Rapid screening method for Schistosoma japonicum infection using questionnaires in flood area of the People's Republic of China

A rapid, simple, and effective method using questionnaires is described for screening of high-risk individuals of schistosomiasis japonica after the occurrence of major flooding. A case-control study design was adopted in two randomly selected villages from Dongting Lake area in the People's Republic of China that are endemic for Schistosoma japonicum. Information about contagious water exposure history and several other risk factors were collected retrospectively from 246 individuals, aged 9-60 years. A probability model was developed by logistic regression analysis, which included six variables, namely (i) knowledge of Schistosoma transmission, (ii) education attainment, (iii) annual income before flood year per person, (iv) duration of contagious water exposure due to swimming and paddling, (v) intensity of contagious water exposure due to occupational activities, and (vi) duration of contagious water exposure due to recreational activities. The receiver-operating characteristic (ROC) curve was plotted and the sensitivity and specificity were calculated. The internal consistency of the probability model was good. The area below the ROC curve was 0.90. If the probability cutoff value of diagnosing an infection with S. japonicum was defined as 0.35, both sensitivity and specificity were above 82%, whereas positive and negative predictive values were 70 and 91%, respectively. We conclude that questionnaires are a viable tool for screening of high-risk individuals of S. japonicum infections in lake communities of China after flooding occurred, opening new avenues for schistosomiasis control.