Current prevalence of Opisthorchis viverrini infection and associated risk factors in Nakhon Phanom Province, Northeastern Thailand

Opisthorchiasis caused by Opisthorchis viverrini infection is a major public health concern in Thailand. Despite many decades of national campaigns in place to reduce and control opisthorchiasis in Thailand, the infections remain to exist particularly in the northern and northeastern parts of the country. This study aimed to evaluate the current prevalence of O. viverrini infection in rural communities in northeast Thailand. A cross-sectional survey was conducted between February and October 2018 in three districts (Na Kae, That Phanom and Wang Yang) in Nakhon Phanom Province, Thailand. Demographic data were collected using a standardised questionnaire. Stool samples were collected and processed using the Kato-Katz technique to determine the presence of O. viverrini and other intestinal parasites. In total, 564 individuals were enrolled. The overall intestinal helminth infections were 15.2% (95% CI: 12.4-18.5). Species distribution included a majority of O. viverrini mono-infections (12.9%), followed by Strongyloides stercoralis (1.4%) and Taenia spp. (0.4%). The prevalence of O. viverrini was significantly higher in Wang Yang district (P = 0.022), in males (P = 0.004) and those previously positive with helminth infections (P<0.001) and received treatment of anti-helminths (P<0.001), than in their counterparts. Multivariate regression analysis revealed that being male (adjusted odds ratio [aOR] 1.77, P = 0.035) and those who previously tested positive for helminth infections (aOR 8.69, P<0.001) were significantly associated with a higher odd of O. viverrini infections, but lower in those who had previous stool examination (aOR 0.22, P = 0.001). This study demonstrated that the updated prevalence of O. viverrini infection is still high in rural communities in northeast Thailand. The data of this study will be useful to guide and improve strategies for future O. viverrini and other helminths prevention and control in this region.