DYNAMIC MODELING OF EPIDEMIOLOGIC PATTERNS OF SCHISTOSOMIASIS MORBIDITY

This paper uses preliminary mathematical models to examine how the dyn amic relationship between schistosomiasis infection and disease is alt ered by chemotherapy. Two types of morbidity are examined: an acute fo rm that is proportional to current infection intensity and that resolv es after treatment, and a chronic form that represents accumulated exp erience of infection and that does not resolve after treatment, or res olves according to some delay function. The analyses indicate that non linearities in the age and frequency distributions of infection intens ity have a marked impact on the patterns of morbidity. They also sugge st that treatment close to the age of maximum infection intensity (i.e ., children of schoolage) is most effective in controlling morbidity i n the community as a whole. These models are preliminary, and their fu rther development to include more realistic assumptions in relation to held data is discussed.