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Ouedraogo MO, Meda IB, Kourouma K, Wienne FY, Nare D, Bougouma C, Compaore J, Kouanda S. Effects of Five Years of Treatment of Onchocerciasis with Ivermectin under Community Guidelines in Resurgent Areas of Burkina Faso: A before-and-after Analysis. Trop Med Infect Dis 2024; 9:207. [PMID: 39330896 PMCID: PMC11435634 DOI: 10.3390/tropicalmed9090207] [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: 08/08/2024] [Revised: 08/29/2024] [Accepted: 09/05/2024] [Indexed: 09/28/2024] Open
Abstract
BACKGROUND Almost the entire country of Burkina Faso was endemic to onchocerciasis. Onchocerciasis control efforts thus brought the prevalence of O. volvulus to a level where the disease was no longer a public health problem in 2002. A resurgence of onchocerciasis cases has been observed in two regions (Cascades and the Southwest) located around several river basins in 2010-2011. In accordance with WHO guidelines for the management of resurgent cases, community-directed treatment with ivermectin (CDTI) was implemented in the affected areas. The aim of this study was to determine the effects of this intervention on parasitological indices of onchocerciasis, depending on the distance between villages and rivers. METHODOLOGY We conducted a paired pre-post study using aggregated village-level data from two cross-sectional surveys conducted in each region. A Wilcoxon signed-rank test was used to compare the standardized microfilarodermia prevalence and community microfilarial load (CMFL). RESULTS A total of 43 villages in 6 health districts, in the Southwest (18) and Cascades (25) regions were included in the study. The key findings were that standardized microfilaria prevalence and CMFL decreased significantly after the implementation of CDTI in both regions (p < 0.0001). The median standardized microfilaria prevalence was 2.8 [interquartile range (IQR): 0.2-6.6] before CDTI and 0.72 [IQR: 0.0-2.17] after CDTI. The results showed also a decline in standardized microfilaria prevalence and CMFL in all villages, regardless of the distance separating the village from the streams. However, the results were not statistically significant for the villages located 5 km or more from streams (p = 0.0816 and 0.0542 for standardized microfilaria prevalence and CMFL, respectively). CONCLUSION Our results thus show that the implementation of effective CDTI could stop the transmission of O. volvulus in these two regions. The main challenge for stopping transmission could be the migration of populations to neighboring countries and migration of the vector from one country to another, as Burkina Faso shares some river basins with neighboring countries.
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Affiliation(s)
- Micheline O. Ouedraogo
- Helen Keller International, Ouagadougou 06 P.O. Box 9515, Burkina Faso; (F.Y.W.); (D.N.)
| | - Ivlabèhirè Bertrand Meda
- African Institute of Public Health (IASP), Ouagadougou 12 P.O. Box 199, Burkina Faso; (I.B.M.); (S.K.)
| | - Karifa Kourouma
- National Center for Training and Research in Rural Health of Maferinyah (CNFRSR), Maferinyah P.O. Box 2649, Guinea;
| | - Fanny Yago Wienne
- Helen Keller International, Ouagadougou 06 P.O. Box 9515, Burkina Faso; (F.Y.W.); (D.N.)
| | - Dieudonné Nare
- Helen Keller International, Ouagadougou 06 P.O. Box 9515, Burkina Faso; (F.Y.W.); (D.N.)
| | - Clarisse Bougouma
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou 06 P.O. Box 9515, Burkina Faso; (C.B.); (J.C.)
| | - Justin Compaore
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou 06 P.O. Box 9515, Burkina Faso; (C.B.); (J.C.)
| | - Seni Kouanda
- African Institute of Public Health (IASP), Ouagadougou 12 P.O. Box 199, Burkina Faso; (I.B.M.); (S.K.)
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Vinkeles Melchers NVS, Agoro S, Togbey K, Padjoudoum K, Telou IG, Karabou P, Djatho T, Datagni M, Dorkenoo AM, Kassankogno Y, Bronzan R, Stolk WA. Impact of ivermectin and vector control on onchocerciasis transmission in Togo: Assessing the empirical evidence on trends in infection and entomological indicators. PLoS Negl Trop Dis 2024; 18:e0012312. [PMID: 39038058 PMCID: PMC11293710 DOI: 10.1371/journal.pntd.0012312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 08/01/2024] [Accepted: 06/08/2024] [Indexed: 07/24/2024] Open
Abstract
BACKGROUND The World Health Organization's 2021-2030 Road Map for Neglected Tropical Diseases boosted global commitment towards the elimination of onchocerciasis, but the timeline to elimination will vary strongly between countries in Africa. To assess progress towards elimination in the Republic of Togo, we reviewed the history of control and time trends in infection. METHODOLOGY/PRINCIPAL FINDINGS We collated all available programmatic, entomological, and epidemiological data since the initiation of the Onchocerciasis Control Programme (OCP) in Togo through different data sources. We then visualised data trends over time, to assess the impact of interventions on infection and transmission levels. Vector control was initiated by OCP from 1977 (northern and central parts of Togo) or 1988 (southern regions) up to 2002 (most areas) or 2007 ("special intervention zones" [SIZ], parts of Northern and Central Togo). Between 1988 and 1991, Togo initiated ivermectin mass drug administration (MDA) in eligible communities. The impact of vector control was high in most river basins, resulting in low annual biting rates and annual transmission potential declining to very low levels; the impact was lower in river basins designated as SIZ. Repeated, longitudinal ivermectin mass treatments have overall strongly reduced onchocerciasis transmission in Togo. Epidemiological surveys performed between 2014 and 2017 showed that the prevalence of skin microfilariae (mf) and anti-OV16 IgG4 antibodies had declined to low levels in several districts of the Centrale, Plateaux, and Maritime region. Yet, relatively high mf prevalences (between 5.0% and 32.7%) were still found in other districts during the same period, particularly along the Kéran, Mô and Ôti river basins (SIZ areas). CONCLUSIONS/SIGNIFICANCE Trends in infection prevalence and intensity show that onchocerciasis levels have dropped greatly over time in most areas. This demonstrates the large impact of long-term and wide-scale interventions, and suggest that several districts of Togo are approaching elimination.
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Affiliation(s)
- Natalie V. S. Vinkeles Melchers
- Health & Society Group, Department of Social Sciences, Wageningen University & Research, Hollandseweg 1, Wageningen, The Netherlands
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Sibabi Agoro
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Kwamy Togbey
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Koffi Padjoudoum
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Ibrahim Gado Telou
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Potchoziou Karabou
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Touka Djatho
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | - Michel Datagni
- National Institute of Hygiene, Ministry of Health, Public Hygiene and Universal Access to Care, Lomé, Togo
| | | | | | - Rachel Bronzan
- Bill & Melinda Gates Foundation, Seattle, Washington, United States of America
| | - Wilma A. Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Bhattacharyya S, Vinkeles Melchers NVS, Siewe Fodjo JN, Vutha A, Coffeng LE, Logora MY, Colebunders R, Stolk WA. Onchocerciasis-associated epilepsy in Maridi, South Sudan: Modelling and exploring the impact of control measures against river blindness. PLoS Negl Trop Dis 2023; 17:e0011320. [PMID: 37235598 DOI: 10.1371/journal.pntd.0011320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 04/19/2023] [Indexed: 05/28/2023] Open
Abstract
BACKGROUND Onchocerciasis, also known as "river blindness", is caused by the bite of infected female blackflies (genus Simuliidae) that transmit the parasite Onchocerca volvulus. A high onchocerciasis microfarial load increases the risk to develop epilepsy in children between the ages of 3 and 18 years. In resource-limited settings in Africa where onchocerciasis has been poorly controlled, high numbers of onchocerciasis-associated epilepsy (OAE) are reported. We use mathematical modeling to predict the impact of onchocerciasis control strategies on the incidence and prevalence of OAE. METHODOLOGY We developed an OAE model within the well-established mathematical modelling framework ONCHOSIM. Using Latin-Hypercube Sampling (LHS), and grid search technique, we quantified transmission and disease parameters using OAE data from Maridi County, an onchocerciasis endemic area, in southern Republic of South Sudan. Using ONCHOSIM, we predicted the impact of ivermectin mass drug administration (MDA) and vector control on the epidemiology of OAE in Maridi. PRINCIPAL FINDINGS The model estimated an OAE prevalence of 4.1% in Maridi County, close to the 3.7% OAE prevalence reported in field studies. The OAE incidence is expected to rapidly decrease by >50% within the first five years of implementing annual MDA with good coverage (≥70%). With vector control at a high efficacy level (around 80% reduction of blackfly biting rates) as the sole strategy, the reduction is slower, requiring about 10 years to halve the OAE incidence. Increasing the efficacy levels of vector control, and implementing vector control simultaneously with MDA, yielded better results in preventing new cases of OAE. CONCLUSIONS/SIGNIFICANCES Our modeling study demonstrates that intensifying onchocerciasis eradication efforts could substantially reduce OAE incidence and prevalence in endemic foci. Our model may be useful for optimizing OAE control strategies.
