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da Trindade MAO, Fonseca ÁLS, Dias IHL, de Sousa SRM, Enk MJ, Lima KVB, de Paula Souza E Guimarães RJ. Geospatial analysis and prevalence of Schistosoma mansoni and soil-transmitted helminth infections in an endemic area in Eastern Brazilian Amazon. Trop Med Int Health 2024; 29:507-517. [PMID: 38659108 DOI: 10.1111/tmi.13993] [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] [Indexed: 04/26/2024]
Abstract
OBJECTIVES This study evaluated the occurrence of Schistosoma mansoni and soil-transmitted helminths in an endemic area in the Eastern Brazilian Amazon, analysing prevalence and spatial distribution. METHODS The study was conducted in four localities of Primavera Municipality, in Pará state. Data was obtained from the Decit 40/2012 project and the participants were divided into five age range categories for evaluation: children, adolescents, young adults, adults and elderly individuals. For the diagnostic tests, Kato-Katz slides were prepared to detect S. mansoni and soil-transmitted helminths eggs. The spatial distribution map and the Kernel Density Estimation were performed to assess the presence and location of infections. RESULTS Stool samples revealed the presence of hookworms, S. mansoni, Ascaris lumbricoides and Trichuris trichiura eggs. Mono-, bi- and poly-parasitic infections were observed, with a significant prevalence of hookworm monoparasitism. CONCLUSIONS The high frequency of children infected with soil-transmitted helminths confirms their significance as an ongoing public health problem in the poorest municipalities of Brazil. The Geographic Information System plays a crucial role in environmental surveillance and in the control of epidemics and endemic diseases, enabling accurate assessment and informed decision-making for their control.
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Affiliation(s)
| | - Álvaro Luan Santana Fonseca
- Programa de Pós-Graduação Strictu Sensu em Biologia Parasitária na Amazônia, Universidade do Estado do Pará (UEPA), Belém, Brazil
| | - Isabelle Helena Lima Dias
- Programa de Pós-Graduação Strictu Sensu em Biologia Parasitária na Amazônia, Universidade do Estado do Pará (UEPA), Belém, Brazil
| | | | - Martin Johannes Enk
- Laboratório de Parasitoses Intestinais e Esquistossomose (LPIE), Seção de Parasitologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Brazil
| | - Karla Valéria Batista Lima
- Programa de Pós-Graduação Strictu Sensu em Biologia Parasitária na Amazônia, Universidade do Estado do Pará (UEPA), Belém, Brazil
- Laboratório de Biologia Molecular, Seção de Bacteriologia e Micologia, Instituto Evandro Chagas/SVSA/MS, Ananindeua, Brazil
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Kajero OT, Janoušková E, Bakare EA, Belizario V, Divina B, Alonte AJ, Manalo SM, Paller VG, Betson M, Prada JM. OUP accepted manuscript. Trans R Soc Trop Med Hyg 2022; 116:727-735. [PMID: 35169848 PMCID: PMC9356178 DOI: 10.1093/trstmh/trac002] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 10/01/2021] [Accepted: 01/11/2022] [Indexed: 12/02/2022] Open
Abstract
Background A large number of studies have assessed risk factors for infection with soil-transmitted helminths (STH), but few have investigated the interactions between the different parasites or compared these between host species across hosts. Here, we assessed the associations between Ascaris, Trichuris, hookworm, strongyle and Toxocara infections in the Philippines in human and animal hosts. Methods Faecal samples were collected from humans and animals (dogs, cats and pigs) in 252 households from four villages in southern Philippines and intestinal helminth infections were assessed by microscopy. Associations between worm species were assessed using multiple logistic regression. Results Ascaris infections showed a similar prevalence in humans (13.9%) and pigs (13.7%). Hookworm was the most prevalent infection in dogs (48%); the most prevalent infection in pigs was strongyles (42%). The prevalences of hookworm and Toxocara in cats were similar (41%). Statistically significant associations were observed between Ascaris and Trichuris and between Ascaris and hookworm infections in humans, and also between Ascaris and Trichuris infections in pigs. Dual and triple infections were observed, which were more common in dogs, cats and pigs than in humans. Conclusions Associations are likely to exist between STH species in humans and animals, possibly due to shared exposures and transmission routes. Individual factors and behaviours will play a key role in the occurrence of co-infections, which will have effects on disease severity. Moreover, the implications of co-infection for the emergence of zoonoses need to be explored further.
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Affiliation(s)
- Olumayowa T Kajero
- School of Veterinary Medicine, Faculty of Health & Medical Sciences, University of Surrey, GU2 7AL, UK
| | - Eva Janoušková
- School of Veterinary Medicine, Faculty of Health & Medical Sciences, University of Surrey, GU2 7AL, UK
| | - Emmanuel A Bakare
- Biomathematics and Applied Mathematical Modelling Research Group, Modelling Simulation and Data Science Network, Department of Mathematics, Federal University Oye-Ekiti, 371104, Ekiti, Nigeria
| | - Vicente Belizario
- College of Public Health, University of Philippines, Manila, 1000, Philippines
| | - Billy Divina
- Department of Veterinary Paraclinical Sciences, College of Veterinary Medicine, University of the Philippines Los Baños, 4030, Philippines
| | - Allen Jethro Alonte
- Animal Biology Division, Institute of Biological Sciences, University of the Philippines, Los Baños, 4030, Philippines
| | - Sheina Macy Manalo
- Department of Veterinary Paraclinical Sciences, College of Veterinary Medicine, University of the Philippines Los Baños, 4030, Philippines
| | - Vachel Gay Paller
- Department of Veterinary Paraclinical Sciences, College of Veterinary Medicine, University of the Philippines Los Baños, 4030, Philippines
| | - Martha Betson
- School of Veterinary Medicine, Faculty of Health & Medical Sciences, University of Surrey, GU2 7AL, UK
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Genetic background affects the mucosal SIgA levels, parasite burden, lung inflammation and susceptibility of male mice to Ascaris suum infection. Infect Immun 2021; 90:e0059521. [PMID: 34807734 DOI: 10.1128/iai.00595-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ascariasis is a neglected tropical disease, widespread in the world and causing important socioeconomic impacts. The presence of various stages of worm development in the pulmonary and intestinal mucosa induces a humoral and cellular immune response. However, although there is much evidence of the protective role of mucosal immunity against various pathogens, including helminthes, there is still a gap in the knowledge about the immune response and the mechanisms of action that are involved in protection against diseases, especially in the initial phase of ascariasis. Then, the aim of this study was to evaluate the kinetic aspects of the immune parasitological parameters in intestinal and pulmonary mucosa in male mice with early ascariasis. Therefore, two mice strains showed a different susceptibility to ascariasis (BALB/c and C57BL6/j), when experimentally infected with 2,500 infective eggs of Ascaris suum from time-point 0 and the immune parasitological parameters evaluated each two days after infection, during the period of 12 days. The results were suggestive of a synergetic action of intestinal and pulmonary SIgA contributing for the protection against early ascariasis by reducing the amount of migrating larval as well as the influx of leukocytes in the lung and the consequent impair of the pulmonary capacity.
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Scope and limitations of a multiplex conventional PCR for the diagnosis of S. stercoralis and hookworms. Braz J Infect Dis 2021; 25:101649. [PMID: 34774469 PMCID: PMC9392200 DOI: 10.1016/j.bjid.2021.101649] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/23/2021] [Accepted: 10/17/2021] [Indexed: 11/20/2022] Open
Abstract
OBJECTIVES Describe the diagnostic characteristics of a conventional multiplex PCR for the diagnosis of S. stercoralis, N. americanus and Ancylostomas spp. METHODS Fecal samples were collected from a cross-sectional study in Orán department, Salta province, Argentina. The stool samples were analyzed using concentration-sedimentation, Harada Mori, McMaster, and Baermann techniques. DNA was extracted from 50 mg fecal sample using the FastPrep® Spin Kit for Soil. Three pairs of primers were used for the amplification of three products of 101, 330, and 577 base pairs (bp) for S. stercoralis, N. americanus and Ancylostoma spp, respectively. The sensitivity and analytical specificity of multiplex PCR were evaluated, as well as the sensitivity and diagnostic specificity, using a composite standard and Bayesian approach. RESULTS AND CONCLUSIONS Multiplex PCR did not present cross-reaction with other intestinal parasites, and the detection limit for multiplex PCR was between 2 and 20 pg of genomic DNA. In addition it presented a diagnostic sensitivity of 97.4% for S. stercoralis and 90.3% for hookworms with a specificity of 100% and 87.6%, respectively. PCR identified a higher proportion (p <0.01) of coinfections (15.3%) than microscopic techniques (3.5%). Also, multiplex PCR showed that there was a positive association between S. stercoralis and hookworms (odds ratio = 2.12). However, this association was due to N. americanus (odds ratio= 3.22), since no association was observed between S. stercoralis and Ancylostoma spp. Neither was an association observed between the two species of hookworms.
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Habig B, Chowdhury S, Monfort SL, Brown JL, Swedell L, Foerster S. Predictors of helminth parasite infection in female chacma baboons ( Papio ursinus). Int J Parasitol Parasites Wildl 2021; 14:308-320. [PMID: 33898232 PMCID: PMC8056146 DOI: 10.1016/j.ijppaw.2021.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 11/26/2022]
Abstract
Helminth parasite infection can impose major consequences on host fitness. Several factors, including individual characteristics of hosts, environmental conditions, and patterns of coinfection, are thought to drive variation in parasite risk. Here, we report on four key drivers of parasite infection-phase of reproduction, steroid hormone profiles, rainfall, and patterns of coinfection-in a population of wild female chacma baboons (Papio ursinus) in South Africa. We collected data on reproductive state and hormone profiles over a 3-year span, and quantified helminth parasite burdens in 2955 fecal samples from 24 female baboons. On a host level, we found that baboons are sensitive to parasite infection during the costliest phases of the reproductive cycle: pregnant females harbored higher intensities of Protospirura eggs than cycling and lactating females; lactating and cycling females had a higher probability of Oesophagostomum infection than pregnant females; and cycling females exhibited lower Trichuris egg counts than pregnant and lactating females. Steroid hormones were associated with both immunoenhancing and immunosuppressive properties: females with high glucocorticoid concentrations exhibited high intensities of Trichuris eggs but were at low risk of Oesophagostomum infection; females with high estrogen and progestagen concentrations exhibited high helminth parasite richness; and females with high progestagen concentrations were at high risk of Oesophagostomum infection but exhibited low Protospirura egg counts. We observed an interaction between host reproductive state and progestagen concentrations in infection intensity of Protospirura: pregnant females exhibited higher intensities and non-pregnant females exhibited lower intensities of Protospirura eggs with increasing progestagen concentrations. At a population level, rainfall patterns were dominant drivers of parasite risk. Lastly, helminth parasites exhibited positive covariance, suggesting that infection probability increases if a host already harbors one or more parasite taxa. Together, our results provide a holistic perspective of factors that shape variation in parasite risk in a wild population of animals.
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Affiliation(s)
- Bobby Habig
- Department of Biology, Queens College, City University of New York, 65-30 Kissena Blvd. Flushing, NY, 11367, USA
| | - Shahrina Chowdhury
- Department of Anthropology, Brooklyn College, City University of New York, 2900 Bedford Ave, Brooklyn, NY, 11210, USA
- Anthropology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York NY, 10016, USA
- New York Consortium in Evolutionary Primatology, Anthropology Program, 365 Fifth Avenue, New York, NY, 10016, USA
| | - Steven L. Monfort
- Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - Janine L. Brown
- Smithsonian Conservation Biology Institute, National Zoological Park, 1500 Remount Road, Front Royal, VA, 22630, USA
| | - Larissa Swedell
- Anthropology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York NY, 10016, USA
- New York Consortium in Evolutionary Primatology, Anthropology Program, 365 Fifth Avenue, New York, NY, 10016, USA
- Department of Anthropology, Queens College, City University of New York, 65-30 Kissena Blvd. Flushing, NY, 11367, USA
- Department of Archaeology, University of Cape Town, Private Bag X3, Rondebosch, 7701, Cape Town, South Africa
| | - Steffen Foerster
- Department of Evolutionary Anthropology, Duke University, Durham, NC, 27710, USA
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Beknazarova M, Whiley H, Traub R, Ross K. Opportunistic Mapping of Strongyloides stercoralis and Hookworm in Dogs in Remote Australian Communities. Pathogens 2020; 9:E398. [PMID: 32455702 PMCID: PMC7281600 DOI: 10.3390/pathogens9050398] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Revised: 05/12/2020] [Accepted: 05/19/2020] [Indexed: 12/17/2022] Open
Abstract
Both Strongyloides stercoralis and hookworms are common soil-transmitted helminths in remote Australian communities. In addition to infecting humans, S. stercoralis and some species of hookworms infect canids and therefore present both environmental and zoonotic sources of transmission to humans. Currently, there is limited information available on the prevalence of hookworms and S. stercoralis infections in dogs living in communities across the Northern Territory in Australia. In this study, 274 dog faecal samples and 11 faecal samples of unknown origin were collected from the environment and directly from animals across 27 remote communities in Northern and Central Australia. Samples were examined using real-time polymerase chain reaction (PCR) analysis for the presence of S. stercoralis and four hookworm species: Ancylostoma caninum, Ancylostoma ceylanicum, Ancylostoma braziliense and Uncinaria stenocephala. The prevalence of S. stercoralis in dogs was found to be 21.9% (60/274). A. caninum was the only hookworm detected in the dog samples, with a prevalence of 31.4% (86/274). This study provides an insight into the prevalence of S. stercoralis and hookworms in dogs and informs future intervention and prevention strategies aimed at controlling these parasites in both dogs and humans. A "One Health" approach is crucial for the prevention of these diseases in Australia.
