Association between praziquantel treatment and cholangiocarcinoma: a hospital-based matched case-control study

Spatial analysis of cholangiocarcinoma in Thailand from 2012 to 2021; a population-based cancer registries study

BACKGROUND

Cholangiocarcinoma (CCA) is major health issue in Thailand, with high incidences in different parts of country. This study examines the association between spatial variables and CCA in Thailand.

METHODS

Thailand's four population-based cancer registries provided data for this retrospective cohort analysis between January 1, 2012, and December 31, 2021. 6,379 diagnosed CCA cases were found in 554 sub-districts. Moran's I and Local Indicators of Spatial Association (LISA) measured geographic dispersion and estimated sex age-standardized rates (ASRs). Multivariable log-linear regression assessed geography and CCA, calculating adjusted incidence rate ratios (IRRs) and 95% confidence interval (CI).

RESULTS

Of 6,379 CCA cases, 63.9% were male, and the mean age at diagnosis was 66.2 years (standard deviation = 11.07 years). CCA ASRs for both sexes in Thailand was 8.9 per 100,000 person-years. The northeastern region had the greatest ASR at 13.4 per 100 000 person-years. Moran's I and LISA studies grouped regions by spatial variables. The association between spatial variables and CCA demonstrated that the northern region exhibited elevation (adjusted IRRs = 0.82, 95%CI: 0.78 to 0.87) and distance from water sources variable (adjusted IRRs = 0.91, 95%CI: 0.82 to 0.99). The central region elevation variable (adjusted IRRs = 0.85, 95%CI: 0.76 to 0.94). This was the distance from water sources (adjusted IRRs = 0.96, 95%CI: 0.93 to 0.99) and population density variable (adjusted IRRs = 0.94, 95%CI: 0.93 to 0.96) in the northeastern region. Population density (adjusted IRRs = 1.09, 95%CI: 1.02 to 1.15) and average temperature variable (adjusted IRRs = 1.05, 95%CI: 1.02 to 1.09) were significant in the southern region.

CONCLUSION

Spatial variables associated with CCA indicate that ASR differs across Thailand. So environmental and climate factors can inform targeted public health strategies to address CCA in high-risk areas throughout Thailand.

A study protocol for a multi-country cluster randomized controlled trial of the impact of a multi-component One Health strategy to eliminate Opisthorchis viverrini and soil transmitted helminths in the Lower Mekong Basin

BACKGROUND

Opisthorchis viverrini (OV) and soil-transmitted helminths (STH) are two of the most common helminths contributing to the Neglected Tropical Disease (NTDs) burden in the Lower Mekong Basin. Although mass drug administration is the cornerstone of control programs to reduce morbidity caused by these infections, this approach has limitations in preventing re-infections. Elimination requires additional measures such as reservoir host treatment, improved hygiene and health education to reinforce MDA's impact. This study aims to examine the impact of a scalable multi-component One Health Helminth Elimination program in the Lower Mekong Basin (HELM) that combines human praziquantel (PZQ) and albendazole (ALB) treatment with a program that includes the "Magic Glasses" and the "Lawa Model" interventions with health promotion at their core.

METHODS

This study will employ a cluster randomized controlled trial (cRCT) in 18 rural communities (with sub-district or villages as cluster units) across Cambodia, Laos and Thailand. The control arm will receive one round of PZQ/ALB treatment, while in the intervention arm, multi-component HELM program will be implemented, which includes PZQ/ALB treatment together with the Magic Glasses and Lawa Model interventions. OV and STH infections levels will be evaluated in individuals aged 5-75 years at baseline and will be repeated at follow-up (12 months after the HELM intervention), using modified formalin ethyl-acetate concentration technique and quantitative PCR. The primary outcome of the study will be cumulative incidence of human OV and STH infections. Outcomes between the study arms will be compared using generalized linear mixed models, accounting for clustering.

DISCUSSION

Evidence from this trial will quantify the impact of a multi-component One Health control strategy in interrupting Ov and STH infections in the Lower Mekong Basin.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12622000353796. Prospectively registered 28 February 2022.

Pesticide exposure and risk of cholangiocarcinoma: A hospital-based matched case-control study

BACKGROUND

Cholangiocarcinoma (CCA) caused by Opisthorchis viverrini is a well-known and significant public health issue in northeastern Thailand; however, a link between pesticide exposure (PE) and CCA risk has not yet been established. Therefore, our research objective was to investigate the relationship between PE and CCA risk.

METHODS

A hospital-based matched case-control study was carried out. All cases (in-patients) and controls (out-patients) were volunteers at a tertiary hospital in northeast Thailand. Between 2015 and 2019, 178 incident cases of pathologically-confirmed CCA and 356 controls were selected from the check-up clinic from the Srinagarind Hospital outpatient database (two controls per case). The recruited controls were individually-matched to the CCA cases based on sex, age (±5 years) and admission date (±3 months). During face-to-face interviews, a standardised pre-tested questionnaire was used to collect data. Multivariable conditional logistic regression was used to analyse the data.

RESULTS

The respective frequency of PE between the 178 CCA cases and 356 controls was 77.0% versus 87.6% for never used, 14.6% versus 5.3% for have used but stopped and 8.4% versus 7.0% for currently using. After adjusting for the highest educational attainment, smoking behaviour, alcohol use and family history of cancer, PE was not significantly associated with CCA (p-value = 0.086). Using volunteers who have never used PE as the reference group, the respective odds of developing CCA for those who have ever used but have since stopped and are currently using was 2.04 (adjusted OR = 2.04; 95% CI: 1.03-4.04) versus 0.83 (adjusted OR = 0.83; 95% CI: 0.39-1.76) times more likely to develop CCA than those who had never used PE.

