BackgroundAn increased prevalence of epilepsy has been reported in many onchocerciasis endemic areas. The objective of this study was to determine the prevalence of epilepsy in onchocerciasis endemic areas in the Democratic Republic of the Congo (DRC) and investigate whether a higher annual intake of Ivermectin was associated with a lower prevalence of epilepsy.Methodology/Principle findingsBetween July 2014 and February 2016, house-to-house epilepsy prevalence surveys were carried out in areas with a high level of onchocerciasis endemicity: 3 localities in the Bas-Uele, 24 in the Tshopo and 21 in the Ituri province. Ivermectin uptake was recorded for every household member. This database allowed a matched case-control pair subset to be created that enabled putative risk factors for epilepsy to be tested using univariate logistic regression models. Risk factors relating to onchocerciasis were tested using a multivariate random effects model. To identify presence of clusters of epilepsy cases, the Kulldorff's scan statistic was used. Of 12, 408 people examined in the different health areas 407 (3.3%) were found to have a history of epilepsy. A high prevalence of epilepsy was observed in health areas in the 3 provinces: 6.8–8.5% in Bas-Uele, 0.8–7.4% in Tshopo and 3.6–6.2% in Ituri. Median age of epilepsy onset was 9 years, and the modal age 12 years. The case control analysis demonstrated that before the appearance of epilepsy, compared to the same life period in controls, persons with epilepsy were around two times less likely (OR: 0.52; 95%CI: (0.28, 0.98)) to have taken Ivermectin than controls. After the appearance of epilepsy, there was no difference of Ivermectin intake between cases and controls. Only in Ituri, a significant cluster (p-value = 0.0001) was identified located around the Draju sample site area.ConclusionsThe prevalence of epilepsy in health areas in onchocerciasis endemic regions in the DRC was 2–10 times higher than in non-onchocerciasis endemic regions in Africa. Our data suggests that Ivermectin protects against epilepsy in an onchocerciasis endemic region. However, a prospective population based intervention study is needed to confirm this.

HighlightsIn Titule, onchocerciasis suspected skin lesions were associated with epilepsy.Frequent activities at rapid flowing rivers were associated with epilepsy.A historical lack of Ivermectin treatment was a risk factors for epilepsy.

BackgroundNodding syndrome (NS) is an epilepsy disorder occurring in children in South Sudan, northern Uganda and Tanzania. The etiology of NS is unknown, but epidemiological studies demonstrate an association between NS and onchocerciasis.MethodsBetween November 2013 and July 2015 we visited onchocerciasis endemic regions in South Sudan, Uganda, and the Democratic Republic of the Congo (DRC) to assess the epilepsy situation. In South Sudan we interviewed patients and affected families, health officials, colleagues and healthcare workers, and performed a small household survey to estimate the epilepsy prevalence in the village of Mvolo, Western Equatoria State. Most information from Uganda was collected through discussions with colleagues and a review of published literature and reports. In the Bas-Uélé district of the DRC, we visited the villages of Liguga, Titule and Dingila, interviewed patients with epilepsy and family members and conducted a preliminary entomological assessment.ResultsIn South Sudan there is an ongoing NS and epilepsy epidemic in the Western Equatoria state that started around 1990. A survey of 22 households in Mvolo revealed that 28 out of 168 (16.7 %) children suffered from NS or another form of epilepsy. Thirteen (59 %) households had at least one child, and nine (41 %) households at least two children with NS or another form of epilepsy. In northern Uganda, an NS and epilepsy epidemic started around 2000. The occurrence of new NS cases has been in decline since 2008 and no new NS cases were officially reported in 2013. The decline in NS cases coincided with the bi-annual distribution of ivermectin and the treatment of blackfly-breeding rivers with larvicides. In Bas-Uélé district in the DRC, epilepsy appears to be endemic with cases clustered in villages close to blackfly-infested, rapid-flowing rivers. The majority of epilepsy cases in Liguga, Dingila and Titule presented with generalized (tonic–clonic) seizures without nodding, but with mental retardation. In Titule, an epilepsy prevalence of 2.3 % was documented. The only anthropophilic species of blackfly collected in the region belonged to the Simulium damnosum complex.ConclusionBlackflies may play a key role in the transmission of an etiological agent that either directly or indirectly cause, not only NS, but also other forms of epilepsy in onchocerciasis endemic regions.

HighlightsA high epilepsy prevalence in the Aketi health zone was observed despite 14 years of community-directed treatment with ivermectin.The high prevalence of OV16 antibodies in children is indicative of high ongoing onchocerciasis transmission.High onchocerciasis transmission is the consequence of high exposure to blackflies and low intake of ivermectin.Head nodding seizures were observed in 13.8% of the persons with epilepsy.Ivermectin coverage needs to be increased and bi-annual distribution should be considered.

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