Current Prevalence of Infection with Opisthorchis viverrini and Intestinal Parasites in Rural Communities in Northeast Thailand Using Stool Examinations and Serological Screening Methods

Helminthiases are common neglected tropical diseases in Thailand; thus, regular surveillance is necessary for their control. Among these helminthiases, the small liver fluke, Opisthorchis viverrini (O. viverrini), which is endemic in northeast Thailand, has been the focus of national control and eradication campaigns in the country for several decades. However, these helminths still exist and raise concerns regarding public health. Stool samples, blood samples, and demographic data were obtained from 307 participants. Stool examination via the formalin-ethyl acetate concentration technique (FECT) and agar plate culture (APC) was performed, and parasite eggs and larvae were identified microscopically by experienced technicians. Of 307 individuals, 91 (29.6%) were positive for intestinal helminths and protozoans according to FECT and APC testing. Eggs of the O. viverrini species were the most commonly found (16% of participants), followed by Strongyloides stercoralis (14%), hookworms (1%), Taenia spp. (0.7%) and Blastocystis sp. (0.97%). The positive rates of anti-Opisthorchis viverrini IgG antibody, as evaluated via the immunochromatographic test (ICT) and ELISA, were 26.1% and 31.6%, respectively. The differences in positive results between the FECT (O. viverrini egg-positive) and anti-O. viverrini IgG antibody detected via ICT or ELISA were statistically significant (P <0.05). The ICT and ELISA could possibly be used as the screening tools of choice for the diagnosis of human opisthorchiasis to aid in future treatment, prevention, and control measures.