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

Abstract

BackgroundSince the 1990s, evidence has accumulated of an increased prevalence of epilepsy in onchocerciasis-endemic 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 bodyProviding 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 117 000 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 264 000 persons in onchocerciasis-endemic areas where OAE has never been investigated before. The total number of YLDs due to OAE was 39 300 and 88 700 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 anti-epileptic drug for OAE cases would have been a minimum of 12.4 million US$.ConclusionsThese 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.Electronic supplementary materialThe online version of this article (10.1186/s40249-018-0481-9) contains supplementary material, which is available to authorized users.

Economic evaluations of onchocerciasis interventions: a systematic review and research needs

“…Interestingly, the same age group (those aged below 20 years) for which there is a statistically significant higher risk of mortality for a given microfilarial load in comparison to those aged 20 years and older , is the group with the onset and higher incidence of nodding syndrome, a type of epilepsy that is increasingly recognised as associated with onchocerciasis . Preliminary studies of the disease burden of onchocerciasis‐associated epilepsy have been conducted . These studies should be followed by economic evaluations of both onchocerciasis‐associated epilepsy and the impact of onchocerciasis interventions.…”

Zoonotic Implications of Onchocerca Species on Human Health

“…It has been estimated that onchocerciasis-associated epilepsy (OAE) affected between 300 and 400,000 people worldwide in 2015 [150]. The onset of OAE is between the ages of 3 and 18 years old, and OAE is an important cause of mortality among children and adolescents in onchocerciasis endemic areas with ongoing transmission [151].…”

Turning a Drug Target into a Drug Candidate: A New Paradigm for Neurological Drug Discovery?

“…Onchocerciasis (River Blindness), which affects 25 million people, [ 35 ] is the result of infection by a parasitic nematode worm Onchocerca volvulus . The common name for the disease stems from its transmission following bites by blackflies of the genus Simulium , whose early life stages are aquatic.…”