Elimination of transmission of onchocerciasis (river blindness) with long-term ivermectin mass drug administration with or without vector control in sub-Saharan Africa: a systematic review and meta-analysis.
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SUBMITTER: Mutono N
PROVIDER: S-EPMC11009120 | biostudies-literature | 2024 May
REPOSITORIES: biostudies-literature
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Elimination of transmission of onchocerciasis (river blindness) with long-term ivermectin mass drug administration with or without vector control in sub-Saharan Africa: a systematic review and meta-analysis.
Mutono Nyamai N Basáñez Maria-Gloria MG James Ananthu A Stolk Wilma A WA Makori Anita A Kimani Teresia Njoki TN Hollingsworth T Déirdre TD Vasconcelos Andreia A Dixon Matthew A MA de Vlas Sake J SJ Thumbi S M SM
The Lancet. Global health 20240311 5
<h4>Background</h4>WHO has proposed elimination of transmission of onchocerciasis (river blindness) by 2030. More than 99% of cases of onchocerciasis are in sub-Saharan Africa. Vector control and mass drug administration of ivermectin have been the main interventions for many years, with varying success. We aimed to identify factors associated with elimination of onchocerciasis transmission in sub-Saharan Africa.<h4>Methods</h4>For this systematic review and meta-analysis we searched for publish ...[more]
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Project description:BackgroundOnchocerciasis (river blindness) is a parasitic disease transmitted by blackflies. Symptoms include severe itching, skin lesions, and vision impairment including blindness. More than 99% of all cases are concentrated in sub-Saharan Africa. Fortunately, vector control and community-directed treatment with ivermectin have significantly decreased morbidity, and the treatment goal is shifting from control to elimination in Africa.MethodsWe estimated financial resources and societal opportunity costs associated with scaling up community-directed treatment with ivermectin and implementing surveillance and response systems in endemic African regions for alternative treatment goals--control, elimination, and eradication. We used a micro-costing approach that allows adjustment for time-variant resource utilization and for the heterogeneity in the demographic, epidemiological, and political situation.ResultsThe elimination and eradication scenarios, which include scaling up treatments to hypo-endemic and operationally challenging areas at the latest by 2021 and implementing intensive surveillance, would allow savings of $1.5 billion and $1.6 billion over 2013-2045 as compared to the control scenario. Although the elimination and eradication scenarios would require higher surveillance costs ($215 million and $242 million) than the control scenario ($47 million), intensive surveillance would enable treatments to be safely stopped earlier, thereby saving unnecessary costs for prolonged treatments as in the control scenario lacking such surveillance and response systems.ConclusionsThe elimination and eradication of onchocerciasis are predicted to allow substantial cost-savings in the long run. To realize cost-savings, policymakers should keep empowering community volunteers, and pharmaceutical companies would need to continue drug donation. To sustain high surveillance costs required for elimination and eradication, endemic countries would need to enhance their domestic funding capacity. Societal and political will would be critical to sustaining all of these efforts in the long term.
| S-EPMC4567329 | biostudies-literature
Project description:River blindness (onchocerciasis) causes severe itching, skin lesions, and vision impairment including blindness. More than 99% of all current cases are found in sub-Saharan Africa. Fortunately, vector control and community-directed treatment with ivermectin have significantly reduced morbidity. Studies in Mali and Senegal proved the feasibility of elimination with ivermectin administration. The treatment goal is shifting from control to elimination in endemic African regions. Given limited resources, national and global policymakers need a rigorous analysis comparing investment options. For this, we developed scenarios for alternative treatment goals and compared treatment timelines and drug needs between the scenarios. Control, elimination, and eradication scenarios were developed with reference to current standard practices, large-scale studies, and historical data. For each scenario, the timeline when treatment is expected to stop at country level was predicted using a dynamical transmission model, and ivermectin treatment needs were predicted based on population in endemic areas, treatment coverage data, and the frequency of community-directed treatment. The control scenario requires community-directed treatment with ivermectin beyond 2045 with around 2.63 billion treatments over 2013-2045; the elimination scenario, until 2028 in areas where feasible, but beyond 2045 in countries with operational challenges, around 1.48 [corrected] billion treatments; and the eradication scenario, lasting until 2040, around 1.30 billion treatments. The eradication scenario is the most favorable in terms of the timeline of the intervention phase and treatment needs. For its realization, strong health systems and political will are required to overcome epidemiological and political challenges.
