Purpose: In the Littoral Province of Cameroon, in the Sanaga River Valley, a door-to-door epidemiological study was carried out in order to evaluate the prevalence of epilepsy in a small village located in a geographically isolated area, hyper-endemic for onchocerciasis. It was followed by an electro-clinical evaluation of patients and a case-control study.
Methods: The study involved a three-phases design: in phase I, a screening questionnaire was administered, in phase II, the presence of epilepsy was confirmed with electro-clinical evaluation, and in phase III, risk factors for epilepsy, socio-economical factors and life habits were evaluated in patients and two matched controls for the age (+/-1 year) residents in the same village. Endemicity level of onchocerciasis was assessed in the village by measuring the prevalence of nodules in adult males aged >or=20 years (PNAM).
Results: One hundred eighty-one subjects (100 male and 81 female) were examined (91.9% of the overall population). The crude prevalence rate of active epilepsy was 105 per 1000 pop (CI 95% 60-150) while the age-adjusted prevalence rate was 134.5 cases per 1000 pop (CI 95% 90-178). Seizures were classified as generalized in 10 patients (52.6%) and partial in nine (47.4%). In 17 patients EEG was recorded. Afterward the electro-clinical classification this distribution was inverted: generalized seizures occurred in 35.3% of cases and partial seizures in 64.7% of cases. The PNAM was 62.5%. The surveyed village was classified as hyper-endemic for onchocerciasis. Among risk factors, only positive family history for epilepsy was found (p=0.031). A sample pedigree of a family with 10 epileptic cases (4 included in the epidemiological study) was showed.
Conclusions: To our knowledge, this is the first door-to-door study that produce an adjusted prevalence rate on epilepsy in Cameroon. In according to studies done in Tanzania, Liberia, Uganda, and Ethiopia, our results (i.e., the high prevalence rate in a restricted area, the clinical characteristics of epileptic seizures, the positive family history for epilepsy and the type of pedigree of a family with epileptic patients) may be accounted for by the presence of an strong interaction between environmental and genetic factors in some circumscribed areas.