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Affiliation(s)
- Samit Bhattacharyya
- Department of Mathematics, School of Natural Sciences, Shiv Nadar Institution of Eminence, Dadri, Uttar Pradesh, India
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | | | | | - Amit Vutha
- Department of Mathematics, Ohio State University, Columbus, Ohio, United States of America
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Makoy Y Logora
- National Neglected Tropical Disease Programme, Ministry of Health South Sudan, Juba, South Sudan
| | | | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
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Anti-Onchocercal Properties of Extracts of Scoparia dulcis and Cylicodiscus gabunensis. J Trop Med 2022; 2022:4279689. [DOI: 10.1155/2022/4279689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 10/19/2022] [Accepted: 10/25/2022] [Indexed: 11/17/2022] Open
Abstract
Introduction. The elimination of onchocerciasis is hampered by the absence of suitable drugs that are effective against adult filariae. This study is aimed at assessing the anti-onchocercal effects of extracts of Scoparia dulcis and Cylicodiscus gabunensis that could serve as drug leads against onchocerciasis. Methods. Different parts of the plants (Scoparia dulcis and Cylicodiscus gabunensis) were extracted with hexane, methylene chloride, and methanol. The extracts were tested in vitro against the bovine model parasite, Onchocerca ochengi. Adult female worm viability was determined biochemically by MTT/formazan colorimetry, while the adult male and microfilariae viability were determined by microscopy based on % inhibition of worm motility score. Cytotoxicity and acute toxicity of active extracts were tested on monkey kidney epithelial cells (LLC-MK2) and Balb/C mice, respectively. Results. The hexane extract of Scoparia dulcis recorded the highest activity, with IC50s of 50.78 μg/ml on both adult male and female worms and 3.91 μg/ml on microfilariae. For Cylicodiscus gabunensis extract, the highest activity was seen with the methylene chloride extract, with IC50s of 50.78 μg/ml, 62.50 μg/ml, and 16.28 μg/ml on, respectively, adult male, female, and microfilariae. The 50% cytotoxic concentration on the LLC-MK2 cells was 31.25 μg/ml for the most active extracts. No acute toxicity was recorded for the extracts. Phytochemical analysis of the extracts revealed the presence of alkaloids, flavonoids, sterols, saponins, phenols, and glycosides. Conclusion. This study validates the traditional use of these plants in treating onchocerciasis and suggests S. dulcis and C. gabunensis as new potential sources for the isolation of anti-onchocerca lead compounds.
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Ekpo UF, Eneanya OA, Nwankwo EN, Soneye IY, Weil GJ, Fischer PU, Nwaorgu OC. Persistence of onchocerciasis in villages in Enugu and Ogun states in Nigeria following many rounds of mass distribution of ivermectin. BMC Infect Dis 2022; 22:832. [PMID: 36357828 PMCID: PMC9650792 DOI: 10.1186/s12879-022-07811-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 10/27/2022] [Indexed: 11/11/2022] Open
Abstract
Background Onchocerciasis is endemic in most local government areas (LGAs) in Enugu and Ogun states. Most meso- and hyper-endemic LGAs have received many rounds of ivermectin mass drug administration (MDA). This study aimed to determine the current prevalence of onchocerciasis in villages in Enugu and Ogun states that were formerly highly endemic and to assess progress toward elimination of the infection in areas believed to be at high risk for persistence. Methods Cross-sectional community surveys were conducted 8 to 12 months after the last round of MDA in 16 villages (6 in Enugu state and 10 in Ogun state) in individuals aged ≥ 18 years. Study participants were examined for the presence of palpable subcutaneous nodules. Skin snips from the posterior iliac crests were used to assess microfiladermia (Mf) prevalence and density. Results 643 subjects were palpated for nodules and 627 individuals (225 in Enugu state; 402 in Ogun state) provided skin snips. Nodule prevalence in the study villages ranged from 42 to 66.7% in Enugu state and from 0 to 25.0% in Ogun state. Mf prevalence in the Enugu and Ogun study villages ranged from 32 to 51.1% and 0 to 28.6%, respectively. Geometric mean skin Mf density in surveyed Enugu state villages ranged between 1 and 3.1 Mf/mg; these values were < 1 Mf/mg in all but one community in Ogun state villages. Conclusion Results from this study show that onchocerciasis persists in adults in many villages in Enugu and Ogun states despite many prior rounds of ivermectin MDA. Prevalence was higher in villages surveyed in Enugu than in Ogun. Low Mf densities suggest the MDA program is working well to reduce disease, but more time will be required to reach the elimination goal. Supplementary Information The online version contains supplementary material available at 10.1186/s12879-022-07811-7.
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Shey RA, Ghogomu SM, Nebangwa DN, Shintouo CM, Yaah NE, Yengo BN, Nkemngo FN, Esoh KK, Tchatchoua NMT, Mbachick TT, Dede AF, Lemoge AA, Ngwese RA, Asa BF, Ayong L, Njemini R, Vanhamme L, Souopgui J. Rational design of a novel multi-epitope peptide-based vaccine against Onchocerca volvulus using transmembrane proteins. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.1046522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Almost a decade ago, it was recognized that the global elimination of onchocerciasis by 2030 will not be feasible without, at least, an effective prophylactic and/or therapeutic vaccine to complement chemotherapy and vector control strategies. Recent advances in computational immunology (immunoinformatics) have seen the design of novel multi-epitope onchocerciasis vaccine candidates which are however yet to be evaluated in clinical settings. Still, continued research to increase the pool of vaccine candidates, and therefore the chance of success in a clinical trial remains imperative. Here, we designed a multi-epitope vaccine candidate by assembling peptides from 14 O. volvulus (Ov) proteins using an immunoinformatics approach. An initial 126 Ov proteins, retrieved from the Wormbase database, and at least 90% similar to orthologs in related nematode species of economic importance, were screened for localization, presence of transmembrane domain, and antigenicity using different web servers. From the 14 proteins retained after the screening, 26 MHC-1 and MHC-II (T-cell) epitopes, and linear B-lymphocytes epitopes were predicted and merged using suitable linkers. The Mycobacterium tuberculosis Resuscitation-promoting factor E (RPFE_MYCTU), which is an agonist of TLR4, was then added to the N-terminal of the vaccine candidate as a built-in adjuvant. Immune simulation analyses predicted strong B-cell and IFN-γ based immune responses which are necessary for protection against O. volvulus infection. Protein-protein docking and molecular dynamic simulation predicted stable interactions between the 3D structure of the vaccine candidate and human TLR4. These results show that the designed vaccine candidate has the potential to stimulate both humoral and cellular immune responses and should therefore be subject to further laboratory investigation.
