1
|
Eyang-Assengone ER, Makouloutou-Nzassi P, Mbou-Boutambe C, Bangueboussa F, Atsame J, Boundenga L. Status of Onchocerciasis Elimination in Gabon and Challenges: A Systematic Review. Microorganisms 2023; 11:1946. [PMID: 37630506 PMCID: PMC10458829 DOI: 10.3390/microorganisms11081946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Revised: 07/19/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
Control and treatment programs (CDTI) have been set up nationally in all endemic countries to overcome the impact of onchocerciasis on the affected populations. However, Gabon must still succeed in setting up real onchocerciasis control programs. Here, various database articles have been used to provide the scientific community with a summary document showing the mapping of this disease in Gabon. The articles dealing with onchocerciasis, animal reservoirs, surveillance, and elimination were analyzed. Results showed that little research has been performed. Most studies are concentrated in one region (The area of Lastourville). In addition, we observed that the distribution of the disease varies significantly across the country. Indeed, specific environments present a hyper-endemicity of the disease, while others are meso and hypo-endemic. So, we found some departments with a prevalence ranging from 0% to over 20%; within them, villages had infection levels comprising 10% to 60%, indicating potential hotspots. Vectors activities were studied in some areas. This paper showed the challenges encountered in the country to eliminate this disease. One solution is a deeper understanding of the disease's bioecology to establish effective health policies to eliminate onchocerciasis in Gabon effectively.
Collapse
Affiliation(s)
- Elsa-Rush Eyang-Assengone
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville BP 769, Gabon; (P.M.-N.); (C.M.-B.); (F.B.)
| | - Patrice Makouloutou-Nzassi
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville BP 769, Gabon; (P.M.-N.); (C.M.-B.); (F.B.)
- Département de Biologie et Ecologie Animale, Institut de Recherche en Ecologie Tropicale (IRET/CENAREST), Libreville BP 13354, Gabon
| | - Clark Mbou-Boutambe
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville BP 769, Gabon; (P.M.-N.); (C.M.-B.); (F.B.)
| | - Félicien Bangueboussa
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville BP 769, Gabon; (P.M.-N.); (C.M.-B.); (F.B.)
| | - Julienne Atsame
- Programme de Lutte Contre les Maladies Parasitaires, Ministère de la Santé du Gabon, Libreville BP 2434, Gabon;
| | - Larson Boundenga
- Unité de Recherche en Ecologie de la Santé (URES), Centre Interdisciplinaire de Recherches Médicales de Franceville (CIRMF), Franceville BP 769, Gabon; (P.M.-N.); (C.M.-B.); (F.B.)
- Département d’anthropologie, Université de Durham, South Road, Durham DH1 3LE, UK
| |
Collapse
|
2
|
Koala L, Tirados I, Nikiema AS, Thomsen E, McCall PJ, Dabire RK. Prospects for developing efficient targets for the xenomonitoring and control of Simulium damnosum s.l., the major vectors of onchocerciasis in Africa. MEDICAL AND VETERINARY ENTOMOLOGY 2022; 36:235-246. [PMID: 35866620 PMCID: PMC9543835 DOI: 10.1111/mve.12598] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Despite the ethical issues concerning the continued use of Human Landing Catches (HLC) to monitor the Simulium damnosum complex for epidemiological monitoring of onchocericasis, few attempts to develop alternatives have been reported. In studies on a wild population of S. damnosum in Burkina Faso, we tested visual targets (different sizes and shapes) and olfactory stimuli (CO2 , and POCA and BG-lure® odour blends) for their ability to attract and collect host seeking blackflies. At each trap, blackflies were caught with appropriately sized electrocuting grids and results from Latin square design tests were compared. Throughout, HLCs captured more blackflies than the targets. Of the traps tested, small targets (0.0625 and 0.5 m2 ) were the most efficient visual lure in terms of the number of S. damnosum captured per unit area 1.7-5× more than larger targets. Overall, results suggested that sticky black targets of horizontal rectangular shape (0.125-0.5 m2 ) and baited with a POCA and/or CO2 mixture could provide a cheap practical field alternative to HLC for onchocerciasis xenomonitoring, subject to confirmation that the design has no inherent bias for certain members of the S. damnosum species complex.
