Praziquantel efficacy against Schistosoma mansoni among HIV-1 infected and uninfected adults living in fishing villages along Lake Victoria, Northwest Tanzania

BACKGROUND Animal studies have demonstrated that functional immune responses, as determined by the levels of CD4(+) cell counts and anti-schistosome antibodies responses, determine the efficacy of praziquantel. Based on this evidence, it has been hypothesised that the immunodeficiency effects of the human immunodeficiency virus (HIV)-1 infection may affect the efficacy of praziquantel in co-infected human hosts. Thus, the present study assessed the efficacy of praziquantel by comparing parasitological cure rates and the reduction in infection intensity in HIV-1 seronegative individuals infected with S. mansoni and HIV-1 seropositive individuals co-infected with S. mansoni, following treatment with a single oral dose of praziquantel. METHODS This was a prospective longitudinal study which included, at baseline, 555 S. mansoni infected adults aged 21-55 years, who were either co-infected or not with HIV-1 and who lived in fishing villages along Lake Victoria in Northwest Tanzania. These individuals were treated with a single oral dose of praziquantel (40 mg/kg) and, at 12 weeks, single stool samples were obtained and examined for S. mansoni eggs using the Kato-Katz technique. Finger prick and venous blood samples were collected for HIV-1 screening and CD4(+) cell quantification. RESULTS The parasitological cure rate did not differ significantly from the HIV-1 serostatus (P = 0.12): among the co-infected individuals, the cure rate was 48.3% (14/29), and among the individuals infected only with S. mansoni, the cure rate was 62.6% (329/526). The egg reduction rate did not vary with the HIV-1 serostatus (P = 0.22): 77.22% for HIV-1 seronegative and 75% for HIV-1 seropositive individuals. The level of CD4(+) cell counts (median 228 cells/μL: range 202-380 cells) did not influence the cure rate (P = 0.23) or the reduction in the intensity of the infection (P = 0.37). CONCLUSION The HIV-1 infection per se or its moderate immunodeficiency effects, demonstrated by the range of CD4(+) cell counts observed in co-infected individuals, did not affect praziquantel efficacy, as measured by the parasitological cure rate and the reduction in intensity of infection in the present study cohort.