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Sokolow SH, Nova N, Jones IJ, Wood CL, Lafferty KD, Garchitorena A, Hopkins SR, Lund AJ, MacDonald AJ, LeBoa C, Peel AJ, Mordecai EA, Howard ME, Buck JC, Lopez-Carr D, Barry M, Bonds MH, De Leo GA. Ecological and socioeconomic factors associated with the human burden of environmentally mediated pathogens: a global analysis. Lancet Planet Health 2022; 6:e870-e879. [PMID: 36370725 PMCID: PMC9669458 DOI: 10.1016/s2542-5196(22)00248-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 08/22/2022] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Billions of people living in poverty are at risk of environmentally mediated infectious diseases-that is, pathogens with environmental reservoirs that affect disease persistence and control and where environmental control of pathogens can reduce human risk. The complex ecology of these diseases creates a global health problem not easily solved with medical treatment alone. METHODS We quantified the current global disease burden caused by environmentally mediated infectious diseases and used a structural equation model to explore environmental and socioeconomic factors associated with the human burden of environmentally mediated pathogens across all countries. FINDINGS We found that around 80% (455 of 560) of WHO-tracked pathogen species known to infect humans are environmentally mediated, causing about 40% (129 488 of 359 341 disability-adjusted life years) of contemporary infectious disease burden (global loss of 130 million years of healthy life annually). The majority of this environmentally mediated disease burden occurs in tropical countries, and the poorest countries carry the highest burdens across all latitudes. We found weak associations between disease burden and biodiversity or agricultural land use at the global scale. In contrast, the proportion of people with rural poor livelihoods in a country was a strong proximate indicator of environmentally mediated infectious disease burden. Political stability and wealth were associated with improved sanitation, better health care, and lower proportions of rural poverty, indirectly resulting in lower burdens of environmentally mediated infections. Rarely, environmentally mediated pathogens can evolve into global pandemics (eg, HIV, COVID-19) affecting even the wealthiest communities. INTERPRETATION The high and uneven burden of environmentally mediated infections highlights the need for innovative social and ecological interventions to complement biomedical advances in the pursuit of global health and sustainability goals. FUNDING Bill & Melinda Gates Foundation, National Institutes of Health, National Science Foundation, Alfred P. Sloan Foundation, National Institute for Mathematical and Biological Synthesis, Stanford University, and the US Defense Advanced Research Projects Agency.
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Affiliation(s)
- Susanne H Sokolow
- Woods Institute for the Environment, Stanford University, Stanford, CA, USA; Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Nicole Nova
- Department of Biology, Stanford University, Stanford, CA, USA; High Meadows Environmental Institute, Princeton University, Princeton, NJ, USA.
| | - Isabel J Jones
- Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
| | - Chelsea L Wood
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA, USA
| | - Kevin D Lafferty
- US Geological Survey, Western Ecological Research Center, c/o Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Andres Garchitorena
- MIVEGEC, Université Montpellier, Centre National de la Recherche Scientifique, Institut de Recherche pour le Développement, Montpellier, France; PIVOT, Division of Global Health Equity, Brigham and Women's Hospital, Boston, MA, USA
| | | | - Andrea J Lund
- Emmett Interdisciplinary Program in Environment and Resources (E-IPER), Stanford University, Stanford, CA, USA
| | - Andrew J MacDonald
- Department of Biology, Stanford University, Stanford, CA, USA; Earth Research Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | | | - Alison J Peel
- Centre for Planetary Health and Food Security, Griffith University, Nathan, QLD, Australia
| | - Erin A Mordecai
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Meghan E Howard
- Department of Biology, Stanford University, Stanford, CA, USA
| | - Julia C Buck
- Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA
| | - David Lopez-Carr
- Department of Geography, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Michele Barry
- Woods Institute for the Environment, Stanford University, Stanford, CA, USA; Center for Innovation in Global Health, Stanford University, Stanford, CA, USA
| | - Matthew H Bonds
- PIVOT, Division of Global Health Equity, Brigham and Women's Hospital, Boston, MA, USA; Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA
| | - Giulio A De Leo
- Woods Institute for the Environment, Stanford University, Stanford, CA, USA; Department of Biology, Stanford University, Stanford, CA, USA; Hopkins Marine Station, Stanford University, Pacific Grove, CA, USA
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Ojekunle OZ, Esan RO, Balogun MA, Ademolu KO, Adegoke KA, Taiwo AM. Ecological assessment of Black Fly (Simuliumdamnosum, Sensulato) breeding sites in two tributaries of Ogun river, Ogun state, Nigeria. ENVIRONMENTAL MONITORING AND ASSESSMENT 2022; 194:220. [PMID: 35201429 DOI: 10.1007/s10661-022-09770-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
Onchocerciasis is a disease transmitted by blackfly vector of the genus Simuliumdamnosum complex having public and socio-economic consequences. The abundance of blackfly is directly linked to fluvial ecosystems in both tropical and non-tropical countries of the world. This study assessed the ecology of blackfly breeding sites in two tributaries of River Ogun located in Olokemeji and Lisa villages, Ogun State. A total of eighteen water samples were collected for physicochemical analysis during high rainfall (May, June and July), low rainfall (August, September and October) and dry season (November and December) with mean rainfall values of 163.17, 88.03 and 8.95 mm, respectively, in both tributaries. Physicochemical parameters such as temperature (oC), electrical conductivity (EC), pH, total solids (TS), dissolved oxygen (DO), biochemical oxygen demand (BOD), total suspended solids (TSS), hardness (H), sulphate (SO4), phosphate (PO4), alkalinity, acidity, nitrate (NO3) and total dissolved solids (TDS) were analysed using standard laboratory methods. Digestive enzymes were analysed using 1 g of frozen gut of Simulium larvae grounded with 20 ml of 0.067 g of potassium hydrogen and 20 ml of 0.1 M sodium reagent. A total of 766 and 482 samples of Simulium larvae were collected from Olokemeji and Lisa tributaries using Eppendorf tubes. The zooplanktons collected from Olokemeji and Lisa tributary were 904 and 802, while phytoplanktons collected from Olokemeji and Lisa tributary were 635 and 582 during the study period. Data obtained were analysed using both descriptive analysis and T-test. The results obtained for the physicochemical parameters were 28.7 °C, 137.5 µS/cm, 6.3, 248.1 mg/L, 58 mg/L, 108.8 mg/L, 90.8 mg/L, 2.24 mg/L, 2.24 mg/L, 30.76 mg/L, 42.35 mg/L, 1.99 mg/L, 2.07 mg/L and 2.55 mg/L for Temperature, EC, pH, TS, DO, BOD, TSS, H, SO4, PO4, alkalinity, acidity, NO3 and TDS, respectively. There were significant (p < 0.05) differences between the means of EC, pH, TS, TDS, TSS and hardness of Lisa tributary, and water samples were also viewed under an electron microscope for zooplanktons and phytoplanktons. The values of species diversity which were greater than 0.5 indicated that the species were abundant and evenly distributed. There were significant (p < 0.05) differences between the tributaries in all the digestive enzymes except amylase content. The regression analysis between TSS, nitrate, sulphate, phosphate, acidity, hardness, TS, pH and Simulium larvae abundance showed a positive correlation, R2 with values of 0.828, 0.994, 0.948, 0.933, 0.986, 0.997, 0.889 and 0.981, respectively. The R2 values between Simulium larvae abundance with phytoplanktons and rainfall have values of 0.868 at p < 0.01 and 0.911 at p < 0.05.
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Affiliation(s)
- Olusheyi Zaccheaus Ojekunle
- Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Rotimi Olabode Esan
- Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Mujeeb Adeyemi Balogun
- Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
- Faculty of Science and Technology, University of the Basque Country, Basque, Spain
- College of Science and Technology, University of Bordeaux, Bordeaux, France
- Faculty of Sciences, University of Liège, Liège, Belgium
| | - Kehinde O Ademolu
- Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
| | - Kayode Adesina Adegoke
- Department of Chemical Sciences, University of Johannesburg, Johannesburg, South Africa.
| | - Adewale Matthew Taiwo
- Department of Environmental Management and Toxicology, Federal University of Agriculture, Abeokuta, Ogun State, Nigeria
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Brattig NW, Cheke RA, Garms R. Onchocerciasis (river blindness) - more than a century of research and control. Acta Trop 2021; 218:105677. [PMID: 32857984 DOI: 10.1016/j.actatropica.2020.105677] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 08/06/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022]
Abstract
This review summarises more than a century of research on onchocerciasis, also known as river blindness, and its control. River blindness is an infection caused by the tissue filaria Onchocerca volvulus affecting the skin, subcutaneous tissue and eyes and leading to blindness in a minority of infected persons. The parasite is transmitted by its intermediate hosts Simulium spp. which breed in rivers. Featured are history and milestones in onchocerciasis research and control, state-of-the-art data on the parasite, its endobacteria Wolbachia, on the vectors, previous and current prevalence of the infection, its diagnostics, the interaction between the parasite and its host, immune responses and the pathology of onchocerciasis. Detailed information is documented on the time course of control programmes in the afflicted countries in Africa and the Americas, a long road from previous programmes to current successes in control of the transmission of this infectious disease. By development, adjustment and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas, in Uganda, in Sudan and elsewhere, followed by onchocerciasis eliminations. The current state and future perspectives for control, elimination and eradication within the next 20-30 years are described and discussed. This review contributes to a deeper comprehension of this disease by a tissue-dwelling filaria and it will be helpful in efforts to control and eliminate other filarial infections.
