The spatial-temporal risk profiling of Clonorchis sinensis infection over 50 years implies the effectiveness of control programs in South Korea: a geostatistical modeling study.

Background: Over the past 50 years, two national control programs on Clonorchis sinensis infection have been conducted in South Korea. Spatial-temporal profiles of infection risk provide useful information on assessing the effectiveness of the programs and planning spatial-targeted control strategies. Methods: Advanced Bayesian geostatistical joint models with spatial-temporal random effects were developed to analyze disease data collecting by a systematic review with potential influencing factors, and to handle issues of preferential sampling and data heterogeneities. Changes of the infection risk were analyzed. Findings: We presented the first spatial-temporal risk maps of C. sinensis infection at 5 × 5 km2 resolution from 1970 to 2020 in South Korea. Moderate-to-high risk areas were shrunk, but temporal variances were shown in different areas. The population-adjusted estimated prevalence across the country was 5.99% (95% BCI: 5.09-7.01%) in 1970, when the first national deworming campaign began. It declined to 3.95% (95% BCI: 2.88-3.95%) in 1995, when the campaign suspended, and increased to 4.73% (95% BCI: 4.00-5.42%) in 2004, just before the Clonorchiasis Eradication Program (CEP). The population-adjusted prevalence was estimated at 2.77% (95% BCI: 1.67-4.34%) in 2020, 15 years after CEP started, corresponding to 1.42 (95% BCI: 0.85-2.23) million infected people. Interpretation: The first nationwide campaign and the CEP showed effectiveness on control of C. sinensis infection. Moderate-to-high risk areas identified by risk maps should be prioritized for control and intervention. Funding: The National Natural Science Foundation of China (project no. 82073665) and the Natural Science Foundation of Guangdong Province (project no. 2022A1515010042).

The spatial-temporal distribution of soil-transmitted helminth infections in Guangdong Province, China: A geostatistical analysis of data derived from the three national parasitic surveys.

BACKGROUND: The results of the latest national survey on important human parasitic diseases in 2015-2016 showed Guangdong Province is still a moderately endemic area, with the weighted prevalence of soil-transmitted helminths (STHs) higher than the national average. High-resolution age- and gender-specific spatial-temporal risk maps can support the prevention and control of STHs, but not yet available in Guangdong. METHODOLOGY: Georeferenced age- and gender-specific disease data of STH infections in Guangdong Province was derived from three national surveys on important human parasitic diseases, conducted in 1988-1992, 2002-2003, and 2015-2016, respectively. Potential influencing factors (e.g., environmental and socioeconomic factors) were collected from open-access databases. Bayesian geostatistical models were developed to analyze the above data, based on which, high-resolution maps depicting the STH infection risk were produced in the three survey years in Guangdong Province. PRINCIPAL FINDINGS: There were 120, 31, 71 survey locations in the first, second, and third national survey in Guangdong, respectively. The overall population-weighted prevalence of STH infections decreased significantly over time, from 68.66% (95% Bayesian credible interval, BCI: 64.51-73.06%) in 1988-1992 to 0.97% (95% BCI: 0.69-1.49%) in 2015-2016. In 2015-2016, only low to moderate infection risk were found across Guangdong, with hookworm becoming the dominant species. Areas with relatively higher risk (>5%) were mostly distributed in the western region. Females had higher infection risk of STHs than males. The infection risk of A. lumbricoides and T. trichiura were higher in children, while middle-aged and elderly people had higher infection risk of hookworm. Precipitation, elevation, land cover, and human influence index (HII) were significantly related with STH infection risk. CONCLUSIONS/SIGNIFICANCE: We produced the high-resolution, age- and gender-specific risk maps of STH infections in the three national survey periods across nearly 30 years in Guangdong Province, which can provide important information assisting the control and prevention strategies.

Cost-effectiveness evaluation of different control strategies for Clonorchis sinensis infection in a high endemic area of China: A modelling study.

