P. falciparum population genetic approaches offer promising tools for understanding transmission and spread of the disease, but a high prevalence of multi-clone or polygenomic infections can render estimation of even the most basic parameters, such as allele frequencies, challenging. A previous method, COIL, was developed to estimate complexity of infection (COI) from single nucleotide polymorphism (SNP) data, but relies on monogenomic infections to estimate allele frequencies or requires external allele frequency data which may not available. Estimates limited to monogenomic infections may not be representative, however, and when the average COI is high, they can be difficult or impossible to obtain. Therefore, we developed THE REAL McCOIL, Turning HEterozygous SNP data into Robust Estimates of ALelle frequency, via Markov chain Monte Carlo, and Complexity Of Infection using Likelihood, to incorporate polygenomic samples and simultaneously estimate allele frequency and COI. This approach was tested via simulations then applied to SNP data from cross-sectional surveys performed in three Ugandan sites with varying malaria transmission. We show that THE REAL McCOIL consistently outperforms COIL on simulated data, particularly when most infections are polygenomic. Using field data we show that, unlike with COIL, we can distinguish epidemiologically relevant differences in COI between and within these sites. Surprisingly, for example, we estimated high average COI in a peri-urban subregion with lower transmission intensity, suggesting that many of these cases were imported from surrounding regions with higher transmission intensity. THE REAL McCOIL therefore provides a robust tool for understanding the molecular epidemiology of malaria across transmission settings.
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Affiliation(s)
- Hsiao-Han Chang
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Colin J. Worby
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Adoke Yeka
- Makerere University School of Public Health, College of Health Sciences, Kampala, Uganda
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Joaniter Nankabirwa
- Infectious Disease Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Moses R. Kamya
- Infectious Disease Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Sarah G. Staedke
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States
| | - Maxwell Murphy
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States
| | - Daniel E. Neafsey
- Genome Sequencing and Analysis Program, Broad Institute, Cambridge, Massachusetts, United States
| | - Anna E. Jeffreys
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Christina Hubbart
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Kirk A. Rockett
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Roberto Amato
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Dominic P. Kwiatkowski
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Caroline O. Buckee
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, United States
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, California, United States
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Ayanful-Torgby R, Oppong A, Abankwa J, Acquah F, Williamson KC, Amoah LE. Plasmodium falciparum genotype and gametocyte prevalence in children with uncomplicated malaria in coastal Ghana. Malar J 2016; 15:592. [PMID: 27938356 PMCID: PMC5148883 DOI: 10.1186/s12936-016-1640-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 11/25/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum gametocytes are vital to sustaining malaria transmission. Parasite densities, multiplicity of infection as well as asexual genotype are features that have been found to influence gametocyte production. Measurements of the prevalence of Plasmodium sp. gametocytes may serve as a tool to monitor the success of malaria eradication efforts. METHODS Whole blood was collected from 112 children aged between 6 months and 13 years with uncomplicated P. falciparum malaria attending three health facilities in southern Ghana from June to August, 2014 before (day 0) and 4 days after completion of anti-malaria drug treatment (day 7). Malaria parasites were observed by microscopy and polymerase chain reaction (PCR); submicroscopic gametocyte carriage was measured by a Pfs25 (PF3D7_1031000) mRNA real time reverse transcriptase polymerase chain reaction (RT-PCR). Parasite genotyping was performed on gDNA extracted from dried filter paper blood blots by amplification of the polymorphic regions of msp1 (PF3D7_0930300) and msp2 (PF3D7_0206800) using PCR. RESULTS Microscopy estimated 3.1% (3/96) of the total population to carry gametocytes on day 0, which decreased to 2.1% (2/96) on day 7. In contrast, reverse transcriptase-real time PCR (RT-PCR) analysis of a subset of 35 samples estimated submicroscopic gametocyte carriage to be as high as 77% (27/35) using primers specific for Pfs25 (CT < 35) on day 0 and by day 7 this only declined to 60% (21/35). Genotyping the msp2 gene identified higher levels of MOI than the msp1 gene. CONCLUSIONS Although below detection by microscopy, gametocyte prevalence at submicroscopic levels are high in this region and emphasize the need for more effective elimination approaches like the development of transmission-blocking vaccines and safer gametocytocidal drugs.
