Consumption Of Raw Freshwater Fish Research Articles

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.

Current status of Clonorchis sinensis and clonorchiasis in Korea: epidemiological perspectives integrating the data from human and intermediate hosts.

Clonorchis sinensis is a carcinogenic liver fluke that causes clonorchiasis in humans. Clonorchiasis is prevalent in East Asian countries, and approximately 15–20 million individuals are estimated to be infected with this fluke globally. This review highlights the current status of C. sinensis and clonorchiasis in Korea from the epidemiological perspective involving the analysis of humans and intermediate hosts. Despite the recent decline in C. sinensis infection rate in Korea, C. sinensis infections remain endemic in 5 major river basins (Han-gang, Geum-gang, Seomjin-gang, Yeongsan-gang and Nakdong-gang; gang means river) with a high incidence of cholangiocarcinoma. A noticeable pattern involves increasing mild infections among patients diagnosed positive for C. sinensis eggs. The infection rate of C. sinensis metacercariae in the second intermediate host, freshwater fish, is also maintained at a substantial level. Thus, the One Health approach integrating different sectors and disciplines is recommended to accelerate and sustain control of C. sinensis, thereby leading to successful eradication. Health promotion via information dissemination and health education should be extended to prevent the consumption of raw freshwater fish by residents living in high-risk 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.

The control of clonorchiasis in Guangdong province, southern China

Oriental liver fluke disease (clonorchiasis), caused by Clonorchis sinensis, is endemic in 81 counties in Guangdong province, China. This study was conducted following increasing lack of clonorchiasis awareness and increased consumption of raw freshwater fish and raw fish porridge at home and restaurants, which has been attributed to improved living standards in China, and is considered to have led to a higher C. sinensis infection rate in the country. A total of 61,517 individuals were investigated from 123 sites during a provincial survey in 1988, with average C. sinensis infection rate of 1.82% that increased to 4.08% (335/8217) in 1997. Higher infection rate was observed in adult men than women, with heavy infection rate in fishermen and businessmen because they have access and means to get raw fishes for consumption. Thus, clonorchiasis has become a serious public health problem in Guangdong province. Efforts targeting clonorchiasis prevention and control in Guangdong province started in the 1990s. These included carrying out large-scale surveys and chemotherapy in epidemic regions, research on promotion of environmental sanitation and methods for freshwater aquaculture. Establishment and promotion of clonorchiosis demonstration plots for comprehensive control measures, as well as the development of clonorchiasis-prevention community-out-patient clinics were initiated and their effectiveness was evaluated. However, there seem to be no obvious decline in the prevalence of C. sinensis with 4.90% (608/12,401) in 2015, at Guangdong province due to the people's habit of eating raw fishes in endemic areas. This has led to increasing calls to improve environmental sanitation in the aquaculture industry. It is, however, believed that control efforts on clonorchiosis in the province are at an early stage and require strengthening through the cooperation of different departments to work out effective strategies for sustainable field application of control mechanisms.

Modeling the Transmission Dynamics of Clonorchiasis in Foshan, China

Clonorchiasis, known as the Chinese liver fluke disease, is caused by Clonorchis sinensis infection with food-borne liver fluke, which is transmitted via snails to freshwater fish and then to human beings or other piscivorous mammals. Clonorchis sinensis infection is mainly related to liver and biliary disorders, especially cholangiocarcinoma, and has an increased human-health impact due to the greater consumption of raw freshwater fish. In this article, we propose a deterministic model to describe the spread of clonorchiasis among human-snail-fish populations and use the model to simulate the data on the numbers of inspected and infected individuals of Foshan City, located in Guangdong Province in the southeast of P.R China, from 1980–2010. Mathematical and numerical analyses of the model are carried out to understand the transmission dynamics of clonorchiasis and explore effective control measures for the local outbreaks of the disease. We find that (i) the transmission of clonorchiasis from cercariae to fish plays a more important role than that from eggs to snails and from fish to humans; (ii) As the cycle of infection-treatment-reinfection continues, it is unlikely that treatment with drugs alone can control and eventually eradicate clonorchiasis. These strongly suggest that a more comprehensive approach needs to include environmental modification in order to break the cercariae-fish transmission cycle, to enhance awareness about the disease, and to improve prevention measures.

Characterisation of bone and joint infections due to Group B Streptococcus serotype III sequence type 283.

