Abstract:

Background: Praziquantel is an antihelminthic drug of choice for treating schistosome infection and has been used for more than 40 years. Traditionally its efficacy is measured using parasitological cure rates and egg reduction rates using Kato Katz technique, which has several limitations. An alternative diagnostic test recommended for assessing the efficacy of praziquantel is point-of-care circulating cathodic antigen test. However, there is little evidence on the ability of the PZQ to clear circulating cathodic antigen which are released by a live Schistosomes and it’s expected once the worms have been killed following treatment its level will fall and become undetectable in urine samples. However, there are little evidence to support this hypothesis. The objective of this study was to determine the efficacy of praziquantel in clearing Circulating cathodic antigen among Schistosoma mansoni infected pre-and-primary school children in northwest Tanzania using a single dose of praziquantel.

Methodology: A longitudinal study characterized by two cross-sectional studies at baseline and at day 21 post-treatment was conducted among (n=114) pre-and- primary school children aged 2- 17 years old at Bezi Island, North-Western Tanzania. A single urine and stool samples were obtained from the study participants and screened for S. mansoni eggs using the Kato Katz technique and for circulating cathodic antigen using the Point-of-Care circulating cathodic antigen rapid test. Demographics information of the children were collected using a questionnaire. All infected children were treated using a single dose of praziquantel (40mgkgBWT) and followed at day 21 to assess the egg reduction rate and parasitological cure rate of the drug.

Results: Of all the study participants, 44.1% and 55.9% were boys and girls. The overall mean age of study participants was 8.03 ±3.25 years. The overall prevalence of Schistosoma mansoni was 70% (95%CI: 61.8 – 77.1) by using KK and 70.8% (114/161) (95%CI: 62.5 – 76.8) by using the POC-CCA test. The arithmetic mean egg at baseline was 854.69 ± 1325.092 and at follow-up was 226.06 ± 424.955, which indicated there was a reduction of eggs after treatment. In relation to intensity of infection, at baseline, 28.5%, 26.5% and 44.9% of participants had light, moderate and heavy infection intensity. The overall egg reduction rate was 73.55%. The parasitological cure rate was 66.30%, 95% CI:27-100% by using KK techniques. The cure rate was high in females (55.74%) compared with males (44.26%) though the difference was not statistically significant (P=0.88). Based on POC-CCA test, parasitological cure rate was 27.55%, 95% CI: 23-100%, though was not statistically significant (P =0.94) compared with KK test. The cure rate in boys was higher (32.61%) than that of girls (23.08%), though the difference was not statistically significant (P=0.41). The sensitivity and specificity of POC-CCA tests at baseline were 82.6% and 52.4% respectively. The Negative predictive value was 56.4% and the Positive Predictive Value of the test was 80.2%. After treatment, the sensitivity was 77.8%, specificity was 29.8%, PPV was 34.4% and NPV was 73.9%.

Conclusion: This study revealed that praziquantel administrated at a single standard dose of 40 mg/kg was adequately efficacious regardless of having low cure rate on POC-CCA. The outcomes of praziquantel efficacy depend on the diagnostic test used hence we found a large gap between the two tests. The POC-CCA to assess the efficacy of PZQ drug requires further followup. The fact that the efficacy is moderate, we advise to continue using the drug in mass drug administration by the national NTD programs among pre- and- school children and other group at risk but close monitoring and follow-up should be done in the endemic areas after mass drug administration to prevent possible resistance to praziquantel in future.