Malumfashi Endemic Diseases Research Project, XV

Abstract

Schistosomiasis is endemic in Nigeria. Schistosoma haematobium predominates in the dry, northern regions where the infection is focal and acquired in seasonal pools—there is little S. mansoni in the Malumfashi area. The degree of endemicity was much lower than expected, for research at Malumfashi followed a period of drought which produced a marked decline in S. haematobium transmission and a consequent low prevalence of medical complications. Boys were the principal group at risk and the main environmental contaminators. Screening tests of renal function showed no significant impairment in a selected group of infected males, but there were very few with serious urological lesions. Infected subjects with heavy proteinuria represented less than 1% of the population, but they had a good prognosis and responded well to metrifonate. High urinary blood and protein levels were related to intense infection and indicated lower renal tract pathology. Micturition disturbance was common but required further objective study of its importance.

The study area was included in a scheme responsible for widespread agricultural development and water conservation in the northern regions. Experience in Africa suggests that this ecological change will sustain a recent upward trend in transmission to a level where urinary schistosomiasis assumes public health importance. Abandonment of continued research prompted our recommendation of a realistic future solution based on annual detection and treatment of heavily infected subjects. Instant and rapid detection of intense infection by urinalysis reagent strips, using a combined criterion of haematuria and 30 mg/100 ml or more urinary protein, may replace the inconvenience of microscopy. Single oral dose metrifonate-niridazole combination is a further simplification which suggests that selective chemotherapy programmes could be executed at low cost by non-technical junior staff. A selective programme should centre on schools, where all boys should receive treatment if transmission of schistosomiasis reaches hyper-endemic proportions.