Clonorchiasis is an important food-borne parasitic disease caused by Clonorchis sinensis infection. The evaluation of long-term cost-effectiveness of control strategies is important for disease control and prevention. The present study aimed to assess the cost-effectiveness of the three recommended strategies (i.e., WHO, Chinese and Guangdong strategies) and different combinations of commonly used measures (i.e., preventive chemotherapy, information, education, and communication (IEC) and environmental improvement) on clonorchiasis. The study area, Fusha town in Guangdong Province, was a typical high endemic area in China. The analysis was based on a multi-group transmission model of C. sinensis infection. We set the intervention duration for 10 years and post-intervention period for 50 years. The corresponding costs and DALYs were estimated. Strategies with incremental cost-effectiveness ratios (ICERs) less than 1/5 of the willingness-to-pay threshold were identified as highly cost-effective strategies. The optimal control strategy was obtained using the next best comparator method. The ICERs of Guangdong strategy were $172 (95% CI: $143-$230) US for praziquantel and $106 (95% CI: $85-$143) US for albendazole, suggesting the highest cost-effectiveness among the three recommended strategies. For praziquantel, 470 sets of control strategies were identified as highly cost-effective strategies for achieving infection control (prevalence<5%). The optimal strategy consisted of chemotherapy targeted on at-risk population, IEC and environmental improvement, with coverages all being 100%, and with the ICER of $202 (95% CI: $168-$271) US. The results for transmission control (prevalence<1%) and albendazole were obtained with the same procedures. The findings may help to develop control policies for C. sinensis infection in high endemic areas. Moreover, the method adopted is applicable for assessment of optimal strategies in other endemic areas.

The comparative studies on the magnetic relaxation behaviour of the axially-elongated pentagonal-bipyramidal dysprosium and erbium ions in similar one-dimensional chain structures.

A family of cyano-bridged 3d-4f 1D chain compounds, {RE[TM(CN)6(2-PNO)5]}·(H2O)4 {RE = YIII, TM = [FeIII]LS (1); RE = DyIII, TM = CoIII (3); RE = ErIII, TM = [FeIII]LS (4), CoIII (5); 2-PNO = 2-picoline-N-oxide} and {RE[TM(CN)6(2-PNO)5]} {RE = DyIII, TM = [FeIII]LS (2)}, were synthesized and characterized. Single-crystal X-ray diffraction studies reveal that compounds 1 and 3-5 are isostructural, while compound 2 has a similar 1D chain structure with a different chain to chain arrangement. An axially-elongated pentagonal bipyramidal (D5h) coordination geometry is formed with five 2-PNO ligands in the equatorial plane and two [TM(CN)6]3- on the apical sites around the rare earth ions in these compounds. A comparison of the magnetic relaxation behaviour in detail reveals that it is more favorable for the Er (4 and 5) than the Dy analogues (2 and 3) to exhibit SIM properties in this axially-elongated D5h coordination environment. Under zero dc field, ac susceptibility measurements show that the Dy analogues have no magnetic relaxation behaviour, while the Er analogues exhibit frequency dependence despite the strong QTM effect. Under a 1 kOe dc field, the Er analogues generally show 1-2 orders of magnitude longer relaxation time at each selected temperature and a higher relaxation energy barrier than the Dy analogues. And the RECo compounds (3 and 5) show a more suppressed QTM effect than the corresponding REFe (2 and 4) compounds, which may be ascribed to the elimination of the fluctuation field from the neighbouring [FeIII]LS ions. The ab initio calculations indicate the misplacement between the orientation of the main magnetic axis and the structural axis in the Dy analogues, and the relative consistency in the Er analogues, which should be the source of the Er analogues showing better SIM properties than the Dy analogues.

Effectiveness of a community-based integrated strategy to control soil-transmitted helminthiasis and clonorchiasis in the People's Republic of China.