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Walker M, Hamley JID, Milton P, Monnot F, Kinrade S, Specht S, Pedrique B, Basáñez MG. Supporting drug development for neglected tropical diseases using mathematical modelling. Clin Infect Dis 2021; 73:e1391-e1396. [PMID: 33893482 PMCID: PMC8442785 DOI: 10.1093/cid/ciab350] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Indexed: 11/14/2022] Open
Abstract
Drug-based interventions are at the heart of global efforts to reach elimination as a public health problem (trachoma, soil-transmitted helminthiases, schistosomiasis, lymphatic filariasis) or elimination of transmission (onchocerciasis) for 5 of the most prevalent neglected tropical diseases tackled via the World Health Organization preventive chemotherapy strategy. While for some of these diseases there is optimism that currently available drugs will be sufficient to achieve the proposed elimination goals, for others—particularly onchocerciasis—there is a growing consensus that novel therapeutic options will be needed. Since in this area no high return of investment is possible, minimizing wasted money and resources is essential. Here, we use illustrative results to show how mathematical modeling can guide the drug development pathway, yielding resource-saving and efficiency payoffs, from the refinement of target product profiles and intended context of use to the design of clinical trials.
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Affiliation(s)
- Martin Walker
- Department of Pathobiology and Population Sciences and London Centre for Neglected Tropical Disease Research, Royal Veterinary College, UK.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, UK
| | - Jonathan I D Hamley
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, UK
| | - Philip Milton
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, UK
| | - Frédéric Monnot
- Drugs for Neglected Diseases initiative (DNDi), Geneva, Switzerland
| | - Sally Kinrade
- Medicines Development for Global Health, Southbank VIC, Australia
| | - Sabine Specht
- Drugs for Neglected Diseases initiative (DNDi), Geneva, Switzerland
| | - Bélen Pedrique
- Drugs for Neglected Diseases initiative (DNDi), Geneva, Switzerland
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, UK
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11
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Nikièma AS, Koala L, Sondo AK, Post RJ, Paré AB, Kafando CM, Kambiré RS, Sow B, Bougouma C, Dabiré RK, Traoré S. The impact of ivermectin on onchocerciasis in villages co-endemic for lymphatic filariasis in an area of onchocerciasis recrudescence in Burkina Faso. PLoS Negl Trop Dis 2021; 15:e0009117. [PMID: 33647010 PMCID: PMC7920372 DOI: 10.1371/journal.pntd.0009117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 01/08/2021] [Indexed: 11/18/2022] Open
Abstract
In Burkina Faso, onchocerciasis was no longer a public health problem when the WHO Onchocerciasis Control Programme in West Africa closed at the end in 2002. However, epidemiological surveillance carried out from November 2010 to February of 2011, showed a recrudescence of infection in the Cascades Region. This finding was made at a time when ivermectin, a drug recommended for the treatment of both onchocerciasis and lymphatic filariasis, had been distributed in this area since 2004 for the elimination of lymphatic filariasis. It was surprising that ivermectin distributed for treating lymphatic filariasis had not prevented the recrudescence of onchocerciasis. Faced with this situation, the aim of our study was to evaluate the effectiveness of ivermectin on the onchocerciasis parasite. The percentage reduction in microfilarial load after treatment with ivermectin was used as a proxy measure for assessing possible resistance. A cohort study was carried out with 130 individuals who had tested positive for microfilariae of Onchocerca volvulus in 2010 using microscopic examination of skin-snip biopsies from five endemic villages. Subjects were followed from July 2011 to June 2012. The microfilarial load of each individual was enumerated by skin-snip biopsy in 2010, prior to the first ivermectin treatment against onchocerciasis under community guidelines. All individuals received two ivermectin treatments six months apart. In 2012, the microfilarial loads were determined again, six months after the second round of ivermectin and the reductions in parasite loads were calculated to measure the impact of the drug. The percentage reduction of the microfilarial loads ranged from 87% to 98% in the villages. In all villages, there was a statistically significant difference between the average microfilarial loads in 2010 and 2012. The level of reduction of microfilarial loads suggests that ivermectin is effective against the recrudescent population of O. volvulus in Cascades Region of Burkina Faso. Further investigations would be necessary to determine the causes of the recrudescence of onchocerciasis. (For French language abstract, see S1 Alternative Language Abstract—Translation of the Abstract into French by the authors.) In 1989, onchocerciasis had been eliminated as a public health problem throughout Burkina Faso by insecticidal treatment of vector breeding sites, but epidemiological surveys along the Comoé River in 2010/11 revealed a recrudescence of infection rates. Modern onchocerciasis control is based upon mass drug administration using ivermectin, and hence biannual distribution of ivermectin was instigated to bring the recrudescence under control. However, it was by no means certain that this was an appropriate strategy because the area was already under mass drug administration with ivermectin since 2004 to eliminate lymphatic filariasis. Onchocerca volvulus adult females with reduced susceptibility to ivermectin have been reported from Ghana, and if the Burkinabe recrudescence was the result of reduced susceptibility, ivermectin might fail to solve the problem. To test this, a cohort of positive people was examined for the density of microfilariae in their skin six months after the second round of ivermectin. The reduction in microfilarial load was substantial, and comparable to levels found in ivermectin-naïve populations (normally assumed to be susceptible), but greater than Ghanaian populations with reduced susceptibility. On this basis we conclude that the Burkinabe recrudescence was not the result of parasites with reduced susceptibility to ivermectin, and biannual treatment remains the chosen means to deal with the recrudescence.
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Affiliation(s)
- Achille S. Nikièma
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l’Ouest, Bobo Dioulasso, Burkina Faso
- * E-mail:
| | - Lassane Koala
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l’Ouest, Bobo Dioulasso, Burkina Faso
| | - Apoline K. Sondo
- Université Ouaga I Pr Joseph ki-Zerbo, Unité de Formation et de Recherche en Sciences de la Santé, Ouagadougou, Burkina Faso
| | - Rory J. Post
- Disease Control Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- School of Biological & Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Alain B. Paré
- Ministère de la Santé, Direction de la Protection de la Santé de la Population, Programme National lutte contre les Maladies Tropicales Négligées, Ouagadougou, Burkina Faso
| | - Claude M. Kafando
- Ministère de la Santé, Direction de la Protection de la Santé de la Population, Programme National lutte contre les Maladies Tropicales Négligées, Ouagadougou, Burkina Faso
| | - Roger S. Kambiré
- Ministère de la Santé, Direction de la Protection de la Santé de la Population, Programme National lutte contre les Maladies Tropicales Négligées, Ouagadougou, Burkina Faso
| | - Bazoumana Sow
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l’Ouest, Bobo Dioulasso, Burkina Faso
| | - Clarisse Bougouma
- Ministère de la Santé, Direction de la Protection de la Santé de la Population, Programme National lutte contre les Maladies Tropicales Négligées, Ouagadougou, Burkina Faso
| | - Roch K. Dabiré
- Institut de Recherche en Sciences de la Santé (IRSS), Direction Régionale de l’Ouest, Bobo Dioulasso, Burkina Faso
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12
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Ryan NM, Hess JA, de Villena FPM, Leiby BE, Shimada A, Yu L, Yarmahmoodi A, Petrovsky N, Zhan B, Bottazzi ME, Makepeace BL, Lustigman S, Abraham D. Onchocerca volvulus bivalent subunit vaccine induces protective immunity in genetically diverse collaborative cross recombinant inbred intercross mice. NPJ Vaccines 2021; 6:17. [PMID: 33500417 PMCID: PMC7838260 DOI: 10.1038/s41541-020-00276-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023] Open
Abstract
This study tests the hypothesis that an Onchocerca volvulus vaccine, consisting of two recombinant antigens (Ov-103 and Ov-RAL-2) formulated with the combination-adjuvant Advax-2, can induce protective immunity in genetically diverse Collaborative Cross recombinant inbred intercross mice (CC-RIX). CC-RIX lines were immunized with the O. volvulus vaccine and challenged with third-stage larvae. Equal and significant reductions in parasite survival were observed in 7 of 8 CC-RIX lines. Innate protective immunity was seen in the single CC-RIX line that did not demonstrate protective adaptive immunity. Analysis of a wide array of immune factors showed that each line of mice have a unique set of immune responses to vaccination and challenge suggesting that the vaccine is polyfunctional, inducing different equally-protective sets of immune responses based on the genetic background of the immunized host. Vaccine efficacy in genetically diverse mice suggests that it will also be effective in genetically complex human populations.