CONCLUSION

There is no association between PE and the risk of CCA. Notwithstanding the finding, future research should focus on enhancing PE assessment methods that consider complex chemical mixtures, chemicals of interest, historical exposure and exposure pathways. Moreover, there is need for more extensive and longer population-based cohort studies that include younger, non-occupationally exposed individuals during periods of developmental susceptibility.

Curcumin and Its Supramolecular Complex with Disodium Glycyrrhizinate as Potential Drugs for the Liver Fluke Infection Caused by Opisthorchis felineus

Opisthorchiosis is a parasitic liver disease found in mammals that is widespread throughout the world and causes systemic inflammation. Praziquantel remains the drug of choice for the treatment of opisthorchiosis, despite its many adverse effects. An anthelmintic effect is attributed to the main curcuminoid of Curcuma longa L. roots-curcumin (Cur)-along with many other therapeutic properties. To overcome the poor solubility of curcumin in water, a micellar complex of curcumin with the disodium salt of glycyrrhizic acid (Cur:Na₂GA, molar ratio 1:1) was prepared via solid-phase mechanical processing. In vitro experiments revealed a noticeable immobilizing effect of curcumin and of Cur:Na₂GA on mature and juvenile Opisthorchis felineus individuals. In vivo experiments showed that curcumin (50 mg/kg) had an anthelmintic effect after 30 days of administration to O. felineus-infected hamsters, but the effect was weaker than that of a single administration of praziquantel (400 mg/kg). Cur:Na₂GA (50 mg/kg, 30 days), which contains less free curcumin, did not exert this action. The complex, just as free curcumin or better, activated the expression of bile acid synthesis genes (Cyp7A1, Fxr, and Rxra), which was suppressed by O. felineus infection and by praziquantel. Curcumin reduced the rate of inflammatory infiltration, whereas Cur:Na₂GA reduced periductal fibrosis. Immunohistochemically, a decrease in liver inflammation markers was found, which is determined by calculating the numbers of tumor-necrosis-factor-positive cells during the curcumin treatment and of kynurenine-3-monooxygenase-positive cells during the Cur:Na₂GA treatment. A biochemical blood test revealed a normalizing effect of Cur:Na₂GA (comparable to that of curcumin) on lipid metabolism. We believe that the further development and investigation of therapeutics based on curcuminoids in relation Opisthorchis felineus and other trematode infections will be useful for clinical practice and veterinary medicine.

Epidemiology and Control of Opisthorchis viverrini Infection: Implications for Cholangiocarcinoma Prevention

It is known that Opisthorchis viverrini (OV) is the most significant risk factor for the development of cholangiocarcinoma (CCA); hence, it is also known as carcinogenic parasite. Effective control and elimination of OV infection should significantly reduce O. viverrini-related CCA. This chapter includes details of the three recently developed innovative tools, namely the Isan cohort database software, an OV-RDT for screening of O. viverrini, and an ultrasound telecommunication system. Past and current control programs, i.e., education, medication, and sanitation were discussed and stressed the need for a comprehensive control program which encompasses primary, secondary, and tertiary patient care programs for confirmation and management of suspected CCA cases. The approach of mathematical modeling for control of OV and CCA was also briefly described. Additionally, we highlighted the current progress toward control of OV and CCA in Thailand and potential for expansion into nearby countries in Southeast Asia.

Prevalence and Associated Risk Factors of Intestinal Parasitic Infections: A Population-Based Study in Phra Lap Sub-District, Mueang Khon Kaen District, Khon Kaen Province, Northeastern Thailand

Intestinal parasitic infections are still a crucial problem among communities in Northeast Thailand. Misuse of antiparasitic drugs and unhealthy food behaviors are known. This study aimed to explore the prevalence, behavioral health factors, and motivation for self-treatment of anti-parasitic drugs in this area. A community-based cross-sectional study was conducted in Phra Lap sub-district, Mu Khon Kaen district, Khon Kaen province, Northeast Thailand, in 2016. A total of 419 participants were recruited to complete a self-administered questionnaire and stool examination. Binary logistic regression was used to assess the association between the risk factor and parasitic infection. Forty-two participants (10%; 95%CI 7.5-13.3) were positive for at least one parasite species. In this community, the most detected intestinal parasite was Opisthorchis viverrini (5.3%), followed by Strongyloides stercoralis (3.1%). A total of 67.5% of the participants had the experience of anti-parasitic drug treatment within previous 1 year, and "Often eat raw food" was the most common reason for the use of anti-parasitic drugs. On multivariate analysis, parasitic infections were significantly associated with male gender (ORadj. 2.42; 95%CI 1.00-5.85), age ≥ 60 years (ORadj. 7.55; 95%CI 1.60-35.76), and often consuming raw food of at least one type (ORadj. 2.37; 95%CI 1.03-5.44). Given these findings, correction of the dietary habit of eating raw fish/meat, which is the most important measure, and limitation of the use of anthelmintic treatment for individuals with stools positive for ova as well as emphasis on sanitary toilets will be implemented for the prevention and control of parasitic infection in endemic communities.

