Transmission of intestinal schistosomiasis in Addis Ababa, Ethiopia.

Malacological and parasitological surveys were made in Bole-Kotobe area in Addis Ababa in April 1996 to investigate the transmission of intestinal schistosomiasis. Malacological survey conducted in Kotobe river showed Schistosoma mansoni cercarial infection rate of 2.6% (one out of 38) in Biomphalaria pfeifferi. In a total of 197 stool specimens from school children examined using Kato thin smear method in Misrak Bar Number 1 and Wondirad Elementary and Junior Secondary Schools, the overall prevalence rate of Schistosomas mansoni was 4% and 10%, respectively while the intensity of infection was 66 and 37 eggs per gram (EPG) of stool, respectively. Out of the 13 children found infected in the two schools, nine gave a history of having swam in Kotobe river and had never been outside of Addis Ababa since birth. The collection of B. pfeifferi infected with S. mansoni, the establishment of the isolated S. mansoni in laboratory mice and the finding of schistosome infected children who had never been outside of Addis Ababa confirmed that transmission of intestinal schistosomiasis is actually taking place in Addis Ababa. Further surveys in other water-bodies in the city for mapping of schistosomiasis infection sites and transmission foci are recommended to enable immediate control measures before the situation gets out of control.