Genetic Differentiation of -Like Eggs in Northern Thailand Using Stool Specimens Under National Strategic Plan to Control Liver Fluke Infection and Cholangiocarcinoma.

Liver fluke infection caused by is recognized as a potential risk factor for cholangiocarcinoma (CCA). The National Strategic Plan to Control Liver Fluke Infection and Cholangiocarcinoma has implemented microscopic-based stool examination screening. However, eggs of and minute intestinal flukes (MIFs) are nearly morphologically similar and could result in inaccurate diagnosis. Stool specimens were collected from eight districts of Chiang Mai Province in northern Thailand. -like eggs were identified with the Kato-Katz technique and differentiated for and MIFs using molecular study by PCR and PCR-restriction fragment length polymorphism targeting the internal transcribed spacer 2 (ITS2) gene. Prevalence of -like eggs was 5.9% from a total of 9,570 specimens. From PCR assays, all liver flukes were and all MIFs were The distribution of species was (38.2%), (10.5%), coinfection of and (37.2%), and 14.1% were negative from PCR. Totally, was found in 75.4% of infections from -like specimens. ITS2 nucleotide sequencing analysis showed a single variant of with no variation and two variants of . This study first revealed the genetic background of like eggs in northern Thailand. Minute intestinal flukes are occasionally misdiagnosed as leading to misinterpretation and overestimation of the burden of infection. Molecular diagnosis such as PCR could effectively discriminate species of -like eggs and help shape the robustness of epidemiological data to control liver fluke infection and raise awareness of other risk factors for CCA.