Current status of human liver fluke infections in the Greater Mekong Subregion

The Greater Mekong Subregion (GMS) is a trans-national region of the Mekong River basin in Southeast Asia comprising Cambodia, the People's Republic of China (specifically Yunnan Province and Guangxi Zhuang Autonomous Region), Lao People's Democratic Republic (Lao PDR), Myanmar, Thailand, and Vietnam home to more than 340 million people or almost 4.5% of the global population. Human liver fluke infections caused by Opisthorchis viverrini and Clonorchis sinensis have been major public health problems in this region for decades. Opisthorchiasis caused by O. viverrini is prevalent in Thailand, Lao PDR, Cambodia and central-southern Vietnam with more than 12 million people infected. Clonorchiasis caused by C. sinensis is endemic in northern Vietnam and Guangxi with estimated 3.5 -5 million infected. The infections can cause several liver and biliary diseases such as cholangitis, periductal fibrosis, gallstones, and cholangiocarcinoma (CCA), a fatal bile duct cancer. Key determinants of the geographical distribution differences of the two liver fluke species are snail species and geographic barriers. Main risk behaviour of the infections is the culture of eating raw fish "the raw attitude" of people in the GMS, especially the Tai/Dai/Thai/Laos ethnic groups, the major population in the GMS. Over the past 20 years, there is a big change in prevalence of the infections. Opisthorchiasis has long been endemic, particularly in northern and northeastern Thailand and Lao PDR with over 8-10 million cases estimated. However, after several rounds of national campaign against opisthorchiasis using integrated control approach in Thailand over the past three decades, the prevalence of O. viverrini infection has reduced from over 15% in 1996 to 2.2% in 2019. High prevalence of O. viverrini infection continues in Lao PDR and central Vietnam. Emerging high prevalence, up to a maximum of 47.5%, has been noted in Cambodia during the past 10 years possibly due to more studies being conducted rather than increasing prevalence. O. viverrini infection has now also been reported in Lower Myanmar in recent years. Clonorchiasis has been known in northern Vietnam and southern China for a long time. Several surveys have reported infections in Guangxi in the last 10 years, and until now liver fluke infected cases have not been reported in Yunnan. Overall, nowadays, there is a shift in high risk areas for GMS liver fluke infection from northeastern Thailand to Lao PDR, Cambodia, Vietnam, Myanmar, and Guangxi P.R. China. Urgent systematic disease mapping and integrated liver fluke control using One Health approaches should be implemented nationwide in GMS countries.

Effects of Three-time Administration of a Supramolecular Complex of Praziquantel with Disodium Glycyrrhizinate on Trematode Opisthorchis felineus in Hamsters

BACKGROUND

Praziquantel (PZQ) is the most commonly used anthelmintic drug for treating trematodiases. It was shown here that PZQ in complex with disodium glycyrrhizinate (PZQ-Na₂GA, in the 1:10 ratio) has higher bioavailability than PZQ alone. Our aim was to determine the effects of three-time administration of PZQ-Na₂GA in an experimental opisthorchiasis felinea model.

METHODS

The PZQ-Na₂GA complex (1:10) at a 400 mg/kg dose (meaning 36.4 mg/kg PZQ) was administered to Opisthorchis felineus-infected hamsters three times under a "9:00 am-6:00 pm-9:00 am" regimen (PZQ-Na₂GA × 3). Effects of treatment were assessed as a reduction of helminth load in the hamsters and as changes in physiological, hematological, and blood biochemical parameters. The helminths extracted from the liver of the hamsters that received PZQ-Na₂GA thrice were assayed for sensitivity to PZQ in vitro.

RESULTS

PZQ-Na₂GA × 3 reduced the number of O. felineus helminths in the liver by 87%, which is 30% better than a previously reported effect of one-time administration of the complex. Meanwhile, relative weights of the liver and thymus diminished, and some hematological parameters improved. The helminths extracted from the hamsters 1 month after the PZQ-Na₂GA × 3 treatment showed elevated sensitivity to PZQ, as determined in vitro.

CONCLUSION

Compared with previously published data on the effectiveness of various drugs in experimental opisthorchiasis felinea, PZQ-Na₂GA × 3 exerts the most potent anthelmintic effect. In addition, PZQ-Na₂GA × 3 improves physiological status of O. felineus-infected hamsters and sensitizes the surviving parasites to subsequent PZQ treatment.

Public health interventions for preventing re-infection of Opisthorchis viverrini: application of the self-efficacy theory and group process in high-prevalent areas of Thailand

OBJECTIVE

To study the effectiveness of public health interventions in preventing Opisthorchis viverrini (OV) re-infection in high-prevalence areas of Thailand.

METHODS

68 people from Sisaket, the province with the second-highest prevalence in Thailand, who tested positive for OV eggs in faeces and took praziquantel before the start of the study, participated. 34 participants were allocated to the experimental group, which received a 12-week public health intervention based on the self-efficacy theory and group process between July and October 2018. The control group received the usual services. Data were collected using a questionnaire with a reliability of 0.84. Faecal examinations using the formalin-ether concentration technique were conducted before and after the experiment. The re-infection rate was analysed after the experimental 12 weeks and after one year. Descriptive and inferential statistics, including paired t-test and independent t-test, were employed for data analysis.

RESULTS

After the experiment, the mean scores of knowledge, perceived self-efficacy, self-efficacy expectation and OV prevention behaviour of the experimental group were significantly higher than before the experiment and also higher than scores of the control group (P < 0.05).

CONCLUSION

The public health intervention is useful. It educated the experimental group about OV, perceived self-efficacy and self-efficacy expectation in changing behaviour to prevent OV re-infection. As a result, no re-infections were observed after the 12-week intervention nor at the one-year follow-up. Public health benefits will be evident if the results are extended to other high-prevalence areas.

