The Past and Present Situation of Opisthorchis viverrini Infection in Thailand

Abstract

Opisthorchis viverrini, a major foodborne trematode, remains a major public health concern in Thailand, particularly in the northern and northeastern provinces. O. viverrini can be transferred to people and reservoir hosts through the consumption of uncooked cyprinid fish with metacercariae. Chronic infection with O. viverrini can lead to a severe condition known as cholangiocarcinoma (CCA). According to the Nationwide Hospital Admission Database, Thailand has experienced the highest incidence of CCA globally in recent years. Particularly, between 2009 and 2013, there was an incidence rate of 14.6 cases per 100,000 individuals within the population and a corresponding mortality rate (MR) of 14%. In addition, high incidence rates of CCA were reported in Khon Kaen Province from 1989 to 2018, with a rate of 36.1 per 100,000 person-years in men and 14.4 per 100,000 person-years in women. Despite the reduction in the overall prevalence of O. viverrini at the national level, several studies have indicated that the infection remains highly prevalent in some communities in the northeastern and northern regions. Some communities have demonstrated a prevalence of O. viverrini exceeding 20%, and rates reaching as high as 45.7%. Therefore, in populations with a high prevalence, programs to control this parasite should be implemented, including monitoring eating habits. This review article provides a comprehensive overview of the current distribution of O. viverrini in Thailand, outlining its pathophysiology, background, and preventive and control strategies. In addition, this review suggests that individuals in high-risk communities should act to eradicate liver fluke, as this is crucial for the overall health of the community.