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Affiliation(s)
- Meruyert Beknazarova
- Faculty of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia; (H.W.); (K.R.)
| | - Harriet Whiley
- Faculty of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia; (H.W.); (K.R.)
| | - Rebecca Traub
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC 3052, Australia;
| | - Kirstin Ross
- Faculty of Science and Engineering, Flinders University, Bedford Park, SA 5042, Australia; (H.W.); (K.R.)
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Clark NJ, Owada K, Ruberanziza E, Ortu G, Umulisa I, Bayisenge U, Mbonigaba JB, Mucaca JB, Lancaster W, Fenwick A, Soares Magalhães RJ, Mbituyumuremyi A. Parasite associations predict infection risk: incorporating co-infections in predictive models for neglected tropical diseases. Parasit Vectors 2020; 13:138. [PMID: 32178706 PMCID: PMC7077138 DOI: 10.1186/s13071-020-04016-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 03/10/2020] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Schistosomiasis and infection by soil-transmitted helminths are some of the world's most prevalent neglected tropical diseases. Infection by more than one parasite (co-infection) is common and can contribute to clinical morbidity in children. Geostatistical analyses of parasite infection data are key for developing mass drug administration strategies, yet most methods ignore co-infections when estimating risk. Infection status for multiple parasites can act as a useful proxy for data-poor individual-level or environmental risk factors while avoiding regression dilution bias. Conditional random fields (CRF) is a multivariate graphical network method that opens new doors in parasite risk mapping by (i) predicting co-infections with high accuracy; (ii) isolating associations among parasites; and (iii) quantifying how these associations change across landscapes. METHODS We built a spatial CRF to estimate infection risks for Ascaris lumbricoides, Trichuris trichiura, hookworms (Ancylostoma duodenale and Necator americanus) and Schistosoma mansoni using data from a national survey of Rwandan schoolchildren. We used an ensemble learning approach to generate spatial predictions by simulating from the CRF's posterior distribution with a multivariate boosted regression tree that captured non-linear relationships between predictors and covariance in infection risks. This CRF ensemble was compared against single parasite gradient boosted machines to assess each model's performance and prediction uncertainty. RESULTS Parasite co-infections were common, with 19.57% of children infected with at least two parasites. The CRF ensemble achieved higher predictive power than single-parasite models by improving estimates of co-infection prevalence at the individual level and classifying schools into World Health Organization treatment categories with greater accuracy. The CRF uncovered important environmental and demographic predictors of parasite infection probabilities. Yet even after capturing demographic and environmental risk factors, the presences or absences of other parasites were strong predictors of individual-level infection risk. Spatial predictions delineated high-risk regions in need of anthelminthic treatment interventions, including areas with higher than expected co-infection prevalence. CONCLUSIONS Monitoring studies routinely screen for multiple parasites, yet statistical models generally ignore this multivariate data when assessing risk factors and designing treatment guidelines. Multivariate approaches can be instrumental in the global effort to reduce and eventually eliminate neglected helminth infections in developing countries.
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Affiliation(s)
- Nicholas J. Clark
- UQ Spatial Epidemiology Laboratory, School of Veterinary Science, The University of Queensland, Gatton, QLD 4343 Australia
| | - Kei Owada
- UQ Spatial Epidemiology Laboratory, School of Veterinary Science, The University of Queensland, Gatton, QLD 4343 Australia
- Children Health and Environment Program, Child Health Research Centre, The University of Queensland, South Brisbane, QLD 4101 Australia
| | - Eugene Ruberanziza
- Neglected Tropical Diseases and Other Parasitic Diseases Unit, Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Giuseppina Ortu
- Schistosomiasis Control Initiative (SCI), Department of Infectious Diseases Epidemiology, Imperial College, London, UK
| | - Irenee Umulisa
- Neglected Tropical Diseases and Other Parasitic Diseases Unit, Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Ursin Bayisenge
- Neglected Tropical Diseases and Other Parasitic Diseases Unit, Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Jean Bosco Mbonigaba
- Neglected Tropical Diseases and Other Parasitic Diseases Unit, Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Kigali, Rwanda
| | - Jean Bosco Mucaca
- Microbiology Unit, National Reference Laboratory (NRL) Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
| | | | - Alan Fenwick
- Schistosomiasis Control Initiative (SCI), Department of Infectious Diseases Epidemiology, Imperial College, London, UK
| | - Ricardo J. Soares Magalhães
- UQ Spatial Epidemiology Laboratory, School of Veterinary Science, The University of Queensland, Gatton, QLD 4343 Australia
- Children Health and Environment Program, Child Health Research Centre, The University of Queensland, South Brisbane, QLD 4101 Australia
| | - Aimable Mbituyumuremyi
- Malaria and Other Parasitic Diseases Division, Rwanda Biomedical Center, Ministry of Health, Kigali, Rwanda
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de Rezende MC, Moreira JMP, Fernandes LLM, Rodrigues VF, Negrão-Corrêa D. Strongyloides venezuelensis-infection alters the profile of cytokines and liver inflammation in mice co-infected with Schistosoma mansoni. Cytokine 2020; 127:154931. [DOI: 10.1016/j.cyto.2019.154931] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 11/13/2019] [Accepted: 11/14/2019] [Indexed: 02/06/2023]
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Lepper HC, Prada JM, Davis EL, Gunawardena SA, Hollingsworth TD. Complex interactions in soil-transmitted helminth co-infections from a cross-sectional study in Sri Lanka. Trans R Soc Trop Med Hyg 2019; 112:397-404. [PMID: 30053259 PMCID: PMC6092609 DOI: 10.1093/trstmh/try068] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 06/19/2018] [Indexed: 11/14/2022] Open
Abstract
Background Co-infection with multiple soil-transmitted helminth (STH) species is common in communities with a high STH prevalence. The life histories of STH species share important characteristics, particularly in the gut, and there is the potential for interaction, but evidence on whether interactions may be facilitating or antagonistic are limited. Methods Data from a pretreatment cross-sectional survey of STH egg deposition in a tea plantation community in Sri Lanka were analysed to evaluate patterns of co-infection and changes in egg deposition. Results There were positive associations between Trichuris trichiura (whipworm) and both Necator americanus (hookworm) and Ascaris lumbricoides (roundworm), but N. americanus and Ascaris were not associated. N. americanus and Ascaris infections had lower egg depositions when they were in single infections than when they were co-infecting. There was no clear evidence of a similar effect of co-infection in Trichuris egg deposition. Conclusions Associations in prevalence and egg deposition in STH species may vary, possibly indicating that effects of co-infection are species dependent. We suggest that between-species interactions that differ by species could explain these results, but further research in different populations is needed to support this theory.
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Affiliation(s)
- Hannah C Lepper
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematics Institute and School of Life Sciences, University of Warwick, UK
| | - Joaquín M Prada
- School of Veterinary Medicine, University of Surrey, Guilford, UK
| | - Emma L Davis
- Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, Mathematics Institute and School of Life Sciences, University of Warwick, UK
| | | | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Donohue RE, Cross ZK, Michael E. The extent, nature, and pathogenic consequences of helminth polyparasitism in humans: A meta-analysis. PLoS Negl Trop Dis 2019; 13:e0007455. [PMID: 31211774 PMCID: PMC6599140 DOI: 10.1371/journal.pntd.0007455] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/28/2019] [Accepted: 05/09/2019] [Indexed: 02/07/2023] Open
Abstract
Background Individual helminth infections are ubiquitous in the tropics; geographical overlaps in endemicity and epidemiological reports suggest areas endemic for multiple helminthiases are also burdened with high prevalences of intestinal protozoan infections, malaria, tuberculosis (TB), and human immunodeficiency virus (HIV). Despite this, pathogens tend to be studied in isolation, and there remains a need for a better understanding of the community ecology and health consequences of helminth polyparasitism to inform the design of effective parasite control programs. Methodology We performed meta-analyses to (i) evaluate the commonality of polyparasitism for helminth-helminth, helminth-intestinal protozoa, helminth-malaria, helminth-TB, and helminth-HIV co-infections, (ii) assess the potential for interspecies interactions among helminth-helminth and helminth-intestinal protozoan infections, and (iii) determine the presence and magnitude of association between specific parasite pairs. Additionally, we conducted a review of reported health consequences of multiply-infected individuals compared to singly- or not multiply-infected individuals. Principal findings We found that helminth-helminth and helminth-intestinal protozoan multiple infections were significantly more common than single infections, while individuals with malaria, TB, and HIV were more likely to be singly-infected with these infections than co-infected with at least one helminth. Most observed species density distributions significantly differed from the expected distributions, suggesting the potential presence of interspecies interactions. All significant associations between parasite pairs were positive in direction, irrespective of the combination of pathogens. Polyparasitized individuals largely exhibited lower hemoglobin levels and higher anemia prevalence, while the differences in growth-related variables were mostly statistically insignificant. Conclusions Our findings confirm that helminth polyparasitism and co-infection with major diseases is common in the tropics. A multitude of factors acting at various hierarchical levels, such as interspecies interactions at the within-host infra-parasite community level and environmental variables at the higher host community level, could explain the observed positive associations between pathogens; there remains a need to develop new frameworks which can consider these multilevel factors to better understand the processes structuring parasite communities to accomplish their control. Helminth infections are a highly prevalent global health problem. These parasitic worm infections occur in areas also burdened with intestinal protozoan infections, malaria, tuberculosis, and human immunodeficiency virus. While these pathogens tend to be studied in isolation, there remains a need to better understand the nature, extent, and health consequences of helminth polyparasitism and co-infection with major diseases. Here, we reviewed the literature and performed meta-analyses to evaluate the commonality of helminth polyparasitism and co-infection, the potential for interspecies interactions between parasites, the association between parasite pairs, and the health consequences among multiply-infected individuals. We confirmed that polyparasitism and co-infection with major diseases are common in the global South and found that multiply-infected individuals experienced worse health consequences when compared to singly or not-multiply infected individuals. Our analysis suggested the potential presence of interspecies interactions and we identified the existence of positive associations between parasite pairs. These findings support the call for integrating deworming into malaria, TB, and HIV treatment protocols and suggest there remains a need to improve our understanding of the factors influencing co-transmission to achieve sustainable parasite control.
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Affiliation(s)
- Rose E. Donohue
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Zoë K. Cross
- University of Utah, Salt Lake City, Utah, United States of America
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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Akinyi MY, Jansen D, Habig B, Gesquiere LR, Alberts SC, Archie EA. Costs and drivers of helminth parasite infection in wild female baboons. J Anim Ecol 2019; 88:1029-1043. [PMID: 30972751 DOI: 10.1111/1365-2656.12994] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 03/08/2019] [Indexed: 11/30/2022]
Abstract
Helminth parasites can have wide-ranging, detrimental effects on host reproduction and survival. These effects are best documented in humans and domestic animals, while only a few studies in wild mammals have identified both the forces that drive helminth infection risk and their costs to individual fitness. Working in a well-studied population of wild baboons (Papio cynocephalus) in the Amboseli ecosystem in Kenya, we pursued two goals, to (a) examine the costs of helminth infections in terms of female fertility and glucocorticoid hormone levels and (b) test how processes operating at multiple scales-from individual hosts to social groups and the population at large-work together to predict variation in female infection risk. To accomplish these goals, we measured helminth parasite burdens in 745 faecal samples collected over 5 years from 122 female baboons. We combine these data with detailed observations of host environments, social behaviours, hormone levels and interbirth intervals (IBIs). We found that helminths are costly to female fertility: females infected with more diverse parasite communities (i.e., higher parasite richness) exhibited longer IBIs than females infected by fewer parasite taxa. We also found that females exhibiting high Trichuris trichiura egg counts also had high glucocorticoid levels. Female infection risk was best predicted by factors at the host, social group and population level: females facing the highest risk were old, socially isolated, living in dry conditions and infected with other helminths. Our results provide an unusually holistic understanding of the factors that contribute to inter-individual differences in parasite infection, and they contribute to just a handful of studies linking helminths to host fitness in wild mammals.
