Reduction patterns of prevalence and intensity of Schistosoma haematobium infection after MDA with praziquantel between regions with and without previous intervention in Sudan

Abstract

Background: Mass drug administration (MDA) with praziquantel has been the mainstay for schistosomiasis control in endemic countries. To evaluate the effects of repeated MDA, we compared urogenital schistosomiasis prevalence at two localities in White Nile State, Sudan: Al Jabalain with previous MDA and El Salam without previous MDA. Methods: A cross-sectional survey was carried out to examined the prevalence and intensity of Schistosoma haematobium infection using urine samples from 10,644 primary school-aged children (SAC) of two localities at the baseline survey, and then a single dose of 40 mg/kg praziquantel was mass administered to whole SAC of both localities. Of the total, 3,197 SAC of sentinel schools were examined urine samples at 8 months after the MDA. Results: The overall prevalence of S. haematobium infection was 5.5% in Al Jabalain and 27.5% in El Salam at the baseline survey. In sentinel schools, the prevalences in Al Jabalain and El Salam were significantly reduced after MDA, 80.3% and 84.4% respectively, not significant between two localities. The geometric mean intensity (GMI) of egg counts from the infected children at the baseline survey was 14.5 eggs per 10 mL of urine (EP10) in Al Jabalain and 18.5 EP10 in El Salam. At the follow-up survey, the GMI reduction rate was significantly reduced, 51.0% in Al Jabalain and 39.5% in El Salam, however the infection intensity after MDA was reduced significantly less in SAC who had higher baseline prevalence and infection intensity. The overall intensity of infection was significantly reduced after MDA in girls, but not in boys. Conclusions: Single MDA produces a similar prevalence reduction regardless of endemicity but less reduction of infection intensity in highly endemic populations. It is necessary to implement repeated MDAs to eliminate urogenital schistosomiasis in endemic regions..