In 2015, an epidemic of Group B Streptococcus (GBS) serotype III sequence type 283 (ST283) disease was reported in Singapore, associated with consumption of raw freshwater fish. In this study, we further characterise the characteristics of bone and joint infections associated with ST283 GBS in adults and the differences between ST283 and non-ST283 manifestations. A retrospective study of 54 inpatients with invasive GBS disease involving bones and/or joints from 2010 to 2015 was performed. Archived isolates were identified as GBS serotype III and ST283 positive using PCR methods. Clinical data were collected from a review of clinical charts. Twenty-three cases were ST283 and 31 were non-ST283. ST283 GBS patients were more likely to be of Chinese ethnicity, have lower Charlson comorbidity scores, and have fewer overall comorbidities, including diabetes mellitus with end-organ damage, peripheral vascular disease, and previous stroke, compared to non-ST283 GBS patients. ST283 patients had more oligoarthritis, with greater involvement of the knee, shoulder, and vertebrae, compared to monoarticular joint involvement in non-ST283 patients. Six patients had a unique combination of knee and shoulder joint involvement. All ST283 cases were mono-microbial, compared to a significant proportion of polymicrobial cultures in non-ST283 patients. Non-ST283 patients had a significantly longer length of stay and were more likely to undergo amputation or wound debridement. This study adds to growing evidence of a distinct clinical presentation associated with ST283 GBS, involving predominantly healthier patients without significant comorbidities, and with distinct clinical manifestations with regard to bone and joint disease.

2015 Epidemic of Severe Streptococcus agalactiae Sequence Type 283 Infections in Singapore Associated With the Consumption of Raw Freshwater Fish: A Detailed Analysis of Clinical, Epidemiological, and Bacterial Sequencing Data.

Streptococcus agalactiae (group B Streptococcus [GBS]) has not been described as a foodborne pathogen. However, in 2015, a large outbreak of severe invasive sequence type (ST) 283 GBS infections in adults epidemiologically linked to the consumption of raw freshwater fish occurred in Singapore. We attempted to determine the scale of the outbreak, define the clinical spectrum of disease, and link the outbreak to contaminated fish. Time-series analysis was performed on microbiology laboratory data. Food handlers and fishmongers were screened for enteric carriage of GBS. A retrospective cohort study was conducted to assess differences in demographic and clinical characteristics of patients with invasive ST283 and non-ST283 infections. Whole-genome sequencing was performed on human and fish ST283 isolates from Singapore, Thailand, and Hong Kong. The outbreak was estimated to have started in late January 2015. Within the study cohort of 408 patients, ST283 accounted for 35.8% of cases. Patients with ST283 infection were younger and had fewer comorbidities but were more likely to develop meningoencephalitis, septic arthritis, and spinal infection. Of 82 food handlers and fishmongers screened, none carried ST283. Culture of 43 fish samples yielded 13 ST283-positive samples. Phylogenomic analysis of 161 ST283 isolates from humans and fish revealed they formed a tight clade distinguished by 93 single-nucleotide polymorphisms. ST283 is a zoonotic GBS clone associated with farmed freshwater fish, capable of causing severe disease in humans. It caused a large foodborne outbreak in Singapore and poses both a regional and potentially more widespread threat.

Effects of interactions between environmental factors and KIF1B genetic variants on the risk of hepatocellular carcinoma in a Chinese cohort.

To examine the effect of the potential interaction between KIF1B variants (rs17401966 and rs3748578) and environmental factors on the risk of hepatocellular carcinoma (HCC) in a high-risk region in China. Three hundred and six patients with HCC and 306 hospital-based control participants residing in the Shunde region of Guangdong Province, China were enrolled. Clinical characteristics were collected by reviewing the complete medical histories from the patient archives, and epidemiological data were collected using a questionnaire and clinical examination. Two single nucleotide polymorphisms (SNPs) of KIF1B (rs17401966 and rs3748578) were chosen for the current study. All subjects were genotyped using a TaqMan real-time polymerase chain reaction. Multiplicative and additive logistic regression models were used to evaluate various gene-environment interactions. Smoking, frequent consumption of raw freshwater fish, hepatitis B virus (HBV) infection, and a family history of HCC were important risk factors for HCC in this population. Chronic infection with HBV was the most important environmental risk factor for HCC [odds ratio (OR) = 12.02; 95% confidence interval (95%CI): 6.02-24.00]. No significant association was found between the KIF1B variants alone and the risk of HCC. Nevertheless, a significant additive effect modification was observed between rs17401966 and alcohol consumption (P for additive interaction = 0.0382). Compared with non-drinkers carrying either the AG or GG genotype of rs17401966, individuals classified as alcohol consumers with the AA genotype of rs17401966 had a significantly increased risk of HCC (OR = 2.36; 95%CI: 1.49-3.74). The gene-environment interaction between the KIF1B rs17401966 variant and alcohol consumption may contribute to the development of HCC in Chinese individuals.