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Affiliation(s)
- Mercy Y Akinyi
- Department of Biology, Duke University, Durham, North Carolina.,Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya
| | - David Jansen
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana
| | - Bobby Habig
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana.,Department of Biology, Queens college, City University of New York, Flushing, New York
| | | | - Susan C Alberts
- Department of Biology, Duke University, Durham, North Carolina.,Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya.,Department of Evolutionary Anthropology, Duke University, Durham, North Carolina
| | - Elizabeth A Archie
- Institute of Primate Research, National Museums of Kenya, Nairobi, Kenya.,Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana
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Evaluation of diagnostic methods for the detection of intestinal schistosomiasis in endemic areas with low parasite loads: Saline gradient, Helmintex, Kato-Katz and rapid urine test. PLoS Negl Trop Dis 2018; 12:e0006232. [PMID: 29470516 PMCID: PMC5823366 DOI: 10.1371/journal.pntd.0006232] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 01/11/2018] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND In some tropical countries, such as Brazil, schistosomiasis control programs have led to a significant reduction in the prevalence and parasite burden of endemic populations. In this setting, the Kato-Katz technique, as the standard diagnostic method for the diagnosis of Schistosoma mansoni infections, which involves the analysis of two slides from one fecal sample, loses its sensitivity. As a result, a significant number of infected individuals are not detected. The objective of this study was to perform extensive parasitological testing of up to three fecal samples and include a rapid urine test (POC-CCA) in a moderate prevalence area in Northern Minas Gerais, Brazil, and evaluate the performance of each test separately and in combination. METHODS AND FINDINGS A total of 254 individuals were examined with variants of the standard Kato-Katz technique (up to18 Kato-Katz slides prepared from three fecal samples), a modified Helmintex (30 g of feces), the saline gradient (500 mg of feces), and the POC-CCA methods. We established a reference standard taking into consideration all the positive results in any of the parasitological exams. Evaluation of the parasite burden by two Kato-Katz slides confirmed that most of the individuals harbored a light infection. When additional slides and different parasitological methods were included, the estimated prevalence rose 2.3 times, from 20.4% to 45.9%. The best sensitivity was obtained with the Helmintex method (84%). All parasitological methods readily detected a high or moderate intensity of infection; however, all lost their high sensitivity in the case of low or very low intensity infections. The overall sensitivity of POC-CCA (64.9%) was similar to the six Kato-Katz slides from three fecal samples. However, POC-CCA showed low concordance (κ = 0.34) when compared with the reference standard. CONCLUSIONS The recommended Kato-Katz method largely underestimated the prevalence of S. mansoni infection. Because the best performance was achieved with a modified Helmintex method, this technique might serve as a more precise reference standard. An extended number of Kato-Katz slides in combination with other parasitological methods or with POC-CCA was able to detect more than 80% of egg-positive individuals; however, the rapid urine test (POC-CCA) produced a considerable percentage of false positive results.
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Gordon CA, Kurscheid J, Jones MK, Gray DJ, McManus DP. Soil-Transmitted Helminths in Tropical Australia and Asia. Trop Med Infect Dis 2017; 2:E56. [PMID: 30270913 PMCID: PMC6082059 DOI: 10.3390/tropicalmed2040056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/16/2017] [Accepted: 10/17/2017] [Indexed: 12/21/2022] Open
Abstract
Soil-transmitted helminths (STH) infect 2 billion people worldwide including significant numbers in South-East Asia (SEA). In Australia, STH are of less concern; however, indigenous communities are endemic for STH, including Strongyloides stercoralis, as well as for serious clinical infections due to other helminths such as Toxocara spp. The zoonotic hookworm Ancylostoma ceylanicum is also present in Australia and SEA, and may contribute to human infections particularly among pet owners. High human immigration rates to Australia from SEA, which is highly endemic for STH Strongyloides and Toxocara, has resulted in a high prevalence of these helminthic infections in immigrant communities, particularly since such individuals are not screened for worm infections upon entry. In this review, we consider the current state of STH infections in Australia and SEA.
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Affiliation(s)
- Catherine A Gordon
- QIMR Berghofer Medical Research Institute, Molecular Parasitology Laboratory, Queensland 4006, Australia.
| | - Johanna Kurscheid
- Australian National University, Department of Global Health, Research School of Population Health, Australian Capital Territory 2601, Australia.
| | - Malcolm K Jones
- School of Veterinary Science, University of Queensland, Brisbane, QLD 4067, Australia.
| | - Darren J Gray
- Australian National University, Department of Global Health, Research School of Population Health, Australian Capital Territory 2601, Australia.
| | - Donald P McManus
- QIMR Berghofer Medical Research Institute, Molecular Parasitology Laboratory, Queensland 4006, Australia.
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[Profiles of intestinal polyparasitism in a community of the Colombian Amazon region]. BIOMEDICA 2017; 37:368-377. [PMID: 28968014 DOI: 10.7705/biomedica.v37i3.3395] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Intestinal parasite infections and polyparasitism are highly prevalent in the most vulnerable populations of developing countries due to environmental, biological and social determinants common in the transmission of parasites. Children between 1 and 15 years of age are the most affected population. OBJECTIVE To describe the prevalence and profiles of intestinal polyparasitism in 1 to 15 year-old children from native communities in the Colombian Amazon region. MATERIALS AND METHODS We used a non-probability sampling of 300 children between 1 and 15 years of age from several rural settlements and the main urban area of Puerto Nariño, Amazonas, Colombia, who participated voluntarily in the study. We obtained fecal samples that were analyzed by the direct method (0.85% saline solution-lugol) and the Kato-Katz technique. The most prevalent polyparasitism profiles were identified using Cohen's kappa coefficient with a 95% confidence interval. RESULTS The prevalence of polyparasitism, defined as the presence of at least two intestinal pathogenic parasites, was 84% (95 % CI: 79.35-87.96). Polyparasitism by two or three of the following parasites: Ascaris lumbricoides, Trichuris trichiura, Blastocystis sp., Ancylostoma duodenale and Necator americanus from the Ancylostomatidae family, and Entamoeba histolytica, E. dispar and E. moshkovskii of the Entamoeba complex, had the highest prevalence. CONCLUSION Several intestinal polyparasitism profiles were found, although in most cases fewer than six parasites were involved. Better prevalence estimations and identification of determinant factors will allow to priorize and direct resources to control these infections.
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Hook, Line and Infection: A Guide to Culturing Parasites, Establishing Infections and Assessing Immune Responses in the Three-Spined Stickleback. ADVANCES IN PARASITOLOGY 2017; 98:39-109. [PMID: 28942772 DOI: 10.1016/bs.apar.2017.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The three-spined stickleback (Gasterosteus aculeatus) is a model organism with an extremely well-characterized ecology, evolutionary history, behavioural repertoire and parasitology that is coupled with published genomic data. These small temperate zone fish therefore provide an ideal experimental system to study common diseases of coldwater fish, including those of aquacultural importance. However, detailed information on the culture of stickleback parasites, the establishment and maintenance of infections and the quantification of host responses is scattered between primary and grey literature resources, some of which is not readily accessible. Our aim is to lay out a framework of techniques based on our experience to inform new and established laboratories about culture techniques and recent advances in the field. Here, essential knowledge on the biology, capture and laboratory maintenance of sticklebacks, and their commonly studied parasites is drawn together, highlighting recent advances in our understanding of the associated immune responses. In compiling this guide on the maintenance of sticklebacks and a range of common, taxonomically diverse parasites in the laboratory, we aim to engage a broader interdisciplinary community to consider this highly tractable model when addressing pressing questions in evolution, infection and aquaculture.
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Diemert DJ, Freire J, Valente V, Fraga CG, Talles F, Grahek S, Campbell D, Jariwala A, Periago MV, Enk M, Gazzinelli MF, Bottazzi ME, Hamilton R, Brelsford J, Yakovleva A, Li G, Peng J, Correa-Oliveira R, Hotez P, Bethony J. Safety and immunogenicity of the Na-GST-1 hookworm vaccine in Brazilian and American adults. PLoS Negl Trop Dis 2017; 11:e0005574. [PMID: 28464026 PMCID: PMC5441635 DOI: 10.1371/journal.pntd.0005574] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/23/2017] [Accepted: 04/17/2017] [Indexed: 11/18/2022] Open
Abstract
Necator americanus Glutathione-S-Transferase-1 (Na-GST-1) plays a role in the digestion of host hemoglobin by adult N. americanus hookworms. Vaccination of laboratory animals with recombinant Na-GST-1 is associated with significant protection from challenge infection. Recombinant Na-GST-1 was expressed in Pichia pastoris and adsorbed to aluminum hydroxide adjuvant (Alhydrogel) according to current Good Manufacturing Practice. Two Phase 1 trials were conducted in 142 healthy adult volunteers in the United States and Brazil, first in hookworm-naïve individuals and then in residents of a N. americanus endemic area in Brazil. Volunteers received one of three doses of recombinant Na-GST-1 (10, 30, or 100 μg) adjuvanted with Alhydrogel, adjuvanted with Alhydrogel and co-administered with an aqueous formulation of Glucopyranosyl Lipid A (GLA-AF), or the hepatitis B vaccine. Vaccinations were administered via intramuscular injection on days 0, 56, and 112. Na-GST-1/Alhydrogel was well tolerated in both hookworm-naïve and hookworm-exposed adults, with the most common adverse events being mild to moderate injection site pain and tenderness, and mild headache and nausea; no vaccine-related severe or serious adverse events were observed. Antigen-specific IgG antibodies were induced in a dose-dependent fashion, with increasing levels observed after each vaccination in both trials. The addition of GLA-AF to Na-GST-1/Alhydrogel did not result in significant increases in specific IgG responses. In both the US and Brazil studies, the predominant IgG subclass induced against Na-GST-1 was IgG1, with lesser amounts of IgG3. Vaccination of both hookworm-naïve and hookworm-exposed adults with recombinant Na-GST-1 was safe, well tolerated, and resulted in significant antigen-specific IgG responses. Based on these results, this vaccine will be advanced into clinical trials in children and eventual efficacy studies. Hookworm infection caused by Necator americanus is a major neglected tropical disease with significant associated morbidity. New tools, such as vaccines, are needed due to the inadequacy of current control strategies. Glutathione-S-Transferase-1 of N. americanus (Na-GST-1) is one of the lead hookworm vaccine candidates; antibodies induced by this vaccine are postulated to interfere with the digestion of host hemoglobin by adult N. americanus hookworms, thereby impairing their development and survival. We conducted two Phase 1 trials of recombinant Na-GST-1 adjuvanted with Alhydrogel in 142 healthy adults living in the United States and Brazil. Each participant received three vaccinations every 2 months by intramuscular injection of the vaccine administered with or without an aqueous solution of the Toll-like receptor-4 agonist, Glucopyranosyl Lipid A (GLA-AF). Na-GST-1/Alhydrogel was well tolerated in both hookworm-exposed and hookworm-naïve adults; no vaccine-related severe or serious adverse events were observed. Antigen-specific IgG antibodies were induced in a dose-dependent fashion with increasing levels observed after each vaccination. The addition of GLA-AF to the vaccine did not result in significantly higher antibody responses. Based on these results, the vaccine will be advanced into clinical trials in children and eventual efficacy studies.