Collapse
Affiliation(s)
- Lassane Koala
- Departement Biomédicale et Santé PubliqueCentre National de Recherche Scientifique et Technologique (CNRST)/Institut de Recherche en Sciences de la Santé (IRSS)/Direction Régionale de l'OuestBobo DioulassoBurkina Faso
| | - Inaki Tirados
- Vector Biology DepartmentLiverpool School of Tropical MedicineLiverpoolUK
| | - Achille S. Nikiema
- Departement Biomédicale et Santé PubliqueCentre National de Recherche Scientifique et Technologique (CNRST)/Institut de Recherche en Sciences de la Santé (IRSS)/Direction Régionale de l'OuestBobo DioulassoBurkina Faso
| | - Edward Thomsen
- Vector Biology DepartmentLiverpool School of Tropical MedicineLiverpoolUK
| | - Philip J. McCall
- Vector Biology DepartmentLiverpool School of Tropical MedicineLiverpoolUK
| | - Roch K. Dabire
- Departement Biomédicale et Santé PubliqueCentre National de Recherche Scientifique et Technologique (CNRST)/Institut de Recherche en Sciences de la Santé (IRSS)/Direction Régionale de l'OuestBobo DioulassoBurkina Faso
| |
Collapse
|
3
|
Willen L, Milton P, Hamley JID, Walker M, Osei-Atweneboana MY, Volf P, Basáñez MG, Courtenay O. Demographic patterns of human antibody levels to Simulium damnosum s.l. saliva in onchocerciasis-endemic areas: An indicator of exposure to vector bites. PLoS Negl Trop Dis 2022; 16:e0010108. [PMID: 35020729 PMCID: PMC8789114 DOI: 10.1371/journal.pntd.0010108] [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: 09/30/2021] [Revised: 01/25/2022] [Accepted: 12/17/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In onchocerciasis endemic areas in Africa, heterogenous biting rates by blackfly vectors on humans are assumed to partially explain age- and sex-dependent infection patterns with Onchocerca volvulus. To underpin these assumptions and further improve predictions made by onchocerciasis transmission models, demographic patterns in antibody responses to salivary antigens of Simulium damnosum s.l. are evaluated as a measure of blackfly exposure. METHODOLOGY/PRINCIPAL FINDINGS Recently developed IgG and IgM anti-saliva immunoassays for S. damnosum s.l. were applied to blood samples collected from residents in four onchocerciasis endemic villages in Ghana. Demographic patterns in antibody levels according to village, sex and age were explored by fitting generalized linear models. Antibody levels varied between villages but showed consistent patterns with age and sex. Both IgG and IgM responses declined with increasing age. IgG responses were generally lower in males than in females and exhibited a steeper decline in adult males than in adult females. No sex-specific difference was observed in IgM responses. CONCLUSIONS/SIGNIFICANCE The decline in age-specific antibody patterns suggested development of immunotolerance or desensitization to blackfly saliva antigen in response to persistent exposure. The variation between sexes, and between adults and youngsters may reflect differences in behaviour influencing cumulative exposure. These measures of antibody acquisition and decay could be incorporated into onchocerciasis transmission models towards informing onchocerciasis control, elimination, and surveillance.