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Affiliation(s)
- Ruth Ayanful-Torgby
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Akua Oppong
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joana Abankwa
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Festus Acquah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | | | - Linda Eva Amoah
- Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana.
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Duah NO, Matrevi SA, Quashie NB, Abuaku B, Koram KA. Genetic diversity of Plasmodium falciparum isolates from uncomplicated malaria cases in Ghana over a decade. Parasit Vectors 2016; 9:416. [PMID: 27460474 PMCID: PMC4962487 DOI: 10.1186/s13071-016-1692-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 07/11/2016] [Indexed: 11/11/2022] Open
Abstract
Background Genotyping malaria parasites to assess their diversity in different geographic settings have become necessary for the selection of antigenic epitopes for vaccine development and for antimalarial drug efficacy or resistance investigations. This study describes the genetic diversity of Plasmodium falciparum isolates from uncomplicated malaria cases over a ten year period (2003–2013) in Ghana using the polymorphic antigenic marker, merozoite surface protein 2 (msp2). Methods Archived filter paper blood blots from children aged nine years and below with uncomplicated malaria collected from nine sites in Ghana were typed for the presence of the markers. A total of 880 samples were genotyped for msp2 for the two major allelic families, FC27 and 3D7, using nested polymerase chain reaction (PCR). The allele frequencies and the multiplicity of infection were determined for the nine sites for five time points over a period of ten years, 2003–2004, 2005–2006, 2007–2008, 2010 and 2012–2013 malaria transmission seasons. Results The number of different alleles detected for the msp2 gene by resolving PCR products on agarose gels was 14. Both of the major allelic families, 3D7 and FC27 were common in all population samples. The highest multiplicity of infection (MOI) was observed in isolates from Begoro (forest zone, rural site): 3.31 for the time point 2007–2008. A significant variation was observed among the sites in the MOIs detected per infection (Fisher's exact test, P < 0.001) for the 2007 isolates and also at each of the three sites with data for three different years, Hohoe, P = 0.03; Navrongo, P < 0.001; Cape Coast, P < 0.001. Overall, there was no significant difference between the MOIs of the three ecological zones over the years (P = 0.37) and between the time points when data from all sites were pooled (P = 0.40). Conclusions The diversity and variation between isolates detected using the msp2 gene in Ghanaian isolates were observed to be profound; however, there was homogeneity throughout the three ecological zones studied. This is indicative of gene flow between the parasite populations across the country probably due to human population movements (HPM). Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1692-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nancy O Duah
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG581, Legon, Ghana.
| | - Sena A Matrevi
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG581, Legon, Ghana
| | - Neils B Quashie
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG581, Legon, Ghana.,Centre for Tropical Clinical Pharmacology and Therapeutics, School of Medicine and Dentistry, College of Health Sciences, University of Ghana, P. O. Box GP 4260, Accra, Ghana
| | - Benjamin Abuaku
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG581, Legon, Ghana
| | - Kwadwo A Koram
- Epidemiology Department, Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, P. O. Box LG581, Legon, Ghana
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28
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Kateera F, Nsobya SL, Tukwasibwe S, Mens PF, Hakizimana E, Grobusch MP, Mutesa L, Kumar N, van Vugt M. Malaria case clinical profiles and Plasmodium falciparum parasite genetic diversity: a cross sectional survey at two sites of different malaria transmission intensities in Rwanda. Malar J 2016; 15:237. [PMID: 27113354 PMCID: PMC4845397 DOI: 10.1186/s12936-016-1287-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 04/13/2016] [Indexed: 11/10/2022] Open
Abstract
