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.

Natural variables separate the endemic areas of Clonorchis sinensis and Opisthorchis viverrini along a continuous, straight zone in Southeast Asia

BACKGROUND

Clonorchiasis and opisthorchiasis, caused by the liver flukes Clonorchis sinensis and Opisthorchis viverrini respectively, represent significant neglected tropical diseases (NTDs) in Asia. The co-existence of these pathogens in overlapping regions complicates effective disease control strategies. This study aimed to clarify the distribution and interaction of these diseases within Southeast Asia.

METHODS

We systematically collated occurrence records of human clonorchiasis (n = 1809) and opisthorchiasis (n = 731) across the Southeast Asia countries. Utilizing species distribution models incorporating environmental and climatic data, coupled machine learning algorithms with boosted regression trees, we predicted and distinguished endemic areas for each fluke species. Machine learning techniques, including geospatial analysis, were employed to delineate the boundaries between these flukes.

RESULTS

Our analysis revealed that the endemic range of C. sinensis and O. viverrini in Southeast Asia primarily spans across part of China, Vietnam, Thailand, Laos, and Cambodia. During the period from 2000 to 2018, we identified C. sinensis infections in 84 distinct locations, predominantly in southern China (Guangxi Zhuang Autonomous Region) and northern Vietnam. In a stark contrast, O. viverrini was more widely distributed, with infections documented in 721 locations across Thailand, Laos, Cambodia, and Vietnam. Critical environmental determinants were quantitatively analyzed, revealing annual mean temperatures ranging between 14 and 20 °C in clonorchiasis-endemic areas and 24-30 °C in opisthorchiasis regions (P < 0.05). The machine learning model effectively mapped a distinct demarcation zone, demonstrating a clear separation between the endemic areas of these two liver flukes with AUC from 0.9 to1. The study in Vietnam delineates the coexistence and geographical boundaries of C. sinensis and O. viverrini, revealing distinct endemic zones and a transitional area where both liver fluke species overlap.

CONCLUSIONS

Our findings highlight the critical role of specific climatic and environmental factors in influencing the geographical distribution of C. sinensis and O. viverrini. This spatial delineation offers valuable insights for integrated surveillance and control strategies, particularly in regions with sympatric transmission. The results underscore the need for tailored interventions, considering regional epidemiological variations. Future collaborations integrating eco-epidemiology, molecular epidemiology, and parasitology are essential to further elucidate the complex interplay of liver fluke distributions in Asia.

Clonorchis sinensis calcium-binding protein Cs16 causes acute hepatic injury possibly by reprogramming the metabolic pathway of bone marrow-derived monocytes

Introduction

Clonorchis sinensis infection results in various complications in the liver and biliary systems and is a neglected tropical disease in Eastern Asia. In this study, we report that C. sinensis calcium-binding protein Cs16 activates host immune cells and induces immunopathology in liver.

Methods

Immunohistochemistry was used to detect the localization of Cs16 in C. sinensis adult worms. ELISA was used to detect the serum levels of anti-Cs16 IgG antibody in infected humans and mice. Bile duct injection model was used to figure out the role of Cs16 in vivo. RT-qPCR and ELISA were used to detect the cytokine production from Cs16-treated BMMs in vitro. Seahorse assay was used to detect the metabolic pathway of Cs16-treated BMMs in vitro.

Result

Cs16 localizes in the tegument and gut of C. sinensis. Humans and mice with C. sinensis infection exhibited increased levels of anti-Cs16-specific antibody. Using the bile duct injection technique, we found that Cs16 induced obvious inflammation and hepatic necrosis in vivo. Cs16 treatment caused the upregulation of inflammatory cytokines in innate immune cells. Moreover, Cs16-treated monocytes relied more on the glycolytic metabolic pathway.

Discussion

Our findings suggest that Cs16 is a potential pathogenic factor derived from C. sinensis adult worm. By reprogramming the metabolic pathway of innate immune cells, Cs16 triggers pro-inflammatory responses in the liver, and therefore, Cs16 is a potential target for the prevention and treatment of clonorchiasis.

Soil-transmitted helminthiasis in mainland China from 2016 to 2020: a population-based study

Background

Soil-transmitted helminthiasis is epidemic in China and many other countries of the world, and has caused substantial burdens to human health. We conducted successive national monitoring in China from 2016 to 2020 to analyze the prevalence, changing trends, and factors influencing soil-transmitted helminthiasis, which provided a reference for future control strategies.

