• Parasites, Hosts and Diseases
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• v.54 no.3
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• pp.357-361
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• 2016

Following the first report of Opisthorchis viverrini infection in a domestic duck in Phu My District of Binh Dinh Province, Central Vietnam, many other cases were observed in the province. We determined the infection rate and intensity of O. viverrini infection in ducks in 4 districts of the province. A total of 178 ducks were randomly selected from 34 farms for examination of flukes in the liver and gall bladder. An infection rate of 34.3% (range 20.7-40.4% among districts) was found; the intensity of infection was 13.8 worms per infected duck (range 1-100). These findings show the role of ducks as a host for O. viverrini, duck genotype, which is sympatric with the human O. viverrini genotype in this province. It also stresses the need for investigations on the zoonotic potential and the life cycle of this parasite.

• Parasites, Hosts and Diseases
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• v.52 no.6
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• pp.695-699
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• 2014

Chronic Opisthorchis viverrini-induced hepatobiliary disease is associated with significant leukocyte infiltration, including activated macrophages; however, the polarization of infiltrating macrophages remains to be fully characterized. In this study, we characterized macrophage polarization and phenotype in chronic O. viverrini-induced hepatobiliary disease in humans and hamsters using gene expression and histochemical analysis. Chronic O. viverrini infection and associated hepatobiliary diseases were associated with iron loaded M2-like macrophages in both humans and hamsters. This study provides suggestive evidence that iron loaded M2-like macrophages promote hepatobiliary disease in chronic O. viverrini infection.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.5245-5249
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• 2012

Background: Opisthorchis viverrini infection is a serious public-health problem in Southeast Asia especially in Lao PDR and Thailand. It is associated with a number of hepatobiliary diseases and the evidence strongly indicates that liver fluke infection is the major etiology of cholangiocarcinoma. Objectives: This study aimed to determine actual levels of Opisthorchis viverrini infection in Nakhon Ratchasima province, Northeast Thailand. Methods: A cross-sectional survey was conducted during a one year period from October 2010 to September 2011. O. viverrini infection was determined using a modified Kato's thick smear technique and socio-demographic data were collected using predesigned semi-structured questionnaires. Results: A total of 1,168 stool samples were obtained from 516 males and 652 females, aged 5-90 years. Stool examination showed that 2.48% were infected with O. viverrini. Males were slightly more likely to be infected than females, but the different was not statistically significant. O. viverrini infection was most frequent in the 51-60 year age group and was found to be positively associated with education and occupation. Positive results were evident in 16 of 32 districts, the highest prevalence being found in Non Daeng with 16.7%, followed by Pra Thai with 11.1%, Kaeng Sanam Nang with 8.33%, and Lam Ta Men Chai (8.33%) districts. Conclusion: This study indicates that O viverrini is still a problem in some areas of Nakhon Ratchasima, the patients in this study bing suitable for the purpose of monitoring projects.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.8
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• pp.3413-3418
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• 2015

Background: Liver fluke infection caused by the parasite Opisthorchis viverrini (O. viverrini), a human carcinogen, is endemic in north-eastern Thailand and remains a major health problem. Objectives: The objectives of the study were to (1) resurvey the prevalence of O. viverrini infection in a field site from the Khon Kaen Cohort Study (in newly recruited subjects as well as previous cohort subjects surveyed in 1992); (2) investigate how subjects' lifestyle habits and their exposure to health promotion initiatives influence changes in prevalence of O. viverrini infection. Materials and Methods: The prevalence of O. viverrini infection in the cohort subjects (as well as new subjects) was investigated using faecal egg counts. Information on demographic factors, lifestyle and awareness of health promotion initiatives were obtained through questionnaires. Results: O. viverrini infection rates in the same individuals of the cohort were lower in 2006 than in 1992. Also, by studying the period effect, the current 35-44 year olds had a 12.4% (95% CI 3.9% to 20.9%) lower prevalence of O. viverrini infection than the 35-44 year olds in 1992 (24.2% versus 11.8%). Lifestyle choices showed that smoking and alcohol consumption were associated with an increased chance of acquiring O. viverrini infection with adjusted odds ratios of 10.1 (95%CI 2.4-41.6) and 5.3 (95%CI 1.2-23.0), respectively. Conclusions: Our study has demonstrated that although the prevalence of O. viverrini infection over a 14-year period has decreased, unhealthy lifestyle was common with smoking and alcohol consumption being associated with increased chances of infection, emphasising the double burden of disease which developing countries are facing.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7803-7807
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• 2015

