The associations between Schistosoma mansoni infection, pre-treatment symptoms, praziquantel side effects, and treatment efficacy in Ugandan school-aged children

Background Over 240 million people have schistosomiasis. Mass drug administration (MDA) with the anthelmintic praziquantel is the cornerstone of control. Treatment side effects are commonly observed and may be associated with dying worms. Side effects have also been reported as a reason for reduced MDA uptake, potentially resulting in those most in need refusing repeated treatment. An improved understanding of the association between side effects and infection intensity, pre-treatment health, and drug efficacy, may help inform education campaigns to facilitate increased MDA uptake. Methods Using latent class analyses, Beta regression, and dose response curves, we analysed egg and antigen parasitological data alongside health and side-effects survey data pre- and post-praziquantel-treatment from two primary schools (Bugoto Lake View (LV) and Musubi Church of God (CoG)) in Schistosoma mansoni high endemicity Ugandan villages to understand whether pre-treatment infection status or intensity were related to 1) pre-treatment symptoms, 2) post-treatment side effects, and 3) whether parasite clearance after treatment was associated with side effects. Principal findings At Bugoto LV: Abdominal pain, blood-in-stool, and itching/rash symptoms were non-linearly associated with infection intensity; Diarrhoea, headache and vomiting side effects were non-linearly associated with infection intensity. At Musubi CoG: Blood-in-stool, headache, and pain-when-urinating symptoms were non-linearly associated with infection intensity; Abdominal pain, diarrhoea, and vomiting side effects were non-linearly associated with infection intensity. There was no relationship between infection status (infected/ uninfected) and symptoms or side effects at either school. No association was found between infection clearance and the presence of side effects at either school. Conclusions We show no evidence that being infected predisposes someone to side effects, nor that side effects are related to treatment efficacy. Relationships between pre-treatment infection intensity and pre-treatment symptoms or post-treatment side effects varied by school suggesting unmeasured factors such as co-infections or other health conditions could impact symptom and side effect reporting.