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Affiliation(s)
- David J. Diemert
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
- * E-mail:
| | - Janaína Freire
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Vanderson Valente
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Carlos Geraldo Fraga
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Frederico Talles
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Shannon Grahek
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Doreen Campbell
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Amar Jariwala
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Maria Victoria Periago
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Martin Enk
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | | | - Maria Elena Bottazzi
- Department of Pediatrics, Section of Pediatric Tropical Medicine, Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, United States of America
| | - Robert Hamilton
- Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Jill Brelsford
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Anna Yakovleva
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Guangzhao Li
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Jin Peng
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
| | - Rodrigo Correa-Oliveira
- Centro de Pesquisas René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Minas Gerais, Brazil
| | - Peter Hotez
- Department of Pediatrics, Section of Pediatric Tropical Medicine, Sabin Vaccine Institute and Texas Children's Hospital Center for Vaccine Development, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, United States of America
| | - Jeffrey Bethony
- Department of Microbiology, Immunology and Tropical Medicine, School of Medicine and Health Sciences, The George Washington University, Washington DC, United States of America
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Wardell R, Clements ACA, Lal A, Summers D, Llewellyn S, Campbell SJ, McCarthy J, Gray DJ, V. Nery S. An environmental assessment and risk map of Ascaris lumbricoides and Necator americanus distributions in Manufahi District, Timor-Leste. PLoS Negl Trop Dis 2017; 11:e0005565. [PMID: 28489889 PMCID: PMC5440046 DOI: 10.1371/journal.pntd.0005565] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 05/22/2017] [Accepted: 04/11/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In Timor-Leste there have been intermittent and ineffective soil-transmitted helminth (STH) deworming programs since 2004. In a resource-constrained setting, having information on the geographic distribution of STH can aid in prioritising high risk communities for intervention. This study aimed to quantify the environmental risk factors for STH infection and to produce a risk map of STH in Manufahi district, Timor-Leste. METHODOLOGY/PRINCIPAL FINDINGS Georeferenced cross-sectional data and stool samples were obtained from 2,194 participants in 606 households in 24 villages in the Manufahi District as part of cross sectional surveys done in the context of the "WASH for Worms" randomised controlled trial. Infection status was determined for Ascaris lumbricoides and Necator americanus using real-time quantitative polymerase chain reaction. Baseline infection data were linked to environmental data obtained for each household. Univariable and multivariable multilevel mixed-effects logistic regression analysis with random effects at the village and household level were conducted, with all models adjusted for age and sex. For A. lumbricoides, being a school-aged child increased the odds of infection, whilst higher temperatures in the coolest quarter of the year, alkaline soils, clay loam/loam soils and woody savannas around households were associated with decreased infection odds. For N. americanus, greater precipitation in the driest month, higher average enhanced vegetation index, age and sandy loam soils increased infection odds, whereas being female and living at higher elevations decreased the odds of infection. Predictive risk maps generated for Manufahi based upon these final models highlight the high predicted risk of N. americanus infection across the district and the more focal nature of A. lumbricoides infection. The predicted risk of any STH infection is high across the entire district. CONCLUSIONS/SIGNIFICANCE The widespread predicted risk of any STH infection in 6 to 18 year olds provides strong evidence to support strategies for control across the entire geographical area. As few studies include soil texture and pH in their analysis, this study adds to a growing body of evidence suggesting these factors influence STH infection distribution. This study also further supports that A. lumbricoides prefers acidic soils, highlighting a potential relatively unexplored avenue for control. TRIAL REGISTRATION ClinicalTrials.gov ACTRN12614000680662.
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Affiliation(s)
- Rebecca Wardell
- Department of Global Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
| | - Archie C. A. Clements
- Department of Global Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
| | - Aparna Lal
- National Centre for Epidemiology and Population Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
| | - David Summers
- Fenner School of Environment and Society, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
| | - Stacey Llewellyn
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Suzy J. Campbell
- Department of Global Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
| | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
- School of Public Health, University of Queensland, Brisbane, Australia
| | - Darren J. Gray
- Department of Global Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
- School of Public Health, University of Queensland, Brisbane, Australia
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Susana V. Nery
- Department of Global Health, Research School of Population Health, College of Medicine, Biology and the Environment, The Australian National University, Canberra, ACT, Australia
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Babamale OA, Ugbomoiko US, Heukelbach J. High prevalence of Plasmodium falciparum and soil-transmitted helminth co-infections in a periurban community in Kwara State, Nigeria. J Infect Public Health 2017; 11:48-53. [PMID: 28442321 DOI: 10.1016/j.jiph.2017.03.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 02/10/2017] [Accepted: 03/25/2017] [Indexed: 10/19/2022] Open
Abstract
Prevalence of malaria and soil-transmitted helminth infections, and the burden of disease are enormous in sub-Saharan Africa. Co-infections aggravate the clinical outcome, but are common due to an overlap of endemic areas. A cross-sectional survey was conducted to assess prevalence, intensity of infection and association between malaria and soil-transmitted helminth infections in a typical periurban community in Kwara State. Fresh blood and faecal samples were examined using thick blood film and Kato-Katz smear techniques. A total of 383/471 study participants (81.3%) were infected with at least one parasite species, with the following prevalences and mean infection intensities: Plasmodium falciparum 63.7% (2313.6 parasites/μl); Ascaris lumbricoides 63.1% (3152.1 epg); Trichuris trichiura 53.3% (1043.5 epg); and hookworms 30.1% (981.7 epg). Sixty-three percent of the study population were co-infected with two or more parasite species. The prevalence of ascariasis was significantly higher in individuals infected with P. falciparum (adjusted OR: 5.87; 95% CI: 3.30-10.42). Heavy A. lumbricoides and T. trichiura infections were associated with high P. falciparum parasitaemia. Co-endemicity of malaria and soil transmitted helminth infections is an important public health problem in the study area. Multi-target integrated approaches focusing on disease intervention are essential to mitigate morbidity caused by multiple infections.
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Affiliation(s)
| | - Uade S Ugbomoiko
- Parasitology Unit, Department of Zoology, University of Ilorin, Ilorin, Nigeria.
| | - Jorg Heukelbach
- College of Public Health, Medical and Veterinary Sciences, Division of Tropical Health and Medicine, James Cook University, Townsville, Queensland, Australia; Department of Community Health, School of Medicine, Federal University of Ceará, Brazil
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Muñoz-Antoli C, Pavón A, Pérez P, Toledo R, Esteban JG. Soil-transmitted Helminth Infections in Schoolchildren of Laguna de Perlas (Nicaragua). J Trop Pediatr 2017; 63:124-134. [PMID: 27616686 DOI: 10.1093/tropej/fmw061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Soil-transmitted helminth (STH) prevalence, intensity, polyparasitism and co-infections in 425 children from 3 schools of Laguna de Perlas (Nicaragua) were investigated. Single stool samples were analysed by the formalin-ether method and the Kato-Katz. A total of 402 (94.6%) children were infected. Trichuris trichiura 308 (72.4%), Ascaris lumbricoides 115 (27.1%) and Hookworms 54 (12.7%) were the most prevalent STHs. Polyparasitism (322; 75.8%) with two species was most prevalent (109; 25.6%). T. trichiura with A. lumbricoides (19.3%) and T. trichiura with Hookworm (6.8%) were the most common combinations. Positive associations were observed between T. trichiura and A. lumbricoides and T. trichiura and Hookworm (p = 0.0001). Highest Hookworm intensities appeared when three STH co-infections occurred. Moderate- heavy STH intensities appear in up to 42.1% in trichuriasis, 57.5% in ascariasis and 11.1% in Hookworm infections. Integrated control interventions covering children need to be implemented mainly in a rural environment.
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Affiliation(s)
- C Muñoz-Antoli
- Facultad de Farmacia, Departamento de Parasitología, Universidad de Valencia, Av. Vicent Andrés Estellés s/n, Burjassot-Valencia 46100, Spain
| | - A Pavón
- Departamento Bionálisis Clínico, Instituto Politécnico de la Salud (IPS-Polisal), Universidad Nacional Autónoma de Nicaragua, Managua, Nicaragua
| | - P Pérez
- Facultad de Farmacia, Departamento de Parasitología, Universidad de Valencia, Av. Vicent Andrés Estellés s/n, Burjassot-Valencia 46100, Spain
| | - R Toledo
- Facultad de Farmacia, Departamento de Parasitología, Universidad de Valencia, Av. Vicent Andrés Estellés s/n, Burjassot-Valencia 46100, Spain
| | - J G Esteban
- Facultad de Farmacia, Departamento de Parasitología, Universidad de Valencia, Av. Vicent Andrés Estellés s/n, Burjassot-Valencia 46100, Spain
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Afework Bitew A, Abera B, Seyoum W, Endale B, Kiber T, Goshu G, Admass A. Soil-Transmitted Helminths and Schistosoma mansoni Infections in Ethiopian Orthodox Church Students around Lake Tana, Northwest Ethiopia. PLoS One 2016; 11:e0155915. [PMID: 27203749 PMCID: PMC4874599 DOI: 10.1371/journal.pone.0155915] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 05/08/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Soil-transmitted helminths (STH) and Schistosoma mansoni infections are the major neglected tropical diseases that result in serious consequences on health, education and nutrition in children in developing countries. The Ethiopian Orthodox church students, who are called Yekolotemari in Amharic, live in areas with poor sanitation and hygiene. Moreover, they are not included in the national STH control programs. Thus, STH and S. mansoni infections prevalence is unknown. METHODS A cross-sectional study was conducted on 384 students in June 2014 to determine STH and S. mansoni infections prevalence. Moreover, the knowledge of students about STH and S. mansoni was assessed. Data on knowledge and clinical symptoms were collected using structured questionnaires via face to face interview. Stool specimens were examined by formol-ether concentration method. RESULTS The overall prevalence of intestinal helminths infections was 85.9% (95% confidence interval (CI): 82.1-89%). STHs infections prevalence was 65.6% (95% CI: 60.7-70.2%). The prevalence of hookworm, Ascaris lumbricoides and Trichuris trichiura were 31.8% (95% CI: 27.3-36.6%), 29.4% (25-31%) and 3.1% (1.8-5.4%), respectively. On the other hand, S. mansoni prevalence was 14.3% (95% CI: 11.1-18.1%). Majority of students infected with S. mansoni had bloody stool with crud odds-ratio of 2.9 (95% CI: 1.5-5.5). Knowledge assessment showed that 50 (13%) and 18 (4.9%) of the respondents knew about transmission of STH and S. mansoni, respectively. CONCLUSIONS The prevalence of STH and S. mansoni infections were high thus de-worming program should include the students of Ethiopian Orthodox churches. Furthermore, provision and use of sanitary facilities, health education for students to create awareness of parasitic infections and improved personal hygiene should be in place.
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Affiliation(s)
| | - Bayeh Abera
- Department of Microbiology, Immunology and Parasitology, College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia
- * E-mail:
| | | | | | | | - Girma Goshu
- ALKAN University College, Bahir Dar, Ethiopia
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Zoni AC, Catalá L, Ault SK. Schistosomiasis Prevalence and Intensity of Infection in Latin America and the Caribbean Countries, 1942-2014: A Systematic Review in the Context of a Regional Elimination Goal. PLoS Negl Trop Dis 2016; 10:e0004493. [PMID: 27007193 PMCID: PMC4805296 DOI: 10.1371/journal.pntd.0004493] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 02/04/2016] [Indexed: 12/11/2022] Open
Abstract
Background In 2012 the World Health Assembly adopted resolution WHA65.21 on elimination of schistosomiasis, calling for increased investment in schistosomiasis control and support for countries to initiate elimination programs. This study aims to analyze prevalence and intensity of Schistosoma mansoni infection in children in Latin America and the Caribbean countries and territories (LAC), at the second administrative level or lower. Methodology A systematic review of schistosomiasis prevalence and intensity of infection was conducted by searching at PubMed, LILACS and EMBASE. Experts on the topic were informally consulted and institutional web pages were reviewed (PAHO/WHO, Ministries of Health). Only SCH infection among children was registered because it can be a ‘proxi-indicator’ of recent transmission by the time the study is conducted. Principal Findings One hundred thirty two full-text articles met the inclusion criteria and provided 1,242 prevalence and 199 intensity of infection data points. Most of them were from Brazil (69.7%). Only Brazil published studies after 2001, showing several 'hot spots' with high prevalence. Brazil, Venezuela, Suriname and Saint Lucia need to update the epidemiological status of schistosomiasis to re-design their national programs and target the elimination of Schistosoma mansoni transmission by 2020. In Antigua and Barbuda, Dominican Republic, Guadeloupe, Martinique, Montserrat and Puerto Rico schistosomiasis transmission may be interrupted. However the compilation of an elimination dossier and follow-up surveys, per WHO recommendations, are needed to verify that status. Hence, the burden of subtle SCH chronic infection may be still present and even high in countries that may have eliminated transmission. Heterogeneity in the methodologies used for monitoring and evaluating the progress of the schistosomiasis programs was found, making cross-national and chronological comparisons difficult. Conclusions There is a need for updating the schistosomiasis status in the historically endemic countries and territories in LAC to address the required public health interventions for control and elimination programs or to verify the elimination of transmission of Schistosoma mansoni. Improved reporting and standardization of the monitoring and evaluation methodologies used are recommended, while using available WHO guidelines. Meeting a regional elimination goal will require additional and improved epidemiological data by age group and sex. Schistosomiasis (Schistosoma spp) is an intestinal parasitic infection that causes anaemia, stunted growth, impaired cognition, and decreased physical fitness among other pathological effects. Currently, the control of schistosomiasis relies principally on mass drug administration of praziquantel. In addition, the implementation of further interventions such as snail (intermediate host) control, improving access to safe water and sanitation are required to achieve elimination of transmission in humans. An updated epidemiological situation will help countries to design tailor-made interventions enabling a step-up in prevention and control measures with the goal of elimination of transmission of this disease by 2020. In the region of the Americas, Schistosoma mansoni is the only species present that infect humans. This systematic review shows that in this region there is a need for re-mapping the schistosomiasis epidemiological situation in certain areas and countries in order to implement and optimize the best public health interventions needed to interrupt transmission or verify elimination of transmission. The methodology for monitoring and evaluating schistosomiasis control programs are well defined by current WHO guidelines. However, further investigations and guidelines on suitable tools for monitoring and evaluating schistosomiasis elimination programs and criteria and procedures for validating the elimination are required, and are currently being undertaken by WHO.