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

BackgroundInfection by the liver fluke, Opisthorchis viverrini, remains an important public health problem in Thailand and has resulted in the highest prevalence of infection and incidence of subsequent cholangiocarcinoma (CCA) in the world. Praziquantel (PZQ) is the antihelminthic drug of choice for treatment. Previous studies in hamsters showed that repeated infection and PZQ treatment could increase the risk of CCA. However, the few available epidemiology studies in humans have shown unclear evidence of an increased risk of CCA with frequency of PZQ intake. The present study investigated the relationship between the number of repeated PZQ treatments and CCA.MethodsA hospital-based matched case–control study was conducted. All cases and controls were inpatients of a tertiary hospital in Northeast Thailand. During 2012–2014 a total of 210 incident cases of pathologically diagnosed CCA and 840 control subjects were selected from a hospital inpatient database (four controls per case). The four recruited controls were individually matched with CCA cases by gender, age and date of admission. Data were collected in face-to-face interviews using a standardised pre-tested questionnaire. Multivariable conditional logistic regression was used in the analysis of the data.ResultsThe frequencies of PZQ usage among the 210 cases and 840 controls were 48.6 vs. 66.0 for never, 32.9 vs. 24.4 for once, 8.6 vs. 4.9 for twice, and 10.0 % vs. 4.8 % for more than twice, respectively. There was a statistically significant dose–response relationship (p < 0.001). Compared with subjects who never used PZQ, those who used the medication once, twice, and more than twice were 1.49, 1.82, and 2.30 times more likely to develop CCA (95 % confidence intervals: 1.02 - 2.20, 0.92 - 3.60, and 1.20 - 4.40). These odds ratios (adjusted ORs) had already been adjusted for the effects of eating raw fish, a family history of cancer, and highest educational attainment. Additional PZQ usage increased the odds of developing CCA by 23.0 % (adjusted OR = 1.23; 95 % CI: 1.07 - 1.43).ConclusionsThe findings show that repeated PZQ treatments are associated with an increased risk of CCA. Paradoxically, this contradicts the common belief that repeated PZQ treatments decrease the risk of CCA. The study also showed a strong association between the number of repeated PZQ treatments and the consumption of raw freshwater fish. This suggests that repeated PZQ treatments may be a surrogate marker of habit of eating raw fish.Electronic supplementary materialThe online version of this article (doi:10.1186/s12885-015-1788-6) contains supplementary material, which is available to authorized users.

Prevalence and Risk Factors of Clonorchiasis among the Populations Served by Primary Healthcare Posts along Five Major Rivers in South Korea

ObjectivesClonorchiasis is an infectious disease caused by the Chinese liver fluke Clonorchis sinensis. In this study, we investigated the prevalence and risk factors of clonorchiasis among the populations served by primary healthcare posts along five major rivers in South Korea. MethodsForty primary healthcare posts that are located less than 5 km from one of the five rivers were selected from 26 counties. For the purpose of the survey, community health practitioners selected the nearest villages from the riversides in their own catchment area. From January to May 2009, a total of 2788 stool samples were collected and examined using the formalin–ether sedimentation technique. Village inhabitants were also interviewed by means of questionnaires in order to obtain information on potential risk factors. ResultsThe prevalence rates of clonorchiasis at various river basins were as follows: Seomjin River, 21.3%; Nakdong River, 13.5%; Geum River, 9.2%; Han River, 7.6%; and Yeongsan River, 4.9%. The total number of people infected with C. sinensis was 329 (11.3%). By gender, 14.3% of males and 7.6% of females were infected. In case of both males and females, the prevalence rate was highest in those in their 40s. Consumption of raw freshwater fish was confirmed as a risk factor based on a logistic regression analysis. ConclusionThe present findings suggest that clonorchiasis is still highly prevalent among the inhabitants of riverside areas in southern Korea, and, accordingly, it is necessary to implement a systematic control program in the endemic areas.

