Risk factors for Opisthorchis viverrini Infection in Nong Khai Province, Thailand.

BACKGROUND Opisthorchis viverrini (OV) infection is the main risk factor for cholangiocarcinoma and is often found in Northeastern Thailand. The prevalence of OV infection and the incidence of cholangiocarcinoma are major public health problems in this region. OBJECTIVES The objectives of this study were to identify factors associated with OV infection among people in Nong Khai Province in order to develop a prevention programme in the community. MATERIALS AND METHODS The data were collected in July 2013. Stool specimens were examined for intestinal parasites within hours after collection using a normal saline wet preparation and the modified Kato- Katz technique. A case-control study was conducted to collect information about demographic data, the habit of eating unsafely prepared fish, the safe disposal of waste food, and the practice of defaecating in fields. Structured questionnaires were used to interview 351 participants (117 cases and 234 controls) in a random selection of 30 villages across Nong Khai Province. Multiple logistic regression was used to identify risk factors for OV infection. RESULTS In the multivariate analysis, the results showed that the factors which had a statistically significant association with OV infection were the habit of consuming unsafely prepared fish (ORadj=5.17, 95%CI=2.49- 10.74), the similar habit of family members (ORadj=3.25, 95%CI=1.63-6.49) , a history of O. viverrini infection (ORadj=5.64, 95%CI=2.10-15.18), a history of taking praziquantel (ORadj=5.66, 95%CI=3.11-10.29), and the unsafe disposal of waste food (ORadj=2.1, 95%CI=1.10-3.80). CONCLUSIONS The findings of this study highlight the features on which a community programme should focus in order to reduce the prevalence of opisthorchiasis and incidence of bile duct cancer.