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Affiliation(s)
| | - Laura Catalá
- Pan American Health Organization/World Health Organization, Washington, D.C., United States of America
- * E-mail: ;
| | - Steven K. Ault
- Pan American Health Organization/World Health Organization, Washington, D.C., United States of America
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Bartsch SM, Hotez PJ, Hertenstein DL, Diemert DJ, Zapf KM, Bottazzi ME, Bethony JM, Brown ST, Lee BY. Modeling the economic and epidemiologic impact of hookworm vaccine and mass drug administration (MDA) in Brazil, a high transmission setting. Vaccine 2016; 34:2197-206. [PMID: 27002501 DOI: 10.1016/j.vaccine.2016.03.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 03/03/2016] [Accepted: 03/09/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Although mass drug administration (MDA) has helped reduce morbidity attributed to soil-transmitted helminth infections in children, its limitations for hookworm infection have motivated the development of a human hookworm vaccine to both improve morbidity control and ultimately help block hookworm transmission leading to elimination. However, the potential economic and epidemiologic impact of a preventive vaccine has not been fully evaluated. METHODS We developed a dynamic compartment model coupled to a clinical and economics outcomes model representing both the human and hookworm populations in a high transmission region of Brazil. Experiments simulated different implementation scenarios of MDA and vaccination under varying circumstances. RESULTS Considering only intervention costs, both annual MDA and vaccination were highly cost-effective (ICERs ≤ $790/DALY averted) compared to no intervention, with vaccination resulting in lower incremental cost-effectiveness ratios (ICERs ≤ $444/DALY averted). From the societal perspective, vaccination was economically dominant (i.e., less costly and more effective) versus annual MDA in all tested scenarios, except when vaccination was less efficacious (20% efficacy, 5 year duration) and MDA coverage was 75%. Increasing the vaccine's duration of protection and efficacy, and including a booster injection in adulthood all increased the benefits of vaccination (i.e., resulted in lower hookworm prevalence, averted more disability-adjusted life years, and saved more costs). Assuming its target product profile, a pediatric hookworm vaccine drastically decreased hookworm prevalence in children to 14.6% after 20 years, compared to 57.2% with no intervention and 54.1% with MDA. The addition of a booster in adulthood further reduced the overall prevalence from 68.0% to 36.0% and nearly eliminated hookworm infection in children. CONCLUSION Using a human hookworm vaccine would be cost-effective and in many cases economically dominant, providing both health benefits and cost-savings. It could become a key technology in effecting control and elimination efforts for hookworm globally.
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Affiliation(s)
- Sarah M Bartsch
- Public Health Computational and Operational Research (PHICOR), Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA; Global Obesity Prevention Center, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - Peter J Hotez
- National School of Tropical Medicine, and Departments of Pediatrics and Molecular Virology & Microbiology, Baylor College of Medicine, One Baylor Plaza, BCM113, Houston, TX 77030, USA; Sabin Vaccine Institute, 2000 Pennsylvania Avenue NW, Washington, DC 20006, USA
| | - Daniel L Hertenstein
- Public Health Computational and Operational Research (PHICOR), Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA; Global Obesity Prevention Center, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - David J Diemert
- Sabin Vaccine Institute, 2000 Pennsylvania Avenue NW, Washington, DC 20006, USA; Department of Microbiology, Immunology and Tropical Medicine, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Kristina M Zapf
- Public Health Computational and Operational Research (PHICOR), Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA; Global Obesity Prevention Center, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA
| | - Maria Elena Bottazzi
- National School of Tropical Medicine, and Departments of Pediatrics and Molecular Virology & Microbiology, Baylor College of Medicine, One Baylor Plaza, BCM113, Houston, TX 77030, USA; Sabin Vaccine Institute, 2000 Pennsylvania Avenue NW, Washington, DC 20006, USA
| | - Jeffrey M Bethony
- Sabin Vaccine Institute, 2000 Pennsylvania Avenue NW, Washington, DC 20006, USA; Department of Microbiology, Immunology and Tropical Medicine, The George Washington University Medical Center, Washington, DC 20037, USA
| | - Shawn T Brown
- Pittsburgh Supercomputing Center, Carnegie Mellon University, 300S Craig St, Pittsburgh, PA 15213, USA
| | - Bruce Y Lee
- Public Health Computational and Operational Research (PHICOR), Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA; Global Obesity Prevention Center, Johns Hopkins Bloomberg School of Public Health, 615 North Wolfe Street, Baltimore, MD 21205, USA.
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de Rezende MC, Araújo ES, Moreira JMP, Rodrigues VF, Rodrigues JL, Pereira CADJ, Negrão-Corrêa D. Effect of different stages of Schistosoma mansoni infection on the parasite burden and immune response to Strongyloides venezuelensis in co-infected mice. Parasitol Res 2015; 114:4601-16. [DOI: 10.1007/s00436-015-4706-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 08/26/2015] [Indexed: 11/25/2022]
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Soil-Transmitted Helminth Infections and Associated Risk Factors among Schoolchildren in Durbete Town, Northwestern Ethiopia. J Parasitol Res 2015; 2015:641602. [PMID: 26161265 PMCID: PMC4487929 DOI: 10.1155/2015/641602] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/15/2015] [Accepted: 06/07/2015] [Indexed: 12/04/2022] Open
Abstract
Identifying determinants of soil transmitted helminth infection is vital to design control strategy for the disease. This study assessed the prevalence of STH infections and associated factors among schoolchildren in Durbete town, northwestern Ethiopia. Data about the sociodemographic and socioeconomic status of the children were collected using a questionnaire and stool samples were diagnosed using thick Kato-Katz smear. STH infection was more common among school-age children in Durbete town. Hookworm was the most frequent helminth species detected. The prevalence of STH infection was more in children who did not practice wearing shoes and washing hands before eating and in those who were older in age. Deworming of school-age children in the study area would be important. In addition, provision of health education about helminths and the importance of wearing shoes and washing hands before eating would be important to reduce the burden of STH infection in the study area.
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González-Fernández D, Koski KG, Sinisterra OT, Del Carmen Pons E, Murillo E, Scott ME. Interactions among urogenital, intestinal, skin, and oral infections in pregnant and lactating Panamanian Ngäbe women: a neglected public health challenge. Am J Trop Med Hyg 2015; 92:1100-10. [PMID: 25825387 PMCID: PMC4458810 DOI: 10.4269/ajtmh.14-0547] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 02/21/2015] [Indexed: 01/09/2023] Open
Abstract
Interrelationships among bacteria, protozoa, helminths, and ectoparasites were explored in a cross-sectional survey of 213 pregnant and 99 lactating indigenous women. Prevalences in pregnancy and lactation, respectively, were: vaginitis (89.2%; 46.8%), vaginal trichomoniasis (75.3%; 91.1%), bacterial vaginosis (BV; 60.6%; 63.3%), hookworm (56.6%; 47.8%), asymptomatic bacteriuria/urinary tract infection (AB/UTI; 56.2%; 36.2%), cervicitis (33.3%; 6.3%), vaginal yeast (24.9%; 11.4%), Ascaris (32.5%; 17.4%), vaginal diplococci (20.4%; 31.6%), caries (19.7%; 18.2%), scabies (17.4%; 8.1%), and Trichuris (12.5%; 8.7%). Multiple regressions revealed positive associations during pregnancy (trichomoniasis and AB/UTI; diplococci and Ascaris) and lactation (yeast and scabies). Negative associations were detected in pregnancy (BV and trichomoniasis; hookworm and diplococci) and lactation (BV and yeast). Vaginal Lactobacillus reduced odds of diplococci in pregnancy and lactation, but increased Ascaris eggs per gram (epg) and odds of trichomoniasis in pregnancy and yeast in lactation. These associations raised a concern that treatment of one condition may increase the risk of another.
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Affiliation(s)
- Doris González-Fernández
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Kristine G Koski
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Odalis Teresa Sinisterra
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Emérita Del Carmen Pons
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Enrique Murillo
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
| | - Marilyn E Scott
- Institute of Parasitology and Centre for Host-Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada; School of Dietetics and Human Nutrition, McGill University, Ste-Anne de Bellevue, Quebec, Canada; Department of Biochemistry, University of Panamá, Panamá City, Panamá; Department of Nutritional Health, Ministry of Health, Panamá City, Panamá
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Gordon CA, McManus DP, Acosta LP, Olveda RM, Williams GM, Ross AG, Gray DJ, Gobert GN. Multiplex real-time PCR monitoring of intestinal helminths in humans reveals widespread polyparasitism in Northern Samar, the Philippines. Int J Parasitol 2015; 45:477-83. [PMID: 25858090 DOI: 10.1016/j.ijpara.2015.02.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 01/20/2015] [Accepted: 02/16/2015] [Indexed: 12/24/2022]
Abstract
The global socioeconomic importance of helminth parasitic disease is underpinned by the considerable clinical impact on millions of people. While helminth polyparasitism is considered common in the Philippines, little has been done to survey its extent in endemic communities. High morphological similarity of eggs between related species complicates conventional microscopic diagnostic methods which are known to lack sensitivity, particularly in low intensity infections. Multiplex quantitative PCR diagnostic methods can provide rapid, simultaneous identification of multiple helminth species from a single stool sample. We describe a multiplex assay for the differentiation of Ascaris lumbricoides, Necator americanus, Ancylostoma, Taenia saginata and Taenia solium, building on our previously published findings for Schistosoma japonicum. Of 545 human faecal samples examined, 46.6% were positive for at least three different parasite species. High prevalences of S. japonicum (90.64%), A. lumbricoides (58.17%), T. saginata (42.57%) and A. duodenale (48.07%) were recorded. Neither T. solium nor N. americanus were found to be present. The utility of molecular diagnostic methods for monitoring helminth parasite prevalence provides new information on the extent of polyparasitism in the Philippines municipality of Palapag. These methods and findings have potential global implications for the monitoring of neglected tropical diseases and control measures.
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Affiliation(s)
- Catherine A Gordon
- Molecular Parasitology Laboratory, Infectious Diseases Division, QIMR Berghofer Medical Research Institute, Brisbane, Australia; Discipline of Epidemiology and Biostatistics, School of Population Health, University of Queensland, Brisbane, Australia.
| | - Donald P McManus
- Molecular Parasitology Laboratory, Infectious Diseases Division, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Luz P Acosta
- Department of Immunology, Research Institute of Tropical Medicine, Manila, Philippines
| | - Remigio M Olveda
- Department of Immunology, Research Institute of Tropical Medicine, Manila, Philippines
| | - Gail M Williams
- Discipline of Epidemiology and Biostatistics, School of Population Health, University of Queensland, Brisbane, Australia
| | - Allen G Ross
- Griffith Health Institute, Griffith University, Queensland, Australia
| | - Darren J Gray
- Molecular Parasitology Laboratory, Infectious Diseases Division, QIMR Berghofer Medical Research Institute, Brisbane, Australia; Discipline of Epidemiology and Biostatistics, School of Population Health, University of Queensland, Brisbane, Australia; Research School of Population Health, The Australian National University, Canberra, Australia
| | - Geoffrey N Gobert
- Molecular Parasitology Laboratory, Infectious Diseases Division, QIMR Berghofer Medical Research Institute, Brisbane, Australia
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Aderoba AK, Iribhogbe OI, Olagbuji BN, Olokor OE, Ojide CK, Ande AB. Prevalence of helminth infestation during pregnancy and its association with maternal anemia and low birth weight. Int J Gynaecol Obstet 2015; 129:199-202. [PMID: 25733444 DOI: 10.1016/j.ijgo.2014.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 12/03/2014] [Accepted: 02/09/2015] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To determine the prevalence of helminth infestation during pregnancy and the associated risks of adverse maternal and infant outcomes. METHODS A cross-sectional study of women with a singleton pregnancy of at least 34 weeks was conducted at a teaching hospital in Benin City, Nigeria, between April 1 and September 30, 2010. Socioeconomic and clinical data were obtained. Stool samples were used to determine helminth infection. Birth weight was recorded at delivery. Multivariable analysis was used to assess the link between helminth infestation and maternal and perinatal outcomes. RESULTS Among 178 women, 31 (17.4%) had a helminth infestation (15 [8.4%] had ascariasis, 8 [4.5%] trichuriasis, and 25 [14.0%] hookworm infestation). Multivariate analysis found that helminth infestations was associated with maternal anemia (adjusted odds ratio 12.4; 95% confidence interval 4.2-36.3) and low birth weight (adjusted odds ratio 6.8; 95% confidence interval 2.1-21.9). CONCLUSION Approximately one in five women had a helminth infestation in the third trimester of pregnancy. Maternal helminth infestation significantly increased the risks of maternal anemia and low birth weight, indicating that routine administration of anthelminthic drugs during early pregnancy might improve perinatal outcomes.
