An association between onchocerciasis and epilepsy was suspected as early as the 1930’s in Mexico and later reports were published showing clustering of epilepsy in several African onchocerciasis foci. Ecological studies carried out in onchocerciasis endemic areas in West, Central and East Africa found a strong association between the prevalence of onchocerciasis and of epilepsy. In previous case-control studies this association was less clear, but this was probably due to shortcomings in study design and the selection of comparison groups. Moreover there seems to be an association between epilepsy and the degree of infection with Onchocerca volvulus. Indeed, in a study in Cameroon, performed before the introduction of annual ivermectin treatment (to control Onchocerciasis), the prevalence of epilepsy and the community microfilarial load were closely related. Moreover a case-control study demonstrated that the microfilarial loads (microfilariae per skin snip) in the epileptic group were significantly higher than in the control group.