Risk factors for Clonorchis sinensis infection transmission in humans in northern Vietnam: A descriptive and social network analysis study

Epidemiology and risk factors of Clonorchis sinensis infection in the mountainous areas of Longsheng County, Guangxi: insights from automated machine learning

Clonorchis sinensis (C. sinensis) is mainly prevalent in Northeast and South China, with Guangxi being the most severely affected region. This study aimed to evaluate the prevalence and identify the risk factors of C. sinensis infection in Longsheng County, a mountainous area in northern Guangxi. In 2023, a comprehensive study was conducted in Longsheng County, utilizing longstanding inhabitants as study participants. Questionnaires were employed to gather data on fish consumption, awareness of C. sinensis, and residential coordinates, while fecal examinations were utilized to identify C. sinensis infection. Important risk factors for the C. sinensis infection were identified through the development of individual infection risk models using automated machine learning techniques. A total of 740 fecal samples were collected, revealing an overall C. sinensis infection rate of 69.59%. The gradient boosting machine (GBM) was the most accurate predictor with an area under the precision-recall Curve (AUPRC) of 0.997. The model identified years of raw fresh fish consumption, frequency of raw fresh fish consumption, elevation, and water distance as the top four predictors of C. sinensis infection risk. In conclusion, our study has revealed a high infection rate of C. sinensis in the mountainous areas of Longsheng County, with adults, men, and farmers particularly susceptible to both high incidence and infection severity. We developed a high-performance predictive model for individual C. sinensis infection within the county, identifying the key risk factors for local infections. These findings offer valuable guidance for the control and prevention of clonorchiasis.

Risk factors for Clonorchis sinensis infections and control measures reinforced with focused interviews

Clonorchiosis, a disease that develops following the consumption of raw freshwater fish that harbors Clonorchis sinensis metacercariae, seriously threatens the health of residents in endemic areas. We aimed to assess the level of awareness of liver fluke infections among infected residents and restaurant workers in liver fluke infection-endemic areas. To identify and provide a more realistic description of C. sinensis infections, we conducted a focused interview and questionnaire survey of local residents in endemic areas in Korea. Most residents knew that freshwater fish are a source of C. sinensis infection. Nevertheless, the consumption of raw freshwater fish was the main risk factor for their infection with C. sinensis. The residents had little knowledge regarding their residential area being endemic to C. sinensis or about the symptoms and complications of C. sinensis infection. Although the participants had no experience with C. sinensis prevention or health education, they preferred on-site education during visits to village halls. The in-depth interviewees had a high level of knowledge about C. sinensis infection but were unaware that eating raw freshwater fish was its cause. Family and social gatherings encourage the habit of eating raw freshwater fish, which is a risk factor for repetitive infections. Based on these findings, to eliminate clonorchiosis, we propose strengthening the capacity of public health care personnel, giving C. sinensis prevention education, and screening educational videos during visits to village halls. Furthermore, intensive education is recommended for reinfected people and community opinion leaders, as well as reservoir host control.

Amphimeriasis in Ecuador-Prevalence, Knowledge, and Socio-Cultural Practices Among Indigenous Chachi and Montubios Populations: A Mixed-Methods Cross-Sectional Study

Amphimerus, a liver fluke, is the causative agent of amphimeriasis, a foodborne disease acquired thought the consumption of infected raw or undercooked river fish-a practice embedded in traditional culinary customs. Amphimeriasis represents a significant public health issue and has been endemic in Ecuador since 2011, particularly among the Chachi Amerindians and Montubios populations residing in tropical ecoregions. By employing a mixed-methods research design, we conducted a community-based, cross-sectional study. A survey comprising of 63 questions on KAP was administrated in person to community members, health personnel, and academic staff in the two populations. Additionally, 67 semi-structured interviews were performed. Microscopy was achieved on 273 human and 80 dog fecal samples to detect Amphimerus eggs. A total of 86 questionnaires (54 Chachi) and 67 interviews (44 Chachi), out of 300 residents, were completed. Among the respondents, 31.4% were aware of Amphimerus, locally referred to as "liver worm". Although 79.1% reported not consuming raw fish, most admitted eating raw fish with lime juice and salt, a preparation known as "curtido", and 59.3% reported consuming smoked fish. Here, 86.1% of participants considered "liver worm" a serious disease, and 55.8% recognized raw or marinated fish as a potential transmission route. The Chachi showed a preference for smoked fish, whereas the Montubios favoured "curtido". The prevalence of Amphimerus infection was 23% in humans and 16.2% in dogs. Differences in KAP were observed between infected and non-infected individuals. Local health and academic personnel demonstrated insufficient knowledge about amphimeriasis. Some religious individuals refrained from participating, stating that they were "with God". Despite the high prevalence of Amphimerus infection in both humans and dogs, knowledge about the parasite, the disease, and its transmission routes remains limited. Health education initiatives should be designed to modify the population's KAP. It is crucial for national and local health authorities, as well as religious leaders, to be informed and actively involved in the prevention and control of amphimeriasis.