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Affiliation(s)
- Nathan M Ryan
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Jessica A Hess
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Benjamin E Leiby
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Ayako Shimada
- Division of Biostatistics, Department of Pharmacology and Experimental Therapeutics, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA
| | - Lei Yu
- Flow Cytometry Core Facility, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | - Amir Yarmahmoodi
- Flow Cytometry Core Facility, Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Bin Zhan
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital Center for Vaccine Development, 1102 Bates St, Ste. 550, Houston, TX, USA
| | - Maria Elena Bottazzi
- Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX, USA
- Texas Children's Hospital Center for Vaccine Development, 1102 Bates St, Ste. 550, Houston, TX, USA
| | - Benjamin L Makepeace
- Institute of Infection, Veterinary & Ecological Sciences, University of Liverpool, 146 Brownlow Hill, Liverpool, L3 5RF, UK
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsey F. Kimball Research Institute, New York Blood Center, 310 E 67th St, New York, NY, USA
| | - David Abraham
- Department of Microbiology and Immunology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA, USA.
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13
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Lenk EJ, Moungui HC, Boussinesq M, Kamgno J, Nana-Djeunga HC, Fitzpatrick C, Peultier ACMM, Klion AD, Fletcher DA, Nutman TB, Pion SD, Niamsi-Emalio Y, Redekop WK, Severens JL, Stolk WA. A Test-and-Not-Treat Strategy for Onchocerciasis Elimination in Loa loa-coendemic Areas: Cost Analysis of a Pilot in the Soa Health District, Cameroon. Clin Infect Dis 2021; 70:1628-1635. [PMID: 31165855 PMCID: PMC7146010 DOI: 10.1093/cid/ciz461] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Accepted: 06/03/2019] [Indexed: 11/24/2022] Open
Abstract
Background Severe adverse events after treatment with ivermectin in individuals with high levels of Loa loa microfilariae in the blood preclude onchocerciasis elimination through community-directed treatment with ivermectin (CDTI) in Central Africa. We measured the cost of a community-based pilot using a test-and-not-treat (TaNT) strategy in the Soa health district in Cameroon. Methods Based on actual expenditures, we empirically estimated the economic cost of the Soa TaNT campaign, including financial costs and opportunity costs that will likely be borne by control programs and stakeholders in the future. In addition to the empirical analyses, we estimated base-case, less intensive, and more intensive resource use scenarios to explore how costs might differ if TaNT were implemented programmatically. Results The total costs of US$283 938 divided by total population, people tested, and people treated with 42% coverage were US$4.0, US$9.2, and US$9.5, respectively. In programmatic implementation, these costs (base-case estimates with less and more intensive scenarios) could be US$2.2 ($1.9–$3.6), US$5.2 ($4.5–$8.3), and US$5.4 ($4.6–$8.6), respectively. Conclusions TaNT clearly provides a safe strategy for large-scale ivermectin treatment and overcomes a major obstacle to the elimination of onchocerciasis in areas coendemic for Loa loa. Although it is more expensive than standard CDTI, costs vary depending on the setting, the implementation choices made by the institutions involved, and the community participation rate. Research on the required duration of TaNT is needed to improve the affordability assessment, and more experience is needed to understand how to implement TaNT optimally.
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Affiliation(s)
- Edeltraud J Lenk
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam.,Department of Public Health, Erasmus Medical Center, University Medical Center Rotterdam, The Netherlands
| | - Henri C Moungui
- Centre for Research on Filariasis and Other Tropical Diseases, Yaounde, Cameroon
| | - Michel Boussinesq
- Unité Mixte Internationale, TransVIHMI, Institut de Recherche pour le Développement, University of Montpellier, France
| | - Joseph Kamgno
- Centre for Research on Filariasis and Other Tropical Diseases, Yaounde, Cameroon
| | | | | | | | - Amy D Klion
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | | | - Thomas B Nutman
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Sébastien D Pion
- Unité Mixte Internationale, TransVIHMI, Institut de Recherche pour le Développement, University of Montpellier, France
| | | | - William K Redekop
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam
| | - Johan L Severens
- Erasmus School of Health Policy and Management, Erasmus University Rotterdam
| | - Wilma A Stolk
- Department of Public Health, Erasmus Medical Center, University Medical Center Rotterdam, The Netherlands
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14
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Gebrezgabiher G, Mekonnen Z, Yewhalaw D, Hailu A. Status of parasitological indicators and morbidity burden of onchocerciasis after years of successive implementation of mass distribution of ivermectin in selected communities of Yeki and Asosa districts, Ethiopia. BMC Public Health 2020; 20:1233. [PMID: 32787813 PMCID: PMC7425055 DOI: 10.1186/s12889-020-09344-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/04/2020] [Indexed: 11/23/2022] Open
Abstract
Background Control and elimination of onchocerciasis requires regular follow-up and evaluation of community directed treatment with ivermectin (CDTi) program implementation. This research was aimed to assess the epidemiological status of onchocerciasis in disease endemic communities of Asosa and Yeki districts of Ethiopia after 5 and 15 years of successive CDTi respectively, and to evaluate the decline in infection and morbidity burden. Methods A community-based cross-sectional study was conducted from August 2017 to January 2018 (i.e. within 2–7 months since the last treatment) using interview, physical and parasitological examinations. Pre-CDTi epidemiological data were obtained from studies conducted prior to the launch of CDTi. Results A total of 3002 individuals (1567 from Asosa and 1435 from Yeki) were included. No infection was detected from Yeki. In Asosa, the prevalence of infection was 1.6%. The geometric mean intensity of infection was 0.02 mf/mg of skin snip. The prevalence rates of dermatitis, depigmentation, nodule, and atrophy in Yeki were 33(2.3%), 57(4%), 37(2.6%) and 11(0.7%), respectively. The prevalence rates of papular dermatitis, depigmentation, palpable nodule, atrophy, and blindness in Asosa were 94(6%), 38(2.4%), 30(1.9%), 28(1.8%) and 2(0.1%), respectively. Five years of CDTi had significantly reduced prevalence and intensity of infection by 91.8% (p < 0.001) and 99.7% (p < 0.001), respectively. Moreover, CDTi reduced prevalence of papular dermatitis by 95.9% (p < 0.001), palpable nodule by 90.5% (p < 0.001), and atrophy by 30% (p = 0.6) in Yeki. Similarly, CDTi reduced prevalence of papular dermatitis by 88.6% (p < 0.001), depigmentation by 90.3% (p < 0.001), atrophy by 89.5% (p < 0.001), and blindness by 90% (p < 0.001) in Asosa. Conclusions Fifteen years of successive CDTi had brought the infection from high to zero in Yeki. However, thorough entomological and serological data need to be generated to ascertain whether complete interruption of parasite transmission has been attained, and for considerations of an evidence-based CDTi cessation. Five years of CDTi in Asosa has significantly reduced the infection and morbidity of onchocerciasis to very low level. We, hereby, recommend biannual CDTi to continue in Asosa and its surroundings until the infection transmission is fully interrupted.