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Affiliation(s)
- Adeniyi K Aderoba
- Department of Obstetrics and Gynecology, Mother and Child Hospital, Akure, Nigeria.
| | - Oseihie I Iribhogbe
- Department of Obstetrics and Gynecology, University of Benin Teaching Hospital, Benin City, Nigeria
| | - Biodun N Olagbuji
- Women's and Adolescent Health Research Initiative, Department of Obstetrics and Gynecology, Ekiti State University, Ado-Ekiti, Nigeria
| | - Oghenefegor E Olokor
- Department of Obstetrics and Gynecology, University of Benin Teaching Hospital, Benin City, Nigeria
| | - Chiedozie K Ojide
- Department of Medical Microbiology, Ebonyi State University, Abakaliki, Nigeria
| | - Adedapo B Ande
- Department of Obstetrics and Gynecology, University of Benin Teaching Hospital, Benin City, Nigeria
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Gazzinelli MF, Souza VDS, Campos ELW, Fernandes MM, Lobato L. Autonomous decision and behavior required in clinical trials: study with a socioeconomically vulnerable population. TEXTO & CONTEXTO ENFERMAGEM 2014. [DOI: 10.1590/0104-07072014002410013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Quasi-experimental study conducted to assess the effects of an educational intervention based on the Health Action Process Approach Model, in which autonomous decision-making and behaviors required for the participation in a clinical study were favored. This is an intervention study involving participants in a clinical trial conducted in the State of Minas Gerais, Brazil. The intervention was based on the social and cognitive variables of the Health Action Process Approach model and assessed by applying questionnaires before and after intervention. The results were compared using the McNemar test. The educational intervention favored knowledge on both the expectations about the results of the clinical trial and risk of infection by intestinal helminths, development of the ability to plan the behaviors required by the clinical trial and the necessary confidence to lead, keep, and retrieve them. Analysis of the results showed that the educational intervention favored both autonomous decision-making and the behavior required by clinical trials.
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Intestinal parasites coinfection does not alter plasma cytokines profile elicited in acute malaria in subjects from endemic area of Brazil. Mediators Inflamm 2014; 2014:857245. [PMID: 25309052 PMCID: PMC4182071 DOI: 10.1155/2014/857245] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 09/01/2014] [Indexed: 01/13/2023] Open
Abstract
In Brazil, malaria is prevalent in the Amazon region and these regions coincide with high prevalence of intestinal parasites but few studies explore the interaction between malaria and other parasites. Therefore, the present study evaluates changes in cytokine, chemokine, C-reactive protein, and nitric oxide (NO) concentrations in 264 individuals, comparing plasma from infected individuals with concurrent malaria and intestinal parasites to individuals with either malaria infection alone and uninfected. In the studied population 24% of the individuals were infected with Plasmodium and 18% coinfected with intestinal parasites. Protozoan parasites comprised the bulk of the intestinal parasites infections and subjects infected with intestinal parasites were more likely to have malaria. The use of principal component analysis and cluster analysis associated increased levels of IL-6, TNF-α, IL-10, and CRP and low levels of IL-17A predominantly with individuals with malaria alone and coinfected individuals. In contrast, low levels of almost all inflammatory mediators were associated predominantly with individuals uninfected while increased levels of IL-17A were associated predominantly with individuals with intestinal parasites only. In conclusion, our data suggest that, in our population, the infection with intestinal parasites (mainly protozoan) does not modify the pattern of cytokine production in individuals infected with P. falciparum and P. vivax.
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Belo VS, Struchiner CJ, Barbosa DS, Nascimento BWL, Horta MAP, da Silva ES, Werneck GL. Risk factors for adverse prognosis and death in American visceral leishmaniasis: a meta-analysis. PLoS Negl Trop Dis 2014; 8:e2982. [PMID: 25058582 PMCID: PMC4109848 DOI: 10.1371/journal.pntd.0002982] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Accepted: 05/14/2014] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND In the current context of high fatality rates associated with American visceral leishmaniasis (VL), the appropriate use of prognostic factors to identify patients at higher risk of unfavorable outcomes represents a potential tool for clinical practice. This systematic review brings together information reported in studies conducted in Latin America, on the potential predictors of adverse prognosis (continued evolution of the initial clinical conditions of the patient despite the implementation of treatment, independent of the occurrence of death) and death from VL. The limitations of the existing knowledge, the advances achieved and the approaches to be used in future research are presented. METHODS/PRINCIPAL FINDINGS The full texts of 14 studies conforming to the inclusion criteria were analyzed and their methodological quality examined by means of a tool developed in the light of current research tools. Information regarding prognostic variables was synthesized using meta-analysis. Variables were grouped according to the strength of evidence considering summary measures, patterns and heterogeneity of effect-sizes, and the results of multivariate analyses. The strongest predictors identified in this review were jaundice, thrombocytopenia, hemorrhage, HIV coinfection, diarrhea, age <5 and age >40-50 years, severe neutropenia, dyspnoea and bacterial infections. Edema and low hemoglobin concentration were also associated with unfavorable outcomes. The main limitation identified was the absence of validation procedures for the few prognostic models developed so far. CONCLUSIONS/SIGNIFICANCE Integration of the results from different investigations conducted over the last 10 years enabled the identification of consistent prognostic variables that could be useful in recognizing and handling VL patients at higher risk of unfavorable outcomes. The development of externally validated prognostic models must be prioritized in future investigations.
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Affiliation(s)
- Vinícius Silva Belo
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil
- Departamento Básico—Área da Saúde—Campus Governador Valadares, Universidade Federal de Juiz de Fora, Governador Valadares, Minas Gerais, Brasil
- * E-mail:
| | - Claudio José Struchiner
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil
| | - David Soeiro Barbosa
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil
| | | | - Marco Aurélio Pereira Horta
- Departamento de Epidemiologia e Métodos Quantitativos em Saúde, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janiero, Brasil
| | - Eduardo Sérgio da Silva
- Campus Centro-Oeste Dona Lindu, Universidade Federal de São João del Rei, Divinópolis, Minas Gerais, Brasil
| | - Guilherme Loureiro Werneck
- Departamento de Endemias Samuel Pessoa, Escola Nacional de Saúde Pública Sergio Arouca, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brasil
- Departamento de Epidemiologia, Instituto de Medicina Social, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brasil
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Couto LD, Tibiriça SHC, Pinheiro IO, Mitterofhe A, Lima AC, Castro MF, Gonçalves M, Silva MR, Guimarães RJPS, Rosa FM, Coimbra ES. Neglected tropical diseases: prevalence and risk factors for schistosomiasis and soil-transmitted helminthiasis in a region of Minas Gerais State, Brazil. Trans R Soc Trop Med Hyg 2014; 108:363-71. [PMID: 24781377 DOI: 10.1093/trstmh/tru054] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Among the neglected tropical diseases (NTDs), schistosomiasis and the three main soil-transmitted helminthiases (STHs), i.e., ascariasis, trichuriasis and hookworm infection, represent the most common infections in developing countries. In Brazil, there is a lack of epidemiological data in many parts of the country, which favors the unawareness of the real situation concerning these diseases. Due to this, we investigated the occurrence of schistosomiasis and STHs in a region of Minas Gerais State, Brazil. METHODS One stool sample was collected from 503 individuals, whose ages ranged from 0.1 to 91.2 years, and screened using both the Kato-Katz and the Formol-Ether methods. In parallel, a malacological survey was carried out in the main water bodies of the district, and Biomphalaria susceptibility assays and kernel-based techniques were also performed. RESULTS No individual was found infected with Ascaris lumbricoides or hookworm. Schistosoma mansoni was the most common parasite found (1.6%). The prevalence was higher in males and the chance of acquiring the disease increased by 43.35 times with contact with a body of water. None of the Biomphalaria tenagophila and B. glabrata specimens were found naturally infected, but B. glabrata was highly susceptible to infection with Schistosoma mansoni. Using kernel-based techniques, clusters of Biomphalaria were found near the households where the infected individuals lived. CONCLUSIONS Schistosomiasis was the most prevalent parasitic infection found. Our findings show that the occurrence of this disease has been underestimated by the local health care service, and highlight the importance of epidemiological surveillance in areas of low prevalence for schistosomiasis.
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Affiliation(s)
- Luzivalda D Couto
- Programa de Pós-graduação em Saúde Brasileira, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brasil
| | - Sandra H C Tibiriça
- Departamento de Clínica médica, Faculdade de Medicina, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brasil
| | - Izabella O Pinheiro
- Superintendência Regional de Saúde de Juiz de Fora, Secretaria de Estado da Saúde de Minas Gerais, Juiz de Fora, MG, Brasil
| | - Adalberto Mitterofhe
- Superintendência Regional de Saúde de Juiz de Fora, Secretaria de Estado da Saúde de Minas Gerais, Juiz de Fora, MG, Brasil
| | - Adilson C Lima
- Superintendência Regional de Saúde de Juiz de Fora, Secretaria de Estado da Saúde de Minas Gerais, Juiz de Fora, MG, Brasil
| | - Milton F Castro
- Superintendência Regional de Saúde de Juiz de Fora, Secretaria de Estado da Saúde de Minas Gerais, Juiz de Fora, MG, Brasil
| | - Murilo Gonçalves
- Superintendência Regional de Saúde de Juiz de Fora, Secretaria de Estado da Saúde de Minas Gerais, Juiz de Fora, MG, Brasil
| | | | | | - Florence M Rosa
- Departamento de Parasitologia, Microbiologia e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brasil
| | - Elaine S Coimbra
- Departamento de Parasitologia, Microbiologia e Imunologia, Instituto de Ciências Biológicas, Universidade Federal de Juiz de Fora, Juiz de Fora, MG, Brasil
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Hotez PJ, Bethony JM, Oliveira SC, Brindley PJ, Loukas A. Multivalent anthelminthic vaccine to prevent hookworm and schistosomiasis. Expert Rev Vaccines 2014; 7:745-52. [DOI: 10.1586/14760584.7.6.745] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Gouvras AN, Kariuki C, Koukounari A, Norton AJ, Lange CN, Ireri E, Fenwick A, Mkoji GM, Webster JP. The impact of single versus mixed Schistosoma haematobium and S. mansoni infections on morbidity profiles amongst school-children in Taveta, Kenya. Acta Trop 2013; 128:309-17. [PMID: 23313322 DOI: 10.1016/j.actatropica.2013.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 12/26/2012] [Accepted: 01/02/2013] [Indexed: 11/30/2022]
Abstract
Two schistosome species--Schistosoma haematobium and S. mansoni--with two very different pathological profiles (urogenital versus intestinal), are responsible for the majority of human schistosomiasis infections across sub-Saharan Africa. The aim of this study was to determine whether coinfections have an impact on species-specific morbidity measures when compared to single species infections. Children from two neighbouring schools in Taveta, Kenya were grouped by infection status, i.e. uninfected, single species infections or coinfected. Clinical examination of the liver and spleen by palpation was performed and urinary albumin levels were recorded at baseline and at 12 months after praziquantel administration. Additional ultrasonographic profiles of the children's liver, spleen and bladder were incorporated at follow-up. It was found that S. haematobium-associated urogenital morbidity was lower in the coinfected group relative to single S. haematobium infections, even when infection intensities were taken into account. We also observed an association between S. haematobium infection and liver (intestinal-associated) morbidity regardless of coinfections. The findings reported here suggest that further research should be performed on the impact of S. haematobium infections on liver morbidity as well as to determine the impact of mixed schistosome species infections on human morbidity outcomes across different endemic settings.
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Affiliation(s)
- Anouk N Gouvras
- DIDE, School of Public Health, Imperial College, London, UK.
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Oninla SO, Onayade AA, Owa JA. Impact of intestinal helminthiases on the nutritional status of primary-school children in Osun state, south–western Nigeria. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2013; 104:583-94. [DOI: 10.1179/136485910x12851868779786] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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Humphries D, Simms BT, Davey D, Otchere J, Quagraine J, Terryah S, Newton S, Berg E, Harrison LM, Boakye D, Wilson M, Cappello M. Hookworm infection among school age children in Kintampo north municipality, Ghana: nutritional risk factors and response to albendazole treatment. Am J Trop Med Hyg 2013; 89:540-8. [PMID: 23836564 DOI: 10.4269/ajtmh.12-0605] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Children (n = 812) 6-11 years of age attending 16 schools in the Kintampo North Municipality of Ghana were screened for participation in a study on hookworm infection, nutrition, and response to albendazole. The prevalence of Necator americanus hookworm infection (n = 286) was 39.1%, and significant predictors of infection included age, malaria parasitemia, lack of health care, school area, levels of antibodies against hookworm, and low consumption of animal foods. The cure rate after a single dose (400 mg) albendazole was 43%, and the mean fecal egg count reduction rate was 87.3%. Data for an in vitro egg hatch assay showed a trend toward reduced albendazole susceptibility in post-treatment hookworm isolates (P = 0.06). In summary, hookworm infection is prevalent among school age children in the Kintampo North Municipality and animal food intake inversely correlates with infection status. Modest cure rates and fecal egg count reduction rates reinforce the need for further investigation of potential benzimidazole resistance in Ghana.