Soil-transmitted helminthiases (STHs) are caused by a group of intestinal nematode infections due to poor hygiene and environments, and clonorchiasis is a food-borne trematode (FBT) infection caused by ingestion of raw freshwater fish. Both are endemic in the People's Republic of China. To explore a suitable control strategy, integrated interventions were applied between 2007 and 2009 in ten pilot counties (eight for the STHs and two for clonorchiasis). Drug administration was used for treatment and complementary efforts to improve the situation based on health education, provision of clean water and sanitation were carried out. Significant achievements were gained as reflected by a drastic decrease in prevalence these infections were demonstrated. The overall prevalence of STHs and clonorchiasis decreased from 35.9% to 7.8% and from 41.4% to 7.0%, respectively. The reduction of prevalence and high cost-effectiveness were documented supporting large-scale application of this integrated intervention in China and elsewhere.

Assessment of control strategies against Clonorchis sinensis infection based on a multi-group dynamic transmission model.

Clonorchiasis is one of the most important food-borne trematodiases affecting millions of people. Strategies were recommended by different organizations and control programmes were implemented but mostly in short-time periods. It's important to assess the long-term benefits and sustainability of possible control strategies on morbidity control of the disease. We developed a multi-group transmission model to describe the dynamics of C. sinensis transmission among different groups of people with different raw-fish-consumption behaviors, based on which, a full model with interventions was proposed and three common control measures (i.e., preventive chemotherapy, information, education, and communication (IEC) and environmental modification) and their possible combinations were considered. Under a typical setting of C. sinensis transmission, we simulated interventions according to different strategies and with a series of values of intervention parameters. We found that combinations of measures were much beneficial than those singly applied; higher coverages of measures had better effects; and strategies targeted on whole population performed better than that on at-risk population with raw-fish-consumption behaviors. The strategy recommended by the government of Guangdong Province, China shows good and sustainable effects, under which, the infection control (with human prevalence <5%) could be achieved within 7.84 years (95% CI: 5.78-12.16 years) in our study setting (with original observed prevalence 33.67%). Several sustainable strategies were provided, which could lead to infection control within 10 years. This study makes the effort to quantitatively assess the long-term effects of possible control strategies against C. sinensis infection under a typical transmission setting, with application of a multi-group dynamic transmission model. The proposed model is easily facilitated with other transmission settings and the simulation outputs provide useful information to support the decision-making of control strategies on clonorchiasis.

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.

[Research on chemotherapy measures in different Clonorchis sinensis infectiosity endemic areas].

OBJECTIVE: To explore the suitable chemotherapy measures in different Clonorchis sinensis infectiosity endemic areas. METHODS: The interventional groups and control groups were set up in the heavy, moderate and light C. sinensis infectiosity areas in Guangdong Province, respectively. In the intervention groups, the chemotherapy was administered among all the residents aged above 3 years in the heavy endemic areas, the chemotherapy was given among the focus populations in the moderate endemic areas, and the chemotherapy was administered among the residents infected with C. sinensis confirmed by stool examinations in the light endemic areas. No measures were carried out in the control groups. RESULTS: One year after the interventions, the C. sinensis infection rates of the interventional groups decreased by 47.90%, 86.52% and 100%, the abnormal rates of liver B ultrasonic examinations decreased by 26.50%, 31.00% and 100%, the ALT abnormal rates decreased by 48.70%, 62.30% and 100%, and the AST abnormal rates decreased by 55.50%, 39.90% and 100% in the heavy, moderate and light endemic areas, respectively. There was no decreasing trend of above-mentioned indexes in the control groups. CONCLUSION: In the different C. sinensis infectiosity endemic areas, the different chemotherapy measures should be carried out.

[Current prevalence of Clonorchis sinensis infection in Jiangmen, Guangdong Province].

