SCHISTOSOMIASIS-MANSONI IN KENYA - RELATIONSHIP BETWEEN INFECTION ANDANEMIA IN SCHOOLCHILDREN AT THE COMMUNITY-LEVEL

Haematological surveys were carried out in 3 schools in 2 areas where Schistosoma mansoni is endemic in Machakos District, Kenya, before and after a treatment campaign using praziquantel. Earlier clinical impre ssions of differences in the levels of anaemia between the 2 areas wer e not confirmed. Although individual haemoglobin levels and haematocri ts often fell below international norms, significant anaemia with abno rmal red blood cell morphology was rare (<5%), but varied between scho ols. Altitude could have accounted for some of these differences, but other factors, including diet and parasitism, were involved. Anaemia w as associated with splenomegaly and, to a lesser extent, hepatosplenom egaly. Epidemic malaria (mainly Plasmodium fakiparum) appeared to be t he main cause of parasite-induced anaemia. There was no significant as sociation with the scarce hookworm infections (mainly Necator american us); nor did the much commoner S. mansoni cause severe anaemia at the community level, but haemoglobin levels dropped as its intensity incre ased. Treatment with praziquantel eliminated this trend except in a fe w subjects with splenomegaly alone (probably due to malaria) or with s chistosomal hepatosplenic disease. Possible pathogenic mechanisms are reviewed, including the consumption of red blood cells by adult schist osomes as a possible cause of anaemia.