Progress towards onchocerciasis elimination in the participating countries of the African Programme for Onchocerciasis Control: epidemiological evaluation results

Background:The African Programme for Onchocerciasis Control(APOC)was created in 1995 to establish community-directed treatment with ivermectin(CDTi)in order to control onchocerciasis as a public health problem in 20 African countries that had 80%of the global disease burden.When research showed that CDTi may ultimately eliminate onchocerciasis infection,APOC was given in 2008 the additional objective to determine when and where treatment can be safely stopped.We report the results of epidemiological evaluations undertaken from 2008 to 2014 to assess progress towards elimination in CDTi areas with≥6 years treatment.Methods:Skin snip surveys were undertaken in samples of first-line villages to determine the prevalence of O.volvulus microfilariae.There were two evaluation phases.The decline in prevalence was evaluated in phase 1A.Observed and model-predicted prevalences were compared after correcting for endemicity level and treatment coverage.Bayesian statistics and Monte Carlo simulation were used to classify the decline in prevalence as faster than predicted,on track or delayed.Where the prevalence approached elimination levels,phase 1B was launched to determine if treatment could be safely stopped.Village sampling was extended to the whole CDTi area.Survey data were analysed within a Bayesian framework to determine if stopping criteria(overall prevalence<1.4%and maximum stratum prevalence<5%)were met.Results:In phase 1A 127665 people from 639 villages in 54 areas were examined.The prevalence had fallen dramatically.The decline in prevalence was faster than predicted in 23 areas,on track in another 23 and delayed in eight areas.In phase 1B 108636 people in 392 villages were examined in 22 areas of which 13 met the epidemiological criteria for stopping treatment.Overall,32 areas(25.4 million people)had reached or were close to elimination,18 areas(17.4 million)were on track but required more years treatment,and in eight areas(10.4 million)progress was unsatisfactory.Conclusions:Onchocerciasis has been largely controlled as a public health problem.Great progress has been made towards elimination which already appears to have been achieved for millions of people.For most APOC countries,nationwide onchocerciasis elimination is within reach.

Burden of onchocerciasis-associated epilepsy:first estimates and research priorities

Background:Since the 1990s,evidence has accumulated of an increased prevalence of epilepsy in onchocerciasisendemic areas in Africa as compared to onchocerciasis-free areas.Although the causal relationship between onchocerciasis and epilepsy has yet to be proven,there is likely an association.Here we discuss the need for disease burden estimates of onchocerciasis-associated epilepsy(OAE),provide them,detail how such estimates should be refined,and discuss the socioeconomic impact of OAE,including a cost-estimate for anti-epileptic drugs.Main body:Providing OAE burden estimates may aid prevention of epilepsy in onchocerciasis-endemic areas by inciting and informing collaboration between onchocerciasis control programmes and mental health services.Epilepsy not only massively impacts the health of those affected,but it also carries a high socioeconomic burden for the households and communities involved.We used previously published geospatial estimates of onchocerciasis in Africa and a separately published logistic regression model quantifying the association between onchocerciasis and epilepsy to estimate the number of OAE cases.We then applied disability weights for epilepsy to quantify the burden in terms of years of life lived with disability(YLD)and estimate the cost of treatment.We estimate that in 2015 roughly 117000 people were affected by OAE across onchocerciasis-endemic areas previously under the African Programme for Onchocerciases control(APOC)mandate where OAE has ever been reported or suspected,and another 264000 persons in onchocerciasis-endemic areas where OAE has never been investigated before.The total number of YLDs due to OAE was 39300 and 88700 in these areas respectively,based on a weighted mean disability weight of 0.336.The burden of OAE is approximately 13%of the total YLDs attributable to onchocerciasis and 10%of total YLDs attributable to epilepsy.We estimated that by 2015 the total costs of treatment with antiepileptic drug for OAE cases would have been a minimum of 12.4 million US$.Conclusions:These estimates suggest a considerable health,social and economic burden of OAE in Africa.The treatment and care for people with epilepsy,especially in hyperendemic onchocerciasis areas with high epilepsy prevalence thus requires more financial and human resources.

Report of the first international workshop on onchocerciasis-associated epilepsy

Background:Recently,several epidemiological studies performed in Onchocerca volvulus-endemic regions have suggested that onchocerciasis-associated epilepsy(OAE)may constitute an important but neglected public health problem in many countries where onchocerciasis is still endemic.Main text:On October 12-14th 2017,the first international workshop on onchocerciasis-associated epilepsy(OAE)was held in Antwerp,Belgium.The workshop was attended by 79 participants from 20 different countries.Recent research findings strongly suggest that O.volvulus is an important contributor to epilepsy,particularly in meso-and hyperendemic areas for onchocerciasis.Infection with O.volvulus is associated with a spectrum of epileptic seizures,mainly generalised tonic-clonic seizures but also atonic neck seizures(nodding),and stunted growth.OAE is characterised by an onset of seizures between the ages of 3-18 years.Multidisciplinary working groups discussed topics such as how to 1)strengthen the evidence for an association between onchocerciasis and epilepsy,2)determine the burden of disease caused by OAE,3)prevent OAE,4)improve the treatment/care for persons with OAE and affected families,5)identify the pathophysiological mechanism of OAE,and 6)deal with misconceptions,stigma,discrimination and gender violence associated with OAE.An OAE Alliance was created to increase awareness about OAE and its public health importance,stimulate research and disseminate research findings,and create partnerships between OAE researchers,communities,advocacy groups,ministries of health,non-governmental organisations,the pharmaceutical industry and funding organizations.Conclusions:Although the exact pathophysiological mechanism underlying OAE remains unknown,there is increasing evidence that by controlling and eliminating onchocerciasis,OAE will also disappear.Therefore,OAE constitutes an additional argument for strengthening onchocerciasis elimination efforts.Given the high numbers of people with epilepsy in O.volvulus-endemic regions,more advocacy is urgently needed to provide anti-epileptic treatment to improve the quality of life of these individuals and their families.

Elimination of onchocerciasis in Africa by 2025: an ambitious target requires ambitious interventions

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,onchocerciasisrelated 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.