Prevalence and Factors Associated with Opisthorchis viverrini Infection in Khammouane Province, Lao PDR - Saiyachak, Khamphanavanh; Tongsotsang, Sutthiporn; Saenrueang, Thitima; Moore, Malcolm A; Promthet, Supannee (Asian Pacific journal of cancer prevention : APJCP, 2016)