MIGRATORY PATTERN OF OPISTHORCHIS VIVERRINI IN HAMSTERS

Abstract. The migratory pattern of Opisthorchis viverrini was studied by feeding each of 55 hamsters orally with 50 metacercariae collected from cyprinoid fish. The route of migration was followed from the gastrointestinal (GI) to biliary tracts for 3 months after infection at 11 durations: 1, 3, 6, and 12 hours, 1, 3, 7, and 14 days, 1, 2, and 3 months. After sacrifice, the stomach, small intestine, common bile duct, gallbladder, and 3 equal portions of each lobe (right, left, median, and caudal) of the liver were examined and counted for worm burden. The newly excysted worms of O. viverrini migrated from the duodenum into the common bile duct, gallbladder and proximal bile duct of the right lobe as early as 1 hour after infection. The farthest migratory distance, the distal bile ducts of all lobes, occurred with worms aged 14 days. After reaching maturity, the number of worms remaining in the extrahepatic bile ducts was lower than the intrahepatic bile ducts. The worm recovery rates in the right and left lobes were not significantly different, while those in the median and caudal lobes were significantly lower. Less than 5% of juvenile worms could migrate far to the distal part of the bile ducts, but these decreased when the worms became adult. This finding revealed the migratory pattern of O. viverrini in hamsters from the GI to the biliary system in detail, which should be useful for better understanding the host-parasite relationships along these routes of migration. detailed information about the relationship between the route of migration and the duration of infection. The objective of this study was to investigate the migratory pattern of O. viverrini from the gastrointestinal to the biliary tracts of experimentallyinfected hamsters during 3 months of infection. MATERIALS AND METHODS Opisthorchis viverrini metacercariae were obtained from naturally-infected cyprinoid fish from an endemic area in Khon Kaen Province, northeast Thailand, by pepsin-HCl digestion and infiltration. They were identified and collected under a stereomicroscope. Each of 55 male golden Syrian hamsters, aged 6-8 weeks, were infected with 50 metacercariae by intragastric intubation. Five animals were sacrificed at each period of 1, 3, 6 and 12 hours, 1, 3, 7 and 14 days, and 1, 2 and 3 months post-infection. After sacrifice, the position of ampulla of Vater and the terminal part of the common bile duct connecting to the cystic and intrahepatic bile ducts were tied to prevent the movement of worms from the normal position. The stomach, small intestine, common bile duct, gallbladder and 4 lobes (right, left, median, and caudal) of the liver were removed from the host. The cavity structures were opened and sedimented in normal saline, and the number of worms in each part was counted. Each lobe of the liver was divided into 3 portions; proximal, median, and distal, then each was separated into small pieces by 2 forceps, sedimented in normal saline and counted for worm burden per portion

Liver Fluke Induces Cholangiocarcinoma

The authors discuss the molecular pathogenesis of opisthorchiasis and associated cholangiocarcinogenesis, particularly nitrative and oxidative DNA damage and the clinical manifestations of cholangiocarcinoma

Elevated Plasma IL-6 Associates with Increased Risk of Advanced Fibrosis and Cholangiocarcinoma in Individuals Infected by Opisthorchis viverrini

Opisthorchis viverrini is considered among the most important of the food-borne trematodes due to its strong association with advanced periductal fibrosis and bile duct cancer (cholangiocarcinoma). We investigated the relationship between plasma levels of Interleukin (IL)-6 and the risk of developing advanced fibrosis and bile duct cancer from chronic Opisthorchis infection. We show that IL-6 circulates in plasma at concentrations 58 times higher in individuals with advanced fibrosis than age, sex, and nearest-neighbor matched controls and 221 times higher in individuals with bile duct cancer than controls. We also observed a dose-response relationship between increasing levels of plasma IL-6 and increasing risk of advanced fibrosis and bile duct cancer; for example, in age and sex adjusted analyses, individuals with the highest quartiles of plasma IL-6 had a 19 times greater risk of developing advanced periductal fibrosis and a 150 times greater risk of developing of bile duct cancer than individuals with no detectable level of plasma IL-6. Finally, we show that a single plasma IL-6 measurement has excellent positive predictive value for the detection of both advanced bile duct fibrosis and bile duct cancer in regions with high O. viverrini transmission. These data support our hypothesis that common mechanisms drive bile duct fibrosis and bile duct tumorogenesis from chronic O. viverrini infection. Our study also adds a unique aspect to the literature on circulating levels of IL-6 as an immune marker of hepatobiliary pathology by showing that high levels of circulating IL-6 in plasma are not related to infection with O. viverrini, but to the development of the advanced and often lethal pathologies resulting from chronic O. viverrini infection

Modeling liver fluke transmission in northeast Thailand: Impacts of development, hydrology, and control.

Human infection with the Southeast Asian liver fluke Opisthorchis viverrini and liver fluke-associated cholangiocarcinoma cause significant disease burden in Southeast Asia. While there has been considerable work to understand liver fluke pathology and to reduce infection prevalence, there remains a limited understanding of the environmental determinants of parasite transmission dynamics to inform treatment and control programs. A particular setting where targeted control efforts have taken place is the Lawa Lake complex in northeast Thailand. Here, we describe the recent history of host infections, as well as the hydrologic characteristics of this floodplain ecosystem that influence the extent of snail habitat and fish mobility and the transport of human waste and parasite cercariae. Using mathematical modeling, we outline a framework for reconstructing environmental transmission of O. viverrini over the course of the Lawa Project control program from its inception in 2008 until 2016, using locally acquired but fragmentary longitudinal infection data for both humans and environmental hosts. The role of water flow in facilitating movement between snail, fish, human, and reservoir hosts is a particular focus with respect to its relevant scales and its impact on success of interventions. In this setting, we argue that an understanding of the key environmental drivers of disease transmission processes is central to the effectiveness of any environmental intervention

Modeling liver fluke transmission in northeast Thailand: Impacts of development, hydrology, and control.

Human infection with the Southeast Asian liver fluke Opisthorchis viverrini and liver fluke-associated cholangiocarcinoma cause significant disease burden in Southeast Asia. While there has been considerable work to understand liver fluke pathology and to reduce infection prevalence, there remains a limited understanding of the environmental determinants of parasite transmission dynamics to inform treatment and control programs. A particular setting where targeted control efforts have taken place is the Lawa Lake complex in northeast Thailand. Here, we describe the recent history of host infections, as well as the hydrologic characteristics of this floodplain ecosystem that influence the extent of snail habitat and fish mobility and the transport of human waste and parasite cercariae. Using mathematical modeling, we outline a framework for reconstructing environmental transmission of O. viverrini over the course of the Lawa Project control program from its inception in 2008 until 2016, using locally acquired but fragmentary longitudinal infection data for both humans and environmental hosts. The role of water flow in facilitating movement between snail, fish, human, and reservoir hosts is a particular focus with respect to its relevant scales and its impact on success of interventions. In this setting, we argue that an understanding of the key environmental drivers of disease transmission processes is central to the effectiveness of any environmental intervention

Food-borne Trematodes

Key Points:Food-borne trematodes (FBTs), including liver, lung and intestinal flukes, are important "Neglected Tropical Diseases'(NTDs).An estimated 85 million people worldwide are infected with FBT and more than half are in Asia.Humans acquire FBT infection through ingestion of viable metacercariae in second intermediate hosts in undercooked or raw food preparation.The diseases caused by FBTs range from asymptomatic, mild disease, to fatal bile duct cancer.The drugs of choice for treatment of FBTs are praziquantel and triclabendazole