A comprehensive epidemiological study of opisthorchiasis in a rural community of Thailand

Abstract

Opisthorchiasis is a zoonotic parasitic infection caused by human liver flukes. Opisthorchis viverrini (OV) is endemic in Southeast Asia along Mekong basin which estimated 9 million people are infected. Transmission to humans occurs through the consumption of uncooked fish; cyprinoid or white-scale freshwater fish containing infective stage metacercariae. The infection is mainly asymptomatic. Adult flukes could live up in the bile duct in the absence of treatment. Chronic infection is strongly related with bile duct cancer or cholangiocarcinoma. The International Agency for Research on Cancer has declared that Opisthorchis viverrini is a member of group 1 agent, carcinogenic to humans. Thailand has the highest incidence of cholangiocarcinoma in the world. However, opisthorchiasis is acknowledged as a neglected and underestimated disease on the global scale. In the present day, the epidemiological data on opisthorchiasis from OV infection in Thailand are considered outdated. An extensive cross-sectional study was undertaken from 1984 to 2001 under the National Control Program, but data on incidence is very limited. Moreover, infection dynamics are still poorly understood. This project aimed to comprehensively study the infection dynamics of OV infection using multiple tools in order to explore the infection in various aspects. Statistical models were developed to explore epidemiological data; prevalence, incidence and infection intensity, with risk factors for acquiring the infection. Infection dynamics will be described using mathematical modelling. The qualitative technique, by interviewing and group discussions, will be used to explain the cause of uncontrolled infection rate in bio-psycho-social aspect. Integrated study results will be used to develop community intervention strategies under the framework of the public health planning model. The overall outcome will be valuable for Thailand National Health Policy and epidemiological data will provide the basis for further rigorous academic research.