Masculinity and misinformation: Social dynamics of liver fluke infection risk in Thailand

Liver fluke infection through the consumption of raw or undercooked freshwater fish is a major public health problem in the Mekong Region. Despite the extensive efforts of liver fluke health campaigns, Northeast Thailand still reports high human infection prevalence as consumption of raw fish dishes has diminished but not ceased. This study examines the roles of social-cultural factors, particularly the influences of masculinity and misinformation, on liver fluke infection risk. Participant observation, questionnaire surveys and semi-structured interviews were conducted in four villages in Kalasin Province, Thailand, to scrutinize reasons for raw fish consumption, gender differences in raw fish culture, processes of liver fluke information dissemination, and the extent of information mismatch. Our results show that one of the key reasons (76.9%) underlying continued raw fish consumption are deeply embedded cultural practices associated with ways of rural life. About 30% of the participants indicated that they would not avoid eating raw fish, regardless of knowing the health consequences. Gender difference is evident, with 75.6% of males consuming raw fish salad (koi pla), compared to 42.7% of females. Some male participants associate raw meat consumption with virility and strength. Such beliefs underscore the cultural linkage of koi pla consumption with masculinity. Misconceptions of liver fluke life cycle and risk of infection remain, as only 15.3% of the participants correctly selected raw fish as the food source for liver fluke infection while 84.2% misunderstood that other raw foods could lead to infection. The multi-layered and hierarchical structure of public health information dissemination from medical professionals to health officers and village health volunteers to villagers has contributed to information mismatch between different layers. Our study builds on others which call for multi-pronged scientific and social strategies, as well as culturally attuned approaches to public health messaging. The study raises masculinity and misinformation as relevant considerations in disease prevention. Incorporating grounded research and gendered perspectives are part of appreciating the cultural roots of raw fish consumption. Realizing the significant role of village health volunteers in information dissemination and in supplying coherent public health messages is vital for effective health campaigns.

Towards Evidence-based Control of Opisthorchis viverrini

Transmission of the carcinogenic liver fluke Opisthorchis viverrini is ongoing across Southeast Asia. Endemic countries within the region are in different stages of achieving control. However, evidence on which interventions are the most effective for reducing parasite transmission, and the resulting liver cancer, is currently lacking. Quantitative modelling can be used to evaluate different control measures against O. viverrini and assist the design of clinical trials. In this article we evaluate the epidemiological parameters that underpin models of O. viverrini and the data necessary for their estimation, with the aim of developing evidence-based strategies for parasite control at a national or regional level.

Reduction of Reinfection Rates with Opisthorchis viverrini through a Three-Year Management Program in Endemic Areas of Northeastern Thailand

To clarify the reinfection profile associated with risk factors of opisthorchiasis, we conducted an epidemiological study on the chemotherapeutic effects on reinfection with O. viverrini in the endemic areas of Northeastern Thailand for 3 years. A total of 3,674 fecal samples were collected from participants in villages of 5 provinces. They were examined microscopically using a modified technique of formalin ethyl-acetate concentration. Egg-positive residents were reexamined year (2018) by year (2019) after treatment with a single dose (40 mg/kg) of praziquantel. Health education was provided to the participants yearly. The egg-positive rate of O. viverrini was 14.3%, and was highest (22.2%) in the 20–30 year-old group in 2017. The egg positive rate was 15.3% in dogs and 11.4% cats. Human reinfection rate was 15.5% and 6.3% in next 2 years, and was highest (23.2%) among the fishermen. Relative risk factors of reinfection were significantly higher for males, over 40-year-old age, or working as fishermen or farmers, and eating uncooked fish within the preceding year. A significant difference resulting from a health education program was observed in the third year. Therefore, health education and sustainable surveillance for opisthorchiasis should be maintained to decrease the risk of reinfection.

Repositioning of Anthelmintic Drugs for the Treatment of Cancers of the Digestive System

Tumors of the digestive system, when combined together, account for more new cases and deaths per year than tumors arising in any other system of the body and their incidence continues to increase. Despite major efforts aimed at discovering and validating novel and effective drugs against these malignancies, the process of developing such drugs remains lengthy and costly, with high attrition rates. Drug repositioning (also known as drug repurposing), that is, the process of finding new uses for approved drugs, has been gaining popularity in oncological drug development as it provides the opportunity to expedite promising anti-cancer agents into clinical trials. Among the drugs considered for repurposing in oncology, compounds belonging to some classes of anthelmintics—a group of agents acting against infections caused by parasitic worms (helminths) that colonize the mammalian intestine—have shown pronounced anti-tumor activities and attracted particular attention due to their ability to target key oncogenic signal transduction pathways. In this review, we summarize and discuss the available experimental and clinical evidence about the use of anthelmintic drugs for the treatment of cancers of the digestive system.