Methods

Soil-transmitted helminth monitoring was carried out in 31 provinces (autonomous regions or municipalities, herein after referred to as "provinces") throughout China. Each province determined the number and location of monitoring sites (counties), and a unified sampling method was employed. At least 1,000 subjects were investigated in each monitoring county. Stool samples were collected and the modified Kato-Katz thick smear method was employed for stool examination. Infection data and the details of factors influencing soil-transmitted helminthiasis from 2016 to 2020 were collected from national monitoring sites. Additional influencing factors such as environment, climate and human activities were obtained from authoritative websites. Prevalence of soil-transmitted helminths was presented by species, province, sex, and age group. ArcGIS software was used to conduct spatial autocorrelation and hotspot analysis on the infection data. A Poisson distribution model and SaTScan software were used to analyze the infection data with retrospective spatiotemporal scan statistics. A database was built by matching village-level infection rate data with influencing factors. Subsequently, machine learning methods, including a Linear Regression (LR), a Random Forest (RF), a Gradient Boosted Machine (GBM), and an Extreme gradient boosting (XGBOOST) model was applied to construct a model to analyze the main influencing factors of soil-transmitted helminthiasis.

Findings

The infection rates of soil-transmitted helminths at national monitoring sites from 2016 to 2020 were 2.46% (6,456/262,380), 1.78% (5,293/297,078), 1.29% (4,200/326,207), 1.40% (5,959/424,766), and 0.84% (3,485/415,672), respectively. The infection rate of soil-transmitted helminths in 2020 decreased by 65.85% compared to that in 2016. From 2016 to 2020, the infection rate of soil-transmitted helminthiasis was relatively high in southern and southwestern China, including Hainan, Yunnan, Sichuan, Guizhou, and Chongqing. In general, the infection rate was higher in females than in males, with the highest rate in the population aged 60 years and above, and the lowest in children aged 0-6 years. Global autocorrelation and hotspot analyses revealed spatial aggregation in both the national and local distribution of soil-transmitted helminthiasis in China from 2016 to 2020. The hotspots were concentrated in southwestern China. The spatiotemporal scanning analysis revealed aggregation years from 2016 to 2017 located in southwestern China, including Yunnan, Sichuan, Chongqing, Guizhou and Guangxi. The RF model was the best fit model for the infection rate of soil-transmitted helminths in China. The top six influencing factors of this disease in the model were landform, barefoot farming, isothermality, temperature seasonality, year, and the coverage of sanitary toilets.

Interpretation

The overall infection rate of soil-transmitted helminths in China showed a decreasing trend from 2016-2020 due to the implementation of control measures and the economic boom in China. However, there are still areas with high infection rates and the distribution of such areas exhibit spatiotemporal aggregation. As a strategic next step, control measures should be adjusted to local conditions based on the main influencing factors and the prevalence of different sites to aid in the control and elimination of soil-transmitted helminthiasis.

Funding

This research was funded by the National Key Research and Development Program of China (Grant Nos. 2021YFC2300800 and 2021YFC2300804) and the National Natural Science Foundation of China (Grant No. 32161143036).

Children education for sustainable control of liver fluke infections

Significant disease burden is caused by infections with human liver flukes, including Clonorchis sinensis, Opisthorchis viverrini and O. felineus. Epidemiology is characterized by high burden in the male than the female, and in the elder than the younger. Chemotherapy is the mainstream for morbidity control, but it could not prevent re-infection. Meanwhile, behavioral change on the dietary habit of ingesting raw freshwater fish is challenging. In this opinion, we argue why it is important to educate children for sustainable control of liver fluke infections. Then, the design, development and key messages of an educational cartoon for preventing liver fluke infections is introduced. Technical focuses are emphasized based on a pilot using the education cartoon for preventing clonorchiasis in China. Finally, how to further develop and verify this education strategy is discussed.

