Smaller outbreaks in rural areas have subsequently been reported from Zaire, Mozambique, Tanzania and the Central African Republic, figure 1. Sporadic cases of konzo also occur in affected areas, years after an extensive outbreak. The majority of konzo onsets occur during the dry season, especially in drought years. Men are less frequently affected. No breast-fed child has been found to have contracted konzo, which in affected communities means no child below the age of 2.5 years.
Familial clustering is common.
At present a total of 3,700 konzo cases have been documented in studies and reports. Of these, more than 2,000 cases are from Bandundu Region in Zaire. The reported number of cases is undoubtedly an underestimate, as case detection is incomplete in the remote rural areas affected. The onset of konzo is sudden, without prodromata. Often a long walk or hard work seems to trigger the onset.