Behavior-related risk factors for opisthorchiasis-associated cholangiocarcinoma among rural people living along the mekong river in five greater mekong subregion countries

Opisthorchiasis-associated cholangiocarcinoma (OV-CCA) is a major public health problem in Greater Mekong Subregion (GMS) Countries, the poorest region in Asia. People in this region have similar traditions or respect the same religion. There is no difference in lifestyle and food culture. Excluding Thailand, publications on risk factors for OV-CCA from the GMS Countries are few, especially data on behavioral risk factors for OV-CCA. Therefore, this study aimed to assess the behavior-related risk factors and to compare the risk of OV-CCA among rural people living along the Mekong River in five GMS countries. It was a cross-sectional analytic study during June and October 2017. All participants with informed consent completed the questionnaires. Descriptive statistics were used to describe the prevalence of risk factors. Odds ratio with 95% confidence intervals were used to compare the risk of OV-CCA. It was found that there were more drinkers than non-drinkers in all areas, except in Vietnam. The highest history of liver fluke infection was found in Cambodia. Praziquantel use and consumption of raw freshwater fish dishes were mostly found in Lao PDR. The highest consumption of nitrosamine-contaminated foodstuffs was found in Ubon Ratchathani, Thailand. The spatial comparison of OV-CCA risk showed that Lao PDR and Ubon Ratchathani were two risk areas when compared to Tachileik, Myanmar (a reference area). This study provided the behavior-related risk factors for OV-CCA among people in five GMS Countries which would be a major jigsaw puzzle leading to proactive surveillance for OV-CCA prevention in the future.

Association between periductal fibrosis and bile duct dilatation among a population at high risk of cholangiocarcinoma: a cross-sectional study of cholangiocarcinoma screening in Northeast Thailand

OBJECTIVES

To assess associations between periductal fibrosis (PDF) and bile duct dilatation (BDD) in ultrasonography (US) screening of population at risk of cholangiocarcinoma (CCA) due to residence in an endemic area for Opisthorchis viverrini. CCA survival rates are low, and early identification of risk factors is essential. BDD is one symptom that can identify patients at risk of CCA. Detection of PDF by US can also identify at-risk patients, at an earlier stage of CCA development. Identification of association between PDF and BDD will inform screening practices for CCA risk, by increasing the viability of PDF screening for CCA risk.

SETTING

Nine tertiary care hospitals in Northeast Thailand.

DESIGN

Cross-sectional study.

PARTICIPANTS

Study subjects in the Cholangiocarcinoma Screening and Care Program (CASCAP) in Northeast Thailand. CASCAP inclusion criteria are all residents of Northeast Thailand aged ≥40 years. Participants are recruited through CCA screening centres and through primary healthcare units. So far, 394 026 have been enrolled.

METHODS

PDF and BDD were identified through US. PDF was categorised into three groups, PDF1, 2 and 3, depending on their high echo locality in the peripheral, segmental and main bile duct, respectively. Associations between PDF and BDD were determined by adjusted OR and 95% CI using multiple logistic regression.

RESULTS

BDD was found in 6.6% of PDF3, 1.7% of PDF2 and 1.4% of PDF1 cases. Among PDF cases, especially in PDF3, BDD was found in men more than in women (8.9% and 4.6%, respectively). Compared with non-PDF, the association between PDF3 and BDD was highly significant (adjusted OR=5.74, 95% CI 4.57 to 7.21, p<0.001).

CONCLUSIONS

Our findings reveal that there is a relationship between PDF and BDD, which is associated with CCA. Therefore, PDF can also be an indicator for suspected CCA diagnosis through US.

Repeated praziquantel treatment and Opisthorchis viverrini infection: a population-based cross-sectional study in northeast Thailand

Background

Opisthorchis viverrini infection is highly prevalent in northeast Thailand. This liver fluke is classified as a carcinogen due to its causal links with cholangiocarcinoma (CCA) development. Although treatment with praziquantel (PZQ) effectively cures O. viverrini infection, the prevalence remains high due to the traditional consumption of raw fish. Therefore, re-infection is common in the endemic community, leading to severe hepato-biliary morbidities including the fatal CCA. In this study, we evaluate the association between the frequency of previous PZQ treatment and current O. viverrini infections among Thai adults living in the endemic area of northeast Thailand.

Methods

This study includes all participants who were screened for O. viverrini infection in the Cholangiocarcinoma Screening and Care Program (CASCAP), northeast Thailand. History of PZQ treatment was recorded using a health questionnaire. O. viverrini infections were diagnosed using urine antigen detection. Associations between PZQ and O. viverrini were determined by adjusted odds ratio (aOR) and 95% confidence interval (CI) using multiple logistic regression.

Results

Among participants, 27.7% had previously been treated once with PZQ, 8.2% twice, 2.8% three times, and 3.5% more than three times. Current O. viverrini prevalence was 17% (n = 524). Compared with participants who never used PZQ, the aOR for infection among those who used the drug once was 1.09 (95% CI: 0.88–1.37), twice was 1.19 (95% CI: 0.85–1.68), three times was 1.28 (95% CI: 0.74–2.21), and more than three times was 1.86 (95% CI: 1.18–2.93; P = 0.007).

Conclusions

The population with a frequent history of PZQ use and still continued raw fish consumption showed high levels of repeated reinfection with O. viverrini. They were infected, treated and re-infected repeatedly. These findings suggest that certain participants continue raw fish consumption even after previous infection. This is a particular problem in highly endemic areas for O. viverrini and increases the risk of CCA.

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0529-5) contains supplementary material, which is available to authorized users.

