Intestinal parasitic infections (IPIs) are still important to the health of Thai rural residents. IPIs are thecause of many chronic diseases with, for example, opisthorchiasis resulting in progression to cholangiocarcinoma(CCA). This cross-sectional study in a prospective cohort study aimed to examine the prevalence and co-infectionof intestinal parasites among Northeastern Thai rural residents, recruited into the Khon Kaen Cohort Study(KKCS), and who were residing in areas of high-risk for developing CCA. On recruitment, subjects had completedquestionnaires and provided fecal samples for IPI testing using the formalin ethyl acetate concentration technique.Data on selected general characteristics and the results of the fecal tests were analysed. IPI test results wereavailable for 18,900 of cohort subjects, and 38.50% were found to be positive for one or more types of intestinalparasite. The prevalence of Opisthorchis viverrini (O. viverrini) infection was the highest (45.7%), followed byintestinal flukes (31.9%), intestinal nematodes (17.7%), intestinal protozoa (3.02%), and intestinal cestodes(1.69%). The pattern of different infections was similar in all age groups. According to a mapping analysis, ahigher CCA burden was correlated with a higher prevalence of O. viverrini and intestinal flukes and a greaterintensity of O. viverrini. Both prevention and control programs against liver fluke and other intestinal parasitesare needed and should be delivered simultaneously. We can anticipate that the design of future control andprevention programmes will accommodate a more community-orientated and participatory approach.