Clonorchis sinensis infection modulates key cytokines for essential immune response impacted by sex

Infection with helminths can modulate the host immune response, which ultimately shape morbidity and mortality of the associated diseases. We studied key cytokines for essential immune response in sera from 229 southeastern China individuals infected with Clonorchis sinensis and 60 individuals without C. sinensis infection, and measured serum specific IgG and IgE against worms in these people. Individuals infected with C. sinensis had significantly higher antigen-specific IgG and IgE levels, which were positively correlated with egg counts in feces. However, less enhancement of IgE antibody was observed in females when compared to males with similar infection levels. C. sinensis infection caused diminished Th1 cytokines (IL-1β, IL-2, IL-12p70, IFN-γ and TNF-α), Th2 cytokine (IL-4), as well as Th17 cytokine (IL-17A) in sera, which showed decreasing trend by infection intensity. Notably, these phenotypes were more significant in females than those in males. Although C. sinensis infection is associated with the development of hepatobiliary diseases, there was no significant correlation between the dampened cytokine profiles and the hepatobiliary morbidities. Our study indicates C. sinensis infection is strongly related to the immune suppression in human. Sex differences shape the immune milieus of clonorchiasis. This study provides a better understanding of how worms affect immune responses and cause a long-term immune alternation in humans with C. sinensis infection.

National surveillance of hookworm disease in China: A population study

Background

Hookworm disease is endemic in China and is widespread globally. The disease burden to humans is great.

Methods

The study described the national surveillance of hookworm implemented in 31 provinces/autonomous regions/municipalities (P/A/Ms) of China in 2019. Each P/A/M determined the number and location of surveillance spots (counties). A unified sampling method was employed, and at least 1000 subjects were investigated in each surveillance spot. The modified Kato-Katz thick smear method was employed for stool examination. Fifty samples positive with hookworm eggs were cultured in each surveillance spot to discriminate species between A. duodenale and N. americanus. Twenty-five soil samples were collected from each surveillance spot and examined for hookworm larva. The 2019 surveillance results were analyzed and compared with that of 2016–2018.

Results

A total of 424766 subjects were investigated in 31 P/A/Ms of China in 2019, and the overall hookworm infection rate was 0.85% (3580/424766). The weighted infection and standard infection rates were 0.66% (4288357/648063870) and 0.67% (4343844/648063870), respectively. Sichuan province had the highest standard infection rate (4.75%) in 2019, followed by Chongqing (2.54%) and Hainan (2.44%). The standard infection rates of other P/A/Ms were all below 1%, with no hookworm detected in 15 P/A/Ms. The standard hookworm infection rate in the males and the females were 0.61% (2021216/330728900) and 0.71% (2267141/317334970), respectively, with a significant difference between different genders (χ2 = 17.23, P<0.0001). The highest standard hookworm infection rate (1.97%) was among age ≥ 60 years, followed by 45~59 years (0.77%), 15~44 years (0.37%), and 7~14 years (0.20%). The lowest standard infection rate was among the 0~6 years age group (0.12%). A significant difference was observed among different age groups (χ2 = 2 305.17, P<0.0001). The constitute ratio for N. americanus, A. duodenale, and coinfection was 78.70% (1341/1704), 2.03% (346/1704), and 1.00% (17/1704), respectively. The detection rate of hookworm larva from soil was 3.45% (71/2056).

Conclusion

The national surveillance showed that the hookworm infection rate has been decreasing annually from 2016 to 2019, and it is now below 1%. China has made significant progress in controlling hookworm. The national surveillance system is an important way to understand the endemic status and provide important information in this process and thus needs to be continually optimized.

Hookworm disease is endemic in China. The national surveillance system on important parasitic diseases including hookworm infection has been established in China. Stool samples were collected from participants, and the Kato-Katz method was applied to detect helminth eggs while samples with hookworm eggs were further cultured to differentiate the species of the parasite. Additionally, soil samples were collected and examined for hookworm larva. In 2019, the overall infection rate of hookworm in China was 0.85% (3580/424766). High prevalence was demonstrated in Western and Southern China, including Sichuan (4.75%), Chongqing (2.54%) and Hainan (2.44%). The prevalence was high in the females (0.71%) than in the males (0.61%), while it was high in older population especially those age over 60 years. N. americanus dominated the hookworm species. The prevalence of hookworm in soil was 3.45%. Overally, hookworm infection decreased to a low level in China. However, there still exist high endemic areas. Thus, intervention needs to be applied in the high endemic areas and elder population.