Background Malaria remains a public health challenge in sub-Saharan Africa with Plasmodiumfalciparum being the principal cause of malaria disease morbidity and mortality. Plasmodium falciparum virulence is attributed, in part, to its population-level genetic diversity—a characteristic that has yet to be studied in Rwanda. Characterizing P. falciparum molecular epidemiology in an area is needed for a better understand of malaria transmission and to inform choice of malaria control strategies. Methods In this health-facility based survey, malaria case clinical profiles and parasite densities as well as parasite genetic diversity were compared among P.falciparum-infected patients identified at two sites of different malaria transmission intensities in Rwanda. Data on demographics and clinical features and finger-prick blood samples for microscopy and parasite genotyping were collected. Nested PCR was used to genotype msp-2 alleles of FC27 and 3D7. Results Patients’ variables of age group, sex, fever (both by patient report and by measured tympanic temperatures), parasite density, and bed net use were found differentially distributed between the higher endemic (Ruhuha) and lower endemic (Mubuga) sites. Overall multiplicity of P.falciparum infection (MOI) was 1.73 but with mean MOI found to vary significantly between 2.13 at Ruhuha and 1.29 at Mubuga (p < 0.0001). At Ruhuha, expected heterozygosity (EH) for FC27 and 3D7 alleles were 0.62 and 0.49, respectively, whilst at Mubuga, EH for FC27 and 3D7 were 0.26 and 0.28, respectively. Conclusions In this study, a higher geometrical mean parasite counts, more polyclonal infections, higher MOI, and higher allelic frequency were observed at the higher malaria-endemic (Ruhuha) compared to the lower malaria-endemic (Mubuga) area. These differences in malaria risk and MOI should be considered when choosing setting-specific malaria control strategies, assessing p. falciparum associated parameters such as drug resistance, immunity and impact of used interventions, and in proper interpretation of malaria vaccine studies.
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Affiliation(s)
- Fredrick Kateera
- Medical Research Centre Division, Rwanda Biomedical Centre, PO Box 7162, Kigali, Rwanda. .,Division of Internal Medicine, Department of Infectious Diseases, Centre of Tropical Medicine and Travel Medicine, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands.
| | - Sam L Nsobya
- Molecular Research Laboratory, Infectious Disease Research Collaboration, New Mulago Hospital Complex, PO Box 7051, Kampala, Uganda.,Department of Pathology, School Biomedical Science, College of Health Science, Makerere University, PO Box 7072, Kampala, Uganda
| | - Stephen Tukwasibwe
- Molecular Research Laboratory, Infectious Disease Research Collaboration, New Mulago Hospital Complex, PO Box 7051, Kampala, Uganda
| | - Petra F Mens
- Division of Internal Medicine, Department of Infectious Diseases, Centre of Tropical Medicine and Travel Medicine, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands.,Royal Tropical Institute/Koninklijk Instituutvoor de Tropen, KIT Biomedical Research, Meibergdreef 39, 1105 AZ, Amsterdam, The Netherlands
| | - Emmanuel Hakizimana
- Medical Research Centre Division, Rwanda Biomedical Centre, PO Box 7162, Kigali, Rwanda
| | - Martin P Grobusch
- Division of Internal Medicine, Department of Infectious Diseases, Centre of Tropical Medicine and Travel Medicine, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands
| | - Leon Mutesa
- School of Medicine, College of Medicine and Health Sciences, University of Rwanda, PO Box 3286, Kigali, Rwanda
| | - Nirbhay Kumar
- Department of Tropical Medicine, School of Public Health and Tropical Medicine, Vector-Borne Infectious Disease Research Centre, Tulane University, 333 S Liberty Street, Mail code 8317, New Orleans, LA, 70112, USA
| | - Michele van Vugt
- Division of Internal Medicine, Department of Infectious Diseases, Centre of Tropical Medicine and Travel Medicine, Meibergdreef 9, 1100 DD, Amsterdam, The Netherlands
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Niang M, Loucoubar C, Sow A, Diagne MM, Faye O, Faye O, Diallo M, Toure-Balde A, Sall AA. Genetic diversity of Plasmodium falciparum isolates from concurrent malaria and arbovirus co-infections in Kedougou, southeastern Senegal. Malar J 2016; 15:155. [PMID: 26969623 PMCID: PMC4788873 DOI: 10.1186/s12936-016-1208-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 03/02/2016] [Indexed: 11/24/2022] Open
Abstract
