Morbidity in Schistosomiasis Mansoni in Relation to Intensity of Infection: Study of a Community in Kisumu, Kenya *

Abstract

Abstract A random household sample of 30% of the population of 1,393 of Nduru, Kisumu, Kenya was examined in a cross-sectional study of the correlation of morbidity with the prevalence and intensity of schistosomiasis mansoni as determined by standard medical examination. The 384 individuals in 66 households studied had a male:female ratio of 45:55 and an age structure in which more than 50% were below age 20. Malaria was holoendemic in the area, with a spleen rate equal to or greater than Hackett 2 in 34% of individuals without schistosomiasis. S. mansoni infection, as determined by quantitative Kato thick smears, had an overall prevalence of 47% with a peak of 75% in the 40- to 49-year age group. With respect to intensity, 53% were uninfected, 26% had light (10–100 eggs/g), 15% moderate (101–400), and 6% heavy (greater than 401) infections. Peak intensity occurred in females at ages 20–24 years (236 eggs/g) and in males at ages 30–39 (453 eggs/g). A history of not feeling well enough to carry out usual activities occurred in about ⅓ to ½ of the population but was not correlated with presence or intensity of infection. Abdominal pain was reported more frequently by heavily infected individuals. Hepatomegaly was less prevalent in those more heavily infected. Splenomegaly, which occurred in 34% of the uninfected population, was seen in only 5% of those with egg counts greater than 400/g. The methodology of this study of a rural fishing community (Kisumu District) of Nilotic extraction in an area holoendemic for malaria and with schistosomiasis of moderate prevalence and intensity was virtually identical to that of a previous study of a rural farming community (Machakos District) of Bantu extraction in which malaria was rare and schistosomiasis was of high prevalence and intensity. The results in these two communities are compared.