A study of the morbidity of schistosomiasis mansoni was made in 138 school-children (age range, 7–16 years) in St. Lucia. The study was based on quantitative egg excretion data collected over a 4-year period before the study and included a comparable uninfected control group. All examinations were carried out “blind.” Infected subjects were divided into three levels of intensity of infection: heavy, 400 or more eggs/ml of feces; moderate, 100 to 300 eggs/ml; and light, 10 to 75 eggs/ml. The children were hospitalized for medical histories and physical and laboratory examinations. Gastrointestinal symptoms were present at relatively high levels in all groups, and were no more frequent in the Schistosoma mansoni-infected subjects than in the controls. Anthropometric measurements showed no differences among the groups. Hepatomegaly and splenomegaly were significantly more frequent in the heavy-moderate infection group, and extension of the liver below the costal margin was found to increase with intensity of infection. Serum globulin level and skin-test reactivity were directly related to intensity of infection; serum albumin level was inversely related. It was clear that in this St. Lucian study, infection with S. mansoni did not result in disease in most of the school-age subjects investigated; assessment of possible long-term (>4 years) effects was not made. This study provides a method for assessing morbidity of schistosomiasis based on quantitative egg excretion and demonstrates the relation of objective morbidity to intensity of infection.
Staff member, The Rockefeller Foundation.
External staff, British Medical Research Council; seconded to The Rockefeller Foundation.