Collapse
Affiliation(s)
- Laura Willen
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
- Centre for the Evaluation of Vaccinations, Vaccine and Infectious Disease Institute, University of Antwerp, Wilrijk, Belgium
- * E-mail: (LW); (OC)
| | - Philip Milton
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Jonathan I. D. Hamley
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | | | - Petr Volf
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Orin Courtenay
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (LW); (OC)
| |
Collapse
|
4
|
Human immune response against salivary antigens of Simulium damnosum s.l.: A new epidemiological marker for exposure to blackfly bites in onchocerciasis endemic areas. PLoS Negl Trop Dis 2021; 15:e0009512. [PMID: 34157020 PMCID: PMC8253393 DOI: 10.1371/journal.pntd.0009512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 07/02/2021] [Accepted: 05/27/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Simulium damnosum sensu lato (s.l.) blackflies transmit Onchocerca volvulus, a filarial nematode that causes human onchocerciasis. Human landing catches (HLCs) is currently the sole method used to estimate blackfly biting rates but is labour-intensive and questionable on ethical grounds. A potential alternative is to measure host antibodies to vector saliva deposited during bloodfeeding. In this study, immunoassays to quantify human antibody responses to S. damnosum s.l. saliva were developed, and the salivary proteome of S. damnosum s.l. was investigated. METHODOLOGY/PRINCIPAL FINDINGS Blood samples from people living in onchocerciasis-endemic areas in Ghana were collected during the wet season; samples from people living in Accra, a blackfly-free area, were considered negative controls and compared to samples from blackfly-free locations in Sudan. Blackflies were collected by HLCs and dissected to extract their salivary glands. An ELISA measuring anti-S. damnosum s.l. salivary IgG and IgM was optimized and used to quantify the humoral immune response of 958 individuals. Both immunoassays differentiated negative controls from endemic participants. Salivary proteins were separated by gel-electrophoresis, and antigenic proteins visualized by immunoblot. Liquid chromatography mass spectrometry (LC-MS/MS) was performed to characterize the proteome of S. damnosum s.l. salivary glands. Several antigenic proteins were recognized, with the major ones located around 15 and 40 kDa. LC-MS/MS identified the presence of antigen 5-related protein, apyrase/nucleotidase, and hyaluronidase. CONCLUSIONS/SIGNIFICANCE This study validated for the first time human immunoassays that quantify humoral immune responses as potential markers of exposure to blackfly bites. These assays have the potential to facilitate understanding patterns of exposure as well as evaluating the impact of vector control on biting rates. Future studies need to investigate seasonal fluctuations of these antibody responses, potential cross-reactions with other bloodsucking arthropods, and thoroughly identify the most immunogenic proteins.
Collapse
|
5
|
Cheke RA, Little KE, Young S, Walker M, Basáñez MG. Taking the strain out of onchocerciasis? A reanalysis of blindness and transmission data does not support the existence of a savannah blinding strain of onchocerciasis in West Africa. ADVANCES IN PARASITOLOGY 2021; 112:1-50. [PMID: 34024357 DOI: 10.1016/bs.apar.2021.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Onchocerciasis (also known as 'river blindness'), is a neglected tropical disease (NTD) caused by the (Simulium-transmitted) filarial nematode Onchocerca volvulus. The occurrence of 'blinding' (savannah) and non-blinding (forest) parasite strains and the existence of corresponding, locally adapted Onchocerca-Simulium complexes were postulated to explain greater blindness prevalence in savannah than in forest foci. As a result, the World Health Organization (WHO) Onchocerciasis Control Programme in West Africa (OCP) focused anti-vectorial and anti-parasitic interventions in savannah endemic areas. In this paper, village-level data on blindness prevalence, microfilarial prevalence, and transmission intensity (measured by the annual transmission potential, the number of infective, L3, larvae per person per year) were extracted from 16 West-Central Africa-based publications, and analysed according to habitat (forest, forest-savannah mosaic, savannah) to test the dichotomous strain hypothesis in relation to blindness. When adjusting for sample size, there were no statistically significant differences in blindness prevalence between the habitats (one-way ANOVA, P=0.68, mean prevalence for forest=1.76±0.37 (SE); mosaic=1.49±0.38; savannah=1.89±0.26). The well-known relationship between blindness prevalence and annual transmission potential for savannah habitats was confirmed and shown to hold for (but not to be statistically different from) forest foci (excluding data from southern Côte d'Ivoire, in which blindness prevalence was significantly lower than in other West African forest communities, but which had been the focus of studies leading to the strain-blindness hypothesis that was accepted by OCP planners). We conclude that the evidence for a savannah blinding onchocerciasis strain in simple contrast with a non-blinding forest strain is equivocal. A re-appraisal of the strain hypothesis to explain patterns of ocular disease is needed to improve understanding of onchocerciasis epidemiology and disease burden estimates in the light of the WHO 2030 goals for onchocerciasis.
Collapse
Affiliation(s)
- Robert A Cheke
- Natural Resources Institute, Department of Agriculture, Health & Environment, University of Greenwich at Medway, Kent, United Kingdom; London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom
| | | | - Stephen Young
- Natural Resources Institute, Department of Agriculture, Health & Environment, University of Greenwich at Medway, Kent, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Populations Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom; MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom.
| |
Collapse
|
6
|
Hamley JID, Milton P, Walker M, Basáñez MG. Modelling exposure heterogeneity and density dependence in onchocerciasis using a novel individual-based transmission model, EPIONCHO-IBM: Implications for elimination and data needs. PLoS Negl Trop Dis 2019; 13:e0007557. [PMID: 31805049 PMCID: PMC7006940 DOI: 10.1371/journal.pntd.0007557] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/07/2020] [Accepted: 06/18/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin. METHODOLOGY/PRINCIPAL FINDINGS Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d'Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model. CONCLUSIONS/SIGNIFICANCE This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment.
