Effects of single-dose praziquantel on morbidity and mortality resulting from intestinal schistosomiasis.

The long-term effect of single-dose praziquantel on morbidity and mortality from Schistosoma mansoni was investigated in surveys in 1987 and 1994 in central Sudan. Prevalence of infection dropped from 53% to 34%, and intensity of infection (> or = 400 eggs/g of faeces) from 31% to 18%. There was a reduction in hepatomegaly and hepatosplenomegaly, although splenomegaly alone was unchanged. Prevalence of periportal fibrosis decreased from 14% to 10%. Endoscopic investigation of patients with fibrosis showed a reduction in oesophageal varices from 47% to 30%. Mortality due to bleeding varices was high (community-wide, up to 11/100 infected patients with bleeding). Thus praziquantel mass treatment can be spaced to a much longer period, reducing the expense of treatment, delivery and distribution.