Effectiveness of health education in improving knowledge, attitude and practice related to foodborne zoonotic trematodes in Vietnam, with a particular focus on Clonorchis sinensis

OBJECTIVE

Foodborne zoonotic trematodes (FZT), which infect the liver, lungs and intestines of humans, are an emerging public health concern in tropical countries including Vietnam. In northern Vietnam, Clonorchis sinensis is recognised as the most important species of the FZT. Up to now, small-scale studies conducted in the country have indicated that health education could improve participants' knowledge and practices related to clonorchiasis, however strong evidence is still lacking. We conducted an intervention trial between 2020 and 2021 in four communes in Yen Bai and Thanh Hoa province, aiming to evaluate the impact of an extended educational package on knowledge, attitude and practices related to clonorchiasis, as well as on knowledge on the large liver fluke and minute intestinal flukes.

METHODS

To this end, baseline and post-intervention questionnaires were conducted. Generalised estimating equations models were run to analyse the impact of the intervention on knowledge, attitudes and practices over time in the intervention versus control group. Finally, 172 people in the intervention group and 162 in the control group were included for analysis.

RESULTS

Results demonstrated that the intervention significantly improved clonorchiasis knowledge, attitudes and practices, with higher odds for a correct knowledge response (odds ratio (OR) = 2.80, 95% confidence interval (CI) = 1.84-4.27, p-value < 0.001), increased average mean attitude score (mean = 0.363, 95%CI = 0.182-0.544, p-value < 0.001), and a reduced odds of consuming raw fish (OR = 0.15, 95%CI = 0.06-0.40, p = 0.002) in the intervention group compared to the control group post-intervention versus baseline. Additionally, participants in the intervention group exhibited enhanced basic knowledge of the large liver fluke and minute intestinal flukes post-intervention.

CONCLUSIONS

These findings demonstrate the potential of health education programs in preventing clonorchiasis in endemic areas, emphasising the importance of continued health education as a critical component of integrated control programs for clonorchiasis.

Clonorchiasis and opisthorchiasis: epidemiology, transmission, clinical features, morbidity, diagnosis, treatment, and control

Clonorchis sinensis, Opisthorchis viverrini, and Opisthorchis felineus are important liver flukes that cause a considerable public health burden in eastern Asia, southeastern Asia, and eastern Europe, respectively. The life cycles are complex, involving humans, animal reservoirs, and two kinds of intermediate hosts. An interplay of biological, cultural, ecological, economic, and social factors drives transmission. Chronic infections are associated with liver and biliary complications, most importantly cholangiocarcinoma. With regard to diagnosis, stool microscopy is widely used in epidemiologic surveys and for individual diagnosis. Immunologic techniques are employed for screening purposes, and molecular techniques facilitate species differentiation in reference laboratories. The mainstay of control is preventive chemotherapy with praziquantel, usually combined with behavioral change through information, education and communication, and environmental control. Tribendimidine, a drug registered in the People's Republic of China for soil-transmitted helminth infections, shows potential against both C. sinensis and O. viverrini and, hence, warrants further clinical development. Novel control approaches include fish vaccine and biological control. Considerable advances have been made using multi-omics which may trigger the development of new interventions. Pressing research needs include mapping the current distribution, disentangling the transmission, accurately estimating the disease burden, and developing new diagnostic and treatment tools, which would aid to optimize control and elimination measures.

Modelling morbidity for neglected tropical diseases: the long and winding road from cumulative exposure to long-term pathology

Reducing the morbidities caused by neglected tropical diseases (NTDs) is a central aim of ongoing disease control programmes. The broad spectrum of pathogens under the umbrella of NTDs lead to a range of negative health outcomes, from malnutrition and anaemia to organ failure, blindness and carcinogenesis. For some NTDs, the most severe clinical manifestations develop over many years of chronic or repeated infection. For these diseases, the association between infection and risk of long-term pathology is generally complex, and the impact of multiple interacting factors, such as age, co-morbidities and host immune response, is often poorly quantified. Mathematical modelling has been used for many years to gain insights into the complex processes underlying the transmission dynamics of infectious diseases; however, long-term morbidities associated with chronic or cumulative exposure are generally not incorporated into dynamic models for NTDs. Here we consider the complexities and challenges for determining the relationship between cumulative pathogen exposure and morbidity at the individual and population levels, drawing on case studies for trachoma, schistosomiasis and foodborne trematodiasis. We explore potential frameworks for explicitly incorporating long-term morbidity into NTD transmission models, and consider the insights such frameworks may bring in terms of policy-relevant projections for the elimination era. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.