Collapse
Affiliation(s)
- Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- * E-mail:
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield, Untied Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
| |
Collapse
|
7
|
Wanji S, Nji TM, Hamill L, Dean L, Ozano K, Njouendou AJ, Abong RA, Obie ED, Amuam A, Ekanya R, Ndongmo WPC, Ndzeshang BL, Fung EG, Nnamdi DB, Nkimbeng DA, Teghen S, Kah E, Piotrowski H, Forrer A, Khan JAM, Woode ME, Niessen L, Watson V, Njoumemi Z, Murdoch ME, Thomson R, Theobald S, Enyong P, Turner JD, Taylor MJ. Implementation of test-and-treat with doxycycline and temephos ground larviciding as alternative strategies for accelerating onchocerciasis elimination in an area of loiasis co-endemicity: the COUNTDOWN consortium multi-disciplinary study protocol. Parasit Vectors 2019; 12:574. [PMID: 31801631 PMCID: PMC6894124 DOI: 10.1186/s13071-019-3826-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 11/25/2019] [Indexed: 12/15/2022] Open
Abstract
Background Onchocerciasis is a priority neglected tropical disease targeted for elimination by 2025. The standard strategy to combat onchocerciasis is annual Community-Directed Treatment with ivermectin (CDTi). Yet, high prevalence rates and transmission persist following > 12 rounds in South-West Cameroon. Challenges include programme coverage, adherence to, and acceptability of ivermectin in an area of Loa loa co-endemicity. Loiasis patients harbouring heavy infections are at risk of potentially fatal serious adverse events following CDTi. Alternative strategies are therefore needed to achieve onchocerciasis elimination where CDTi effectiveness is suboptimal. Methods/design We designed an implementation study to evaluate integrating World Health Organisation-endorsed alternative strategies for the elimination of onchocerciasis, namely test-and-treat with the macrofilaricide, doxycycline (TTd), and ground larviciding for suppression of blackfly vectors with the organophosphate temephos. A community-based controlled before-after intervention study will be conducted among > 2000 participants in 20 intervention (Meme River Basin) and 10 control (Indian River Basin) communities. The primary outcome measure is O. volvulus prevalence at follow-up 18-months post-treatment. The study involves four inter-disciplinary components: parasitology, entomology, applied social sciences and health economics. Onchocerciasis skin infection will be diagnosed by skin biopsy and Loa loa infection will be diagnosed by parasitological examination of finger-prick blood samples. A simultaneous clinical skin disease assessment will be made. Eligible skin-snip-positive individuals will be offered directly-observed treatment for 5 weeks with 100 mg/day doxycycline. Transmission assessments of onchocerciasis in the communities will be collected post-human landing catch of the local biting blackfly vector prior to ground larviciding with temephos every week (0.3 l/m3) until biting rate falls below 5/person/day. Qualitative research, including in-depth interviews and focus-group discussions will be used to assess acceptability and feasibility of the implemented alternative strategies among intervention recipients and providers. Health economics will assess the cost-effectiveness of the implemented interventions. Conclusions Using a multidisciplinary approach, we aim to assess the effectiveness of TTd, alone or in combination with ground larviciding, following a single intervention round and scrutinise the acceptability and feasibility of implementing at scale in similar hotspots of onchocerciasis infection, to accelerate onchocerciasis elimination.
Collapse
Affiliation(s)
- Samuel Wanji
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon. .,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon.