| S-EPMC4393239 | biostudies-literature
Project description:BackgroundGreat strides have been made toward onchocerciasis elimination by mass drug administration (MDA) of ivermectin. Focusing on MDA-eligible areas, we investigated where the elimination goal can be achieved by 2025 by continuation of current practice (annual MDA with ivermectin) and where intensification or additional vector control is required. We did not consider areas hypoendemic for onchocerciasis with loiasis coendemicity where MDA is contraindicated.MethodsWe used 2 previously published mathematical models, ONCHOSIM and EPIONCHO, to simulate future trends in microfilarial prevalence for 80 different settings (defined by precontrol endemicity and past MDA frequency and coverage) under different future treatment scenarios (annual, biannual, or quarterly MDA with different treatment coverage through 2025, with or without vector control strategies), assessing for each strategy whether it eventually leads to elimination.ResultsAreas with 40%-50% precontrol microfilarial prevalence and ≥10 years of annual MDA may achieve elimination with a further 7 years of annual MDA, if not achieved already, according to both models. For most areas with 70%-80% precontrol prevalence, ONCHOSIM predicts that either annual or biannual MDA is sufficient to achieve elimination by 2025, whereas EPIONCHO predicts that elimination will not be achieved even with complementary vector control.ConclusionsWhether elimination will be reached by 2025 depends on precontrol endemicity, control history, and strategies chosen from now until 2025. Biannual or quarterly MDA will accelerate progress toward elimination but cannot guarantee it by 2025 in high-endemicity areas. Long-term concomitant MDA and vector control for high-endemicity areas might be useful.
| S-EPMC5982715 | biostudies-literature
Project description:BackgroundSeveral African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and suboptimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over 2 consecutive rounds of treatment in 10 sentinel communities.MethodsWe evaluated Onchocerca volvulus community microfilarial intensity and prevalence in persons aged ≥20 years before the first, second, and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modeling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed up over the first 2 rounds of biannual treatment.ResultsBiannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified 3 communities-all having been previously recognized as responding suboptimally to ivermectin-with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection.ConclusionsThe strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but suboptimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization's 2020 elimination goals remains uncertain.
| S-EPMC4872292 | biostudies-literature
Project description:BackgroundThe impact of large scale Mass Drug Adminstration (MDA) of ivermectin on active onchocerciasis transmission by Simulium damnosum, which transmits the parasite O. volvulus is of great importance for onchocerciasis control programmes. We investigated in the Mbam river system area, the impact of MDA of ivermectin on entomological indices and also verify if there are river system factors that could have favoured the transmission of onchocerciasis in this area and contribute to the persistence of disease. We compared three independent techniques to detect Onchocerca larvae in blackflies and also analyzed the river system within 9 months post-MDA of ivermectin.MethodSimulium flies were captured before and after 1, 3, 6 and 9months of ivermectin-MDA. The biting rate was determined and 41% of the flies dissected while the rest were grouped into pools of 100 flies for DNA extraction. The extracted DNA was then subjected to O-150 LAMP and real-time PCR for the detection of infection by Onchocerca species using pool screening. The river system was analysed and the water discharge compared between rainy and dry seasons.Principal findingsWe used human landing collection method (previously called human bait) to collect 22,274 adult female Simulium flies from Mbam River System. Of this number, 9,134 were dissected while 129 pools constituted for molecular screening. Overall biting and parous rates of 1113 flies/man/day and 24.7%, respectively, were observed. All diagnostic techniques detected similar rates of O. volvulus infection (P = 0.9252) and infectivity (P = 0.4825) at all monitoring time points. Onchocerca ochengi larvae were only detected in 2 of the 129 pools. Analysis of the river drainage revealed two hydroelectric dams constructed on the tributaries of the Mbam river were the key contributing factor to the high-water discharge during both rainy and dry seasons.ConclusionResults from fly dissection (Microscopy), real-time PCR and LAMP revealed the same trends pre- and post-MDA. The infection rate with animal Onchocerca sp was exceptionally low. The dense river system generate important breeding sites that govern the abundance of Simulium during both dry and rainy seasons.