Biliary Liver Flukes (Opisthorchiasis and Clonorchiasis) in Immigrants in the United States: Often Subtle and Diagnosed Years After Arrival

Biliary liver flukes are extremely common parasites in some regions of the world where consumption of raw fresh-water fish is a cultural practice. Clonorchis sinensis and Opisthorchis spp. are the major biliary liver flukes associated with human disease. Some of these parasites are highly associated with cholangiocarcinoma. It was noted that several cases presenting at our center had been in the US for prolonged periods. This prompted us to retrospectively review cases of liver fluke infection diagnosed at our facility. All cases of biliary liver fluke infection over a 6-year period were retrospectively investigated at a clinic serving international patients, to determine the prevalence and risk factors for infection in a nonendemic area. Cases were identified through review of stool ova and parasite (O&P) records maintained at Regions Hospital/HealthPartners microbiology laboratory. All O&P samples positive for Opisthorchis spp. or Clonorchis sinensis were included in the review. Seventeen cases were identified during the study period. Our center performed approximately 1,800 stool O&P examinations per year on approximately 1,100 individuals per year during the study period. Biliary liver flukes were uncommon, accounting for 1.3% of individuals infected with organisms considered to be potentially pathogenic. Infections were predominantly found in migrants from Laos, Cambodia and Thailand. Cases were also identified in migrants from the former Soviet Union and South America. It is of note that 25% of patients were detected after 5 years of residence in the US. Often, the only clinical clue to infection was a mild absolute eosinophilia (500 to 1000 microL). Although biliary liver fluke is an infrequent cause of infection in immigrants to the US, because of the potential long-term consequences of chronic infection, educational information highlighting routes of infection and the fact that asymptomatic infection is common and may eventually lead to cancer should be aimed at high-risk community members and those who have been visiting friends and relatives in endemic areas.

Prevalence and Intensity of Fish-Borne Zoonotic Trematodes in Cultured Freshwater Fish from Rural and Urban Areas of Northern Vietnam

Consumption of raw freshwater fish produced in both rural farm and urban wastewater ponds is a common practice in Vietnam. The present study assessed the risk of fish-borne zoonotic trematode (FZT) infection from fish raised in both these aquaculture systems in northern Vietnam. The diversity, prevalence, and infection intensity of FZT metacercariae in 1,500 freshwater fish collected from 6 sites located in rural and urban areas in northern Vietnam were investigated. The specific diagnosis of species was made by morphologic methods. The overall FZT prevalence in fish from both urban wastewater ponds and rural farm ponds was 11.2%. In wastewater ponds, the overall prevalence was 5.1%, ranging from 2.0% in tilapia to 7.3% in common and grass carp. In fish from farm ponds, the prevalence was 17.3%, and ranged from 6.7% in mud carp to 26.7% in common carp. The mean intensity of FZT infection was also higher in fish from farm ponds than that in fish from wastewater ponds (6.0% and 8.4%, respectively). The FZT species recovered from infected fish included both liver (Clonorchis sinensis) and intestinal flukes (Haplorchis taichui, Haplorchis pumilio, and Centrocestus formosanus). The prevalence of FZT in fish raised in these common farm systems represents a significant public health risk for a population with a strong cultural preference for consuming raw or inadequately prepared fish. These research results should encourage the public health and agriculture sectors to conduct the risk factor research required to develop control programs for FZT.

A large outbreak of Opisthorchis felineus in Italy suggests that opisthorchiasis develops as a febrile eosinophilic syndrome with cholestasis rather than a hepatitis-like syndrome

We describe the greatest Italian human acute opisthorchiasis outbreak acquired from eating raw tenches. Out of 52 people with suspected opisthorchiasis, 45 resulted in being infected. The most frequent symptoms and laboratory findings were fever, abdominal pain and eosinophilia. Seven tri-phasic computed tomography (CT) scans were done, showing multiple hypodense nodules with hyper-enhancement in the arterial phase. All patients took one day of praziquantel 25 mg/kg TID without failures. Reported symptoms suggested a febrile eosinophilic syndrome with cholestasis rather than a hepatitis-like syndrome. It seems common to find hepatic imaging alterations during acute opisthorchiasis: CT scan could be the most suitable imaging examination. Even if stool test remains the diagnostic gold standard, we found earlier positivity with the serum antibody test. Without previous freezing, the consumption of raw freshwater fish should be avoided.