Butsara Kaewsamut

A Cross-Sectional Study on Intestinal Parasitic Infections in Rural Communities, Northeast Thailand

Despite the existence of effective anthelmintics, parasitic infections remain a major public health problem in Southeast Asia, including Thailand. In rural communities, continuing infection is often reinforced by dietary habits that have a strong cultural basis and by poor personal hygiene and sanitation. This study presents a survey of the prevalence of intestinal parasitic infections among the people in rural Thailand. The community-based cross-sectional study was conducted in villages in Khon Kaen Province, northeastern Thailand, from March to August 2013. A total of 253 stool samples from 102 males and 140 females, aged 2-80 years, were prepared using formalin-ethyl acetate concentration methods and examined using light microscopy. Ninety-four individuals (37.2%) were infected with 1 or more parasite species. Presence of parasitic infection was significantly correlated with gender (P=0.001); nearly half of males in this survey (49.0%) were infected. Older people had a higher prevalence than younger members of the population. The most common parasite found was Opisthorchis viverrini (26.9%), followed by Strongyloides stercoralis (9.5%), Taenia spp. (1.6%), echinostomes (0.4%), and hookworms (0.4%). The prevalence of intestinal protozoa was Blastocystis hominis 1.6%, Entamoeba histolytica 0.8%, Entamoeba coli 0.8%, Balantidium coli 0.4%, Iodamoeba bütschlii 0.4%, and Sarcocystis hominis 0.4%. Co-infections of various helminths and protozoa were present in 15.9% of the people. The present results show that the prevalence of parasitic infections in this region is still high. Proactive education about dietary habits, personal hygiene, and sanitation should be provided to the people in this community to reduce the prevalence of intestinal parasite infections. Moreover, development of policies and programs to control parasites is needed.

Turmeric reduces inflammatory cells in hamster opisthorchiasis

The curcumin compound from turmeric is effective in the treatment of many inflammatory diseases. The aim of our present study was to evaluate the efficacy of turmeric on reducing the histopathological changes of hamster opisthorchiasis. Hamsters were infected with Opisthorchis viverrini and then administered turmeric. Using light microscopic observation, liver function tests for alanine transaminase (ALT), alkaline phosphatase, and direct bilirubin were investigated. The resulting histopathological changes show that turmeric has anti-inflammatory properties—during both N-nitrosodimethylamine administration and O. viverrini infection—by reducing the aggregation of inflammatory cells surrounding the hepatic bile ducts, which correlates with a decreased serum ALT level. The decrease in direct bilirubin levels in the hamsters treated with turmeric suggests that turmeric may enhance biliary contraction. The present study found that turmeric clearly reduces the inflammatory cells in hamster opisthorchiasis at an early stage. This finding may be connected with a reduction in the risk factors of cholangiocarcinoma development.

Involvement of c-Ski Oncoprotein in Carcinogenesis of Cholangiocacinoma Induced by Opisthorchis viverrini and N-nitrosodimethylamine

Opisthorchiasis is the major public health problem in the endemic areas of Thailand and Laos because Opisthorchis viverrini infection causes serious hepatobiliary diseases including CCA. The molecular mechanism of the CCA carcinogenesis induced by the infection remains obscure. To reveal the potential genes and signaling pathways to involve in the carcinogenesis, the present study investigated the expression of c-Ski, an oncogene, and two TGF-β signaling pathway relative genes, TGF-β and Smad4, during the development of CCA induced by O. viverrini infection in hamster model, and in human opisthorchiasis associated CCA. The results showed that the expression of c-Ski gene was greatly up-regulated during the carcinogenesis of CCA in hamster model. The overexpression of c-Ski was confirmed by immunohistological staining result which showed the increased expression of c-Ski protein in cytoplasm of the epithelial lining of hepatic bile ducts. Moreover, the immunohistological staining of the specimens of human opisthorchiasis associated CCA revealed the up-regulated expression of c-Ski and Smad4 proteins in the cytoplasm of the epithelial lining of hepatic bile ducts and stomal fibrosis respectively. The expression of TGF-β and Smad4 were up-regulated, which expression kinetics was time-dependent of CCA development. These results suggest that c-Ski is likely involved in the carcinogenesis of CCA induced by O. viverrini infection through regulating TGF-β signaling pathway.

Animal models for Opisthorchis viverrini infection

We investigated the utility of various animal models for the study of opisthorchiasis in humans and its common sequel of cholangiocarcinoma (CCA). Rats, mice, gerbils, and hamsters were infected with Opisthorchis viverrini metacercariae. Worms from the infected animal hosts were recovered from livers and counts made of eggs per gram of feces. Worms were observed in and recovered from hamsters and gerbils but not rats and mice. The recovered worms from the infected gerbils were larger and more physiologically developed than those from the infected hamsters. The results suggest that gerbils are more susceptible to infection by Opisthorchis viverrini and thus more suitable for modeling opisthorchiasis and its connection to CCA.

Alterations of gene expression of RB pathway in Opisthorchis viverrini infection-induced cholangiocarcinoma

Opisthorchiasis has the significant relationship with the high prevalence of cholangiocarcinoma (CCA; a bile duct cancer) in the endemic areas in Southeast Asia. To reveal the molecular mechanism of the tumorigenesis induced by Opisthorchis viverrini infection, the present study investigated the kinetic expression of RB pathway genes, including RB1, p16INK4, cyclin D1, and CDK4, during the development of opisthorchiasis-associated CCA in hamster model. The results of quantitative real-time polymerase chain reaction indicated that the expressions of RB1 and p16INK4 were down-regulated during the development of CCA induced by infection plus N-nitrosodimethylamine treatment in a time-dependent manner. On the other hand, the expressions of cyclin D1 and CDK4 were up-regulated. The expression kinetics was corresponding to the pathological progression of the opisthorchiasis-associated CCA, revealed by histopathological observation. Moreover, the analysis of the expression of these genes in human opisthorchiasis-associated CCA cases showed the decreased expression of RB1 and p16INK4 in 50% and 82.7% cases and overexpression of cyclin D1 and CDK4 in half cases, respectively. The results suggested that RB pathway is likely involved in the tumorigenesis of opisthorchiasis-induced CCA and proposed the potential application of some of these genes as biomarkers in predispose and molecular therapy of the parasite-associated cancer.