[Risk factors associated with reinfection of Schistosoma japonicum].

Objective: To explore the risk factors of Schistosoma japonicum reinfection after chemotherapy in a hilly endemic area.
Methods: In a hilly endemic area of S. japonica, data on contact to contaminated water and the rates of reinfection after mass praziquantel treatment were collected from residents who participated in a prospective cohort study on S. japonica. An unconditional logistic regression analysis was performed to identify the risk factors associated with the reinfection of S. japonicum.
Results: Logistic regression analysis data showed that three factors were associated with S. japonicum reinfection: eggs per gram stool (EPG) prior to chemotherapy (OR = 2.066, 95% CI: 1.173 - 3.639), gender (OR = 4.260, 95% CI: 1.275 - 14.235) and average degree of exposure (Index B) from April to October (OR = 1.138, 95% CI: 1.045 - 1.240). Interaction between gender and average exposure Index B from April to October was identified (OR = 0.875, 95% CI: 0.817 - 0.982).
Conclusion: Eggs per gram stool (EPG) prior to chemotherapy, level of exposure to infected water and gender were risk factors for reinfection with S. japonicum after chemotherapy. In addition, there appeared an antagonism between gender and level of exposure to infected water.