A Socio-Ecological Framework for Examining Foodborne Parasitic Infection Risk

Human liver fluke infection through the consumption of raw freshwater fish is one of the foodborne parasitic infections of global concern. Despite decades of health campaign efforts, high prevalence of infection remains in different areas of the Lower Mekong Basin. This necessitates the consideration of the infection differences between places and the human-environment complexities of disease transmission. This paper used the socio-ecological model as a framework to unraveled the social science dimensions of liver fluke infection. We conducted questionnaire surveys in Northeast Thailand to gather participants' knowledge on liver fluke infection and reasons for raw fish consumption. We synthesized our findings with prior work to identify factors influencing liver fluke infection at four socio-ecological levels. At the individual level, gender and age differences in food consumption habits and personal hygiene of open defection presented the behavioral risks. At the interpersonal level, family tradition and social gathering affected the disease risk. At the community level, physical-social-economic environments of land use and modernization, community health infrastructure and health volunteer support accounted for the varying degree of infection. At the policy level, impacts of regional and national regulations on disease control, health system organization structure, and government development projects were of concerned. The findings provide insights into how infection risks are shaped by people's behavior, social connectedness, interactions with places, and the interplay of these multi-level socio-ecological influences. The framework therefore allows a more comprehensive understanding of liver fluke infection risks to inform a culturally sensitive and sustainable disease control program.

Examining ecosystem (dis-)services on liver fluke infection in rural Northeast Thailand

BACKGROUND

The direct reliance of humans on and their interactions with freshwater ecosystems in the Lower Mekong Basin have given rise to parasitic infections, which is particularly prevalent in Northeast Thailand where raw fish consumption is practiced. This study examined the interactions between environments, ecosystem (dis-)services, human raw fish consumption habits, and raw fish dish sharing on liver fluke infection risk.

METHOD

Water fecal contents and the first intermediate snail host were sampled between June and September of 2019. One hundred twenty questionnaires were surveyed in two villages of different environmental surroundings, one next to a river and the other located inland, in Northeast Thailand. Multivariate regression analyses using linear mixed effect models assessed the influence of social, behavioral and perceptual factors on raw fish consumption frequency, willingness to avoid consumption and liver fluke infection status. Social network analysis compared the degree of raw fish dish sharing between the villages and assessed the probable influence of connections to fish procurement locations and sharing activities on liver fluke infection risk.

RESULTS

High abundance of the first intermediate snail host and presence of fecal contamination in water could endanger both villages to ecosystem disservices of parasitic transmission. The river-side village relied more on provisioning ecosystem services than the inland village (29.7% vs. 16.1% of villages) to consume raw fish as their main source of protein. Males in both villages (64.5 and 40.4 days/year for the respective villages) are also likely to consume koi pla and pla som, higher risk fish dishes, more frequently than females (4.1 and 4.3 days/year for the respective villages). The consumption habits of both villages were driven mostly by deriving cultural ecosystem services. Participation in raw fish dish sharing activities significantly reduced the odds of an individual being willing to avoid the consumption (Odds ratio = 0.19). Network analysis suggested that river-side villagers had a more direct raw fish dish sharing interaction and they procured fish from multiple locations; these characteristics might potentially account for more liver fluke infected households in the village.

CONCLUSION

Villagers' raw fish consumption is driven by deriving cultural ecosystem services, and the geographic settings of the villages potentially affect villagers' fish procurement locations and infection risk. The findings underscore the linkages between villagers and their surrounding ecosystem environments as pertinent determinants for foodborne parasitic disease risk.

Incidence of fish-borne trematode infections and associated factors: results from a cohort study in highly endemic communities in northern Vietnam

Fish-borne trematodes (FiBT) are an important group of zoonotic parasites negatively affecting human health, mainly in Asia. Most studies on FiBT have applied a cross-sectional design, which provides weaker evidence on potential risk factors for transmission than a cohort study. This cohort study aimed to estimate the incidence and identify associated risk factors for FiBT infection in Vietnam. Between April 2018 and May 2019, two communes in Yen Bai province, a highly endemic area for FiBT, were visited for sampling. Participants with a negative stool result for FiBT at baseline, were invited for follow-up and data collection, at months 4, 9, and 13. Stools were examined using Kato-Katz and formalin-ethyl acetate concentration techniques to detect FiBT eggs, whereas a questionnaire was used for interviewing participants to determine the risk factors for FiBT infection during each follow-up period. The incidence risk and the incidence rate were calculated, and univariate and multivariable models were run to identify the risk factors for FiBT. A total of 194 people, negative for FiBT eggs at the baseline survey, were invited to participate in the study, and 111 people agreed to enroll in the follow-up. The incidence risk at months 4, 9, and 13 was 9.0%, 6.4%, and 5.1%, respectively. We finally used data from 95 participants for the risk factor analysis, excluding 16 people lost for the follow-up. Overall, 20 people became infected with FiBT (IR = 21.1%). The incidence rate of FiBT infection was 21.4/100 person-year. In the univariate analysis, consumption of raw fish was the main risk factor (RR = 4.59, 95%CI = 1.95-10.82), followed by being male (RR = 3.41, 95%CI = 1.56-7.45) and drinking alcohol (RR = 3.25, 95%CI = 1.49-7.11). In the multivariable analysis, only consumption of raw-fish dishes was significantly associated with FiBT infection. The people who consumed raw fish were 3.44 (95%CI = 1.11-10.70) times more at risk of infection with FiBT as compared to individuals who did not consume raw fish. It can be concluded that the FiBT incidence is high in the study area. More awareness campaigns are needed to stop eating raw fish in these areas to reduce FBT infection.

