Persistent Urogenital Schistosomiasis and Its Associated Morbidity in Endemic Communities within Southern Ghana: Suspected Praziquantel Resistance or Reinfection?

BACKGROUND: schistosomiasis is a neglected tropical disease caused by helminths of the genus Schistosoma. The disease has a worldwide distribution, with more cases occurring in Africa. Urogenital schistosomiasis caused by S. haematobium with its associated morbidity is prevalent in many areas of Ghana. Praziquantel is still the recommended drug of choice for schistosomiasis treatment, although a number of studies have reported sub-therapeutic effects and associated treatment failure. The current study, therefore, assessed whether persistent schistosomiasis, with its associated morbidity among children living in endemic areas within the Greater Accra Region of Ghana, is as a result of reinfection or suspected praziquantel resistance. METHODOLOGY: this was a longitudinal study involving a baseline and follow-up sampling after praziquantel treatment. Urine samples were collected from school children (whose parents had also consented) for the detection of S. haematobium ova using a sedimentation technique. The morbidity parameters were examined with urine chemistry strips, as well as microscopy. Viability was assessed using a modified hatchability technique, vital staining (0.4% trypan blue and 1% neutral red) and fluorescent (Hoechst 33258) microscopy. Infected individuals were treated with a single dose of praziquantel (40mg/kg). Resampling to determine reinfection was done sixth months post-treatment, after evidence of total egg clearance. For possible resistance assessment, egg counts and viability testing were conducted on the positive samples at the baseline, as well as weekly post-treatment follow-ups for 12 weeks. RESULTS: out of the 420 school children sampled, 77 were initially positive but, after the sixth month sampling for reinfection assessment, eight out of the initial positives were infected again, giving a reinfection percentage of 10.4%. No suspected praziquantel resistance was recorded in the 21 positives detected out of the 360 sampled for suspected resistance assessment. The egg reduction rate increased weekly in the follow-up samples with a gradual reduction in the egg count. The study also recorded a gradual decrease in the percentage of live eggs after the first week; with all viability testing methods used complimenting each other. The morbidity parameters (proteinuria, haematuria and pyuria) changed between the baseline and post-treatment samples, eventually reducing to zero. CONCLUSIONS: the outcome of this study suggests that the persistent schistosomiasis, with its associated morbidity observed in these endemic communities, is not likely to be as a result of praziquantel resistance, but reinfection. Even though there was no suspected resistance observed in the study, there remains the need to continuously intensify the monitoring of praziquantel in other endemic communities.