Urinary Tract Morbidity in Schistosomiasis Haematobia: Associations with Age and Intensity of Infection in an Endemic Area of Coast Province, Kenya

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  • Departments of Medicine and Epidemiology and Biostatistics, Case Western Reserve University and University Hospitals, Kenyatta General Hospital and Ministry of Health, Cleveland, Ohio, Kenya

To gain better understanding of the natural history of Schistosoma haematobium associated disease, age- and intensity-related urinary tract morbidity were assessed in a cross-sectional study of Kilole (population 719) in Coast Province, Kenya. Overall prevalence of infection was 65% (39% light, 16% moderate, 9% heavy). Infection prevalence and mean intensity of infection were highest in the 5-14-year-old bracket for both sexes. Although significant intensity-associated increases in hematuria prevalence were noted for both children and adults in all infection categories, hematuria was more common in those < 15 years of age. Children had a significant increase in the prevalence of dysuria at higher levels of infection, whereas adults did not. Radiographic study of a 1:9 random sample, stratified for age, revealed a greater prevalence of urinary tract granulomas in those < 15 years. Subjects > 15 years of age had a greater frequency of hydronephrosis. Hydronephrosis, hydroureter, and bladder calcification were not associated with higher infection intensity.

Among individuals with bladder calcification, a potential marker of cumulative inflammation, 87% had hydronephrosis or hydroureter, compared to a 40% prevalence among individuals without bladder calcification. These findings suggest that certain structural forms of urinary tract disease, such as hydronephrosis, progress during the course of untreated schistosomiasis haematobia despite age-related reductions in egg burden, whereas other forms of morbidity, such as hematuria, remain sensitive to the level of urinary egg excretion at the time of diagnosis.