Global prevalence of 4 neglected foodborne trematodes targeted for control by WHO: A scoping review to highlight the gaps

BACKGROUND

Foodborne trematodiases (FBTs) are a group of trematodes targeted for control as part of the World Health Organization (WHO) road map for neglected tropical diseases from 2021 to 2030. Disease mapping; surveillance; and capacity, awareness, and advocacy building are critical to reach the 2030 targets. This review aims to synthesise available data on FBT prevalence, risk factors, prevention, testing, and treatment.

METHODS

We searched the scientific literature and extracted prevalence data as well as qualitative data on the geographical and sociocultural risk factors associated with infection, preventive/protective factors, and methods and challenges of diagnostics and treatment. We also extracted WHO Global Health Observatory data representing the countries that reported FBTs during 2010 to 2019.

RESULTS

One hundred and fifteen studies reporting data on any of the 4 FBTs of focus (Fasciola spp., Paragonimus spp., Clonorchis sp., and Opisthorchis spp.) were included in the final selection. Opisthorchiasis was the most commonly reported and researched FBT, with recorded study prevalence ranging from 0.66% to 88.7% in Asia, and this was the highest FBT prevalence overall. The highest recorded study prevalence for clonorchiasis was 59.6%, reported in Asia. Fascioliasis was reported in all regions, with the highest prevalence of 24.77% reported in the Americas. The least data was available on paragonimiasis, with the highest reported study prevalence of 14.9% in Africa. WHO Global Health Observatory data indicated 93/224 (42%) countries reported at least 1 FBT and 26 countries are likely co-endemic to 2 or more FBTs. However, only 3 countries had conducted prevalence estimates for multiple FBTs in the published literature between 2010 to 2020. Despite differing epidemiology, there were overlapping risk factors for all FBTs in all geographical areas, including proximity to rural and agricultural environments; consumption of raw contaminated food; and limited water, hygiene, and sanitation. Mass drug administration and increased awareness and health education were commonly reported preventive factors for all FBTs. FBTs were primarily diagnosed using faecal parasitological testing. Triclabendazole was the most reported treatment for fascioliasis, while praziquantel was the primary treatment for paragonimiasis, clonorchiasis, and opisthorchiasis. Low sensitivity of diagnostic tests as well as reinfection due to continued high-risk food consumption habits were common factors.

CONCLUSION

This review presents an up-to-date synthesis on the quantitative and qualitative evidence available for the 4 FBTs. The data show a large gap between what is being estimated and what is being reported. Although progress has been made with control programmes in several endemic areas, sustained effort is needed to improve surveillance data on FBTs and identify endemic and high-risk areas for environmental exposures, through a One Health approach, to achieve the 2030 goals of FBT prevention.

Epidemiology and determinants of Clonorchis sinensis infection: A community-based study in southeastern China

Clonorchiasis is caused by the ingestion of raw freshwater fish and causes high burden in East Asia. The epidemiological profiles and determinants of C. sinensis infection, knowledge, practice and attitude related to clonorchiasis were demonstrated in Hengxian county, Guangxi, China. The overall prevalence of C. sinensis was 60.3%, which was higher in male than in female and in elder population compared to children. The percentage knowing local transmission, transmission route and harm of C. sinensis was 20.9%, 31.4% and 32.5%. A percentage of 60.4% reported ingestion of raw freshwater fish, while 70.1% persons would like to accept treatment if infected with C. sinensis. Of the individuals ingesting raw freshwater fish, 82.0% did at home and 81.3% drunk alcohol when ingesting raw freshwater fish. Sixty-two percent showed the persistence on ingestion of raw freshwater fish in future. The ingestion of raw freshwater fish varied by seasons, with a proportion of 57.8% in spring, 48.3% in summer, 60.2% in autumn and 92.2% in winter. In multivariable regression models, age groups, history with C. sinensis treatment, and frequency on ingesting raw freshwater fish were related to C. sinensis infection, while gender, educational level, history with C. sinensis infection, and knowing local transmission were related to the practice of ingesting raw freshwater fish. Gender, history with C. sinensis treatment, frequency on ingesting raw freshwater fish, duration of ingesting raw freshwater fish and drinking alcohol when ingesting raw freshwater fish were associated to the attitude to the ingestion of raw freshwater fish in future. Great efforts are needed to combat clonorchiasis, in which the heterogeneity of population in knowledge, practice, attitude and infection needs to be considered. Men are of crucial importance in term of the morbidity control through chemotherapy. Meanwhile, massive education is expected to implement, which needs to promote the change of ingesting raw freshwater fish for sustainable control of clonorchiasis.

Epidemiological characterization of Clonorchis sinensis infection in humans and freshwater fish in Guangxi, China

Background

Clonorchiasis is a widespread yet neglected foodborne disease with over 85% of all cases found in China. Guangxi province, located in southeastern China, ranks among the highest endemic provinces. We explore the epidemiological status and determinants of Clonorchis sinensis (C. sinensis) infection in humans and freshwater fish in Guangxi, China.

