Epidemiology of Opisthorchis viverrini Infection.

Opisthorchiasis in the Lower Mekong Subregion is a parasitic disease caused by the liver fluke Opisthorchis viverrini. This parasite has a well-documented distribution in Thailand, Lao PDR, Cambodia, Myanmar and Southern Vietnam. In this chapter, we describe the current knowledge of the epidemiology of O. viverrini infection, highlighting advances in control efforts made in the last four decades in Thailand and identifying ongoing gaps in our epidemiological knowledge which need to be filled to support efforts to permanently overcome the heavy morbidity and mortality burden caused by these parasites within their endemic regions.

Coinfection with Helicobacter pylori and Opisthorchis viverrini Enhances the Severity of Hepatobiliary Abnormalities in Hamsters.

Persistent infection with Opisthorchis viverrini causes hepatobiliary abnormalities, predisposing infected individuals to cholangiocarcinoma (CCA). In addition, Helicobacter pylori is highly prevalent in most countries and is a possible risk factor for CCA; however, its role in enhancing hepatobiliary abnormality is unclear. Here, we investigated the effects of coinfection with H. pylori and O. viverrini on hepatobiliary abnormality. Hamsters were divided into four groups: (i) normal, (ii) H. pylori infected (HP), (iii) O. viverrini infected (OV), and (iv) O. viverrini and H. pylori infected (OV+HP). At 6 months postinfection, PCR and immunohistochemistry were used to test for the presence of H. pylori in the stomach, gallbladder, and liver. In the liver, H. pylori was detected in the following order: OV+HP, 5 of 8 (62.5%); HP, 2 of 5 (40%); OV, 2 of 8 (25%). H. pylori was not detected in normal (control) liver tissues. Coinfection induced the most severe hepatobiliary abnormalities, including periductal fibrosis, cholangitis, and bile duct hyperplasia, leading to a significantly decreased survival rate of experimental animals. The greatest thickness of periductal fibrosis was associated with a significant increase in fibrogenesis markers (expression of alpha smooth muscle actin and transforming growth factor beta). Quantitative reverse transcription-PCR revealed that the highest expression levels of genes for proinflammatory cytokines (interleukin-1 [IL-1], IL-6, and tumor necrosis factor alpha) were also observed in the OV+HP group. These results suggest that coinfection with H. pylori and O. viverrini increased the severity of hepatobiliary abnormalities to a greater extent than either single infection did.

Comparison of infectivity, metacercarial burden and host mortality induced by Opisthorchis viverrini sensu lato cercariae from Lao PDR compared with Thailand in cyprinid fish, Barbonymus gonionotus.

BACKGROUND: Previous studies indicate that Opisthorchis viverrini sensu lato (s.l.) is a species complex with strong associations to geographical regions, i.e., specific wetlands. The present study was conducted to compare the infectivity, establishment and metacercarial burden and survival of the fish host following exposure to O. viverrini s.l. cercariae isolates from two different river wetlands. METHODS: Experimental infections were performed by exposing fish (silver barb, Barbonymus gonionotus) individually to 0 (control) and 100 O. viverrini s.l. cercariae originating from the Songkram River wetland in Thailand and the Nam Ngum River wetland, Lao PDR. Metacercarial burden and fish survivals were monitored after infection. RESULTS: Fish exposed to O. viverrini s.l. cercariae from the Nam Ngum River wetland had significantly greater metacercarial burden and more active motility at 28 and 35 days post infection than those from the Songkram River wetland. The mortality of fish infected with O. viverrini s.l. from the Nam Ngum River wetland was greater than that from the Songkram River wetland (log-rank test, p<0.01). CONCLUSIONS: The findings in this study provided additional evidence supporting the importance of cryptic species of O. viverrini s.l. and it has implications for parasite transmission dynamics, life cycle success and disease ecology.

Altered Expression of Oxidative Metabolism Related Genes in Cholangiocarcinomas.

Cholangiocarcinoma (CCA) is a rare but highly fatal cancer for which the molecular mechanisms and diagnostic markers are obscure. We therefore investigated the kinetic expression of isocitrate dehydrogenase-1 (IDH1), isocitrate dehydrogenase-2 (IDH2) and homogentisate 1,2-dioxygenase (HGD) during the tumorigenesis of O. viverrini infection-associated CCA in an animal model, and confirmed down-regulation of expression in human cases of opisthorchiasis-associated CCA through real time PCR. Kinetic expression of HGD, IDH1 and IDH2 in the animal model of O. viverrini infection-induced CCA was correlated with human CCA cases. In the animal model, expression of HGD was decreased at all time points (p<0.01) and expression of both IDH1 and IDH2 was decreased in the CCA group. In human cases, expression of HGD, IDH1 and IDH2 was decreased more than 2 fold in 55 cases (70.5%), 25 cases (32.1%) and 24 cases (30.8%) respectively. The present study suggests that reduction of HGD, IDH1 and IDH2 may be involve in cholangiocarcinoma genesis and may be useful for molecular diagnosis.