| S-EPMC7815102 | biostudies-literature
Project description:BackgroundMass treatment with ivermectin is a proven strategy for controlling onchocerciasis as a public health problem, but it is not known if it can also interrupt transmission and eliminate the parasite in endemic foci in Africa where vectors are highly efficient. A longitudinal study was undertaken in three hyperendemic foci in Mali and Senegal with 15 to 17 years of annual or six-monthly ivermectin treatment in order to assess residual levels of infection and transmission and test whether ivermectin treatment could be safely stopped in the study areas.Methodology/principal findingsSkin snip surveys were undertaken in 126 villages, and 17,801 people were examined. The prevalence of microfilaridermia was <1% in all three foci. A total of 157,500 blackflies were collected and analyzed for the presence of Onchocerca volvulus larvae using a specific DNA probe, and vector infectivity rates were all below 0.5 infective flies per 1,000 flies. Except for a subsection of one focus, all infection and transmission indicators were below postulated thresholds for elimination. Treatment was therefore stopped in test areas of 5 to 8 villages in each focus. Evaluations 16 to 22 months after the last treatment in the test areas involved examination of 2,283 people using the skin snip method and a DEC patch test, and analysis of 123,000 black flies. No infected persons and no infected blackflies were detected in the test areas, and vector infectivity rates in other catching points were <0.2 infective flies per 1,000.Conclusion/significanceThis study has provided the first empirical evidence that elimination of onchocerciasis with ivermectin treatment is feasible in some endemic foci in Africa. Although further studies are needed to determine to what extent these findings can be extrapolated to other endemic areas in Africa, the principle of elimination has been established. The African Programme for Onchocerciasis Control has adopted an additional objective to assess progress towards elimination endpoints in all onchocerciasis control projects and to guide countries on cessation of treatment where feasible.
| S-EPMC2710500 | biostudies-literature
Project description:Identification of drug resistance before it becomes a public health concern requires a clear distinction between what constitutes a normal and a suboptimal treatment response. A novel method of analyzing drug efficacy studies in human helminthiases is proposed and used to investigate recent claims of atypical responses to ivermectin in the treatment of River Blindness. The variability in the rate at which Onchocerca volvulus microfilariae repopulate host's skin following ivermectin treatment is quantified using an individual-based onchocerciasis mathematical model. The model estimates a single skin repopulation rate for every host sampled, allowing reports of suboptimal responses to be statistically compared with responses from populations with no prior exposure to ivermectin. Statistically faster rates of skin repopulation were observed in 3 Ghanaian villages (treated 12-17 times), despite the wide variability in repopulation rates observed in ivermectin-naïve populations. Another village previously thought to have high rates of skin repopulation was shown to be indistinguishable from the normal treatment response. The model is used to generate testable hypotheses to identify whether atypical rates of skin repopulation by microfilariae could result from low treatment coverage alone or provide evidence of decreased ivermectin efficacy. Further work linking phenotypic poor responses to treatment with parasite molecular genetics markers will be required to confirm drug resistance. Limitations of the skin-snipping method for estimating parasite load indicates that changes in the distribution of microfilarial repopulation rates, rather than their absolute values, maybe a more sensitive indicator of emerging ivermectin resistance.
| S-EPMC2757820 | biostudies-other
Project description:BackgroundAn estimated 25 million people are currently infected with onchocerciasis (a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted by Simulium vectors), and 99% of these are in sub-Saharan Africa. The African Programme for Onchocerciasis Control closed in December 2015 and the World Health Organization has established a new structure, the Expanded Special Project for the Elimination of Neglected Tropical Diseases for the coordination of technical support for activities focused on five neglected tropical diseases in Africa, including onchocerciasis elimination.AimsIn this paper we argue that despite the delineation of a reasonably well-defined elimination strategy, its implementation will present particular difficulties in practice. We aim to highlight these in an attempt to ensure that they are well understood and that effective plans can be laid to solve them by the countries concerned and their international partners.ConclusionsA specific concern is the burden of disease caused by onchocerciasis-associated epilepsy in hyperendemic zones situated in countries experiencing difficulties in strengthening their onchocerciasis control programmes. These difficulties should be identified and programmes supported during the transition from morbidity control to interruption of transmission and elimination.