Methods

Data on C. sinensis infection in humans from January 2008 to December 2017were extracted from the China Information System for Disease Control and Prevention. An active surveillance of C. sinensis infection in fish was conducted in 2016–2017. County level data including potential environmental, social-economical and behavioral determinants was also collected. Univariate and multivariate logistic regression models were used to explore the determinants of C. sinensis infection in humans and fish. Simple and multiple zero-inflated Poisson regression models were fit to assess the associated factors of clonorchiasis in humans at the county level.

Results

Totally, 4526 C. sinensis cases were reported between 2008 and 2017, with an annual prevalencerate of 0.96/100,000 persons. Of 101 counties in Guangxi, 97 reported at least 1 case. Among 2,098 fish samples, 203 (9.7%) from 70 counties contained C. sinensis. The rate was higher in small fish including Pseudorasbora parva (45.3%), Misgurnus anguillicaudatus (41.2%), Hemicculter leuciclus (34.5%), unclassified small fishes (30.9%), Cyprinidae (20.0%), Cirrhinus molitorella (16.4%), Carassius auratus (13.6%) and Cyprinus carpio (13.3%), while it was lower in fish species that are usually used in preparing raw fish dishes including Ctenopharyngodon idellus (3.6%), Spinibarbus denticulatus (3.7%), Monopterus albus (6.4%), Cyprinus carpio (4.4%), Oreochromis mossambicus (3.3%) and Spualiobarbus Curriculus (6.6%). The C. sinensis infection in fish was only associated with fish species. The estimated human clonorchiasis prevalence at the county level was positively associated with raw fish consumption habits and certain rivers.

Conclusions

Clonorchiasis is highly prevalent in both humans and freshwater fish in Guangxi. Environmental, social-economic and behavioral determinants contribute to the high prevalence as well as the significant differential distribution by county. Regular surveillance should be implemented for clonorchiasis to demonstrate the change in epidemiology and burden, which will benefit the design of interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07244-2.

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.

A risk scoring system for seafood supply chain breaches and examination of freshwater fish imported to Australia

Legislative changes have altered the way imported edible seafood is inspected in Australia. Greater onus of responsibility has been placed on exporting countries to provide documentary evidence of adherence to internally recognized food safety standards. According to global trade agreements, any additional safety tests applied to freshwater fish imported into Australia must be justified. Therefore, the aim of this study was to develop a risk scoring method to provide justification for identifying countries as ‘Freshwater fish high risk’ and to examine the seafood they export to Australia for seafood supply chain breaches. Scoring was conducted using six predictor variables, identified in the literature as important contributors to seafood supply chain breaches, to achieve the outcome variable, Country considered ‘Freshwater fish high risk’. Sixty-seven fish fillets (9.55 kg) of the same species were examined from the third highest scoring country (Country 20) and 562 (5.6 kg) whole fish from the sixth highest scoring country (Country 22). Country 20 had supply chain breaches of 28 macroscopic yellow cysts in one fillet. Two hundred and thirteen parasites and other supply chain breaches were identified in fish from Country 22, including retained liver (91 per cent), visible mud (11 per cent), a variety of debris (16 per cent) and, depending on the commodity code, these fish were imported to Australia under full intestine (90 per cent), retained gills (89 per cent), and partial intestine (9 per cent). Three serious physical hazards were recovered from the edible portion of three ‘consumer-ready’ fish and snails of Genus Lymnaea and Indoplanorbis were recovered from gill mud also from ‘consumer-ready’ fish. The study showed variable results from the scoring system and vast differences in seafood supply chain breaches between the third and sixth highest scoring countries.

Risk Factors for Clonorchis sinensis Infection in Residents of Binyang, Guangxi: A Cross-Sectional and Logistic Analysis Study

Background: Clonorchiasis is a serious food-borne parasitic disease caused by Clonorchis sinensis infection. C. sinensis, a major fish-borne trematode, is a known causative agent of cholangiocarcinoma. The risk factors for C. sinensis infection include individual eating behaviors and environmental factors. In this study, we evaluated the C. sinensis infection rate and the associated risk factors among residents in Binyang County, Guangxi, China.

Methods: In 2016 and 2017, five villages from Binyang, Guangxi were selected by multistage cluster random sampling for a cross-sectional study. A modified Kato-Katz thick smear method was used to examine C. sinensis eggs in fecal samples in triplicate (three smears for each sample). Both uni-variate and multi-variate logistic regression analyses were carried out to identify the risk factors for C. sinensis infection.

Results: A total of 1,977 fecal samples were collected from villagers in the investigated areas. The overall infection rates of C. sinensis in Binyang County was 20.49% (405/1,977). The mean age of participants was 39.42 ± 23.48 (range: 3–89 years old), and the highest infection rate (33.72%) was seen in the age group of 40-49 years old, followed by those aged 50–59 (31.83%). Multi-variate logistic regression analysis showed that higher infection rates were significantly associated with males (aOR = 6.51, 95% CI = 4.67–9.08), Zhuang (aOR = 2.41, 95% CI = 1.62–3.59), ages (aOR = 33.51, 95% CI = 10.13–110.86), frequency of raw fresh fish consumption (aOR = 14.56, 95% CI = 9.80–21.63), and close contact with cats and dogs (aOR = 1.53, 95% CI = 1.02–2.30). Occupations and education levels showed no significant association with C. sinensis infection (P > 0.05).