Background Concurrent malaria and arbovirus infections are common and represent an important public health concern in regions where both diseases are endemic. The present study investigates the genetic diversity and complexity of Plasmodium falciparum infection in concurrent malaria-arbovirus infections in Kedougou region, southeastern Senegal. Methods Parasite DNA was extracted from 60 to 27 sera samples collected from P. falciparum isolates of malaria and concurrent malaria-arbovirus infected patients, respectively, and followed by PCR-genotyping targeting the msp-1 (block2) and msp-2 (block3) allelic families. Results The mean number of genotype per allelic family was comparable between the two groups. K1 was the predominant msp-1 allelic type both in malaria (94.91 %) and arbovirus-malaria (92.59 %) groups, whereas IC/3D7 was the most prevalent msp-2 allelic type in malaria (94.91 %) and arbovirus-malaria (96.29 %) groups. Frequencies of msp-1 and msp-2 allelic types were statistically comparable between the two groups (Fisher exact test, P > 0.05) and were not associated with age. FC27 was strikingly the least prevalent in both groups and was absent in children under 5 years of age. The proportions of P. falciparum isolates from malaria-infected patients carrying the three msp-1 allelic types (67.44 %) or the two msp-2 allelic types (76.47 %) were significantly higher than those from arbovirus-malaria co-infected patients (Exact binomial test, P < 0.05). The multiplicities of infection (MOI) were low and comparable for msp-1 (1.19 vs 1.22) and msp-2 (1.11 vs 1.10), respectively between malaria and arbovirus-malaria groups. Conclusion The study showed no difference in the genetic diversity between P. falciparum isolates from malaria and concurrent malaria-arbovirus infected patients in Kedougou. The MOI was low despite intense malaria transmission in Kedougou. The overall results suggest a limited or no influence of arbovirus infections on P. falciparum diversity and complexity of malaria infection.
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Affiliation(s)
- Makhtar Niang
- Immunology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal.
| | - Cheikh Loucoubar
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | - Abdourahmane Sow
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | - Moussa Moise Diagne
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | - Oumar Faye
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | - Ousmane Faye
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | - Mawlouth Diallo
- Medical Entomology Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
| | | | - Amadou A Sall
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur Dakar, 36 Avenue Pasteur, 220, Dakar, Senegal
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Owusu EDA, Buabeng V, Dadzie S, Brown CA, Grobusch MP, Mens P. Characteristics of asymptomatic Plasmodium spp. parasitaemia in Kwahu-Mpraeso, a malaria endemic mountainous district in Ghana, West Africa. Malar J 2016; 15:38. [PMID: 26801407 PMCID: PMC4724116 DOI: 10.1186/s12936-015-1066-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 12/22/2015] [Indexed: 12/01/2022] Open
Abstract
Background Malaria control efforts in Ghana have reduced the countrywide average malaria prevalence from 71 % in 2000 to about 51 % in 2012; however, its main focus is on symptomatic malaria. If further progress is to be made, parasite
reservoirs in asymptomatic carriers need to be moved into focus. This study profiles asymptomatic Plasmodium spp. parasitaemia amongst residents of mountainous Kwahu-Mpraeso in the Eastern region of Ghana. Methods A cross-sectional study of 360 residents was carried out from October to December 2013. This included recording demographics, malaria testing of asymptomatic residents, and gathering of their malaria history. Assessment of malaria transmission was done with molecular identification of vectors, determination of sporozoite rate, insecticide resistance status and biting pattern. Univariate and multivariate analysis were used to establish risk determinants. Results In Mpraeso, in the Kwahu highland of Eastern Region, children were at higher risk of asymptomatic parasitaemia, thereby contributing to the parasite reservoir and hence sustained malaria transmission. As well, findings suggested Hb AC genotype influenced susceptibility to asymptomatic malaria with 8.03-fold increase in odds (univariate) and 11.92-fold higher odds (multivariate) than the normal Hb AA. The mosquito vector predominant in the area was Anopheles gambiae sensu stricto of the homozygous pyrethroid resistant form (RR); with biting mainly occurring indoors. Conclusion For an effective malaria control in this area, interventions should be formulated and implemented to target asymptomatic parasite reservoirs; especially in children and people with Hb AC. The dominant vector species An. gambiae s.s. and its feeding patterns of biting indoors should also be considered.