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Affiliation(s)
- Gebremedhin Gebrezgabiher
- College of Veterinary Medicine, Samara University, P.O. Box 132, Samara, Ethiopia. .,School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia.
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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15
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Milton P, Hamley JID, Walker M, Basáñez MG. Moxidectin: an oral treatment for human onchocerciasis. Expert Rev Anti Infect Ther 2020; 18:1067-1081. [PMID: 32715787 DOI: 10.1080/14787210.2020.1792772] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Moxidectin is a milbemycin endectocide recently approved for the treatment of human onchocerciasis. Onchocerciasis, earmarked for elimination of transmission, is a filarial infection endemic in Africa, Yemen, and the Amazonian focus straddling Venezuela and Brazil. Concerns over whether the predominant treatment strategy (yearly mass drug administration (MDA) of ivermectin) is sufficient to achieve elimination in all endemic foci have refocussed attention upon alternative treatments. Moxidectin's stronger and longer microfilarial suppression compared to ivermectin in both phase II and III clinical trials indicates its potential as a novel powerful drug for onchocerciasis elimination. AREAS COVERED This work summarizes the chemistry and pharmacology of moxidectin, reviews the phase II and III clinical trials evidence on tolerability, safety, and efficacy of moxidectin versus ivermectin, and discusses the implications of moxidectin's current regulatory status. EXPERT OPINION Moxidectin's superior clinical performance has the potential to substantially reduce times to elimination compared to ivermectin. If donated, moxidectin could mitigate the additional programmatic costs of biannual ivermectin distribution because, unlike other alternatives, it can use the existing community-directed treatment infrastructure. A pediatric indication (for children <12 years) and determination of its usefulness in onchocerciasis-loiasis co-endemic areas will greatly help fulfill the potential of moxidectin for the treatment and elimination of onchocerciasis.
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Affiliation(s)
- Philip Milton
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Jonathan I D Hamley
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK.,London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Population Sciences, Royal Veterinary College , Hatfield, UK
| | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
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16
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Murdoch ME. Mapping the burden of onchocercal skin disease. Br J Dermatol 2020; 184:199-207. [PMID: 32302410 DOI: 10.1111/bjd.19143] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2020] [Indexed: 02/06/2023]
Abstract
Onchocerciasis is a neglected tropical disease caused by a nematode parasite, Onchocerca volvulus, and transmitted by bites of Simulium blackflies which breed near fast-flowing rivers. In humans, thousands of microfilariae (immature worms) migrate to the skin and eyes where they cause pathology. Historically, much research was devoted to the serious effect of blindness, from which the disease earns its alternative name of 'river blindness'. Mapping the burden of onchocercal skin disease (OSD) was expedited by the development of a clinical classification and grading system that facilitated comparison of data from different countries. After successful field testing in Nigeria, the classification scheme was used in a multicountry study in seven endemic sites, to estimate the true burden of OSD across Africa. High levels of OSD were found, affecting 28% of the population. A new control programme, the African Programme for Onchocerciasis Control (APOC) was launched in 20 countries using annual doses of ivermectin, donated by Merck & Co., Inc. The multicountry study also found a close correlation between the levels of itching and OSD with the level of endemicity, as determined by the prevalence of onchocercal nodules. This enabled APOC to use Rapid Epidemiological Mapping of Onchocerciasis, which entailed identifying likely vector breeding sites near rivers, then sampling 50 adult males in nearby villages to determine the prevalence of nodules and delineate which villages required treatment. Onchocerciasis is now targeted for elimination in Africa, and the challenge is to complete Onchocerciasis Elimination Mapping of hypoendemic areas using serology.
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Affiliation(s)
- M E Murdoch
- Department of Dermatology, West Herts Hospitals NHS Trust, Watford General Hospital, Watford, WD18 0HB, UK
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17
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The Role of the Maridi Dam in Causing an Onchocerciasis-Associated Epilepsy Epidemic in Maridi, South Sudan: An Epidemiological, Sociological, and Entomological Study. Pathogens 2020; 9:pathogens9040315. [PMID: 32344586 PMCID: PMC7238195 DOI: 10.3390/pathogens9040315] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 11/24/2022] Open
Abstract
Background: An epilepsy prevalence of 4.4% was documented in onchocerciasis-endemic villages close to the Maridi River in South Sudan. We investigated the role of the Maridi dam in causing an onchocerciasis-associated epilepsy epidemic in these villages. Methods: Affected communities were visited in November 2019 to conduct focus group discussions with village elders and assess the OV16 seroprevalence in 3- to 9-year-old children. Entomological assessments to map blackfly breeding sites and determine biting rates around the Maridi River were conducted. Historical data regarding various activities at the Maridi dam were obtained from the administrative authorities. Results: The Maridi dam was constructed in 1954–1955. Village elders reported an increasing number of children developing epilepsy, including nodding syndrome, from the early 1990s. Kazana 2 (the village closest to the dam; epilepsy prevalence 11.9%) had the highest OV16 seroprevalence: 40.0% among children 3–6 years old and 66.7% among children 7–9 years old. The Maridi dam spillway was found to be the only Simulium damnosum breeding site along the river, with biting rates reaching 202 flies/man/h. Conclusion: Onchocerciasis transmission rates are high in Maridi. Suitable breeding conditions at the Maridi dam, coupled with suboptimal onchocerciasis control measures, have probably played a major role in causing an epilepsy (including nodding syndrome) epidemic in the Maridi area.
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18
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Nakkazi E. River blindness in East Africa: gains and losses. BMJ 2020; 368:m155. [PMID: 31964681 DOI: 10.1136/bmj.m155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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Hedtke SM, Kuesel AC, Crawford KE, Graves PM, Boussinesq M, Lau CL, Boakye DA, Grant WN. Genomic Epidemiology in Filarial Nematodes: Transforming the Basis for Elimination Program Decisions. Front Genet 2020; 10:1282. [PMID: 31998356 PMCID: PMC6964045 DOI: 10.3389/fgene.2019.01282] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022] Open
Abstract
Onchocerciasis and lymphatic filariasis are targeted for elimination, primarily using mass drug administration at the country and community levels. Elimination of transmission is the onchocerciasis target and global elimination as a public health problem is the end point for lymphatic filariasis. Where program duration, treatment coverage, and compliance are sufficiently high, elimination is achievable for both parasites within defined geographic areas. However, transmission has re-emerged after apparent elimination in some areas, and in others has continued despite years of mass drug treatment. A critical question is whether this re-emergence and/or persistence of transmission is due to persistence of local parasites-i.e., the result of insufficient duration or drug coverage, poor parasite response to the drugs, or inadequate methods of assessment and/or criteria for determining when to stop treatment-or due to re-introduction of parasites via human or vector movement from another endemic area. We review recent genetics-based research exploring these questions in Onchocerca volvulus, the filarial nematode that causes onchocerciasis, and Wuchereria bancrofti, the major pathogen for lymphatic filariasis. We focus in particular on the combination of genomic epidemiology and genome-wide associations to delineate transmission zones and distinguish between local and introduced parasites as the source of resurgence or continuing transmission, and to identify genetic markers associated with parasite response to chemotherapy. Our ultimate goal is to assist elimination efforts by developing easy-to-use tools that incorporate genetic information about transmission and drug response for more effective mass drug distribution, surveillance strategies, and decisions on when to stop interventions to improve sustainability of elimination.
