Recent studies done in Uganda(1) and Burundi (2), have suggested a possible relationship between onchocerciasis, a dermal cutaneous filariasis causing river blindness, and epileptic seizures. However, this relationship was not found in a study done by our team in Burkina-Faso3 in an onchocerciasis hypoendemic region. Certain authors indicated the need for further investigations4, ln l996,a census carried out by health agents in 40 villages in the Ngaoundaye sub-prefecture of 44 100 persons, in the North Western region endemic for onchocerciasis of Central African Republic, identified as well, people with epilepsy in the region. The onchocercal endemicity in each village was estimated before ivermectin mass treatment Campaign, using a rapid screening technique5. The mean distance from the nearest neighbouring river was estimated for each village. In total, 344epileptics were found and the prevalence of epilepsy was 10.9%. This prevalence varied positively with the onchocerciasis endemicity in the village.
A positive correlation between the onchocercal endemicity and the prevalence of epilepsy (r=0.73; p<0.001) and a negative correlation between epilepsy prevalence and the mean distance of the villages from the nearest river (r=-0.34; p<0.03) were evident. These descriptive results are in favour of an association between onchocerciasis and epilepsy. This study has certain biases: the number of epilepsy cases was probably underestimated, however, this underestimation was uniform among areas of different onchocerciasis endemicities; distances were estimated but not accurate measurements; endemicities were assessed using a rapid method on a community basis and not on individuals; the analytical method was cross-sectional which does not eliminate other confounding factors. Despite all these limitations, these results seem particularly interesting and indicate to set up a detailed study in this country, with epilepsy being confirmed by a neurologist and onchocerciasis confirmed by skin biopsies.
Table: Prevalence of epilepsy and mean distance from the nearest river according to onchocerciasis endemicity. Central African Republic, 1996
|Epilepsy prevalence (for l000Miabitants)||4.9(±l.3)||7.8(±4.9)||24.6 (±18.4)|
|Mean distance from the nearest river (kilometers)||9.5(±7.8)||5.9(±5.9)||2.4(±1.7)|