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Affiliation(s)
- Ewurama D A Owusu
- Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Centre, Centre of Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam, The Netherlands. .,Department of Medical Laboratory Sciences, School of Biomedical and Allied Health Sciences, College of Health Sciences, University of Ghana, Accra, Ghana. .,Department of Parasitology, KIT Biomedical Research Institute, Amsterdam, The Netherlands.
| | - Vincent Buabeng
- Medical Laboratory Department, Atibie Government Hospital, Kwahu-Atibie, Ghana.
| | - Samuel Dadzie
- Medical Entomology Unit, Department of Parasitology, Noguchi Memorial Institute of Medical Research, University of Ghana, Accra, Ghana.
| | - Charles A Brown
- Department of Medical Laboratory Sciences, School of Biomedical and Allied Health Sciences, College of Health Sciences, University of Ghana, Accra, Ghana.
| | - Martin P Grobusch
- Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Centre, Centre of Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam, The Netherlands. .,Centre de Recherches Médicales de Lambaréné (CERMEL), Hôpital Albert Schweitzer, Lambaréné, Gabon. .,Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
| | - Petra Mens
- Department of Infectious Diseases, Division of Internal Medicine, Academic Medical Centre, Centre of Tropical Medicine and Travel Medicine, University of Amsterdam, Amsterdam, The Netherlands. .,Department of Parasitology, KIT Biomedical Research Institute, Amsterdam, The Netherlands.
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Mawili-Mboumba DP, Mbondoukwe N, Adande E, Bouyou-Akotet MK. Allelic Diversity of MSP1 Gene in Plasmodium falciparum from Rural and Urban Areas of Gabon. THE KOREAN JOURNAL OF PARASITOLOGY 2015; 53:413-9. [PMID: 26323839 PMCID: PMC4566513 DOI: 10.3347/kjp.2015.53.4.413] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Revised: 02/23/2015] [Accepted: 08/05/2015] [Indexed: 11/23/2022]
Abstract
The present study determined and compared the genetic diversity of Plasmodium falciparum strains infecting children living in 2 areas from Gabon with different malaria endemicity. Blood samples were collected from febrile children from 2008 to 2009 in 2 health centres from rural (Oyem) and urban (Owendo) areas. Genetic diversity was determined in P. falciparum isolates by analyzing the merozoite surface protein-1 (msp1) gene polymorphism using nested-PCR. Overall, 168 children with mild falciparum malaria were included. K1, Ro33, and Mad20 alleles were found in 110 (65.5%), 94 (55.9%), and 35 (20.8%) isolates, respectively, without difference according to the site (P>0.05). Allelic families' frequencies were comparable between children less than 5 years old from the 2 sites; while among the older children the proportions of Ro33 and Mad20 alleles were 1.7 to 2.0 fold higher at Oyem. Thirty-three different alleles were detected, 16 (48.5%) were common to both sites, and 10 out of the 17 specific alleles were found at Oyem. Furthermore, multiple infection carriers were frequent at Oyem (57.7% vs 42.2% at Owendo; P=0.04) where the complexity of infection was of 1.88 (±0.95) higher compared to that found at Owendo (1.55±0.75). Extended genetic diversity of P. falciparum strains infecting Gabonese symptomatic children and high multiplicity of infections were observed in rural area. Alleles common to the 2 sites were frequent; the site-specific alleles predominated in the rural area. Such distribution of the alleles should be taken into accounts when designing MSP1 or MSP2 malaria vaccine.