Liver Fluke-Associated Biliary Tract Cancer

Cholangiocarcinoma (CCA) is an aggressive cancer arising from epithelial cells of the bile duct. Most patients with CCA have an unresectable tumor at the time of diagnosis. In Western countries, the risk of CCA increases in patients with primary sclerosing cholangitis, whereas liver fluke infection appears to be the major risk factor for CCA in Asian countries. A diagnosis of liver fluke infection often relies on stool samples, including microscopic examination, polymerase chain reaction-based assays, and fluke antigen detection. Tests of serum, saliva and urine samples are also potentially diagnostic. The presence of liver fluke along with exogenous carcinogens magnifies the risk of CCA in people living in endemic areas. The “liver fluke-cholangiocarcinoma” carcinogenesis pathways consist of mechanical damage to the bile duct epithelium, immunopathologic and cellular reactions to the liver fluke’s antigens and excretory/secretory products, liver fluke-induced changes in the biliary tract microbiome and the effects of repeated treatment for liver fluke. A vaccine and novel biomarkers are needed for the primary and secondary prevention of CCA in endemic areas. Importantly, climate change exerts an effect on vector-borne parasitic diseases, and awareness of liver fluke should be enhanced in potentially migrated habitat areas.

Structural Analysis of an Epitope Candidate of Triosephosphate Isomerase in Opisthorchis viverrini

Opisthorchis viverrini, a parasitic trematode, was recategorized as a group 1 biological carcinogen because it causes opisthorchiasis, which may result in cholangiocarcinoma. A new strategy for controlling opisthorchiasis is needed because of issues such as drug resistance and reinfection. Triosephosphate isomerase (TIM), a key enzyme in energy metabolism, is regarded as a potential drug target and vaccine candidate against various pathogens. Here, we determined the crystal structures of wild-type and 3 variants of TIMs from O. viverrini (OvTIM) at high resolution. The unique tripeptide of parasite trematodes, the SAD motif, was located on the surface of OvTIM and contributed to forming a 3₁₀-helix of the following loop in a sequence-independent manner. Through thermal stability and structural analyses of OvTIM variants, we found that the SAD motif induced local structural alterations of the surface and was involved in the overall stability of OvTIM in a complementary manner with another parasite-specific residue, N115. Comparison of the surface characteristics between OvTIM and Homo sapiens TIM (HsTIM) and structure-based epitope prediction suggested that the SAD motif functions as an epitope.

Association between Repeated Praziquantel treatment and Papillary, and Intrahepatic Cholangiocarcinoma

INTRODUCTION AND AIM

The carcinogenesis of tubular and papillary cholangiocarcinoma (CCA) differ. The available epidemiologic studies about risk factors for CCA do not differentiate between the tubular and papillary type. The current study investigated the relationship between the number of repeated use of Praziquantel (PZQ) treatments and each type of CCA.

MATERIAL AND METHODS

This was a hospital-based, matched, case-control study of patients admitted to Srinagarind Hospital, Khon Kaen University. The patients were 210 pathologically-confirmed cases of CCA, while the controls were 840 subjects diagnosed with other diseases. The 4 controls were individually matched with each case by sex, age, and date of admission. The cases were classified according to location (intrahepatic vs. extrahepatic) and cell type (papillary vs. tubular). Multivariable conditional logistic regression was used for the analysis.

RESULTS

After adjusting for confounders, there were statistically significant associations between intrahepatic and papillary CCA and repeated use of PZQ treatment. The respective odds of developing intrahepatic CCA for those who used PZQ once, twice, or more was 1.54 (95%CI:0.92-2.55 ), 2.28 (95%CI:0.91-5.73), and 4.21 (95%CI:1.61-11.05). The respective odds of developing papillary CCA for those who used PZQ once, twice, or more was 1.45 (95%CI:0.80-2.63), 2.96 (95%CI:1.06-8.24), and 3.24 (95%CI:1.09-9.66). There was no association between number of uses of PZQ treatment and developing extrahepatic or tubular CCA.

CONCLUSION

The current study found an association between papillary and intrahepatic CCA and repeated use of PZQ treatment. We suggest further study on the risk factors for papillary and tubular CCA should be performed separately.

Cholangiocarcinoma Trends, Incidence, and Relative Survival in Khon Kaen, Thailand From 1989 Through 2013: A Population-Based Cancer Registry Study

Background

Cholangiocarcinoma (CCA) is a common malignancy in northeastern Thailand. Over the last 4 decades, several policies have been implemented for its prevention, but there has been no update on the trends and relative survival (RS). Our aim was (a) to perform a statistical assessment of the incidence trends of CCA and project future trends, and (b) to estimate relative survival.

Methods

All cases of CCA diagnosed from 1989 through 2013 were abstracted from the Khon Kaen Cancer Registry (KKCR). A jointpoint regression model was used to estimate the annual percentage change (APC) and to project future trends. We also calculated RS.

Results

There were 11,711 cases of CCA. The incidence rate increased with an APC of 1.79% (95% confidence interval [CI], −0.2 to 3.8) from 1989 through 2002, and decreased with an APC of −6.09% (95% CI, −8.2 to −3.9) from 2002 through 2013. The projected incidence of CCA should stable over the next 10 years, albeit higher than the world rate. The respective 5-year RS for both sexes for age groups of 30–40, 41–45, 51–60, and 61–98 years was 22.3% (95% CI, 16.8–29.5), 14.3% (95% CI, 12.0–17.0), 8.6% (95% CI, 7.8–10.0), and 7.2% (95% CI, 6.4–8.0).

Conclusion

The incidence rate of CCA has decreased since 2002, representing a real decline in the risk of CCA. The incidence of CCA is projected to stabilize by 2025. The survival of patients with CCA remains poor.

