Surveillance on Fish-Borne Parasites in Second Intermediate Hosts from Mekong Region of Myanmar, North and Northeast of Thailand

Abstract

Countries of lower Mekong regions are highly alarmed by the spread of fish borne trematode infections i.e. small liver flukes and minute intestinal flukes especially in Thailand, Lao People's Democratic Republic (Lao PDR), Vietnam, Cambodia and Myanmar. Moreover, the incidence of cholangiocarcinoma, a major primary carcinoma of the liver with a very poor prognosis has also been increasing in the endemic area of liver fluke infections. In Thailand, the epicenter of this disease is located in north and northeast region, where high a prevalence of opisthorchiasis coexists with a high incidence of cholangiocarcinoma. Only a few reports have been published concerning the fish borne trematodes infections in the central region of Myanmar. However, there is still a lack of information regarding the status of trematodes infections in second intermediate hosts in the Mekong region of Myanmar. A total of 2884 fishes (48 species) were investigated from total 8 locations from Mekong region of Myanmar, central region of Myanmar, north of Thailand and northeast of Thailand ie; Tachileik, Bago, Chom Thong, Mae Ngat, NikhomKham Soi, Sakon Nakhon, Sisaket, Kalasin. The collected fishes were examined for presence of the infective stage of the parasite, i.e., metacercariae by pepsin-HCl artificial digestion techniques. Detected metacercariae were observed and identified using a stereomicroscope and light microscope. A GIS database for the study of fish borne trematode metacercariae was implemented using Arc Map 10.5 software. A total of 1359 fishes (27 species) were positive with fish borne trematode matacercariae infections. Four Species of fish borne trematode metacercariae i.e.; small liver fluke, Opisthorchis viverrini, minute intestinal flukes Haplorchis taichui, Haplorchis pumilio, Haplorchoides sp. were detected in this study. The geographic information (latitude and longitude) associated with the infection rates among susceptible species of fresh water fish was recorded and built a fish borne geo-dataset for Geographical Information System (GIS) development. GIS can be useful in establishing strategies for the prevention of transmission of food borne diseases originating in infected fish found in water catchment areas. The outcome of this study could be a useful index for the fish borne zoonotic trematode epidemiology in the Mekong area. Besides, the results of our study contribute to filling the gap of information necessary for the control and prevention of fish borne trematode zoonotic infections in the Mekong region.

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