Opisthorchis viverrini infection is a serious public health problem in Southeast Asia especially in the northeast and north of Thailand. Therefore, a cross-sectional survey using multistage sampling was conducted from the rural communities of Surin province, Thailand, during September 2013 to July 2014. O. viverrini infection was determined using Kato's thick smear technique. Socio-demographic, information resources, and history data were collected using predesigned semi-structured questionnaires. A total of 510 participants completed interviews and had stools collected. Some 32 (6.47%) participants were infected with O. viverrini. The rate was slightly higehr in males (6.61%) than females (6.32%). High frequencies were found in the age groups 61-70 (19.4%) and 71-80 years (19.4%), those involved in agriculture (10.5%), and in primary school (10.3%). The distribution of high infection was found in Tha Tum (16.7%) and Sankha district (16.7%), followed by Samrong Thap (13.3%), Si Narong (13.33%), and Buachet district (13.33%). Chi-square testing indicated that age (61-70 and 71-80 year old), education (primary school) and occupation (agriculture), were significantly associated with O. viverrini infection (p-value<0.05). Of 72.6% participants who had past histories with stool examination, 17.0% of them had been infected with O. viverrini and 43.2% treated with praziquantel. This finding confirmed that O. viverrini is still a problem in Surin province, Thailand, and therefore, interventions are urgently required for mass treatment and health education implementation.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.5
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• pp.1751-1758
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• 2015

There has been a strong, positive correlation between opisthorchiasis-associated cholangiocarcinoma and infection with Helicobacter. Here a rodent model of human infection with Opisthorchis viverrini was utilized to further investigate relationships of apparent co-infections with O. viverrini and H. pylori. A total of 150 hamsters were assigned to five groups: i) Control hamsters not infected with O. viverrini; ii) O. viverrini-infected hamsters; iii) non-O. viverrini infected hamsters treated with antibiotics (ABx); iv) O. viverrini-infected hamsters treated with ABx; and v) O. viverrini-infected hamsters treated both with ABx and praziquantel (PZQ). Stomach, gallbladder, liver, colonic tissue, colorectal feces and O. viverrini worms were collected and the presence of species of Helicobacter determined by PCR-based approaches. In addition, O. viverrini worms were cultured in vitro with and without ABx for four weeks, after which the presence of Helicobacter spp. was determined. In situ localization of H. pylori and Helicobacter-like species was performed using a combination of histochemistry and immunohistochemistry. The prevalence of H. pylori infection in O. viverrini-infected hamsters was significantly higher than that of O. viverrini-uninfected hamsters ($p{\leq}0.001$). Interestingly, O. viverrini-infected hamsters treated with ABx and PZQ (to remove the flukes) had a significantly lower frequency of H. pylori than either O. viverr-iniinfected hamsters treated only with ABx or O. viverrini-infected hamsters, respectively ($p{\leq}0.001$). Quantitative RT-PCR strongly confirmed the correlation between intensity H. pylori infection and the presence of liver fluke infection. In vitro, H. pylori could be detected in the O. viverrini worms cultured with ABx over four weeks. In situ localization revealed H. pylori and other Helicobacter-like bacteria in worm gut. The findings indicate that the liver fluke O. viverrini in the biliary tree of the hamsters harbors H. pylori and Helicobacter-like bacteria. Accordingly, the association between O. viverrini and H. pylori may be an obligatory mutualism.

• Parasites, Hosts and Diseases
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• v.51 no.6
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• pp.695-701
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• 2013

Opisthorchis viverrini infection causes inflammation and liver injury leading to periductal fibrosis. Little is known about the pathological alterations in bile canaliculi in opisthorchiasis. This study aimed to investigate bile canalicular alterations in O. viverrini-infected hamsters and to examine the chemopreventive effects of curcumin on such changes. Hamsters were infected with O. viverrini and one group of animals was fed with 1% dietary curcumin supplement. Animals were examined during the acute infection phase, days 21 and 30 post-infection (PI) and chronic infection phase (day 90 PI). Scanning electron microscopy revealed that in the infected group fed with a normal diet, bile canaliculi became slightly tortuous by 30 day PI and more tortuous at day 90 PI. Transmission electron microscopy showed a reduction in microvilli density of canaliculi starting at day 30 PI, with a marked loss of microvilli at day 90 PI. These ultrastructral changes were slightly seen at day 21 PI, which was similar to that found in infected animals fed with 1% curcumin-supplemented diet. Notably, curcumin treatment prevented the reduction of microvilli density, reduced the dilation of bile canaliculi, and decreased the tortuosity of the bile canaliculi relative to non-infected animals on a normal diet at days 30 and 90 PI. These results suggest that curcumin reduces alteration of bile canaliculi and may be a promising agent to prevent the onset of bile duct abnormalities induced by O. viverrini infection.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.2
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• pp.857-862
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• 2016