OBJECTIVE: To investigate the prevalence of clonorchiasis in Jiangmen City. METHODS: From May to December 2011, each town was randomly chosen from east, south, west, north and central area of 7 cities/districts of Jiangmen City. Four or five villages were randomly selected from each town. In each village, the residents above 3-year-old in 10% randomly sampled families were treated as research objects. Total of 14,000 fecal boxes were issued and 12,661 ones back. Eggs in stool were examined by modified Kato-Katz thick smear method (three slides per specimen). RESULTS: A total of 1316 clonorchiasis cases were found from 12,661 pepople in 140 villages with a prevalence of 10.39% (1316/12,661). The average egg density was 98.3 eggs per gram (EPG) feces. Among 7 cities/districts, the prevalence in Pengjiang District (26.68%, 402/1507) was the highest, and that of Taishan City (0.93%, 19/2049) was the lowest. The egg density in Heshan City was the highest (225.4 EPG) and the lowest one was found in Taishan City (5.13 EPG). The prevalence was negatively related with the distance to major rivers (r=-0.61, P<0.01). The prevalence and the egg density in males and females was 13.20% (807/6112) and 80.9 EPG, and 7.77% (509/6549) and 39.4 EPG, respectively. The prevalence and intensity of infection increased obviously in the groups of above 20-year-old. The people with a higher prevalence was the group of 60-69 year-old, and the people above 70 years showed heavier infection (153.8 EPG). Light, moderate and heavy infection occupied 99.91%, 0.09%, and 0. CONCLUSION: Clonorchiasis is endemic in seven districts of Jiangmen City with different epidemic degrees. There are significant differences in the prevalence and intensity of infection among different areas. The villages with higher prevalence distribute along the middle and lower sections of the two major rivers.

Epidemiological profile of Clonorchis sinensis infection in one community, Guangdong, People's Republic of China.

BACKGROUND: Clonorchiasis caused by ingesting improperly prepared fish ranks among the most important but still neglected food-borne parasitic diseases, especially in the People's Republic of China (P.R. China). To promote the implementation of interventions efficiently, the demonstration of an epidemiological profile of Clonorchis sinensis infection is essential in hyper-epidemic areas. METHODS: In one community with higher levels of economic development in Guangdong province, P.R. China, villagers were motivated to provide stool samples for examining helminth eggs. Then, those infected with C. sinensis completed the structured questionnaire including demographical characteristics, knowledge and behavior. RESULTS: A total of 293 villagers infected with C. sinensis participated in questionnaire investigation. Among them, 94.54% were adult and 93.17% were indigenous. The geometric mean of C. sinensis eggs per gram of feces in the children, adult females and adult males was 58, 291 and 443, respectively. The divergence between knowledge and behavior in the adults, especially the adult males, was shown. Out of 228 persons eating raw fish, 160 did it more frequently at restaurants, the proportion of which varied in different populations, showing 25.00%, 54.88% and 80.28% in the children, adult females and adult males, respectively. CONCLUSIONS: Different interventions need to be adopted in different populations. Chemotherapy should be prioritized in the adults, especially the adult males. In addition, health education targeting the children, is essential and may play a crucial role in controlling clonorchiasis in the long term. In order to successfully control clonorchiasis, intervention in the restaurant should not be overlooked in some endemic areas.

Disability weight of Clonorchis sinensis infection: captured from community study and model simulation.

BACKGROUND: Clonorchiasis is among the most neglected tropical diseases. It is caused by ingesting raw or undercooked fish or shrimp containing the larval of Clonorchis sinensis and mainly endemic in Southeast Asia including China, Korea and Vietnam. The global estimations for population at risk and infected are 601 million and 35 million, respectively. However, it is still not listed among the Global Burden of Disease (GBD) and no disability weight is available for it. Disability weight reflects the average degree of loss of life value due to certain chronic disease condition and ranges between 0 (complete health) and 1 (death). It is crucial parameter for calculating the morbidity part of any disease burden in terms of disability-adjusted life years (DALYs). METHODOLOGY/PRINCIPAL FINDINGS: According to the probability and disability weight of single sequelae caused by C. sinensis infection, the overall disability weight could be captured through Monte Carlo simulation. The probability of single sequelae was gained from one community investigation, while the corresponding disability weight was searched from the literatures in evidence-based approach. The overall disability weights of the male and female were 0.101 and 0.050, respectively. The overall disability weights of the age group of 5-14, 15-29, 30-44, 45-59 and 60+ were 0.022, 0.052, 0.072, 0.094 and 0.118, respectively. There was some evidence showing that the disability weight and geometric mean of eggs per gram of feces (GMEPG) fitted a logarithmic equation. CONCLUSION/SIGNIFICANCE: The overall disability weights of C. sinensis infection are differential in different sex and age groups. The disability weight captured here may be referred for estimating the disease burden of C. sinensis infection.

