Opisthorchis viverrini infection among migrant workers in Nakhon Ratchasima province, Thailand, indicates continued need for active surveillance.

Opisthorchis viverrini is a serious problem in Thailand, Cambodia, the Lao People's Democratic Republic and Vietnam. Active surveillance and eradication of O. viverrini is required. A cross-sectional study of 403 immigrant workers was conducted between October 2016 and June 2017 in Nakhon Ratchasima, Thailand. Stool samples were analysed via the formalin-ether concentration technique, with subsequent data analysis performed using descriptive statistics and logistic regression. Overall infection was 24.1% and the results reveals an O. viverrini infection rate was 11.9%. O. viverrini infection was identified in 25.6% of Cambodians, 15.3% of Laotians and 3.6% workers from Myanmar sampled. The majority of infections were found in males, aged e"40 years and working as labourers. Raw or undercooked cyprinoid fish consumption was associated with an elevated risk for O. viverrini infection (ORadj = 2.2, 95% CI = 1.2-4.0). Other intestinal helminthic infections were hookworm (5.5%), Trichuris trichiura (5.2%), Strongyloid stercoralis (0.5%), Ascaris lumbricoides (0.5%) and Taenia spp. (0.5%), respectively. This is the first study to report O. viverrini among immigrant workers in Thailand; therefore, active surveillance is needed among migrant workers to identify and treat O. viverrini infection.