Reduced uptake of mass treatment for schistosomiasis control in absence of food: beyond a randomized trial

BACKGROUND Sustaining high uptake of praziquantel is key for long-term control of schistosomiasis. During mass treatment in 2013, we randomized 12 primary schools into two groups; one group received education messages for schistosomiasis prevention for two months prior to mass treatment, while the other, in addition to the education messages, received a pre-treatment snack shortly before mass treatment. The uptake of praziquantel in the snack schools was 94 % compared to 79 % in the non-snack schools. During mass treatment in 2014, no snack was provided. We compared the uptake of praziquantel in 2014 to that in 2013 and attempt to explain the reasons for the observed differences. METHODS Serial cross sectional surveys were conducted among a random sample of children from the 12 primary schools, 1 month after mass treatment in 2013 and 2014 to measure uptake of praziquantel, reported side effects attributable to praziquantel and prevalence and intensity of schistosomiasis infection. Differences in the demographic and descriptive variables between the 2013 and 2014 samples were compared using chi squared tests for categorical variables and student's t-test for geometric mean intensity of S. mansoni infection. RESULTS Uptake of praziquantel reduced from 93.9 to 78.0 % (p = 0.002) in the snack schools but was unchanged in the non-schools 78.7 and 70.4 % (p = 0.176). The occurence of side-effects attributable to praziquantel increased from 34.4 to 61.2 % (p = 0.001) in the snack schools but was unchanged in the non-snack schools; 46.9 and 53.2 % (p = 0.443). Although the prevalence of S. mansoni infection increased in both the snack and non-snack schools, the differences did not reach statistical significance;1.3 and 7.5 % (p = 0.051) and 14.1 and 22.0 % (p = 0.141), respectively. Similarly, the difference in the geometric mean intensity of S. mansoni infection in both the snack and non-snack schools was not statistically significant; 38.3 eggs per gram of stool (epg) and 145.7 epg (p = 0.197) and 78.4 epg and 322.5 epg (p = 0.120), respectively. CONCLUSION Our results show that in absence of food, uptake of praziquantel reduced and the side-effects of the drug increased. However, the reduced uptake did not affect the prevalence and intensity of schistosomiasis among school children. Rescinding of the provision of the snack is what probably caused the reduction in uptake of treatment in the subsequent mass treatment cycle.