Risk Factors for Opisthorchis Viverrini Infection: A Systematic Review.

Opisthorchis viverrini (O. viverrini) infection is the primary cause of cholangiocarcinoma (CCA) and a major public health challenge along the Mekong River in Thailand, Vietnam, Laos PDR, Cambodia, China and Myanmar. This systematic review appraised the risk factors for O. viverrini infection. Literature searches were conducted using Medical Subject Headings (MeSH) and keywords, without date or language restriction, in PubMed, EMBASE, Global Health, and Thai Journals Online. References from relevant papers also were reviewed to expand the scope of the search. The inclusion criteria were human subjects. The primary outcome was O. viverrini infection. The exclusion criteria were in vitro, animal, genetic research, and systematic reviews. All included studies were summarized and reported as follows: study design, age, sample size, setting, data collection and fecal examination methods, adjusted odds ratio and 95% confidence interval, significant risk factors, and other findings. The search results show that across all databases 1,098 records were identified. Twenty-four articles were included in the systematic review, consisting of cross-sectional studies (79.2%), cohort studies (12.5%), and case-control studies (8.3%). The majority of study settings were in Thailand (75%). The People's Democratic Republic of Laos (Lao PDR) accounted for the second greatest number of studies (20.8%), and 4.2% of the studies originated in Vietnam. Key findings included demographic, environmental, geographic, health behavior, treatment with praziquantel, and a history of O. viverrini infection that was significantly associated with O. viverrini infection. Health professionals should investigate the potential risk factors for the disease and should seek and develop innovative methods for prevention and control of O. viverrini infection in these countries.