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Affiliation(s)
- Shannon M. Hedtke
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Annette C. Kuesel
- Unicef/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | - Katie E. Crawford
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Patricia M. Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD, Australia
| | - Michel Boussinesq
- Unité Mixte Internationale 233 "TransVIHMI", Institut de Recherche pour le Développement (IRD), INSERM U1175, University of Montpellier, Montpellier, France
| | - Colleen L. Lau
- Department of Global Health, Research School of Population Health, Australian National University, Acton, ACT, Australia
| | - Daniel A. Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Warwick N. Grant
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
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Smith ME, Bilal S, Lakwo TL, Habomugisha P, Tukahebwa E, Byamukama E, Katabarwa MN, Richards FO, Cupp EW, Unnasch TR, Michael E. Accelerating river blindness elimination by supplementing MDA with a vegetation "slash and clear" vector control strategy: a data-driven modeling analysis. Sci Rep 2019; 9:15274. [PMID: 31649285 PMCID: PMC6813336 DOI: 10.1038/s41598-019-51835-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 10/09/2019] [Indexed: 01/08/2023] Open
Abstract
Attention is increasingly focusing on how best to accelerate progress toward meeting the WHO's 2030 goals for neglected tropical diseases (NTDs). For river blindness, a major NTD targeted for elimination, there is a long history of using vector control to suppress transmission, but traditional larvicide-based approaches are limited in their utility. One innovative and sustainable approach, "slash and clear", involves clearing vegetation from breeding areas, and recent field trials indicate that this technique very effectively reduces the biting density of Simulium damnosum s.s. In this study, we use a Bayesian data-driven mathematical modeling approach to investigate the potential impact of this intervention on human onchocerciasis infection. We developed a novel "slash and clear" model describing the effect of the intervention on seasonal black fly biting rates and coupled this with our population dynamics model of Onchocerca volvulus transmission. Our results indicate that supplementing annual drug treatments with "slash and clear" can significantly accelerate the achievement of onchocerciasis elimination. The efficacy of the intervention is not very sensitive to the timing of implementation, and the impact is meaningful even if vegetation is cleared only once per year. As such, this community-driven technique will represent an important option for achieving and sustaining O. volvulus elimination.
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Affiliation(s)
- Morgan E Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Shakir Bilal
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Thomson L Lakwo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | | | | | | | - Eddie W Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Thomas R Unnasch
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
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21
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Colebunders R, Stolk WA, Siewe Fodjo JN, Mackenzie CD, Hopkins A. Elimination of onchocerciasis in Africa by 2025: an ambitious target requires ambitious interventions. Infect Dis Poverty 2019; 8:83. [PMID: 31578157 PMCID: PMC6775645 DOI: 10.1186/s40249-019-0593-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Accepted: 09/04/2019] [Indexed: 11/10/2022] Open
Abstract
To achieve the elimination of onchocerciasis transmission in all African countries will entail enormous challenges, as has been highlighted by the active discussion around onchocerciasis intervention strategies and evaluation procedures in this journal.Serological thresholds for onchocerciasis elimination, adapted for the African setting, need to be established. The Onchocerciasis Technical Advisory Subgroup of the World Health Organization is currently developing improved guidelines to allow country elimination committees to make evidence-based decisions. Importantly, onchocerciasis-related morbidity should not be forgotten when debating elimination prospects. A morbidity management and disease prevention (MMDP) strategy similar to that for lymphatic filariasis will need to be developed. This will require collaboration between the onchocerciasis elimination program, the community and other partners including primary health and mental health programs.In order to reach the goal of onchocerciasis elimination in most African countries by 2025, we should prioritize community participation and advocate for tailored interventions which are scientifically proven to be effective, but currently considered to be too expensive.
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Affiliation(s)
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | | | | | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Gravesend, Kent, UK
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22
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Schwartz RA, Al-Qubati Y, Zieleniewski Ł, Shah R, Kapila R. Onchocerciasis (river blindness): larva-induced eczema (onchodermatitis) from an important oculocutaneous tropical disease spilling over into North America and Europe. Int J Dermatol 2019; 59:1065-1070. [PMID: 31513297 DOI: 10.1111/ijd.14614] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/05/2019] [Accepted: 08/09/2019] [Indexed: 11/28/2022]
Abstract
Onchocerciasis is a leading cause of blindness in the world. It may be seen in temperate climates of the United States and Europe in immigrants and travelers from endemic regions, often linked to poverty and war. One should be aware of an incubation period that can be up to 15 months. In its early stage and throughout its course, onchocerciasis has noteworthy skin findings, facilitating diagnosis, as onchodermatitis resembles common eczema with variable degrees of papular, lichenoid, atrophic, and pigmentary alterations, features not suggestive if one is unaware of an individual's immigration and travel history. The same concept applies for the encysted worms (onchocercomas), as they tend to appear as common skin cysts and benign neoplasms. New methods can be employed to increase diagnostic sensitivity and specificity. Ivermectin is the gold standard of therapy, the use of which has almost miraculously eliminated this disease from large areas of the earth. However, its effect remains isolated to microfilariae and can be devastating in those coinfected with Loa loa. Recently, the symbiotic relationship between adult worms and Wolbachia bacteria has been discovered and, with it, the possibility of adding doxycycline as a treatment option. We also discuss coinfection with HIV and other diseases.
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Affiliation(s)
- Robert A Schwartz
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | | | - Łukasz Zieleniewski
- Nicolaus Copernicus University Ludwig Rydygier Medical College, Bydgoszcz, Poland
| | - Radhika Shah
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Rajendra Kapila
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
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23
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Richards FO, Nwoke BEB, Zarroug I, Tukahebwa E, Negussu N, Higazi TB, Oguttu D, Tadesse Z, Miri E, Aziz N, Habomugisha P, Katabarwa M. The positive influence the Onchocerciasis Elimination Program for the Americas has had on Africa programs. Infect Dis Poverty 2019; 8:52. [PMID: 31303175 PMCID: PMC6628490 DOI: 10.1186/s40249-019-0558-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/28/2019] [Indexed: 01/28/2023] Open
Abstract
A recent article “Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes” in Infectious Diseases of Poverty claimed that undue influence on African programs by concepts developed by the Onchocerciasis Elimination Program of the Americas (OEPA) is detrimental to stopping mass drug administration (MDA) in Africa. This claim is made despite a record year for MDA stoppage in four African countries of > 3.5 million treatments in 2018, far exceeding any past OEPA or African Program for Onchocerciasis Control (APOC) stop MDA success.
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Affiliation(s)
- Frank O Richards
- The Carter Center, One Copenhill Avenue, 453 Freedom Parkway, Atlanta, GA, 30307, USA.
| | - B E B Nwoke
- Imo State University Owerri, PMB 2000, Owerri, Nigeria
| | - Isam Zarroug
- Sudan Ministry of Health, P.O. Box 303, Khartoum, Sudan
| | - Edridah Tukahebwa
- Uganda Ministry of Health, 15 Bombo Rd., P. O. Box 1661, Kampala, Uganda
| | - Nebiyu Negussu
- Ethiopia Federal Ministry of Health, P. O. Box 1234, Addis Ababa, Ethiopia
| | - T B Higazi
- Ohio University, 1425 Newark Rd, Zanesville, OH, 43701, USA
| | - David Oguttu
- Uganda Ministry of Health, 15 Bombo Rd., P. O. Box 1661, Kampala, Uganda
| | - Zerihun Tadesse
- The Carter Center-Ethiopia, P. O. Box 13373, Bole K. K. Kebele 05, Addis Ababa, Ethiopia
| | - Emmanuel Miri
- The Carter Center-Nigeria, No. 1 Jeka Kadima St, Jos, Plateau State, Nigeria
| | - Nabil Aziz
- The Carter Center-Sudan, P. O. Box 48, Khartoum, Sudan
| | | | - Moses Katabarwa
- The Carter Center, One Copenhill Avenue, 453 Freedom Parkway, Atlanta, GA, 30307, USA
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Cupp E, Sauerbrey M, Cama V, Eberhard M, Lammie PJ, Unnasch TR. Elimination of onchocerciasis in Africa by 2025: the need for a broad perspective. Infect Dis Poverty 2019; 8:50. [PMID: 31303176 PMCID: PMC6628485 DOI: 10.1186/s40249-019-0557-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/28/2019] [Indexed: 12/16/2022] Open
Abstract
Background In response to the recent publication “Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes” by Dadzie et al., it is important to clarify and highlight the positive and unequivocal research and operational contributions from the American experience towards the worldwide elimination of human onchocerciasis (river blindness). Main text The strategies of twice or more rounds of mass drug administration (MDA) of ivermectin per year, as well as the use of OV-16 serology have allowed four American countries to be verified by World Health Organization to have eliminated transmission of Onchocerca volvulus, the etiological agent. These advances were also implemented in Sudan and Uganda; currently, both are the only African countries where ivermectin MDA was safely stopped in several transmission zones. Conclusions Programmatic treatment and evaluation approaches, pioneered in the Americas, are the most efficient among the existing tools for elimination, and their broader use could catalyze the successful elimination of this disease in Africa. Electronic supplementary material The online version of this article (10.1186/s40249-019-0557-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ed Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA
| | - Mauricio Sauerbrey
- Onchocerciasis Elimination Program for the Americas, 14 Calle 3-51 Zona 10, Edificio Murano Center, Oficina, 1401, Guatemala City, Guatemala
| | - Vitaliano Cama
- Centers for Disease Control and Prevention, 1600 Clifton Rd, MS D-65, Atlanta, GA, 30329, USA
| | - Mark Eberhard
- Centers for Disease Control and Prevention, 1600 Clifton Rd, MS D-65, Atlanta, GA, 30329, USA
| | - Patrick J Lammie
- Task Force for Global Health, 330 W. Ponce de Leon Ave, Decatur, GA, 30030, USA
| | - Thomas R Unnasch
- Center for Global Health Infectious Diseases, University of South Florida College of Public Health, 3720 Spectrum Blvd, Suite 304, Tampa, FL, 33612, USA.
