Morbidity from urinary schistosomiasis in relation to intensity of infection in the Natal Province of South Africa.

Morbidity from urinary schistosomiasis was assessed on clinical, radiological, parasitologic and biochemical evidence in 510 schoolchildren living in a Schistosoma haematobium endemic area. The results were viewed against the background of the prevalence and intensity of infection in the subjects. Clinical morbidity correlated well with the intensity of infection, the latter in turn being influenced by factors such as water contact pattern, sex and water source. A surprisingly high prevalence (42%) of abnormalities was observed in the urinary tract of subjects, but no relationship could be demonstrated between the intensity of infection and structural damage to the urinary tract. Urographic changes were more severe in the 11-15 year age group than in the 6-10 year group. Significant rectal involvement (76%) in S. haematobium-infected subjects was regarded as a reflection of the heavy worm burdens borne by these children. The morbidity described in this study indicates a definite degree of pathology in the infected children but the impression was that they suffered only mild disability. However, given the structural lesions seen on urography and the limited sensitivity of the biochemical tests used for the assessment of renal function, renal pathology cannot be ruled out. Further studies on the renal status of these subjects are essential.