Recent Advances in the Diagnosis and Detection of Opisthorchis viverrini Sensu Lato in Human and Intermediate Hosts for Use in Control and Elimination Programs

Opisthorchiasis is a neglected tropical disease, caused by infection with the fish-borne trematode Opisthorchis viverrini sensu lato that afflicts more than 10million people in Southeast Asia, including Thailand, Lao PDR, Vietnam and Cambodia. The disease is characterized by a chronic infection that induces hepatobiliary inflammation, especially periductal fibrosis, which can be detected by ultrasonography. This chronic inflammation eventually leads to cholangiocarcinoma (CCA), a usually fatal bile duct cancer that develops in approximately 1% of O. viverrini-infected individuals. In Thailand alone, CCA kills up to 20,000 people every year and is therefore of substantial public health importance. Its socioeconomic impacts on impoverished families and communities are considerable. To reduce O. viverrini-associated morbidity and CCA, the primary intervention measures focus on opisthorchiasis control and elimination. Accurate diagnoses of O. viverrini infection, in both mammalian, snail and fish intermediate hosts, are important for achieving these goals. Despite extensive efforts over several decades to find sensitive and specific diagnostics for opisthorchiasis, a simple and robust diagnostic method is still required. Here we review earlier and current developments in the search for new diagnostics for opisthorchiasis, with practical applications in the research laboratory, the clinic and the field. Of the methods currently available, the urine antigen assay shows considerable potential for the diagnosis and screening of opisthorchiasis. Nevertheless, these new assays require validation, determination of their cost-effectiveness when applied for mass screening in an endemic setting in support of policy decisions for national public health programs aimed at the control and elimination of opisthorchiasis.

Opisthorchiasis and cholangiocarcinoma in Southeast Asia: an unresolved problem

The prevalence of cholangiocarcinoma (CCA) in Southeast Asia is much higher than other areas of the world. Eating raw, fermented, or undercooked cyprinid fish, infected with the liver fluke, Opisthorchis viverrini sensu lato (sl), results in chronic biliary inflammation, periductal fibrosis, and increased cancer risk. There may be associated glomerulonephritis. The process of infection is difficult to disrupt because eating practices have proven extremely difficult to change, and the life cycle of the fluke cannot be broken due to high prevalence in canine and feline reservoir hosts. Fecal analysis and enzyme-linked immunosorbent assay tests can be used to diagnose opisthorchiasis. Diagnosis of CCA is complex, partly due to the lack of definitive imaging characteristics but also due to the difficulty of obtaining samples for cytology or histology. This cancer has proven to be resistant to common chemotherapy treatments and so the two avenues of treatment available are surgical resection and liver transplantation, both requiring early detection of the tumor for the best chances of success. Late presentation of symptoms reduces the chances of successful surgical intervention. While liver fluke infections can be treated with praziquantel, individuals will often become reinfected, and multiple reinfections can be more harmful than a singular, long-term infection. A key research on the detection and characterization of novel biomarkers in all parts of the carcinogenic pathway for early diagnosis is needed.

The role of domestic dogs in the transmission of zoonotic helminthes in a rural area of Mekong river basin

Dogs have been bred since ancient times for companionship, hunting, protection, shepherding and other human activities. Some canine helminth parasites can cause significant clinical diseases in humans as Opisthorchis viverrini causing cholangiocarcinoma in Southeast Asian Countries. In this study, socio-cultural questionnaire, canine parasitological analysis, necropsy, parasite molecular confirmation and dog roaming data were evaluated in Savannakhet, Lao-PDR, a typical Mekong Basin area. Dog owners comprised 48.8% of the studied population, with 61.2% owning one dog, 25.1% 2 dogs, 8.5% 3 dogs and 1.8% owning more than 4 dogs. Data from GPS logger attached to dogs showed they walked from 1.4 to 13.3 km per day, covering an area of 3356.38m2 average, with a routine of accessing water sources. Thirteen zoonotic helminth species were observed. Causative agents of visceral and cutaneous larva migrans occurred in 44.1% and 70% of the samples respectively. Spirometra erinaceieuropaei was detected in 44.1% of samples. Importantly, O. viverrini was found in 8.8% of samples. Besides the known importance of dogs in the transmission of Ancylostoma spp., Toxocara spp. and S. erinaceieuropaei, the observed roaming pattern of dogs confirmed it as an important host perpetuating O. viverrini in endemic areas; their routine access to waterbodies may spread O. viverrini eggs in a favorable environment for the fluke development, facilitating the infection of fishes, and consequently infecting humans living in the same ecosystem. Therefore, parasitic NTDs control programs in humans should be done in parallel with parasite control in animals, especially dogs, in the Mekong River basin area.

Prevalence and Factors Associated with Opisthorchis viverrini Infection in Khammouane Province, Lao PDR

Opisthorchis viverrini (OV) liver flukes are common parasites found in central and southern Laos and constitute a major public health problem in the country. Laos people continue to have the habit of extensively consuming raw or half-cooked fish which are intermediate hosts. This study aimed to study the prevalence and factors associated with OV infection in the population of Thakek district, Khammouane Province. This cross-sectional analytic study covered 237 subjects who filled out structured questionnaires. Fecal examination for OV infection was performed by Kato's thick smear method. Data analysis was carried out using STATA Version 10.0. Multiple logistic regression was applied. The results showed that the infection rate of OV was 54.8 %. Factors associated with OV infections were gender, a habit of defecation in fields and raw fish (goi bplaa dip) consumption. Opisthorchiasis and associated cholangiocarcinoma development thus appear to remain as important concerns in Laos.