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Dadzie Y, Amazigo UV, Boatin BA, Sékétéli A. The need for evidence-based strategies and tools for onchocerciasis elimination in Africa. Infect Dis Poverty 2019; 8:62. [PMID: 31303174 PMCID: PMC6628483 DOI: 10.1186/s40249-019-0574-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 06/28/2019] [Indexed: 11/10/2022] Open
Abstract
In a recent article we discussed the feasibility of onchocerciasis elimination in Africa by 2025. We expressed concern that elimination may be impeded by failure to build on the lessons learned in the African onchocerciasis control programmes and the introduction of strategies and tools from the Americas. Richards et al. and Cupp et al. wrote to refute our concern and described recent achievements with stopping treatment in some areas.In this response, we discuss their arguments which did not convince us. We point out several scientific flaws in the American conceptual framework of elimination which has led to longer periods of treatment than necessary, and in the use of an arbitrary threshold for stopping treatment. We show that recent achievements fall significantly short of what would be needed to achieve onchocerciasis elimination by 2025.We conclude our response by advocating for a more objective and inclusive debate on strategies and tools for onchocerciasis elimination.
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Affiliation(s)
| | - Uche V. Amazigo
- P. O. Box 3397, Main Post Office, Okpara Avenue, Enugu, Nigeria
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26
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Gebrezgabiher G, Mekonnen Z, Yewhalaw D, Hailu A. Reaching the last mile: main challenges relating to and recommendations to accelerate onchocerciasis elimination in Africa. Infect Dis Poverty 2019; 8:60. [PMID: 31269966 PMCID: PMC6609392 DOI: 10.1186/s40249-019-0567-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 06/10/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Onchocerciasis (river blindness), caused by the filarial worm species Onchocerca volvulus, is a serious vector-borne neglected tropical disease (NTD) of public health and socioeconomic concern. It is transmitted through the bite of black flies of the genus Simulium, and manifested in dermal and ocular lesions. Ninety-nine percent of the total global risk and burden of onchocerciasis is in Africa. This scoping review examines the key challenges related to the elimination of onchocerciasis by 2020-2025 in Africa, and proposes recommendations to overcome the challenges and accelerate disease elimination. To find relevant articles published in peer-reviewed journals, a search of PubMed and Google Scholar databases was carried out. MAIN TEXT Rigorous regional interventions carried out to control and eliminate onchocerciasis in the past four decades in Africa have been effective in bringing the disease burden under control; it is currently not a public health problem in most endemic areas. Notably, transmission of the parasite is interrupted in some hyperendemic localities. Recently, there has been a policy shift from control to complete disease elimination by 2020 in selected countries and by 2025 in the majority of endemic African countries. The WHO has published guidelines for stopping mass drug administration (MDA) and verifying the interruption of transmission and elimination of human onchocerciasis. Therefore, countries have revised their plans, established a goal of disease elimination in line with an evidence based decision to stop MDA and verify elimination, and incorporated it into their NTDs national master plans. Nevertheless, challenges remain pertaining to the elimination of onchocerciasis in Africa. The challenge we review in this paper are: incomplete elimination mapping of all transmission zones, co-endemicity of onchocerciasis and loiasis, possible emergence of ivermectin resistance, uncoordinated cross-border elimination efforts, conflict and civil unrest, suboptimal program implementation, and technical and financial challenges. This paper also proposes recommendations to overcome the challenges and accelerate disease elimination. These are: a need for complete disease elimination mapping, a need for collaborative elimination activities between national programs, a need for a different drug distribution approach in conflict-affected areas, a need for routine monitoring and evaluation of MDA programs, a need for implementing alternative treatment strategies (ATSs) in areas with elimination anticipated beyond 2025, and a need for strong partnerships and continued funding. CONCLUSIONS National programs need to regularly monitor and evaluate the performance and progress of their interventions, while envisaging the complete elimination of onchocerciasis from their territory. Factors hindering the targeted goal of interruption of parasite transmission need to be identified and remedial actions should be taken. If possible and appropriate, ATSs need to be implemented to accelerate disease elimination by 2025.
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Affiliation(s)
- Gebremedhin Gebrezgabiher
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- College of Veterinary Medicine, Samara University, Samara, Ethiopia
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Colebunders R, Siewe Fodjo JN, Hopkins A, Hotterbeekx A, Lakwo TL, Kalinga A, Logora MY, Basáñez MG. From river blindness to river epilepsy: Implications for onchocerciasis elimination programmes. PLoS Negl Trop Dis 2019; 13:e0007407. [PMID: 31318857 PMCID: PMC6638735 DOI: 10.1371/journal.pntd.0007407] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
| | | | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Kent, United Kingdom
| | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Thomson L. Lakwo
- Neglected Tropical Diseases Control Programme, Ministry of Health, Kampala, Uganda
| | - Akili Kalinga
- National institute for Medical Research, Ministry of Health, Dar es Salaam, Tanzania
| | - Makoy Yibi Logora
- Neglected Tropical Diseases Unit, Ministry of Health, Juba, South Sudan
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC-GIDA), Imperial College London, London, United Kingdom
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28
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Nodding syndrome research, lessons learned from the NSETHIO project. Glob Ment Health (Camb) 2019; 6:e26. [PMID: 31807310 PMCID: PMC6880249 DOI: 10.1017/gmh.2019.24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 09/04/2019] [Accepted: 09/19/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Until recently, nodding syndrome (NS) was considered as a mysterious disease of unknown etiology. A link between onchocerciasis and epilepsy was suspected for a long time. However, onchocerciasis was not considered as the cause of NS because NS was believed to occur only in onchocerciasis-endemic regions in Uganda, South Sudan, and Tanzania. In October 2015, with funding from the European Research Council, the NSETHIO group launched a trans-disciplinary, multi-country research project to identify the cause of NS and to study the link between onchocerciasis and epilepsy. METHODS We reviewed NSETHIO activities as well as all published papers, and compared project findings with results of previous research on NS. RESULTS Findings from the NSETHIO project showed that NS is only one of the clinical manifestations in the wide spectrum of onchocerciasis-associated epilepsy (OAE) that could be prevented by strengthening onchocerciasis elimination programs. NSETHIO demonstrated that OAE is an important neglected public health problem in onchocerciasis-endemic areas with no or a sub-optimally functioning onchocerciasis control strategies. CONCLUSIONS Today there is overwhelming evidence that NS together with the Nakalanga syndrome is clinical presentations of OAE, a condition that could be prevented by strengthening onchocerciasis elimination programs. While research needs to continue to elucidate the pathophysiological mechanisms causing NS, new strategies to accelerate onchocerciasis elimination coupled with community-based surveillance and treatment programs for epilepsy are urgently needed in areas of high Onchocerca volvulus transmission.
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