[The specific features of regenerative processes of hip and shin fractures in patients with superinvasion opisthorchiasis].

Opisthorchis superinvasion retains the natural manifestations of reparative regeneration of skeletal tissues, but activates proliferation stages and increases the promoter manifestations of histogenesis. Irrespective of a surgical option, the rate of infestation, and the place of residence, reparative regeneration of shaft fractures of the shin and hip occurs significantly more rapidly in patients with superinvasion opisthorchiasis than in those without the latter. In superinvasion opisthorchiasis, bone is restituted by early callus formation and accelerated regenerate mineralization.

[Prevention and treatment of opisthorchiasis of the liver]. / Profilaktika i lechenie oslozhnenii opistorkhoza pecheni.

Rare cases of lethal outcomes after surgical operations on the liver were analyzed which were caused by invasion of helminth Opisthorchis felineus. It was shown that prolonged and massive invasion, in the absence of specific treatment, can result in failure of the compensatory potencies of the liver. It occurs mainly due to activation of the pathogenic flora in the bile tree against the background of the intraductal hypertension characteristic of opisthorchiasis. Destructive purulent cholangitis, cholangitic abscesses in the liver and suppuration of opisthorchiasis cysts can develop. The direct cause of death was progressing hepatic insufficiency. The postoperative lethality among patients with opisthorchiasis cysts of the liver was 5.7%, with liver abscesses--12.5%. The external drainage of the biliary tree in patients with this pathology and intraportal infusions reduce lethality and the number of specific postoperative complications.

Cholangiocarcinoma in patients with opisthorchiasis.

Cholangiocarcinoma is very common in areas endemic for the liver fluke Opisthorchis viverrini. Survival after surgical treatment of cholangiocarcinoma associated with opisthorchiasis was studied prospectively in 30 patients, all of whom resided in an endemic area. The median age was 52 (range 32-69) years and twenty-five patients were men. Seven patients had their tumours removed, four with concomitant liver resection. Twenty-two patients underwent palliative biliary bypass procedures to a segmental duct. Laparotomy with biopsy of metastatic lesions was undertaken in one patient with multiple lymph node metastases and peritoneal seedlings. No patient received postoperative chemotherapy or radiation treatment. Patients were followed for 2 years or until death. The 1-year survival rate after tumour resection was 86 per cent and the 2-year survival rate 43 per cent. After palliative procedures the 1-year survival rate was 26 per cent; no patient reached 2 years and the median survival time was 8 months. Survival after surgical treatment of cholangiocarcinoma in patients with opisthorchiasis is broadly similar to that reported for cholangiocarcinoma without liver fluke infestation.

Parasite-associated morbidity: liver fluke infection and bile duct cancer in northeast Thailand.

Infection with the liver fluke, Opisthorchis viverrini, remains a major public health problem in Northeast Thailand, where approximately one-third of the population is infected. The northeast region is largely populated by Laos-descendent Thais who enjoy eating raw fish, which harbour the infective stage of the fluke. The parasite has maintained its presence in the population despite the widespread use of praziquantel and dissemination of health education material throughout the region by vigorous government-sponsored programs in recent years. The most severe consequence of liver fluke infection is cholangiocarcinoma, i.e. cancer of the bile duct epithelium. Although mortality due to the parasites alone appears to be uncommon, cholangiocarcinoma arising as a result of infection is one of the leading causes of death in the region. This paper reviews the pathogenesis of infection and the geographic, hospital-based and community studies which demonstrate the close relationship between infection and cancer. In addition, data from the Cancer Registry of Khon Kaen, Northeast Thailand and population-based studies using ultrasonography to visualize early tumours which illuminate the very high frequency of the cancer among heavily infected individuals and communities are discussed. Finally, the paper will close with a brief commentary on the prospects for control of the parasite and its likely impact on the frequency of cancer given the current epidemiological situation of liver fluke infection.

[Opisthorchiasis in Tobolsk based on 1950-1987 autopsy data]. / Opistorkhoz v Tobol'ske po dannym autopsii za 1950-1987 gg.

Retrospective analysis of medical documentation of the Tobolsk integrated prosectorium in 1950-1987 was made. Uncomplicated opisthorchiasis as the major and direct cause of death was not encountered. In thanatogenesis the complicated opisthorchiasis generally appeared as a mixed abnormality. No evolving opisthorchiasis-induced pathology was found. Positive pathomorphism of opisthorchiasis developed.