Conclusions: High levels of C. sinensis infection were observed among residents in Binyang County, Guangxi. Intervention strategies should be strengthened among the investigated population at high risk, such as males, Zhuang and older individuals, especially those who frequently eat raw fresh fish. In addition, the individuals contacting with cats and/or dogs were observed to have significantly higher infection rate of C. sinensis than those having no contact with cats and dogs. The association between contacting with cats and/or dogs and C. sinensis infection needs to be explored and confirmed in the future study by more epidemiological investigations of human C. sinensis infection from different areas.

Epidemiology and determinants of clonorchiasis in school children in southeastern China

Clonorchiasis is an important food-borne parasitic disease in China because of the popularity in ingesting raw freshwater fish. To explore the epidemiology and determinants of clonorchiasis in children, a cross-sectional survey was implemented in two middle schools in Qiyang county, Hunan province, in southeastern China. Questionnaire survey and fecal examination were implemented. Questionnaires were fed back by 627 students, while stool samples were collected from 557 students, out of which 545 ones also provided questionnaire information. The percentage of students ingesting raw freshwater fish was 40.5% (254/627), while the prevalence with Clonorchis sinensis infection was 18.9% (105/557). Such factors contributed significantly to the students' practice in eating raw freshwater fish including boys, fathers' eating raw freshwater fish, mothers' eating raw freshwater fish, and preparation of raw freshwater fish at home, with an adjusted odds ratio of 1.9 (95% confidence intervals (95% CI): 1.3-2.8), 3.9 (95% CI: 2.3-6.5), 3.0 (95% CI: 1.8-4.8) and 2.8 (95% CI: 1.8-4.5), correspondingly. Ingestion of raw freshwater fish, fathers' eating raw freshwater fish and preparation of raw freshwater fish at home were risk factors of C. sinensis infection in students, and the adjusted odds ratio was 3.2 (95% CI: 1.9-5.5), 2.1 (95% CI: 1.1-3.9) and 1.8 (95% CI: 1.0-3.2), respectively. Thus, clonorchiasis was endemic in the surveyed schools due to the ingestion of raw freshwater fish, which is influenced by family environment. Education should be implemented in schools to promote behavioral change of eating raw freshwater fish.

Risk Factors of Clonorchis sinensis Human Infections in Endemic Areas, Haman-Gun, Republic of Korea: A Case-Control Study

Clonorchis sinensis is the most common fish-borne intestinal parasite in Korea. The aim of the present investigation was to survey the status of C. sinensis infection and analyze associated risk factors in residents of Haman-gun, Gyeongsangnam-do. A total of 5,114 residents from 10 administrative towns/villages voluntarily agreed to participate in the study, which comprised fecal examination, a questionnaire survey for risk factors, ultrasonography, and enzymelinked immunosorbent assay for cancer biomarker detection in the blood. We detected C. sinensis eggs in 5.3% of the subjects. By region, Gunbuk-myeon had the highest number of residents with C. sinensis eggs. The infection rate and intensity were higher in male than in female residents. Based on the risk factor questionnaire, infection was highly associated with drinking, a history of C. sinensis infection, and the practice of eating of raw freshwater fish. Extension of the bile duct, infection intensity, and cancer biomarker detection significantly correlated with the presence of eggs in the study population. In conclusion, the development of feasible, long-term control policies and strategies for the elimination of C. sinensis in Korea is still required.

Prevalence and risk factors associated with Clonorchis sinensis infections in rural communities in northern Vietnam

BACKGROUND

Clonorchiasis, caused by the fish-borne trematode Clonorchis sinensis, is a neglected tropical disease and a public health issue in endemic countries. In Vietnam, an in-depth analysis of risk factors for the condition is missing up to now. This study aimed to determine the prevalence of C. sinensis infection and associated risk factors in rural communities in northern Vietnam.

METHODOLOGY/PRINCIPAL FINDINGS

A cross-sectional survey was conducted in 4 communes in Yen Bai and Thanh Hoa provinces where clonorchiasis is known to be present and raw fish consumption is a common. Using a simple random sampling approach, stool was collected from 841 participants over 6 years old for coprological examination, and a questionnaire measured knowledge, attitudes, and practices with regard to clonorchiasis in 757 participants over 15 years old. Univariable and multivariable logistic regression models were run to identify risk factors for infection with C. sinensis. The overall prevalence of C. sinensis infection was 40.4%, with commune prevalences ranging between 26.5% and 53.3%. In the final model, males were significantly more likely to be infected with C. sinensis (OR 2.00; 95% CI 1.31-3.05). Recent (i.e. last year) consumption of raw fish (OR 8.00, 95% CI 4.78-13.36), low education level (OR 5.57; 95% CI 2.37-13.07), lack of treatment (OR 1.82, 95% CI 1.15-2.89), being between 19 to 39 years old (OR 6.46; 95% CI 1.25-33.37), and the presence of an unhygienic toilet (OR 2.74, 95% CI 1.53-4.92) were significantly associated with C. sinensis infection.