| | - Theobald Mue Nji
- COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon.,COUNTDOWN, Department of Sociology and Anthropology, Faculty of Social and Management Sciences, University of Buea, P.O. Box 63, Buea, Cameroon
| | | | - Laura Dean
- COUNTDOWN, Department of International Public Health, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Kim Ozano
- COUNTDOWN, Department of International Public Health, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Abdel J Njouendou
- COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon.,COUNTDOWN, Department of Biomedical Sciences, Faculty of Health Sciences, University of Buea, P.O. Box 12, Buea, Cameroon
| | - Raphael A Abong
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Elisabeth Dibando Obie
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Andrew Amuam
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Relindis Ekanya
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Winston Patrick Chounna Ndongmo
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Bertrand L Ndzeshang
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Ebua Gallus Fung
- COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon.,COUNTDOWN, Department of Sociology and Anthropology, Faculty of Social and Management Sciences, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Dum-Buo Nnamdi
- COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon.,COUNTDOWN, Department of Sociology and Anthropology, Faculty of Social and Management Sciences, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Desmond Akumtoh Nkimbeng
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Samuel Teghen
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Emmanuel Kah
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Helen Piotrowski
- COUNTDOWN, Department of International Public Health, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Armelle Forrer
- COUNTDOWN, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Jahangir A M Khan
- COUNTDOWN, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Maame E Woode
- Centre for Health Economics, Monash University, Victoria, Australia
| | - Louis Niessen
- COUNTDOWN, Department of International Public Health, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.,Department of International Health, Johns Hopkins School of Public Health, Baltimore, USA
| | - Victoria Watson
- COUNTDOWN, Department of Clinical Sciences, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Zakariaou Njoumemi
- Health Economics Unit, Department of Public Health, Faculty of Medicine and Biomedical Sciences, University of Yaounde I, P.O. Box 1364, Yaounde, Cameroon
| | - Michele E Murdoch
- COUNTDOWN, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.,West Herts Hospitals NHS Trust, Watford General Hospital, Vicarage Road, Watford, UK
| | - Rachael Thomson
- COUNTDOWN, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Sally Theobald
- COUNTDOWN, Department of International Public Health, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Peter Enyong
- COUNTDOWN, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, P.O. Box 63, Buea, Cameroon.,COUNTDOWN, Research Foundation for Tropical Diseases and Environment, P.O. Box 474, Buea, Cameroon
| | - Joseph D Turner
- COUNTDOWN, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK.
| | - Mark J Taylor
- COUNTDOWN, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| |
Collapse
|
8
|
Loum D, Katholi CR, Lakwo T, Habomugisha P, Tukahebwa EM, Unnasch TR. Evaluation of Community-Directed Operation of Black Fly Traps for Entomological Surveillance of Onchocerca volvulus Transmission in the Madi-Mid North Focus of Onchocerciasis in Northern Uganda. Am J Trop Med Hyg 2017; 97:1235-1242. [PMID: 29031285 DOI: 10.4269/ajtmh.17-0244] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Entomological measures of transmission are important metrics specified by the World Health Organization to document the suppression and interruption of transmission of Onchocerca volvulus, the causative agent of onchocerciasis. These metrics require testing of large numbers of vector black flies. Black fly collection has relied on human landing collections, which are inefficient and potentially hazardous. As the focus of the international community has shifted from onchocerciasis control to elimination, replacement of human landing collections has become a priority. The Esperanza window trap (EWT) has shown promise as an alternative method for collection of Simulium damnosum s.l., the primary vector of O. volvulus in Africa. Here, we report the results of a community-based trial of the EWT in northern Uganda. Traps operated by residents were compared with human landing collections in two communities over 5 months. Three traps, when operated by a single village resident, collected over four times as many S. damnosum as did the two-men collection team. No significant differences were noted among the bait formulations. The results suggest that EWTs may be effectively operated by community residents and that the trap represents a viable alternative to human landing collections for entomological surveillance of O. volvulus transmission.