Potential Capacity of China's development assistance for health on neglected tropical diseases

Neglected tropical diseases (NTDs) are important health problem in tropical and sub-tropical regions, which afflict more than a billion people worldwide and cause several million deaths every year, especially in Africa. The World Health Organization has called for global efforts to control and eliminate NTDs. China began its health assistance program from 1950s, especially on medical mission dispatched to more than 50 African countries. In this study, a SWOT analysis was used to analyze the current strengths, weaknesses, opportunities, and threats of China's health assistance relating to NTDs, in order to provide the recommendation to promote the activities on international assistance and cooperation on NTDs. Based on this analysis, interventions for NTDs and suggestions for future cooperation relating to NTDs are proposed. In the context of global health, China should strengthen and improve the capacity on health assistance for NTDs control.

Cost yield of different treatment strategies against Clonorchis sinensis infection

BACKGROUND

Clonorchiasis is attributed to the ingestion of raw freshwater fish harboring Clonorchis sinensis. Morbidity control is targeted through the administration of antihelminthics. This study modelled the cost yield indicated by effectiveness and utility of different treatment strategies against clonorchiasis.

METHODS

About 1000 participants were enrolled from each of 14 counties selected from four provincial-level administrative divisions namely Guangxi, Guangdong, Heilongjiang and Jilin in 2017. Fecal examination was adopted to detect C. sinensis infection, while behavior of ingesting raw freshwater fish was enquired. Counties were grouped into four categories based on prevalence, namely low prevalence group (< 1%), moderate prevalence group (1-9.9%), high prevalence group (10-19.9%) and very high prevalence group (≥ 20%), while population were divided into three subgroups, namely children aged below 14 years old, adult female and adult male both aged over 14 years old. The average of cost effectiveness indicated by the cost to treat single infected cases with C. sinensis and of cost utility indicated by the cost to avoid per disability-adjusted life years (DALYs) caused by C. sinensis infection was calculated. Comparisons were performed between three treatment schedules, namely individual treatment, massive and selective chemotherapy, in which different endemic levels and populations were considered.

RESULTS

In selective chemotherapy strategy, the cost to treat single infected case in very high prevalence group was USD 10.6 in adult male, USD 11.6 in adult female, and USD 13.2 in children. The cost increased followed the decrease of endemic level. In massive chemotherapy strategy, the cost per infected case in very high prevalence group was USD 14.0 in adult male, USD 17.1 in adult female, USD 45.8 in children, which were also increased when the endemic level decreased. In individual treatment strategy, the cost was USD 12.2 in adult male, USD 15.0 in adult female and USD 41.5 in children in very high prevalence group; USD 19.2 in adult male, USD 34.0 in adult female, and USD 90.1 in children in high prevalence group; USD 30.4 in adult male, USD 50.5 in adult female and over USD 100 in children in moderate prevalence group; and over USD 400 in any population in low prevalence group. As to cost utility, the differences by treatment strategies, populations and endemic levels were similar to those in cost effectiveness.

CONCLUSIONS

Both cost effectiveness and cost utility indicators are highly impacted by the prevalence and population, as well as the treatment schedules. Adults especially men in the areas with a prevalence over 10% should be prioritized, in which selective chemotherapy was best and massive chemotherapy was also cost effective. In moderate endemic areas, the yield is not ideal, but selective chemotherapy for adult male may also be adopted. In low endemic areas, all strategies were high costly and new strategies need to be developed.

[Current status and challenges for taeniasis and cysticercosis control in China]

In the WHO new road map for neglected tropical diseases 2021-2030, the disease-specific targets are classified into control, elimination as a public health problem, elimination and eradication, and taeniasis and cysticercosis are targeted for control. The overall prevalence of taeniasis and cysticercosis is low in China, and varies remarkably in regions and populations; however, there are many challenges for elimination of taeniasis and cysticercosis in China. Based on previous taeniasis and cysticercosis control programs, developing a sensitive taeniasis and cysticercosis surveillance-response system, updating criteria for diagnosis of taeniasis and cysticercosis, proposing a national guideline for treatment of taeniasis and cysticercosis, and strengthening interdisciplinary and intersectoral communications and collaborations are urgently needed under the One Health concept.

Soil-transmitted helminthiasis in China: A national survey in 2014-2015

Background

Based on two national surveys, the prevalence of soil-transmitted helminthiasis (STH) in China had decreased from 53.58% in 1988–1992 to 19.56% in 2001–2004. To update the epidemiology and characteristics of STH in China, a third national survey was implemented in 2014–2015.