CONCLUSION/SIGNIFICANCE

This study demonstrated a high prevalence of C. sinensis infection in rural communities in northern Vietnam. Thus, control measures including, mass drug administration for those communes should be applied to reduce the prevalence. Moreover, specific health education activities should be developed for risk groups in C. sinensis endemic areas.

High prevalence of Clonorchis sinensis infections and coinfection with hepatitis virus in riverside villages in northeast China

In China, the prevalence of Clonorchis sinensis (C. sinensis) infections is only evaluated at the provincial level by national sampling surveys, and data from villages and counties are still lacking. In this study, we conducted a cross-sectional survey in 10 villages located along the Lalin River in northeast China. Clonorchiasis was diagnosed using a modified Kato–Katz method that detects the C. sinensis egg in stools. A total of 3,068 persons were screened and 2,911 were recruited for the study. Overall, the prevalence of C. sinensis infection was 29.3%. Among 175 participants who were cured after antiparasitic treatment, 54 (30.86%) were re-infected in this survey. After calibration of potential confounders, male gender, occupation as a farmer, smoking, and occasionally or frequently eating raw fish were independent risk factors for C. sinensis infection. The results of laboratory examinations in the C. sinensis/hepatitis B or C virus co-infection group were similar to those in the hepatitis B or C virus mono-infection groups. In conclusion, C. sinensis is highly endemic in villages along the Lalin River, and the primary route of infection is the consumption of raw freshwater fish. Co-infection with C. sinensis did't aggravate the clinical manifestations of viral hepatitis in this cross-sectional study.

Clonorchiasis in Patients with Biliary and Pancreatic Diseases: Diagnosis and Risk Factors

Background

Many epidemiological studies have investigated the risk factors for clonorchiasis, but endoscopic findings of this disease in endoscopic retrograde cholangiopancreatography (ERCP) have not been well characterized. In this study, we evaluated clonorchiasis in ERCP in patients with biliary and pancreatic diseases.

Methods

This was a retrospective two-center study in hospitalized patients who received ERCP between January 2012 and October 2018. All patients were divided into clonorchiasis and nonclonorchiasis groups. Data were analyzed using univariate analysis and multivariate analyses.

Results

A total of 1119 patients were included, and clonorchiasis was diagnosed in 19.2% patients. Detection of Clonorchis sinensis eggs in bile samples was higher than that in fecal samples (85.9% vs. 58.7%; P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249, P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249, P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249, P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249, P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249, P = 0.001). In multivariate analysis, male patients (95% confidence interval (CI): 1.945-4.249.

Conclusions

The detection of C. sinensis eggs was significantly higher in bile than in fecal samples; thus, bile samples represent a preferable sample for the diagnosis of clonorchiasis in patients with biliary obstruction. We found that male, age ≤ 60 years old, and CBD diameter < 12 mm were independent risk factors for clonorchiasis, while papilla fistula was a protective factor.C. sinensis eggs was significantly higher in bile than in fecal samples; thus, bile samples represent a preferable sample for the diagnosis of clonorchiasis in patients with biliary obstruction. We found that male, age ≤ 60 years old, and CBD diameter < 12 mm were independent risk factors for clonorchiasis, while papilla fistula was a protective factor.

Prevalence, Species Distribution, and Related Factors of Fish-Borne Trematode Infection in Ninh Binh Province, Vietnam

Background. Clonorchis sinensis/Opisthorchis viverrini and minute intestinal flukes (MIF) such as Haplorchis pumilio and H. taichui are fish-borne trematodes (FBT) that may coexist in regions where local people have a habit of eating raw fish like Vietnam. Responses to FBT should be verified according to the data on the distribution of these flukes. This study aims to explore the prevalence of different species of FBT and related factors among local people in a northern province of Vietnam. Methods. A cross-sectional study was conducted in Kim Son and Yen Khanh districts, Ninh Binh province, between March 2016 and March 2017. Four hundred people aged 15 years or older were interviewed and gave stool samples. The FBT eggs in faecal samples were enumerated by modified formalin-ether technique and identified by sequencing of the second internal transcribed spacer (ITS2) region. Result. Among the 400 persons, 19.5% were infected with FBT. On univariate analysis, eating raw fish was the main risk factor (odds ratios (OR)) of 6.769 (95% confidence interval (CI) of 2.655-17.259) followed by being of male gender (3.994 (CI95% 2.117-7.536)) and drinking alcohol (2.680 (CI95% 1.440-4.986)), respectively. There was no risk of increased infection among those living at home without hygienic latrines, those living close to rivers or having ponds, or those raising cats or dogs. By multivariate analysis, FBT infection was only related to the consumption of raw fish and gender. Seventy stool samples with a sufficient amount of faecal matter were subjected to DNA extraction, 42.85% of them yielded DNA production, and all were of Clonorchis sinensis. Conclusion. Results of the study showed the high prevalence of infection of fish-borne trematode, mostly C. sinensis among humans in Ninh Binh province. The prevention of FBT should be strengthened with programs detailed according to the distribution of FBT in different endemic areas.