Collapse
Affiliation(s)
- Denis Loum
- Nwoya District Local Government, Nwoya, Uganda
| | - Charles R Katholi
- Department of Biostatistics, School of Public Health, University of Alabama at Birmingham, Birmingham, Alabama
| | - Thomson Lakwo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | - Thomas R Unnasch
- Global Health Infectious Disease Research, College of Public Health, University of South Florida, Tampa, Florida
| |
Collapse
|
9
|
Lamberton PHL, Cheke RA, Walker M, Winskill P, Crainey JL, Boakye DA, Osei-Atweneboana MY, Tirados I, Wilson MD, Tetteh-Kumah A, Otoo S, Post RJ, Basañez MG. Onchocerciasis transmission in Ghana: the human blood index of sibling species of the Simulium damnosum complex. Parasit Vectors 2016; 9:432. [PMID: 27494934 PMCID: PMC4975878 DOI: 10.1186/s13071-016-1703-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 07/14/2016] [Indexed: 11/10/2022] Open
Abstract
Background Vector-biting behaviour is important for vector-borne disease (VBD) epidemiology. The proportion of blood meals taken on humans (the human blood index, HBI), is a component of the biting rate per vector on humans in VBD transmission models. Humans are the definitive host of Onchocerca volvulus, but the simuliid vectors feed on a range of animals and HBI is a key indicator of the potential for human onchocerciasis transmission. Ghana has a diversity of Simulium damnosum complex members, which are likely to vary in their HBIs, an important consideration for parameterization of onchocerciasis control and elimination models. Methods Host-seeking and ovipositing S. damnosum (sensu lato) (s.l.) were collected from seven villages in four Ghanaian regions. Taxa were morphologically and molecularly identified. Blood meals from individually stored blackfly abdomens were used for DNA profiling, to identify previous host choice. Household, domestic animal, wild mammal and bird surveys were performed to estimate the density and diversity of potential blood hosts of blackflies. Results A total of 11,107 abdomens of simuliid females (which would have obtained blood meal(s) previously) were tested, with blood meals successfully amplified in 3,772 (34 %). A single-host species was identified in 2,857 (75.7 %) of the blood meals, of which 2,162 (75.7 %) were human. Simulium soubrense Beffa form, S. squamosum C and S. sanctipauli Pra form were the most anthropophagic (HBI = 0.92, 0.86 and 0.70, respectively); S. squamosum E, S. yahense and S. damnosum (sensu stricto) (s.s.)/S. sirbanum were the most zoophagic (HBI = 0.44, 0.53 and 0.63, respectively). The degree of anthropophagy decreased (but not statistically significantly) with increasing ratio of non-human/human blood hosts. Vector to human ratios ranged from 139 to 1,198 blackflies/person. Conclusions DNA profiling can successfully identify blood meals from host-seeking and ovipositing blackflies. Host choice varies according to sibling species, season and capture site/method. There was no evidence that HBI is vector and/or host density dependent. Transmission breakpoints will vary among locations due to differing cytospecies compositions and vector abundances. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1703-2) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Poppy H L Lamberton
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.,Present address: Institute of Biodiversity, Animal Health and Comparative Medicine; Wellcome Trust Centre for Molecular Parasitology, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Robert A Cheke
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.,Natural Resources Institute, University of Greenwich at Medway, Central Avenue, Chatham Maritime, Chatham, Kent, ME4 4 TB, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Peter Winskill
- MRC Centre for Outbreak Analysis and Modelling. Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - J Lee Crainey
- Instituto Leônidas e Maria Deane, Fundação Oswaldo Cruz, Rua Terezina 476, Adrianopolis, AM, 69057-070, Manaus, Brazil
| | - Daniel A Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana
| | - Mike Y Osei-Atweneboana
- Department of Environmental Biology and Health, Water Research Institute, Council for Scientific and Industrial Research, PO Box M32, Accra, Ghana
| | - Iñaki Tirados
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Michael D Wilson
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana
| | | | - Sampson Otoo
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, PO Box LG581, Accra, Ghana
| | - Rory J Post
- School of Natural Sciences and Psychology, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AH, UK
| | - María-Gloria Basañez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London, W2 1PG, UK.
| |
Collapse
|
10
|
Rodríguez-Pérez MA, Adeleke MA, Rodríguez-Luna IC, Cupp EW, Unnasch TR. Evaluation of a community-based trapping program to collect Simulium ochraceum sensu lato for verification of onchocerciasis elimination. PLoS Negl Trop Dis 2014; 8:e3249. [PMID: 25340517 PMCID: PMC4207651 DOI: 10.1371/journal.pntd.0003249] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/06/2014] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Collection of the black fly vectors of onchocerciasis worldwide relies upon human landing collections. Recent studies have suggested that the Esperanza Window Trap baited with a human scent lure and CO2 had the potential to replace human hosts for the collection of Simulium ochraceum sensu lato in Southern Chiapas focus, Mexico. The feasibility of utilizing these traps in a community-based approach for the collection of S. ochraceum s.l. was evaluated. METHODOLOGY/PRINCIPAL FINDINGS Local residents of a formerly endemic extra-sentinel community for onchocerciasis were trained to carry out collections using the traps. The residents operated the traps over a 60-day period and conducted parallel landing collections, resulting in a total of 28,397 vector black flies collected. None of the flies collected were found to contain parasite DNA when tested by a polymerase chain reaction assay targeting a parasite specific sequence, resulting in a point estimate of infection in the vectors of zero, with an upper bound of the 95% confidence interval 0.13 per 2,000. This meets the accepted criterion for demonstrating an interruption of parasite transmission. CONCLUSIONS/SIGNIFICANCE These data demonstrate that Esperanza Window Traps may be effectively operated by minimally trained residents of formerly endemic communities, resulting in the collection of sufficient numbers of flies to verify transmission interruption of onchocerciasis. The traps represent a viable alternative to using humans as hosts for the collection of vector flies as part of the verification of onchocerciasis elimination.
