Comparison of praziquantel efficacy at 40 mg/kg and 60 mg/kg in treating Schistosoma haematobium infection among schoolchildren in the Ingwavuma area, KwaZulu-Natal, South Africa

Background: The World Health Organization recommends praziquantel (PZQ) (40 mg/kg body weight) for treating schistosomiasis. However, drug failure has been reported, prompting use of 60 mg/kg, for which results have been inconsistent.

Objectives: To compare the efficacy of PZQ 40 mg/kg and 60 mg/kg in treating schoolchildren infected with Schistosoma haematobium.

Methods: The study was conducted during November 2017 - August 2018 in the Ingwavuma area, uMkhanyakude District, KwaZulu-Natal Province, South Africa. Children aged 10 - 15 years were screened for S. haematobium using a filtration technique. Infected children were randomly assigned to a dose of PZQ of 40 mg/kg or 60 mg/kg. Side-effects were recorded within 24 hours after treatment using questionnaires and direct observation. Four weeks after treatment, participants were retested for S. haematobium infection. Baseline and post-treatment mean egg counts were calculated. Cure rate (CR) and egg reduction rate (ERR) were used to determine PZQ efficacy, while repeated-measures analysis of variance determined the effect of both doses on infection intensity. A χ2 test was used to determine the association of side-effects with treatment, with a p-value ≤0.05.

Results: Forty-three and 36 children were treated with PZQ 40 mg/kg and 60 mg/kg, respectively. The 40 mg/kg group had a CR of 79.0% and an ERR of 97.2%, and the 60 mg/kg group a CR of 83.0% and an ERR of 98.3%. The effect of dose on infection intensity was not significantly different between the two groups (p>0.05). Abdominal pains, dizziness and fatigue were common among children who received PZQ 40 mg/kg, while headache, dizziness and nausea were common in the 60 mg/kg group.

Conclusions: The efficacy of PZQ at 60 mg/kg was similar to that at 40 mg/kg. A dose >40 mg/kg therefore does not add value in treating S. haematobium infection. Transient side-effects (mostly dizziness) were observed more in the 60 mg/kg group than in the 40 mg/kg group. We recommend continued use of 40 mg/kg body weight for treating schistosomiasis.