During the 1984 cholera epidemic in Mali, 1793 cases and 406 deaths were reported, a death-to-case ratio of 23%. In four affected villages, the mean clinical attack rate was 1.5 and 29% of affected persons died. In 66% of cases the illness began more than 48 h after the village outbreak began, when supplies from outside the village were potentially available. Deaths occurred because patients failed to seek care or received only limited rehydration therapy when they did. Case-control studies identified two routes of transmission: drinking water from one well in a village outside the drought area, and eating left-over millet gruel in a drought-affected village. Drought-related scarcity of curdled milk may permit millet gruel to be a vehicle for cholera. Cholera mortality in the Sahel could be greatly reduced by rapid intervention in affected villages, wide distribution of effective rehydration materials, and educating the population to seek treatment quickly.

A new Vibrio cholerae serogroup O139 strain of unknown origin recently emerged in India and Bangladesh, causing a major outbreak of cholera. The genetic relationship between this epidemic strain and the O1 strain responsible for the 7th pandemic of cholera was studied by analyzing the DNA polymorphism of V. cholerae by pulsed-field gel electrophoresis and arbitrarily primed polymerase chain reaction. The restriction patterns of the reference strain O139 Bengal and 10 wild O139 strains isolated early in the Indian outbreak strikingly resemble that of the pandemic O1 strain of V. cholerae El Tor, thus suggesting a close genetic relationship among these strains. This similarity contrasts with the genetic heterogeneity of sporadic non-O1 strains isolated in various parts of the world. Study results strongly suggest that the new epidemic O139 strain is closely related to and might be derived from the pandemic O1 strain of V. cholerae.

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