Methodology/Principal findings

This survey covered rural areas in 31 provinces in mainland of China. Multiple-stage stratified cluster sampling was employed, which included three levels (provinces, ecozones and economical levels). Stool samples were collected and the Kato-Katz method was applied for helminth eggs detection. Samples with hookworm eggs were selected and hatched to differentiate the species based on larval morphology. Between June 2014 and May 2015, a total of 484,210 participants from 604 counties were enrolled. The weighted prevalence of STH overall was 4.49% (95% confidential interval (CI): 2.45%-6.53%), including 2.62% (95% CI: 0.86%-4.38%) hookworm infections, 1.36% (95% CI: 0.49%-2.23%) ascariasis, and 1.02% (95% CI: 0.15%-1.89%) trichuriasis. The estimated population infected was 29.12 million (95% CI: 15.88 million-42.32 million) for all STH; 16.97 million (95% CI: 5.57 million-28.39 million) for hookworm infections; 8.83 million (95% CI: 3.18 million-14.45 million) for ascariasis; and 6.60 million (95% CI: 0.97 million-12.25 million) for trichuriasis. Overall, the prevalence of ascariasis and trichuriasis was relatively high in children, while hookworm infections were more common in the older population, especially those over 60. STH was highly prevalent in western China, and moderately in central areas, but low in eastern and northern regions. Out of 3,579 hookworm cases with species differentiation, 479 cases (13.38%) were infected with only Ancylostoma spp., 2,808 cases (78.46%) with only Necator americanus, and another 292 cases (8.16%) with both species.

Conclusions/Significance

This survey demonstrated the continuous decrease of STH in rural China. However, endemicity still prevails in the western areas of the country. Hookworm, especially N. americanus, is becoming the predominant species. Older farmers in western China should be prioritized for control due to the high prevalence of hookworm.

Soil-transmitted helminthiasis (STH) had decreased significantly in China based on the two national surveys implemented in 1988–1992 and 2001–2004, respectively. In 2014–2015, an updated national survey on STH was implemented in rural China. This survey covered rural areas of 31 provinces in mainland of China and multiple-stage stratified cluster sampling was employed. Stool samples were collected and examined for helminth eggs. Totally, 484,210 villagers from 604 counties in 31 provinces participated in the survey. The adjusted prevalence of STH was 4.49%, and that of hookworm infections, ascariasis, trichuriasis was 2.62%, 1.36%, 1.02%, respectively. The estimated population with STH was 29.12 million, while that with hookworm infections, ascariasis, trichuriasis was 16.97 million, 8.83 million, 6.60 million, respectively. Children showed a high prevalence in ascariasis and trichuriasis, while the older population had a high prevalence of hookworm infections. STH was still highly prevalent in western parts, moderately in central areas, and low in eastern and northern regions. Further efforts are needed to control STH in China.

Nucleic acid amplification techniques for the detection of Schistosoma mansoni infection in humans and the intermediate snail host: a structured review and meta-analysis of diagnostic accuracy

BACKGROUND

Schistosomiasis is a parasitic disease caused by hematodes of genus Schistosoma. This review evaluated the available nucleic acid amplification techniques for diagnosing S. mansoni infections in humans, intermediate host snails, and presumed rodent reservoirs.

METHODS

Sensitivity, specificity, diagnostic odds ratio (DOR), and 95% CI were calculated based on available literature. The potential of PCR, nPCR, PCR-ELISA, qPCR, and LAMP was compared for diagnosing S. mansoni infections.

RESULTS

A total of 546 published records were identified. Quality assessment by QUADAS-2 revealed an uncertain risk in most studies, and 21 references were included in the final. For human samples, the four nucleic acid amplification techniques showed an overall sensitivity of 89.79% (95% CI: 83.92%-93.67%), specificity of 87.70% (95% CI: 72.60%-95.05%), and DOR of 37.73 (95% CI: 21.79-65.33). LAMP showed the highest sensitivity, followed by PCR-ELISA, PCR, and qPCR, while this order was almost reversed for specificity; qPCR had the highest AUC. For rodent samples, qPCR showed modest sensitivity (68.75%, 95% CI: 43.32%-86.36%) and high specificity (92.45%, 95% CI: 19.94%-99.83%). For snail samples, PCR and nPCR assays showed high sensitivity of 90.06% (95% CI: 84.39%-93.82%) and specificity of 85.51% (95% CI: 54.39%-96.69%).