[Control of Opisthorchis viverrini infection for cholangiocarcinoma prevention]

The International Agency for Research on Cancer (IARC) has classified two liver flukes as carcinogenic to humans (Group 1): Opisthorchis viverrini in 1994 and Clonorchis sinensis in 2009. This review is focused on O. viverrini, the most studied of these two trematodes, which infects nearly 10 million people in Southeast Asia. The life cycle involves two intermediate hosts living in fresh water: a snail of the genus Bithynia and a ciprinid fish. The definitive hosts (human, cat, dog) become infected by ingesting raw fish containing metacercariae, the infective stage of the parasite. Adult flukes attach to the epithelium of the bile ducts where they feed for as long as 10 to 30 years, resulting in chronic inflammation, epithelial hyperplasia, periductal fibrosis and formation of granuloma. For a long asymptomatic, the distomatosis is revealed by a chronic cholangitis when the parasite load becomes high. Complications can occur with time: gallstones, cholangitis, liver abscess, pancreatitis and, after a few decades, cholangiocarcinoma (CCA). The epidemiological correlation between the prevalence of O. viverrini infection and the incidence of CCA has been demonstrated in the northeast of Thailand. Specifically, the Khon Kaen province has the highest incidence rate in the world. The CCA can develop asymptomatically for a long time, especially in intrahepatic locations. It is often discovered at a late stage, unresectable. Its prognosis is dreadful with a survival rate less than 5% at 5 years. The phenomenon of carcinogenesis induced by O. viverrini is multifactorial. It has been specially studied using experimental infection on the Syrian golden hamster. Three intricated mechanisms are involved: (i) the direct damage caused by adult worms on the bile duct epithelium, (ii) the immunopathologic processes related to chronic inflammation (oxidative stress) and (iii) the mitogenic and anti-apoptotic effects of the proteins secreted by the parasite. Exogenous cofactors are also involved, such as nitrosamines in fish-based dishes undercoocked or fermented, very popular in these endemic regions. Despite the effectiveness of praziquantel to successfully cure this distomatose, opisthorchiasis persists endemic in areas where the incidence of CCA tends to progress. Mass deworming campaigns are ineffective due to the frequency of reinfection in the exposed population. Repeating alternatively cures and reinfections may promote carcinogenesis. The failure of prevention programs reflects the difficulty of changing the traditional habits of consuming raw or fermented fish. Pending a vaccine prophylaxis, control strategies are based on integrated measures involving the treatment of reservoir hosts, sanitation and efforts of continuing information and education to deter the consumption of uncooked fish and to improve the sanitation in rural areas.

Surveillance of Populations at Risk of Cholangiocarcinoma Development in Rural Communities of Thailand Using the Korat-CCA Verbal Screening Test

Cholangiocarcinoma (CCA) is a serious problem in Thailand, particularly in the northeastern region. Active surveillance in rural communities with an appropriat low-cost screening tool is required to facilitate early detection. Therefore, this study aimed to investigate the population at risk of CCA in Bua Yai district, Nakhon Ratchasima province, Northeastern Thailand using the Korat-CCA verbal screening test (KCVST) during June to October 2015. Reliability of KCVST demonstrated a Cronbach alpha coefficient=0.75 Stepwise-multiple regression showed that alcohol consumption was important for CCA screened, followed by agriculture and pesticide use, under-cooked cyprinoid fish consumption, praziquantel use, naïve northeastern people, opisthorchiasis, family relatives with CCA, and cholangitis or cholecystitis or gallstones, respectively. Population at risk for CCA was classified to low risk (63.4%), moderate risk (33.7%), and high risk (1.32%) for CCA. When CCA was screened using ultrasonography, 4 of 32 high risk participants had an abnormal biliary tract with dilated bile ducts. This study indicates that KCVST is a potential useful too which decrease the cost of large scale CCA screening.

Decreased risk of cholangiocarcinogenesis following repeated cycles of Opisthorchis viverrini infection-praziquantel treatment: Magnetic Resonance Imaging (MRI) and histopathological study in a hamster model

It has been suggested that repeated infection of Opisthorchis viverrini followed by repeated treatment with praziquantel (PZQ) increases risk of development of cholangiocarcinoma (CCA). Evidence for the prediction has accumulated based on findings of indirect approaches involving molecular changes and epidemiological trends. By contrast, here we directly monitored the impact of repeated liver fluke infection and treatment with PZQ on cholangiocarcinogenesis in a rodent model of human opisthorchiasis, using magnetic resonance imaging (MRI) and histopathology. Twenty five Syrian golden hamsters were assigned to five treatment groups: 1) infection with O. viverrini (OV group), 2) treatment with the carcinogen N-nitrosodimethylamine (NDMA) at 12.5ppm (DMN), 3) O. viverrini infection in tandem with NDMA (OD), 4) O. viverrini infection, NDMA, and treatment with PZQ (ODP), and 5) uninfected, untreated control. The repeated infections were established by intragastric inoculation of 50 metacercariae of O. viverrini to the OV, OD and ODP hamsters at weeks 0, 5 and 10. PZQ at 300mg/kg body weight was given to each hamster of the ODP group on weeks 4, 9 and 13 (four weeks after each infection). Imaging by MRI was undertaken on weeks 5, 10 and 14 (i.e. one week after each PZQ treatment). MRI revealed that the ODP hamsters did not develop CCA, whereas necropsy at week 40 revealed CCA in hamsters of the OD and DMN groups. Findings for histopathology and for proliferating cell nuclear antigen index conformed to the MRI findings. In overview, and notwithstanding that the immune response of individual hosts may play roles in cholangiocarcinogenesis, three cycles of the infection with O. viverrini followed treatment of the infection with PZQ did not increase the risk of bile duct cancer in this hamster model of liver fluke infection-induced CCA.