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Affiliation(s)
- Debbie Humphries
- Program in International Child Health, Department of Pediatrics and School of Public Health, Yale School of Medicine, New Haven, CT 06520, USA.
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Yakob L, Williams GM, Gray DJ, Halton K, Solon JA, Clements ACA. Slaving and release in co-infection control. Parasit Vectors 2013; 6:157. [PMID: 23721567 PMCID: PMC3691829 DOI: 10.1186/1756-3305-6-157] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/23/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Animal and human infection with multiple parasite species is the norm rather than the exception, and empirical studies and animal models have provided evidence for a diverse range of interactions among parasites. We demonstrate how an optimal control strategy should be tailored to the pathogen community and tempered by species-level knowledge of drug sensitivity with use of a simple epidemiological model of gastro-intestinal nematodes. METHODS We construct a fully mechanistic model of macroparasite co-infection and use it to explore a range of control scenarios involving chemotherapy as well as improvements to sanitation. RESULTS Scenarios are presented whereby control not only releases a more resistant parasite from antagonistic interactions, but risks increasing co-infection rates, exacerbating the burden of disease. In contrast, synergisms between species result in their becoming epidemiologically slaved within hosts, presenting a novel opportunity for controlling drug resistant parasites by targeting co-circulating species. CONCLUSIONS Understanding the effects on control of multi-parasite species interactions, and vice versa, is of increasing urgency in the advent of integrated mass intervention programmes.
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Affiliation(s)
- Laith Yakob
- Infectious Disease Epidemiology Unit, School of Population Health, University of Queensland, Herston, Brisbane, QLD 4006, Australia.
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Talaat RM, Ali NM, Elwakil HS. Impact of Schistosoma mansoni and Echinococcus granulosus experimental coinfection on interleukin 10 and interferon gamma cytokines profile. Exp Parasitol 2013; 134:474-81. [PMID: 23684568 DOI: 10.1016/j.exppara.2013.05.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 04/20/2013] [Accepted: 05/06/2013] [Indexed: 11/29/2022]
Abstract
The interactions between various aspects of the immune responses mediated by concomitant parasite infections may influence the resultant cytokines profiles. We tested this hypothesis by developing two Schistosoma mansoni and Echinococcus granulosus coinfection murine models. Our aim was to explore the effect of echinoccocis on the immune responses induced by schistosomiasis, either when the two infections were induced synchronously or when echinococcosis was induced during egg deposition period of S. mansoni infection. The proliferation of antigens specific stimulated splenocytes, taken from studied groups, was determined. Then, IFN-γ, and IL-10 production from stimulated cells were measured. Significant elevation of IFN-γ, 4weeks after synchronous coinfection, was occurred compared to S. mansoni infected group, associated with modest elevation of IL10 level. On the other hand, echinococcosis coinfection during egg deposition period of schistosomiasis resulted in significant marked reduction in IL10 level in comparison to S. mansoni infected mice. These results suggested that echinococcosis coinfection, during the switching from Th1 to Th2 cytokine stage of murine schistosomiasis, can alter the ability of S. mansoni infection to skew the cytokines response towards Th2 profile. It is clear that the timing and sequence of concomitant infections are of vital importance for the outcome of the immune response.
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Affiliation(s)
- Roba Mohamed Talaat
- Molecular Biology Department, Genetic Engineering and Biotechnology Research Institute GEBRI, Menofia University, Sadat Branch, Egypt
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Sumbele IU, Ngole VM, Ekosse GIE. Influence of physico-chemistry and mineralogy on the occurrence of geohelminths in geophagic soils from selected communities in the Eastern Cape, South Africa, and their possible implication on human health. INTERNATIONAL JOURNAL OF ENVIRONMENTAL HEALTH RESEARCH 2013; 24:18-30. [PMID: 23574040 DOI: 10.1080/09603123.2013.782600] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Geophagic soils from selected communities in Eastern Cape, South Africa were characterised to determine their properties and geohelminth content. The soils were coarse-textured with cation exchange capacity values ranging from 6.35 to 18.94 cmol (+)/kg. Quartz was the dominant mineral in the samples with SiO2, Al2O3, and Fe2O3(t) having the highest concentrations among major element oxides. The soil properties, mineralogical composition, and low amounts of particle binding substances may favour the survival of geohelminth ova in the soils. Seven of the samples contained at least one of the following geohelminths: Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale and Strongyloides stercoralis. The presence of these geohelminths in the soils was attributed to agricultural and sanitary practices inherent in the communities and the soil properties. Communities need to be sensitised on the importance of safe sanitary and animal husbandry practices to reduce the prevalence of helminth infection among geophagists.
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Affiliation(s)
- Irene U Sumbele
- a Faculty of Science, Department of Zoology and Animal Physiology , University of Buea , Buea , Cameroon
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Geiger SM, Jardim-Botelho A, Williams W, Alexander N, Diemert DJ, Bethony JM. Serum CCL11 (eotaxin-1) and CCL17 (TARC) are serological indicators of multiple helminth infections and are driven by Schistosoma mansoni infection in humans. Trop Med Int Health 2013; 18:750-60. [PMID: 23496801 DOI: 10.1111/tmi.12095] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES To evaluate systemic serum cytokine and chemokine markers for inflammation and Th1/Th2 responses in relation to multiple helminth infections, parasite burden and/or nutritional status of individuals. METHODS In a longitudinal study, stool samples from 210 individuals from an area highly endemic for Ascaris lumbricoides, Necator americanus and Schistosoma mansoni were examined before and 12 months after clearance of parasites by chemotherapy. On both occasions, the presence of mono- or multiple infections and intensities of infection were compared with nutritional parameters and with serum cytokines or chemokines as markers for inflammatory, regulatory or Th1- or Th2-type immune responses. RESULTS Before treatment, we were not able to associate any altered nutritional parameters with increased inflammatory responses, and highest intensities of infection were found in eutrophic participants with multiple infections. In contrast, major changes in serum Th2-type chemokine levels were measured in individuals infected with intestinal helminths and/or S. mansoni, and resulted in significantly higher CCL11 and CCL17 concentrations, both before treatment and after reinfection. CONCLUSIONS The driving force for these elevated type 2 serum chemokine concentrations was an S. mansoni infection and faecal egg counts significantly correlated with serum IL-10 concentrations.
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Affiliation(s)
- Stefan M Geiger
- Universidade Federal de Minas Gerais, Instituto de Ciências Biológicas, Belo Horizonte, Brazil.
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Effects of treatment on IgE responses against parasite allergen-like proteins and immunity to reinfection in childhood schistosome and hookworm coinfections. Infect Immun 2012; 81:23-32. [PMID: 23071136 DOI: 10.1128/iai.00748-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Naturally occurring human immunity to both schistosomiasis and hookworm infection has been associated with IgE responses against parasite allergen-like proteins. Since the two helminths frequently coinfect the same individuals, there is growing advocacy for their concurrent treatment. However, both helminths are known to exert strong immunomodulatory effects; therefore, coinfected individuals could have immune responses different from those characteristically seen in monoinfected individuals. In this study, we measured changes in IgE, IgG1, and IgG4 responses to schistosome and hookworm antigens, including the allergen-like proteins Schistosoma mansoni tegumental-allergen-like 1 protein (SmTAL1), SmTAL2, and Necator americanus Ancylostoma-secreted protein-2 (Na-ASP-2), following concurrent treatment of schoolchildren coinfected with Schistosoma mansoni and hookworm. Antibody responses to schistosome egg (soluble egg antigen and SmTAL2) or somatic adult hookworm (AHW) antigens either decreased after treatment or were unchanged, whereas those to schistosome worm antigens (soluble worm antigen and SmTAL1) increased. The observed different effects of treatment likely reflect the different modes of drug action and sites of infection for these two helminths. Importantly, there was no evidence that the simultaneous treatment of coinfected children with praziquantel and albendazole affected schistosome- and hookworm-specific humoral responses differently from those characteristic of populations in which only one organism is endemic; schistosome- and hookworm-specific responses were not associated, and there was no evidence for cross-regulation. Posttreatment increases in the levels of IgE to schistosome worm antigens were associated with lower Schistosoma mansoni reinfection intensity, while no associations between humoral responses to AHW antigen and protection from hookworm reinfection were observed in this sample of school-aged children.
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Concurrent urinary and intestinal schistosomiasis and intestinal helminthic infections in schoolchildren in Ilobu, South-western Nigeria. Acta Trop 2012; 123:16-21. [PMID: 22440198 DOI: 10.1016/j.actatropica.2012.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 03/04/2012] [Accepted: 03/06/2012] [Indexed: 11/20/2022]
Abstract
A cross-sectional study was conducted in a schistosome-endemic rural community in Southwestern Nigeria. We assessed prevalence and intensity of soil-transmitted nematodes and the co-occurrence with Schistosoma haematobium and Schistosoma mansoni. Urine and stool samples from 419 schoolchildren were examined, and a questionnaire was administered to obtain socio-demographic characteristics. In total, 78.3% (328/419) were infected with at least one helminth species, with a prevalence (mean egg-count) of 55.1% (3069.2) of Ascaris lumbricoides, 41.1% (127.5) of S. haematobium, 22.7% (98.6) of hookworms, 17.9% (161.3) of Trichuris trichiura, and 10.3% (12.9) of S. mansoni. Multiple infections were significantly more common among children from households with more playmates, absence of toilet facilities and low income level (all p<0.001). Children with heavy hookworm burden were at a significantly higher chance of acquiring S. mansoni (OR=36.35; 95% Cl: 13.22-100.97; p<0.0001). The risk of S. mansoni and A. lumbricoides infections was increased in co-infections with S. haematobium. Logistic regression analysis revealed infections by hookworms and S. mansoni (adjusted odds ratio [aOR]=3.90, 95% Cl: 2.03-7.46; p<0.0001), and by hookworms and T. trichiura (aOR=2.46, 95% Cl: 1.44-4.22; p=0.001) as significant risk factors for multiple infections. Our study shows that polyparasitism is common in the study area. Focused interventions such as mass treatment with anthelminthics and health education are needed to improve the well-being of the affected population.
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Abstract
OBJECTIVE To review methods for the statistical analysis of parasite and other skewed count data. METHODS Statistical methods for skewed count data are described and compared, with reference to a 10-year period of Tropical Medicine and International Health (TMIH). Two parasitological datasets are used for illustration. RESULTS The review of TMIH found 90 articles, of which 89 used descriptive methods and 60 used inferential analysis. A lack of clarity is noted in identifying the measures of location, in particular the Williams and geometric means. The different measures are compared, emphasising the legitimacy of the arithmetic mean for the skewed data. In the published articles, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasising (1) non-parametric methods, while noting that they are not simply comparisons of medians, and (2) generalised linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described. CONCLUSIONS Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalised linear models are likely to be sufficient for most analyses.
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Affiliation(s)
- Neal Alexander
- London School of Hygiene and Tropical Medicine, London, UK.
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Belo VS, Oliveira RBD, Fernandes PC, Nascimento BWL, Fernandes FV, Castro CLF, Santos WBD, Silva ESD. Fatores associados à ocorrência de parasitoses intestinais em uma população de crianças e adolescentes. REVISTA PAULISTA DE PEDIATRIA 2012. [DOI: 10.1590/s0103-05822012000200007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJETIVOS: Analisar a prevalência de infecções por parasitos intestinais em crianças e adolescentes matriculados em escolas de ensino fundamental no município de São João del-Rei, Minas Gerais, e os fatores associados à infecção. MÉTODOS: Estudo epidemiológico seccional, realizado entre março/2008 e julho/2009. Foram realizados exames coproscópicos por sedimentação espontânea e Kato-Katz em 1.172 escolares. Foram ajustados modelos de regressão logística múltipla para o estudo dos fatores associados às infecções em geral e, separadamente, por helmintos e por protozoários. RESULTADOS: A prevalência de infecções foi de 29%, havendo uma variação de 7 a 83%, respectivamente, entre as escolas de menor e maior ocorrência. A presença de instalação sanitária no domicílio foi associada a uma ocorrência menor de helmintos; o aumento na idade dos escolares associou-se a uma maior ocorrência de protozoários e de parasitos em geral; enquanto a presença de filtro de água e a localização do domicílio em área urbana mostraram-se associadas a uma ocorrência menor dos três desfechos analisados. Em todas as regiões, foi registrado o consumo de medicação preventiva contra helmintos. CONCLUSÕES: Desigualdades nas condições de vida tornaram as prevalências diferenciadas entre as regiões do estudo. O estudo ressalta a necessidade de promover o uso de filtros de água nas residências de áreas endêmicas e de avaliar o consumo preventivo de medicamentos anti-helmínticos na dinâmica e na saúde dos indivíduos. Medidas de controle que levem em conta os fatores descritos devem ser prioritárias em nível de Saúde Pública.
