Clonorchis Sinensis in Rural Communities in Northern Vietnam and Associated Risk Factors

Background: Clonorchis sinensis is an important fish-borne small liver fluke, that is a listed carcinogen for humans. Approximately 1 million people are infected with small liver flukes in Vietnam. In order for control programmes to be successful, it is essential to identify highly endemic areas and unravel risk factors associated with C. sinensis infection; however, a comprehensive study investigating risk factors for C. sinensis infection in Vietnam is lacking up to now. The aim of this study is to identify the prevalence of C. sinensis infection and associated risk factors in rural communities in northern Vietnam. Methods & Materials: A cross-sectional study was conducted in 4 communes in Yen Bai and Thanh Hoa provinces where C. sinensis infection is known to be present and raw fish consumption is common. A total of 841 residents over 6 years old were recruited for coprological examination, and 757 participants over 15 years old participated in a questionnaire on knowledge, attitudes, and practices with regard to C. sinensis infection. Univariable and multivariable logistic regression models were run to identify risk factors for infection with C. sinensis. Results: The prevalence of C. sinensis infection was 40.4% with commune prevalence estimates ranging between 26.5% and 53.3%. In the final multivariable model, males (OR 2.00; 95% CI 1.31–3.05), people between 19 and 39 years old (OR 6.46; 95%CI 1.25–33.37), with low education level (OR 5.57; 95% CI 2.37–13.07), lack of treatment (OR 1.82, 95% CI 1.15–2.89), use of an unhygienic toilet (OR 2.74, 95%CI 1.53–4.92), and especially recent (i.e. last year) consumption of raw fish (OR 8.00, 95% CI 4.78–13.36), had significantly higher odds for C. sinensis infection. Conclusion: These findings demonstrate a high prevalence of C. sinensis infection in rural communities in northern Vietnam due to variety of factors. Hence, control measures including mass drug administration should be applied for those communes to reduce the prevalence. Moreover, targeted awareness campaigns should be implemented for groups-at-risk in C. sinensis endemic areas.