Background: The prevalence of infection by the liver fluke, Opisthorchis viverrini (O. viverrini), has remained high in Northeast Thailand where it is a major risk factor for the eventual development of cholangiocarcinoma (CCA). The infection is acquired by the consumption of dishes containing unsafely prepared freshwater fish, a dietary tradition which has proved resistant to change. Since many people are aware that dosing with praziquantel (PZQ) is a successful treatment for an episode of the infection, there is a risk that, to avoid the long term consequences, they will engage in a cycle of infection, dosing and reinfection. Objectives: There is a dearth of studies of reinfection by O. viverrini, and the aims of this study were to assess re-infection rates in a typical province of Northeastern Thailand where O. viverrini infection is likely and to investigate factors associated with reinfection. Materials and Methods: A total of infected 607 villagers were treated with PZQ, and those found to be no longer infected were followed up at six-monthly intervals over 12 months. Results: At the end of this period data on 457 subjects were available for analysis using descriptive statistics and logistic regression, and 50 were found to have become reinfected, giving a cumulative reinfection rate of 10.9%. The results of a multiple logistic regression analysis showed that the only factor found to be associated with reinfection was past use of PZQ. Conclusions: Recommendations are made for future larger scale and better designed reinfection studies in the light of limitations of the current study. Further efforts are needed to discourage people from eating fish dishes likely to contain viable metacariae.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.4
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• pp.1235-1240
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• 2012

Background: Opisthorchis viverrini infection is a serious public-health problem in Southeast Asia. It is associated with a number of hepatobiliary diseases and the evidence strongly indicates that liver fluke infection is the etiology of cholangiocarcinoma. Objectives: This study aimed to investigate Opisthorchis viverrini metacercarial infection in cyprinoid fish collected from 32 districts of Nakhon Ratchasima province, Northeastern Thailand during one year period from February 2010 to February 2011. Methods: A cross-sectional study was conducted, data being collected with pepsin-HCl digestion and stereomicroscope, respectively. Analysis was performed using SPSS Windows Version 12.0. Results: A total of 640 Cyprinidae family fish including 5 species were collected from different study sites, and investigated for O. viverrini metacercariae. The infection rate was 12.3% (79/640), predominantly in Cyclocheilichthys armatus, C. repasson, Puntioplites proctzysron, Hampala macrolepitota and Hampala dispar, respectively. The prevalence of O. viverrini metaceria in Nakhon Ratchasima area was 78.1%, predominantly in Sida and KiaKham Thale So. Conclusion: This findings stress that natural fish species in rural communities are still a source of O viverrini infection and put local people at risk, therefore public awareness and prevention campaigns are urgently required.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.373-376
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• 2016

The Mini Parasep SF fecal parasite concentrator (MPSFC) is a new modification of the closed concentration system, which can easily be adopted in any routine clinical pathology laboratory. Here we describe our experience with the system in diagnosing Opisthorchis viverrini. A total of 199 fecal samples was submitted for routine examination in the clinical pathology laboratory of Suranaree University of Technology hospital, Nakhon Ratchasima province, Thailand, during August to October 2015. Out of all samples examined, 10 (5.03%) were positive with intestinal parasites including O. viverrini (2.01%), followed by Strongyloided stercoralis (1.51%), Hookworm (0.5%), Taenia spp. (0.5%), and Entamoeba coli (0.5%). Regarding the distribution of intestinal parasites in relation to the methods used, and found that 4 samples (2.01%) were positive using the direct wet smear method while 10 (5.03%) were positive with the Mini Parasep SF method; the difference was statistically significant ($X^2$-test = 116.506, p-value =0.001). Mean time for processing using the Parasep system was 6.03 min/sample, the conventional direct wet smear method at 0.3 min/sample. Cost per test, conventional direct wet smear method costing less than the Parasep method at USD 0.74/sample versus USD 1.47/sample. This first report of O. viverrini detection using MPSFC indicates that Parasep concentration test is useful in the routine laboratory, increasing the yield of parasites as compared to direct microscopy, but with greater processing time and cost. Further comparisons between the Parasep concentration test and common methods for O. viverrini detection are required, particularly concerning use in epidemiological surveys.