CONCLUSION

Nucleic acid amplification techniques had high diagnostic potential for identifying S. mansoni infections in humans.

Clonorchis sinensis re-infection rate and the determinants: a prospective cohort study in Hengxian County, Guangxi, China

BACKGROUND

To understand Clonorchis sinensis re-infection and the determinants in endemic areas is important in establishment of control measures.

METHODS

A prospective cohort study was implemented in Hengxian County, Guangxi, China. Individuals with C. sinensis infection were completely treated, and those cured were enrolled as study subjects and followed up for 3, 6 and 12 months. The re-infection frequency and incidence were calculated, and a multivariable Cox proportional hazard model was constructed to capture re-infection determinants.

RESULTS

Among 635 enrolled subjects, 436 (68.7%) completed follow-up. Of these, 177 (40.6%) were re-infected; 133 (75.1%) were re-infected once, 41 (23.2%) twice and 3 (1.7%) three times. The incidence of re-infection was 64.0 per 100 person-years. Males (aHR: 1.67, 95% CI: 1.14-2.44), those with underlying diseases (aHR: 1.41, 95% CI: 1.02-1.95), and those with moderate- and heavy-intensity infections (aHR: 1.45, 95% CI: 1.14-1.85) had increasing re-infection probabilities.

CONCLUSIONS

C. sinensis re-infection is high in endemic areas. Males and high-intensity infection are important determinants of re-infection. Repeated chemotherapy is necessary to control re-infection and its associated morbidities, especially in high-risk individuals. In addition, behavioural education is advised to decrease overall re-infection in endemic areas.

[Study on the hospitalization cost and its influencing factors of imported malaria patients in Guangxi Zhuang Autonomous Region and Yunnan Province]

OBJECTIVE

To analyze the hospitalization cost and its influencing factors of imported malaria patients in Guangxi Zhuang Autonomous Region and Yunnan Province, so as to provide insights into the evaluation of the economic burden due to imported malaria, and the guiding of malaria control and the rational allocation of medical resources.

METHODS

The data pertaining to the hospitalization costs of imported malaria patients admitted to Shanglin County People's Hospital in Guangxi Zhuang Autonomous Region during the period from January 1 through December 31, 2019, and Tengchong Municipal People's Hospital in Yunnan Province from January 1, 2015 to December 31, 2019, were collected, and the epidemiological data of these imported malaria patients were extracted from the Information Management System for Parasitic Diseases Control and Prevention, China. The composition of the hospitalization expenses was analyzed using a descriptive method. In addition, the factors affecting the hospitalization expenses of imported malaria patients were identified using a univariate analysis and a recursive system model.

RESULTS

A total of 206 imported malaria patients were included in this study, including 194 men (94.17%) and 12 women (5.83%). The mean length of hospital stay was 5.00 days per patient and the median hospitalization expenses were 2 813.07 Yuan per time, in which the expenses for laboratory examinations were the highest (45.31%, 1 274.62/2 813.07). Univariate analysis showed that hospital (z = 5.43, P < 0.01), type of malaria (χ² = 34.86, P < 0.01) and type of payment (χ² = 7.72, P < 0.05) were factors affecting the hospitalization expenses of imported malaria patients. Recursion system modeling revealed that the total effects on hospitalization expenses of imported malaria patients included length of hospital stay (0.78), selection of hospital (0.34), basic medical insurance for urban and rural residents (0.19), new rural cooperative medical care (0.17), Plasmodium falciparum malaria (0.15), gender (0.11) and P. vivax malaria (0.09).

CONCLUSIONS

The hospitalization expenses of imported malaria patients are affected by multiple factors in Guangxi Zhuang Autonomous Region and Yunnan Province, in which the length of hospital stay is the most predominant influencing factor. A reduction in the length of hospital stay is effective to decrease the hospitalization expenses of imported malaria patients.

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.

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.