Predictive risk factors towards liver fluke infection among the people in Kamalasai District, Kalasin Province, Thailand

BACKGROUND

Liver fluke disease caused by Opisthorchis viverrini remains a major public health problem with its crucial risk factors caused by some individual habits or false beliefs among the people in northeastern Thailand concerning the consumption of raw fish meat dishes.

OBJECTIVES

This study explores the predictive risk factors for the infection of liver fluke disease.

METHODS

The sample consisted of 400 people aged 30 years and above in Thanya sub-district, Kamalasai district, Kalasin province. A cross-sectional analytic study, using the χ2 test, odds ratio and 95% confidence interval, was used to find the influence of each variable, along with the use of multiple logistic regression (p = 0.05). A questionnaire form was used as the research instrument.

RESULTS

Factors found in the results are as follows: households with a cat were 7.00 times more at risk than households without a cat; eating raw fish dishes prepared by themselves increases the risk of infection by 2.58 times; eating raw fish dishes prepared by family members increases the risk by 4.74 times; and raw fish dishes bought from a community market increases the risk by 2.33 times.

CONCLUSION

A campaign should be launched to educate people not to eat raw or undercooked fish dishes, but to fully cook fish dishes before eating, as the food is still delicious, but also safe, healthy, and free from liver fluke infection.

Parasitic infections in relation to practices and knowledge in a rural village in Northern Thailand with emphasis on fish-borne trematode infection

The present study integrates several aspects of a parasitological survey in a rural community village combining community knowledge of parasites, their potential transmission routes and health risk factors. A rural community located in Northern Thailand was surveyed for intestinal parasites, and an overall prevalence of 45.2% for helminths and 4.8% for protozoan infections was identified. Socio-demographic characteristics, customs and perceptions were compiled using individual questionnaires and interviews for participants surveyed for parasitic screening. The results allowed us to determine the knowledge and perception of local people concerning helminthic infection and transmission. Despite the fact that the participants in this community were aware of parasitic transmission routes, their widespread custom of eating raw fish and meat render the reduction of helminthiasis difficult. A detailed study on the infection of fish-borne parasitic trematodes, the most prevalent helminth, allowed us to determine that the distance from a given household to the river is a determinant of infection intensity. Health education activities organised in the local community resulted in a change in perception of risks associated with parasite transmission.

Relationship between blood parameters and Clonorchis sinensis infection: A retrospective single center study

Our study aims to retrospectively investigate neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and eosinophil-to-lymphocyte ratio (ELR) in patients infected with Clonorchis sinensis. This study analyzes a total of 151 patients with C. sinensis infections and 53 healthy control patients from our hospital. We found close relationships between the three candidate markers and the stages of C. sinensis infection-related biliary obstruction. The NLRs, PLRs and ELRs of patients with C. sinensis infections were significantly higher than those of healthy individuals; of those, ELRs showed the most superior diagnostic accuracy (sensitivity = 62.9%, specificity = 92.5%). Further, we constituted a logistic regression prediction model; applying two variables (age and NLR) with a sensitivity of 88.89% and a specificity of 83.78% in differentiating C. sinensis-related cholelithiasis from C. sinensis-untreated patients. Cancer antigen 19-9 (CA19-9) is a commonly used marker in the diagnosis of cholangiocarcinoma. Significant correlation was observed between NLR and CA19-9 in patients with C. sinensis-related cholangiocarcinoma (r = 0.590, P = 0.000). In the receiver operating characteristic analysis for separating C. sinensis-related cholelithiasis and cholangiocarcinoma, the cutoff value of PLR was 145.14 with a sensitivity of 65.62% and a specificity of 68.89%; the sensitivity of CA19-9 was 75.00% with a specificity of 77.78%. PLR showed acceptable efficiency to separate C. sinensis-related cholelithiasis from cholangiocarcinoma. In conclusion, all of the candidate markers (PLRs, NLRs and ELRs) may act as the valuable supplement in detecting C. sinensis infections and diseases.

Clonorchis sinensis and Clonorchiasis: The Relevance of Exploring Genetic Variation

Parasitic trematodes (flukes) cause substantial mortality and morbidity in humans. The Chinese liver fluke, Clonorchis sinensis, is one of the most destructive parasitic worms in humans in China, Vietnam, Korea and the Russian Far East. Although C. sinensis infection can be controlled relatively well using anthelmintics, the worm is carcinogenic, inducing cholangiocarcinoma and causing major suffering in ~15 million people in Asia. This chapter provides an account of C. sinensis and clonorchiasis research-covering aspects of biology, epidemiology, pathogenesis and immunity, diagnosis, treatment and control, genetics and genomics. It also describes progress in the area of molecular biology (genetics, genomics, transcriptomics and proteomics) and highlights challenges associated with comparative genomics and population genetics. It then reviews recent advances in the sequencing and characterisation of the mitochondrial and nuclear genomes for a Korean isolate of C. sinensis and summarises salient comparative genomic work and the implications thereof. The chapter concludes by considering how advances in genomic and informatics will enable research on the genetics of C. sinensis and related parasites, as well as the discovery of new fluke-specific intervention targets.