| S-EPMC5872540 | biostudies-literature
Project description:ObjectivesTo evaluate the effect of ivermectin mass drug administration on strongyloidiasis and other soil transmitted helminthiases.MethodsWe conducted a retrospective analysis of data collected in Esmeraldas (Ecuador) during surveys conducted in areas where ivermectin was annually administered to the entire population for the control of onchocerciasis. Data from 5 surveys, conducted between 1990 (before the start of the distribution of ivermectin) and 2013 (six years after the interruption of the intervention) were analyzed. The surveys also comprised areas where ivermectin was not distributed because onchocerciasis was not endemic. Different laboratory techniques were used in the different surveys (direct fecal smear, formol-ether concentration, IFAT and IVD ELISA for Strongyloides stercoralis).ResultsIn the areas where ivermectin was distributed the strongyloidiasis prevalence fell from 6.8% in 1990 to zero in 1996 and 1999. In 2013 prevalence in children was zero with stool examination and 1.3% with serology, in adult 0.7% and 2.7%. In areas not covered by ivermectin distribution the prevalence was 23.5% and 16.1% in 1996 and 1999, respectively. In 2013 the prevalence was 0.6% with fecal exam and 9.3% with serology in children and 2.3% and 17.9% in adults. Regarding other soil transmitted helminthiases: in areas where ivermectin was distributed the prevalence of T. trichiura was significantly reduced, while A. lumbricoides and hookworms were seemingly unaffected.ConclusionsPeriodic mass distribution of ivermectin had a significant impact on the prevalence of strongyloidiasis, less on trichuriasis and apparently no effect on ascariasis and hookworm infections.
| S-EPMC4635009 | biostudies-literature
Project description:Community-directed treatment with ivermectin (CDTi) is the primary strategy employed to control and eliminate human onchocerciasis in Ethiopia. After long-term mass distribution for onchocerciasis, ivermectin is expected to have additional benefits beyond the envisioned targets by reducing the burden of other co-endemic parasitic infections as to STHs. To date, studies focused on the collateral impact of CDTi on STH in Ethiopia are scanty. Two community-based cross-sectional surveys (baseline in 1997 and post-CDTi in 2017) were conducted to evaluate the impact of long-term CDTi employed to control and eliminate onchocerciasis on the burden of STH infections in Yeki district of southwest Ethiopia. Stool samples were collected and examined using Ritchie`s concentration and Kato-Katz techniques in the baseline and current study, respectively. Overall, 188(38.3%, 95% Confidence interval (CI) 34.1-42.7%) individuals were positive at least for any of the STH species from 491 study participants in the post-CDTi. The prevalence of A. lumbricoides, hookworms, and T. trichiura was 11.2% (95% CI 8.7-14.3%), 16.3% (95% CI 13.3-19.8%), and 29.9% (95% CI 26.1-34.1%), respectively. Individuals aged 5-9 years had a significantly higher prevalence of A. lumbricoides (Adjusted odds ratio (AOR) 6.5, 95% CI 1.7-25.4), T. trichuria (AOR 8, 95% CI 2.6-25.1), and any STH infection (AOR 5, 95% CI 1.7-14.7) than those of ≥ 51 years. Also, significantly higher prevalences of T. trichuria infection were observed in individuals aged 10-14 years (AOR 4.1, 95% CI 1.7-9.9), 15-20 years (AOR 3.1, 95% CI 1.2-8.1), 21-30 years (AOR 2.4, 95% CI 1.1-5.5), and 31-40 years (AOR 3.2, 95% CI 1.3-7.5) compared with those of ≥ 51 years. The prevalence of A. lumbricoides was significantly higher in males (AOR 0.5, 95% CI 0.3-0.9). Of the 491 study participants, only data from 400 individuals who had not been involved in a mass drug administration (MDA) with other STH anthelmintics were considered in the comparative analysis. Before CDTi, the prevalence of A. lumbricoides, T. trichiura, hookworm, and any STH infection was 47.1% (95% CI 41.6-52.7%), 3.3% (95% CI 1.8-5.9%), 37.9% (95% CI 32.7-43.5%), and 58.8% (95% CI 53.2-64.1%), respectively. Long-term CDTi considerably reduced the prevalences of A. lumbricoides and hookworm by 76.2% and 56.9%, respectively (p < 0.001). Nonetheless, CDTi did not affect the prevalence of T. trichiura infection and, in contrast, it was significantly higher in the current study (P < 0.001). Overall post-CDTi prevalence of any STH infection was considerably lower than reported in the baseline (p < 0.001). It is evidenced that long-term CDTi for onchocerciasis control and elimination had additional benefits by reducing the prevalence of STH infections specifically of A. lumbricoides and hookworm, but had no impact on infections with T. trichuria. Our finding of additional health benefits of large-scale ivermectin administration taking it will aid to increase positive engagement and sustain participation of communities during MDA campaigns, and strengthen governmental and non-governmental organizations (NGOs) support for the undergoing national onchocerciasis elimination program.
| S-EPMC8830686 | biostudies-literature