[Strengthening the research on clonorchiasis in China].

Liver flukes mainly include Clonorchis sinensis, Opisthorchis viverrini, and Opisthorchis felineus. The international congress of liver flukes was held in Khon Kaen, Thailand, during 7-8th March, 2011. The congress assembled a wide array of studies and reflected the current status of research, control and prevention of liver flukes in the world. This paper summarizes basic information from the meeting. Meanwhile, based on the research status and needs for control and prevention, priorities of research on clonorchiasis in China are discussed.

Epidemiology of cholangiocarcinoma: an update focusing on risk factors.

Cholangiocarcinoma is relatively rare, but high incidence rates have been reported in Eastern Asia, especially in Thailand. The etiology of this cancer of the bile ducts appears to be mostly due to specific infectious agents. In 2009, infections with the liver flukes, Clonorchis sinensis or Opistorchis viverrini, were both classified as carcinogenic to humans by the International Agency for Research on Cancer for cholangiocarcinoma. In addition, a possible association between chronic infection with hepatitis B and C viruses and cholangiocarcinoma was also noted. The meta-analysis of published literature revealed the summary relative risks of infection with liver fluke (both Opistorchis viverrini and Clonorchis sinensis), hepatitis B virus, and hepatitis C virus to be 4.8 (95% confidence interval [95% CI]: 2.8-8.4), 2.6 (95% CI: 1.5-4.6), and 1.8 (95% CI: 1.4-2.4), respectively - liver fluke infection being the strongest risk factor for cholangiocarcinoma. Countries where human liver fluke infection is endemic include China, Korea, Vietnam, Laos, and Cambodia. The number of infected persons with Clonorchis sinensis in China has been estimated at 12.5 million with considerable variations among different regions. A significant regional variation in Opistorchis viverrini prevalence was also noted in Thailand (average 9.6% or 6 million people). The implementation of a more intensive preventive and therapeutic program for liver fluke infection may reduce incidence rates of cholangiocarcinoma in endemic areas. Recently, advances have been made in the diagnosis and management of cholangiocarcinoma. Although progress on cholangiocarcinoma prevention and treatment has been steady, more studies related to classification and risk factors will be helpful to develop an advanced strategy to cure and prevent cholangiocarcinoma.

A randomized, double-blind, multicenter clinical trial on the efficacy of ivermectin against intestinal nematode infections in China.

To assess the efficacy of ivermectin against intestinal nematode infections, a randomized, double-blind, multicenter clinical trial was carried out in a total of 816 human individuals infected with different nematodes from three counties in China. The subjects were randomly assigned into experimental and control groups and orally given a single dose of 0.1, 0.2, 0.2 and 0.2mg/kg ivermectin against Ascaris lumbricoides, hookworm, Trichuris trichiura and Enterobius vermicularis, respectively. Parallel control groups to each of the ivermectin groups were given a single oral dose of 6.7 mg/kg albendazole. The cure rates with ivermectin and albendazole were 100% (102/102) and 99.0% (101/102) for Ascaris, and 66.7% (68/102) and 67.7% (69/102) for Trichuris, respectively, with no significant difference (P>0.05) between the two treatments. The parasitological cure rates of albendazole were 69.6% (71/102) for hookworm and 94.1% (96/102) for Enterobius, which were significantly higher than ivermectin (33.3% and 52.9%, respectively, P<0.0001). The expulsion of worm in the feces reached its peak 1-2 days after ivermectin treatment. The study showed that ivermectin, with few side effects, could be used as an additional treatment tool for intestinal nematodes, especially for the treatment of Ascaris and Trichuris infections in China.

[Current prevalence of Clonorchis sinensis infection in endemic areas of China].

