[High prevalence of konzo associated with a food shortage crisis in the Bandundu region of zaire].

Konzo is a form of spastic paraparesis reported from several rural areas in Sub-Saharan Africa. It has been attributed to cyanide exposure from exclusive consumption of insufficiently processed bitter cassava roots. We have tested this attribution in a community based epidemiological survey in an area of Bandundu region in Zaire composed of two agro-ecological zones: savanna and forest. In the savanna area with poor soils we found 78 konzo cases in 1,936 inhabitants, a prevalence of 4%; but in the forest area only 9 cases in 5,531 inhabitants (0.2%). This geographical distribution as well as the temporal distribution coincide with frequent short-soaking of cassava roots (only one night) induced by an agro-ecological crisis. High levels of blood cyanide, mean 13.3 mumol/l (range: 0.1-76.3) and serum thiocyanate, mean (+/- SD) 401 (+/- 126) mumol/l, in a sample of 18 subjects from the savanna area confirm high cyanide exposure in this population with high prevalence of konzo. Prevention of konzo in Zaire is possible by promotion of sufficient soaking of cassava with strict adherence to traditional three nights soaking and the use of completely dry flour.