Severe hepatobiliary morbidity is associated with Clonorchis sinensis infection: The evidence from a cross-sectional community study

Clonorchis sinensis infection is highly prevalent in Asia. Diverse hepatobiliary morbidity has been documented for C. sinensis infection. This study aimed to assess the association between C. sinensis infection and hepatobiliary morbidity, taking into consideration of the control, confounders and infection intensity. A cross-sectional community survey was implemented in Hengxian county, southeastern China. Helminth infections were detected by fecal examination. Physical examination and abdominal ultrasonography were then conducted. After excluding confounding effects from gender, age and alcohol drinking, quantitative association between C. sinensis infection and hepatobiliary morbidity was assessed, and the effect from infection intensity was also evaluated, through adjusted odds ratio (aOR) and 95% confidence intervals (95% CI). 696 villagers older than 10 years were enrolled. The prevalence and infection intensity of C. sinensis were higher in male, elder people and the individuals consuming alcohol. Light C. sinensis infection was associated with the increase of diarrhoea (aOR: 2.2, 95% CI: 1.1–4.5). C. sinensis infection was associated with the increase of fatty liver (aOR: 2.7, 95% CI: 1.4–5.2), and the effect was similar in different infection intensities. Moderate C. sinensis infection was associated with the increase of gallbladder stone (aOR: 3.0, 95% CI: 1.1–8.6), while moderate and heavy infections with the increase of intrahepatic bile duct dilatation (aOR: 2.2, 95% CI: 1.0–4.9 and aOR: 4.3, 95% CI: 1.9–9.9, respectively). C. sinensis infection had an effect on the development of periductal fibrosis (aOR: 3.2, 95% CI: 2.1–4.9), which showed increasing trend by infection intensity. The length and width of gallbladder in those with C. sinensis infection were enlarged, especially in those over 30 years old. C. sinensis infection is significantly associated with hepatobiliary morbidity. The occurrence of some morbidity was strongly related to the infection intensity. Awareness on harm of clonorchiasis should be raised both for policy-makers and villagers to adopt effective interventions.

Clonorchiasis is caused by ingestion of raw freshwater fish, which carries the larvae of Clonorchis sinensis. In this study, we aimed to assess the damages associated with clonorchiasis. A cross-sectional field survey was carried out in Hengxian county, southeastern China. Stool samples were collected and examined for helminth infections. Then, physical examination and abdominal ultrasonography were conducted. In total, 696 villagers older than 10 years were included. The prevalence and infection intensity of C. sinensis were higher in male, elder people and those drinking alcohol. Excluding the impact from gender, age and alcohol drinking, it was demonstrated that light C. sinensis infection was associated with the increase of diarrhoea, moderate infection with gallbladder stone, and moderate and heavy infections with intrahepatic bile duct dilatation. C. sinensis infection was relevant to the increase of fatty liver, and the effect was similar in different infection intensities. C. sinensis infection was associated with the development of periductal fibrosis and the effect increased by infection intensity. The length and width of gallbladder in individuals with C. sinensis infection were enlarged, especially in those over 30 years old. Thus, our study demonstrates that C. sinensis infection is associated with severe hepatobiliary morbidity, and the effect is strongly related to infection intensity for some morbidity. Concerted efforts should be exerted to tackle the morbidity in clonorchiasis endemic areas.

Model-based spatial-temporal mapping of opisthorchiasis in endemic countries of Southeast Asia

Opisthorchiasis is an overlooked danger to Southeast Asia. High-resolution disease risk maps are critical but have not been available for Southeast Asia. Georeferenced disease data and potential influencing factor data were collected through a systematic review of literatures and open-access databases, respectively. Bayesian spatial-temporal joint models were developed to analyze both point- and area-level disease data, within a logit regression in combination of potential influencing factors and spatial-temporal random effects. The model-based risk mapping identified areas of low, moderate, and high prevalence across the study region. Even though the overall population-adjusted estimated prevalence presented a trend down, a total of 12.39 million (95% Bayesian credible intervals [BCI]: 10.10–15.06) people were estimated to be infected with O. viverrini in 2018 in four major endemic countries (i.e., Thailand, Laos, Cambodia, and Vietnam), highlighting the public health importance of the disease in the study region. The high-resolution risk maps provide valuable information for spatial targeting of opisthorchiasis control interventions.