OBJECTIVE: To investigate the current prevalence of Clonorchis sinensis infection in the known endemic areas of China. METHODS: According to different endemic level and river system, the lamination stochastic group sampling was carried out in 27 Provinces/Municipalities/Autonomous Regions (P/M/A) from 2002 to 2004. Eggs in stool were examined by modified Kato-Katz thick smears method. RESULT: A total of 5,230 cases of Clonorchis infection was found from 217,829 sampled population of 27 P/M/A, and the mean prevalence was 2.40% by which the number of infected people was estimated to be 12.49 millions. The geometry mean worm egg density was 2,208 EPG (stool). Light, moderate and heavy infection occupied 78.93%, 17.40%, and 3.67% respectively. Infection was found in 19 out of 27 P/M/A investigated, with the highest prevalence in the provinces of Guangdong (16.42%, 2,278/13,876), Guangxi (9.75%, 1,365/13,990) and Heilongjiang (4.72%, 636/13,458). Males showed higher prevalence (2.94%, 3,267/111,262) than females (1.84%, 1,963/106,567). There was infection in all age groups,with the highest prevalence in the group of 50 to 59 years (9.16%). By occupations, more infections were found in businessmen (13.42%, 124/924), followed by factory workers ((7.9%, 298/3,773), and retirees and veterans (5.28%, 70/1,327). Adults showed heavier infection in some provinces where the main infection way was raw fish-eating, but in children in other provinces. For geographical distribution, the terrain in network of rivers and lakes showed higher prevalence (5.23%, 687/13,125) than the hilly terrain (2.34%, 1,111/47,552). Prevalence showed family-aggregation feature. CONCLUSION: Clonorchiasis is widely endemic in China with a high prevalence in some provinces. Male adults have been more involved with a family aggregation.

[Effect of a novel drug--enteric coated tribendimidine in the treatment of intestinal nematode infections].

OBJECTIVE: To study the therapeutic effect and possible adverse effects of tribendimidine enteric coated tablets in the treatment of infections due to hookworms, Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis. METHODS: According to the standard clinical trial design and protocol, persons infected with hookworms, Ascaris lumbricoides, Trichuris trichiura, or Enterobius vermicularis respectively, were treated with tribendimidine enteric coated tablets in four counties of Guangdong and Jiangsu Provinces, albendazole was used as control. RESULTS: For hookworm infection, the curative rate (eggs negative in the faeces) were 89.5% (85/95) and 70.6% (60/85) with tribendimidine (400 mg) and albendazole(400 mg) respectively; for Ascaris infection, 97.4% (114/117) and 98.9% (91/92) with tribendimidine(300 mg) and albendazole(400 mg) respectively; for Trichuris infection, 33.3% (25/75) and 56.1% (23/41) with tribendimidine(400 mg/day for 3 days) and albendazole(400 mg/day for 3 days) respectively; for Enterobius infection in children, 74.1% (60/81) and 93.0% (40/43) with tribendimidine(200 mg) and albendazole(200 mg) respectively. No considerable side effect was found. CONCLUSION: Tribendimidine is highly active in the treatment of hookworm, Ascaris lumbricoides infections, free of major adverse effect and easy to administer. It is more effective than albendazole for the infection of Necator americanus.

Clonorchiasis: a key foodborne zoonosis in China.

The oriental liverfluke, Clonorchis sinensis, is of major socioeconomic importance in parts of Asia, including China, Japan, Korea, Taiwan, and Vietnam. The parasite is transmitted via snails to freshwater fish, and then to human beings and other piscivorous mammals, and causes substantial clinical or subclinical disease, known as clonorchiasis. There is considerable evidence for an aetiological relation between clonorchiasis and cholangiocarcinoma in human beings. It is estimated that about 35 million people are infected globally, of whom approximately 15 million are in China. Although very little information from China has been published in the English language, recent analyses of epidemiological data sets suggest that clonorchiasis is having an increased human-health impact due to the greater consumption of raw freshwater fish. To gain an improved insight into clonorchiasis in China, this review provides a background on the parasite and its life cycle, summarises key aspects regarding the pathogenesis, diagnosis, and treatment of clonorchiasis, describes the geographic distribution and prevalence of clonorchiasis, and makes some recommendations for future research and the control of this important disease.