Efficacy of praziquantel on Schistosoma haematobium and re-infection rates among school-going children in the Ndumo area of uMkhanyakude district, KwaZulu-Natal, South Africa

Background: Despite its low cure rates and possible resistance, praziquantel (PZQ) is the only drug available for schistosomiasis treatment. Hence, monitoring its efficacy is crucial. This study assessed the efficacy of PZQ, determined re-infection and incidence rates of Schistosoma haematobium infection among school-going children in the Ndumo area, KwaZulu-Natal. Methods: A cohort of 320 school-going children (10 - 15 years) in 10 primary schools was screened for S. haematobium infection using the filtration technique. Infected children were treated at different times and hence were divided into two sub-cohorts; A1 and A2. Non-infected children constituted the sub-cohort B. Children who continued excreting viable eggs 4 weeks post-treatment received a second dose of PZQ. Re-infection rates were determined in sub-cohort A1 and A2 at 28 and 20 weeks post-treatment, respectively. Cure rates (CR) and egg reduction rates (ERR) were calculated. Incidence rate was assessed 28 weeks post baseline survey using children that were negative for schistosome eggs at that survey. Analysis of data was done using the Chi square and the Wilcoxon rank test. A 95% confidence interval with a P-value < 0.05 determined significance. Results: At baseline, 120 (37.5%) of the 320 study participants were found infected with Schistosoma haematobium. Heavy infections accounted for 36.7%. The calculated cure rates were 88.07% and 82.92% for females and males, respectively. Egg Reduction Rates of 80% and 64% for females and males were observed 4 weeks after the initial treatment. After the second treatment, CR was 100% in females and 50% in males with an ERR of 100% in females and 70% in males. At 20 and 28 weeks post treatment, reinfection rates of 8.03% and 8.00% were observed, respectively, giving an overall rate of 8.1%. An incidence rate of 4.1% was observed 28 weeks after the baseline screening. Conclusions: The study indicated high CR while the ERR was low suggesting a reduced PZQ efficacy. The efficacy improved among females after the second dose. Re-infection rates at 20 and 28 weeks post-treatment were low. The study also indicated a low incidence rate for the 28 weeks period.