Collapse
Affiliation(s)
- Mario A. Rodríguez-Pérez
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México
- Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, México
| | - Monsuru A. Adeleke
- Public Health Entomology and Parasitology Unit, Department of Biological Sciences, Osun State University, Osogbo, Nigeria
| | | | - Eddie W. Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Thomas R. Unnasch
- Global Health Infectious Disease Research Program, Department of Global Health, University of South Florida, Tampa, Florida, United States of America
| |
Collapse
|
11
|
Optimization of the Esperanza window trap for the collection of the African onchocerciasis vector Simulium damnosum sensu lato. Acta Trop 2014; 137:39-43. [PMID: 24794201 DOI: 10.1016/j.actatropica.2014.04.029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 04/21/2014] [Accepted: 04/24/2014] [Indexed: 11/21/2022]
Abstract
A simple inexpensive trap (Esperanza window trap) was shown recently to collect significant numbers of Simulium ochraceum sensu lato, a major vector of Onchocerca volvulus in Mesoamerica. Here, we report studies optimizing this trap for the collection of Simulium damnosum s.l., the major vector of O. volvulus in Africa. A shortened, blue and black striped version of the Esperanza window trap, when baited with a combination of CO2 and worn trousers, rivalled human landing collections in the number of S. damnosum s.l. females collected. Traps baited with a commercially available human skin lure and CO2 resulted in collections that were not significantly different than those obtained from traps baited with worn trousers and CO2. This suggests that the Esperanza window trap may offer a replacement for human landing collections for monitoring onchocerciasis transmission in Africa.
Collapse
|
12
|
Rodríguez-Pérez MA, Adeleke MA, Burkett-Cadena ND, Garza-Hernández JA, Reyes-Villanueva F, Cupp EW, Toé L, Salinas-Carmona MC, Rodríguez-Ramírez AD, Katholi CR, Unnasch TR. Development of a novel trap for the collection of black flies of the Simulium ochraceum complex. PLoS One 2013; 8:e76814. [PMID: 24116169 PMCID: PMC3792067 DOI: 10.1371/journal.pone.0076814] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 08/29/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Human landing collections are currently the standard method for collecting onchocerciasis vectors in Africa and Latin America. As part of the efforts to develop a trap to replace human landing collections for the monitoring and surveillance of onchocerciasis transmission, comprehensive evaluations of several trap types were conducted to assess their ability to collect Simulium ochraceum sensu lato, one of the principal vectors of Onchocerca volvulus in Latin America. METHODOLOGY/PRINCIPAL FINDINGS Diverse trap designs with numerous modifications and bait variations were evaluated for their abilities to collect S. Ochraceum s.l. females. These traps targeted mostly host seeking flies. A novel trap dubbed the "Esperanza window trap" showed particular promise over other designs. When baited with CO2 and BG-lure (a synthetic blend of human odor components) a pair of Esperanza window traps collected numbers of S. Ochraceum s.l. females similar to those collected by a team of vector collectors. CONCLUSIONS/SIGNIFICANCE The Esperanza window trap, when baited with chemical lures and CO2 can be used to collect epidemiologically significant numbers of Simulium ochraceum s.l., potentially serving as a replacement for human landing collections for evaluation of the transmission of O. volvulus.