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Affiliation(s)
- Denise Patricia Mawili-Mboumba
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Noé Mbondoukwe
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Elvire Adande
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
| | - Marielle Karine Bouyou-Akotet
- Department of Parasitology-Mycology, Faculty of Medicine, Université des Sciences de la Santé. BP4009, Libreville, Gabon
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Jones S, Grignard L, Nebie I, Chilongola J, Dodoo D, Sauerwein R, Theisen M, Roeffen W, Singh SK, Singh RK, Singh S, Kyei-Baafour E, Tetteh K, Drakeley C, Bousema T. Naturally acquired antibody responses to recombinant Pfs230 and Pfs48/45 transmission blocking vaccine candidates. J Infect 2015; 71:117-27. [PMID: 25869538 DOI: 10.1016/j.jinf.2015.03.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Revised: 03/13/2015] [Accepted: 03/28/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVES Pfs48/45 and Pfs230 are Plasmodium falciparum sexual stage proteins and promising malaria transmission-blocking vaccine candidates. Antibody responses against these proteins may be naturally acquired and target antigens may be under selective pressure. This has consequences for the future evaluation of vaccine immunogenicity and efficacy in populations naturally exposed to malaria. METHODS We determined naturally acquired antibody responses to the recombinant proteins Pfs48/45-10C and Pfs230-230CMB in children from three malaria endemic settings in Ghana, Tanzania and Burkina Faso. We also examined genetic polymorphisms in the P. falciparum gene pfs48/45. RESULTS Antibody prevalence was 1.1-18.2% for 10C and 6.7-18.9% for 230CMB. In Burkina Faso we observed evidence of an age-dependent acquisition pattern for both 10C (p < 0.001) and 230CMB (p = 0.031). Membrane feeding assays on a separate dataset demonstrated an association between functional transmission reducing activity and antibody prevalence for both 10C (p = 0.017) and 230CMB (p = 0.049). 17 single nucleotide polymorphisms were found in pfs48/45 (from 126 samples), with 5 non-synonymous SNPs in the Pfs48/45 10C region. CONCLUSIONS We conclude there are naturally acquired antibody responses to both vaccine candidates which have functional relevance by reducing the transmissibility of infected individuals. We identified genetic polymorphisms, in pfs48/45 which exhibited geographical specificity.
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Affiliation(s)
- Sophie Jones
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Lynn Grignard
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Issa Nebie
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Daniel Dodoo
- Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Michael Theisen
- Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institut, Copenhagen, Denmark; Centre for Medical Parasitology at Department of International Health, Immunology, and Microbiology, University of Copenhagen, Denmark; Department of Infectious Diseases, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Will Roeffen
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | | | - Sanjay Singh
- Gennova Bio Pharmaceuticals Limited, Pune, India
| | - Eric Kyei-Baafour
- Noguchi Memorial Institute for Medical Research, University of Ghana, Ghana
| | - Kevin Tetteh
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chris Drakeley
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, London, United Kingdom; Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
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Oyebola MK, Idowu ET, Nyang H, Olukosi YA, Otubanjo OA, Nwakanma DC, Awolola ST, Amambua-Ngwa A. Microsatellite markers reveal low levels of population sub-structuring of Plasmodium falciparum in southwestern Nigeria. Malar J 2014; 13:493. [PMID: 25496185 PMCID: PMC4300683 DOI: 10.1186/1475-2875-13-493] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2014] [Accepted: 12/09/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genetic diversity studies provide evidence of Plasmodium falciparum differentiation that could affect fitness and adaptation to drugs and target antigens for vaccine development. This study describes the genetic structure of P. falciparum populations in urban and rural sites from southwestern Nigeria. METHODOLOGY Ten neutral microsatellite loci were genotyped in 196 P. falciparum infections from three localities: Aramoko-Ekiti, a rural community; Lekki, an urban location and Badagry, a peri-urban border settlement. Analysis was performed on the genetic diversity, linkage disequilibrium, population structure and inter-population differentiation. RESULTS Allelic diversity values were similar across all populations, with mean expected heterozygosity (HE) values between 0.65 and 0.79. No matching multilocus haplotypes were found and analysis of multilocus LD showed no significant index of association. Genetic differentiation between populations was low (ΦPT = 0.017). CONCLUSION The absence of detectable population structure of P. falciparum in southwestern Nigeria is evident in the lack of significant differentiation between populations separated by about 200 km. This implies that a fairly uniform malaria control strategy may be effective over a wide geographic range in this highly endemic region. However, more wide-scale survey across the country will be required to inform malaria control in this large and densely populated endemic region.
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