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Diemert DJ, Pinto AG, Freire J, Jariwala A, Santiago H, Hamilton RG, Periago MV, Loukas A, Tribolet L, Mulvenna J, Correa-Oliveira R, Hotez PJ, Bethony JM. Generalized urticaria induced by the Na-ASP-2 hookworm vaccine: implications for the development of vaccines against helminths. J Allergy Clin Immunol 2012; 130:169-76.e6. [PMID: 22633322 DOI: 10.1016/j.jaci.2012.04.027] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 03/20/2012] [Accepted: 04/06/2012] [Indexed: 11/29/2022]
Abstract
BACKGROUND Necator americanus Ancylostoma-secreted protein 2 (Na-ASP-2) is secreted by infective hookworm larvae on entry into human hosts. Vaccination of laboratory animals with recombinant Na-ASP-2 provides significant protection against challenge infections. In endemic areas antibodies to Na-ASP-2 are associated with reduced risk of heavy N americanus infections. OBJECTIVE To assess the safety and immunogenicity of recombinant Na-ASP-2 adjuvanted with Alhydrogel in healthy Brazilian adults previously infected with N americanus. METHODS Participants were randomized to receive Na-ASP-2 or hepatitis B vaccine. Major IgG and IgE epitopes of the Na-ASP-2 molecule were mapped by using sera from these same subjects. Seroepidemiologic studies in adults and children residing in hookworm-endemic areas were conducted to assess the prevalence of IgE responses to Na-ASP-2. RESULTS Vaccination with a single dose of Na-ASP-2 resulted in generalized urticarial reactions in several volunteers. These reactions were associated with pre-existing Na-ASP-2-specific IgE likely induced by previous hookworm infection. Surveys revealed that a significant proportion of the population in hookworm-endemic areas had increased levels of IgE to Na-ASP-2. Epitope mapping demonstrated sites on the Na-ASP-2 molecule that are uniquely or jointly recognized by IgG and IgE antibodies. CONCLUSION Infection with N americanus induces increased levels of total and specific IgE to Na-ASP-2 that result in generalized urticaria on vaccination with recombinant Na-ASP-2. These data advance knowledge of vaccine development for helminths given their propensity to induce strong T(H)2 responses. Study data highlight the important differences between the immune responses to natural helminth infection and to vaccination with a recombinant helminth antigen.
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Affiliation(s)
- David J Diemert
- Albert B. Sabin Vaccine Institute, Washington, DC 20037, USA.
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Coinfection of Schistosoma (Trematoda) with bacteria, protozoa and helminths. ADVANCES IN PARASITOLOGY 2012; 77:1-85. [PMID: 22137582 DOI: 10.1016/b978-0-12-391429-3.00005-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
This review examines coinfection of selected species of Schistosoma with bacteria, protozoa and helminths and focuses on the effects of the coinfection on the hosts. The review is based mainly on tables that contain the salient information on the coinfecting organisms in vertebrate hosts. Further explanation and clarification of the tables are given in the text. A table is also provided that gives synoptic information on the 37 species in the 19 genera considered in this review. Coinfection studies with Schistosoma species and the other organisms were considered in six tables plus the accompanying text. Considerations of the Schistosoma interactions with another species of organism include studies on coinfection with Plasmodium, with protozoa other than Plasmodium; with Salmonella, with bacteria other than Salmonella; and with Fasciola, with helminths other than Fasciola. Numerous factors were found to influence the effects of coinfection on the vertebrate host, including organisms and hosts used in the studies, order and time interval between the first and the second infection, studies on natural versus experimental hosts, dosage of the infectious agents, strains and pedigrees of the parasites, age of hosts at time of exposure to the infectious agents and age of hosts at the time of necropsy. Overall, a prior infection with Schistosoma, particularly a patent infection, often has an effect on the subsequent infection by a protozoan, bacterium or other helminth. In relatively few cases, a prior infection with Schistosoma decreased the severity of the subsequent infection as with Helicobacter pylori, Fasciola hepatica, Echinostoma or Plasmodium, the latter only exhibiting this behaviour when coinfected with Schistosoma haematobium. More often, however, a prior infection with Schistosoma increased the severity of the second infection as with Leishmania, Toxoplasma gondii, Entamoeba histolytica, Staphylococcus aureus or Salmonella. In some of these coinfection studies, the increased severity of the subsequent infection was associated with a specific, prolonged form of the disease in humans, which has implications for patient treatment and recovery. Additional research is needed, particularly on Schistosoma coinfections which currently have a small body of research and are current problems in human populations. Examples of such Schistosoma interactions include the genera of Mycobacteria, Leishmania, Staphylococcus, Necator and Strongyloides. Hopefully, future studies will elucidate valuable new information on the interesting subject of coinfection of Schistosoma with other organisms.
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Necator americanus and helminth co-infections: further down-modulation of hookworm-specific type 1 immune responses. PLoS Negl Trop Dis 2011; 5:e1280. [PMID: 21909439 PMCID: PMC3167770 DOI: 10.1371/journal.pntd.0001280] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 07/08/2011] [Indexed: 11/30/2022] Open
Abstract
Background Helminth co-infection in humans is common in tropical regions of the world where transmission of soil-transmitted helminths such as Ascaris lumbricoides, Trichuris trichiura, and the hookworms Necator americanus and Ancylostoma duodenale as well as other helminths such as Schistosoma mansoni often occur simultaneously. Methodology We investigated whether co-infection with another helminth(s) altered the human immune response to crude antigen extracts from either different stages of N. americanus infection (infective third stage or adult) or different crude antigen extract preparations (adult somatic and adult excretory/secretory). Using these antigens, we compared the cellular and humoral immune responses of individuals mono-infected with hookworm (N. americanus) and individuals co-infected with hookworm and other helminth infections, namely co-infection with either A. lumbricoides, Schistosoma mansoni, or both. Immunological variables were compared between hookworm infection group (mono- versus co-infected) by bootstrap, and principal component analysis (PCA) was used as a data reduction method. Conclusions Contrary to several animal studies of helminth co-infection, we found that co-infected individuals had a further downmodulated Th1 cytokine response (e.g., reduced INF-γ), accompanied by a significant increase in the hookworm-specific humoral immune response (e.g. higher levels of IgE or IgG4 to crude antigen extracts) compared with mono- infected individuals. Neither of these changes was associated with a reduction of hookworm infection intensity in helminth co-infected individuals. From the standpoint of hookworm vaccine development, these results are relevant; i.e., the specific immune response to hookworm vaccine antigens might be altered by infection with another helminth. Parasitic infections in humans are common in tropical regions and under bad housing and sanitation conditions multiple parasitic infections are the rule rather than the exception. For helminth infections, which are thought to affect almost a quarter of the world's population, most common combinations include soil-transmitted helminths, such as hookworm, roundworm, and whipworm, as well as extra-intestinal infections by schistosomes. In order to develop and test a hookworm vaccine in endemic areas, the understanding of the impact of multiple helminth infections (co-infection) on the immune response against hookworm in infected individuals is crucial. The authors report in their article, that several parameters of the cellular (T cell markers, cytokines, chemokines) and humoral immune response (e.g. IgG4 and IgE antibodies) against hookworm are significantly affected or modulated in individuals co-infected with hookworm, roundworm and/or schistosomes. These results imply that the immune response against components of a hookworm vaccine might be altered by previous contact with other helminth species in endemic areas.
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Cundill B, Alexander N, Bethony JM, Diemert D, Pullan RL, Brooker S. Rates and intensity of re-infection with human helminths after treatment and the influence of individual, household, and environmental factors in a Brazilian community. Parasitology 2011; 138:1406-16. [PMID: 21819640 PMCID: PMC3827741 DOI: 10.1017/s0031182011001132] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
This study quantifies the rate and intensity of re-infection with human hookworm and Schistosoma mansoni infection 12 months following successful treatment, and investigates the influence of socio-economic, geographical and environmental factors. A longitudinal study of 642 individuals aged over 5 years was conducted in Minas Gerais State, Brazil from June 2004 to March 2006. Risk factors were assessed using interval censored regression for the rate and negative binomial regression for intensity. The crude rate and intensity of hookworm re-infection was 0·21 per year (95% confidence interval (CI) 0·15-0·29) and 70·9 epg (95% CI 47·2-106·6). For S. mansoni the rate was 0·06 per year (95% CI 0·03-0·10) and intensity 6·51 epg (95% CI 3·82-11·11). Rate and intensity of re-infection with hookworm were highest among males and positively associated with previous infection status, absence of a toilet and house structure. Rate and intensity of S. mansoni re-infection were associated with previous infection status as well as geographical, environmental and socio-economic factors. The implications of findings for the design of anti-helminth vaccine trials are discussed.
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Affiliation(s)
- Bonnie Cundill
- London School of Hygiene and Tropical Medicine, London, UK.
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Control of soil-transmitted helminths in sub-Saharan Africa: diagnosis, drug efficacy concerns and challenges. Acta Trop 2011; 120 Suppl 1:S4-11. [PMID: 20654570 DOI: 10.1016/j.actatropica.2010.07.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 06/28/2010] [Accepted: 07/02/2010] [Indexed: 10/19/2022]
Abstract
Soil-transmitted helminthiasis (STH) occur throughout the developing world and remain a major public health problem in the poorest communities with enormous consequences on health and development of school-aged and preschool children. The extent of the problem has long been neglected because these diseases rarely kill at a young age, due to their insidious and chronic nature. Today there exists a momentum and an unprecedented opportunity for a cost-effective control of these neglected tropical diseases. The control of these diseases has become a priority on the agenda of many governments, donors and international agencies, which provides important funding opportunities for STH control through integration and co-implementation of control interventions. In the era of preventive chemotherapy, the intensification of mass administration of anthelminthic drugs will result in epidemiological changes of STH transmission levels, with a rapid increase of light infections as far as control programmes are successful. As consequence, the current diagnostic tools may not be always appropriate and may therefore require adaptation or development of alternative assays adapted to the stage of control. This paper reviews aspects relevant to diagnosis and appropriate tools for accurate surveillance and monitoring of STH control programmes and drug efficacy. Prospects, opportunities and challenges for the control are discussed.
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Rellstab C, Louhi KR, Karvonen A, Jokela J. Analysis of trematode parasite communities in fish eye lenses by pyrosequencing of naturally pooled DNA. INFECTION GENETICS AND EVOLUTION 2011; 11:1276-86. [DOI: 10.1016/j.meegid.2011.04.018] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2011] [Revised: 04/14/2011] [Accepted: 04/16/2011] [Indexed: 11/27/2022]
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Tarafder MR, Carabin H, McGarvey ST, Joseph L, Balolong E, Olveda R. Assessing the impact of misclassification error on an epidemiological association between two helminthic infections. PLoS Negl Trop Dis 2011; 5:e995. [PMID: 21468317 PMCID: PMC3066162 DOI: 10.1371/journal.pntd.0000995] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Accepted: 03/03/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Polyparasitism can lead to severe disability in endemic populations. Yet, the association between soil-transmitted helminth (STH) and the cumulative incidence of Schistosoma japonicum infection has not been described. The aim of this work was to quantify the effect of misclassification error, which occurs when less than 100% accurate tests are used, in STH and S. japonicum infection status on the estimation of this association. METHODOLOGY/PRINCIPAL FINDINGS Longitudinal data from 2276 participants in 50 villages in Samar province, Philippines treated at baseline for S. japonicum infection and followed for one year, served as the basis for this analysis. Participants provided 1-3 stool samples at baseline and 12 months later (2004-2005) to detect infections with STH and S. japonicum using the Kato-Katz technique. Variation from day-to-day in the excretion of eggs in feces introduces individual variations in the sensitivity and specificity of the Kato-Katz to detect infection. Bayesian logit models were used to take this variation into account and to investigate the impact of misclassification error on the association between these infections. Uniform priors for sensitivity and specificity of the diagnostic test to detect the three STH and S. japonicum were used. All results were adjusted for age, sex, occupation, and village-level clustering. Without correction for misclassification error, the odds ratios (ORs) between hookworm, Ascaris lumbricoides, and Trichuris trichiura, and S. japonicum infections were 1.28 (95% Bayesian credible intervals: 0.93, 1.76), 0.91 (95% BCI: 0.66, 1.26), and 1.11 (95% BCI: 0.80, 1.55), respectively, and 2.13 (95% BCI: 1.16, 4.08), 0.74 (95% BCI: 0.43, 1.25), and 1.32 (95% BCI: 0.80, 2.27), respectively, after correction for misclassification error for both exposure and outcome. CONCLUSIONS/SIGNIFICANCE The misclassification bias increased with decreasing test accuracy. Hookworm infection was found to be associated with increased 12-month cumulative incidence of S. japonicum infection after correction for misclassification error. Such important associations might be missed in analyses which do not adjust for misclassification errors.
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Affiliation(s)
- Mushfiqur R Tarafder
- Department of Biostatistics and Epidemiology, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America.
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