Collapse
Affiliation(s)
- Mario A. Rodríguez-Pérez
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México
- Facultad de Medicina, Universidad Autónoma de Nuevo León, Monterrey, Nuevo León, México
| | - Monsuru A. Adeleke
- Department of Biological Sciences, Osun State University, Osogbo, Nigeria
| | - Nathan D. Burkett-Cadena
- Global Health Infectious Disease Research Program, Department of Global Health, University of South Florida, Tampa, Florida, United States of America
| | | | | | - Eddie W. Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Laurent Toé
- Multidisease Surveillance Centre, World Health Organization, Ouagadougou, Burkina Faso
| | | | - Américo D. Rodríguez-Ramírez
- Centro Regional de Investigación en Salud Pública, Instituto Nacional de Salud Pública, Tapachula, Chiapas, México
| | - Charles R. Katholi
- Department of Biostatistics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Thomas R. Unnasch
- Global Health Infectious Disease Research Program, Department of Global Health, University of South Florida, Tampa, Florida, United States of America
| |
Collapse
|
13
|
Katabarwa MN, Lakwo T, Habomugisha P, Agunyo S, Byamukama E, Oguttu D, Tukesiga E, Unoba D, Dramuke P, Onapa A, Tukahebwa EM, Lwamafa D, Walsh F, Unnasch TR. Transmission of Onchocerca volvulus continues in Nyagak-Bondo focus of northwestern Uganda after 18 years of a single dose of annual treatment with ivermectin. Am J Trop Med Hyg 2013; 89:293-300. [PMID: 23690555 DOI: 10.4269/ajtmh.13-0037] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The objective of the study was to determine whether annual ivermectin treatment in the Nyagak-Bondo onchocerciasis focus could safely be withdrawn. Baseline skin snip microfilariae (mf) and nodule prevalence data from six communities were compared with data collected in the 2011 follow-up in seven communities. Follow-up mf data in 607 adults and 145 children were compared with baseline (300 adults and 58 children). Flies collected in 2011 were dissected, and poolscreen analysis was applied to ascertain transmission. Nodule prevalence in adults dropped from 81.7% to 11.0% (P < 0.0001), and mf prevalence dropped from 97.0% to 23.2% (P < 0.0001). In children, mf prevalence decreased from 79.3% to 14.1% (P < 0.0001). Parous and infection rates of 401 flies that were dissected were 52.9% and 1.5%, respectively, whereas the infective rate on flies examination by polymerase chain reaction (PCR) was 1.92% and annual transmission potential was 26.9. Stopping ivermectin treatment may result in onchocerciasis recrudescence.
Collapse
|
14
|
Predictive and epidemiologic modeling of the spatial risk of human onchocerciasis using biophysical factors: a case study of Ghana and Burundi. Spat Spatiotemporal Epidemiol 2012; 3:273-85. [PMID: 23149324 DOI: 10.1016/j.sste.2012.08.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2012] [Revised: 08/09/2012] [Accepted: 08/10/2012] [Indexed: 11/21/2022]
Abstract
Although recent efforts taken have substantially contained human onchocerciasis in many African countries, published reports indicate a recrudescence of the disease. To understand this problem, biophysical factors that favor the establishment of human onchocerciasis in Ghana and Burundi-countries identified as threat locations of recrudescence for neighboring countries-were analyzed. Data pertaining to the prevalence of human onchocerciasis in both countries was obtained from published sources. Findings in this study suggest that there was a gradient in prevalence of onchocerciasis in geographic locations near the water streams. The predictive models suggest that rainfall, humidity, and elevation were statistically significant for Burundi data while in Ghana, only the effect of elevation was highly significant (p<0.0001). In 2010, the estimated at-risk population was 4,817,280 people (19.75% of the total population) and 522,773 people (6.23% of the total population) in Ghana and Burundi, respectively. Findings can help in the effective design of preventive control measures.
Collapse
|
15
|
Mackenzie CD, Homeida MM, Hopkins AD, Lawrence JC. Elimination of onchocerciasis from Africa: possible? Trends Parasitol 2011; 28:16-22. [PMID: 22079526 DOI: 10.1016/j.pt.2011.10.003] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2011] [Revised: 10/13/2011] [Accepted: 10/13/2011] [Indexed: 11/19/2022]
Abstract
Human onchocerciasis, a parasitic disease found in 28 African countries, six Latin American countries and Yemen, causes blindness and severe dermatological problems. In 1987, efforts to control this infection shifted from vector approaches to include the mass distribution of ivermectin - a drug donated by Merck & Co. for disease control in Africa and for disease elimination in the Americas. Currently, almost 25 years later, with the Americas being highly successful and now approaching elimination, new evidence points towards the possibility of successful elimination in Africa. We suggest several major changes in the programmatic approach that through focused goal-directed effort could achieve global elimination of onchocerciasis by 2025.
Collapse
Affiliation(s)
- Charles D Mackenzie
- Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA.
| | | | | | | |
Collapse
|