Helminthiases in the People's Republic of China: Status and prospects

Helminth infections, many of them listed as neglected tropical diseases by the World Health Organization, remain a public health issue in many parts of the world. The People's Republic of China (P.R. China) stands out due to impressive progress in the control and local elimination of helminth infections. An important contextual factor is P.R. China's sustained social and economic development that allowed implementation of health-related poverty alleviation, improving water, sanitation and hygiene, enhancing information, education and communication, coupled with major engineering and infrastructure development and intersectoral collaboration. Nonetheless, food-borne trematodiases, soil-transmitted helminthiases, echinococcosis, cysticercosis/taeniasis and schistosomiasis still exert a considerable burden in P.R. China, even though the numbers of infected people have decreased substantially since the new millennium. This special issue of Acta Tropica provides a comprehensive update of the current knowledge of the main helminth infections in P.R. China, summarises progress in research and discusses future prospects for gaining and sustaining control towards the final goal of breaking transmission and hence, eliminating helminthiases. It consists of 34 articles with a wide coverage that can be grouped into six domains: (i) epidemiological assessment and disease burden estimates; (ii) diagnostics and antigen characterisation; (iii) drug and vaccine development; (iv) host-parasite interactions and snail genetics; (v) surveillance and public health response; and (vi) capacity building and international cooperation. The control and elimination of helminthiases not only furthers the health and wellbeing of the Chinese people, but also provides innovative approaches, tools and strategies, which can be adopted and applied in other countries and regions of the world where helminthiases still prevail.

[Prevalence of soil - borne nematode infections among residents living in urban/town areas of China in 2015]

OBJECTIVE

To understand the prevalence of soil-borne nematode infections among residents living in urban/town areas of China, so as to provide insights into the control and elimination of soil-borne nematodiasis.

METHODS

A total of 5 epidemic areas were classified in China according to the prevalence of human Clonorchis sinensis infections captured from the 2014-2015 national survey on major human parasitic diseases in China, and the total sample size was estimated according to the binomial distribution and Poisson's distribution. Then, the total sample size was allocated proportionally to each province (autonomous region, municipality) of China based on the percentage of residents living in urban and town areas, and the number of survey sites in each province (autonomous region, municipality) was proportionally assigned according to the percentages of residents living in urban and town areas. Then, stratified sampling was performed at county, township and community levels according to the number of sampling sites in each province (autonomous region, municipality), and the survey site (community) was defined as the smallest sampling unit. All permanent residents in the survey sites were selected as the study subjects, and their stool samples were collected for identification and counting of parasite egg using a Kato-Katz technique. The prevalence and intensity of each parasite species were calculated.

RESULTS

From 2014 to 2015, among the 133 231 residents detected in 31 provinces (autonomous regions, municipalities) of China, the overall prevalence of soil-borne nematode infections was 1.23% (1 636/133 231), and the prevalence rates of hookworm, Ascaris lumbricoides and Trichuris trichiura infections were 0.77% (1 032/133 231), 0.32% (426/133 231) and 0.17% (224/133 231), respectively. The highest prevalence of soil-borne nematode infections was seen in Jiangxi (4.03%, 82/2 034) and Chongqing (4.03%, 524/13 012), followed by in Hainan (3.47%, 72/2 075). The prevalence of soilborne nematode infections was 1.07% (662/62 139) in men and 1.37% (974/71 092) in women, and the greatest prevalence was found in residents at ages of 65 to 70 years (2.56%, 219/8 569). With regard to occupations and education levels, herdsmen (2.47%, 2/81) and illiterate residents (3.33%, 226/6 795) were found to have the highest prevalence of soil-borne nematode infections, respectively. In addition, mild infections were predominantly identified in hookworm-, A. lumbricoides- and T. trichiura-infected individuals (all > 90%).

CONCLUSIONS

The overall prevalence of soil-borne nematodiasis remains low in urban and town areas of China; however, human infections are widespread. According to the epidemiological features, health education combined with deworming are recommended to reduce the prevalence of soil-borne nematode infections among residents living in urban and town areas of China.

Effectiveness of health education in improving knowledge, practice and belief related to clonorchiasis in children

Clonorchiasis is caused by the ingestion of raw freshwater fish containing Clonorchis sinensis larvae. Health education is crucial in sustainable control of clonorchiasis but extremely challenging when dealing with adults. To investigate if education in children would be a beneficial long-term approach, a cluster-controlled trial was implemented in two primary schools between 2017 and 2019 in Binyang county, Guangxi, China. A baseline survey was conducted in both schools, and then comprehensive education activities were implemented in the interventional one. Six and 12 months later, all pupils were subjected to a survey to assess the potential change of knowledge, practice and belief related to clonorchiasis. Finally, 247 pupils in interventional school and 151 ones in control were eligible for analysis. In the interventional school, the percentage of pupils with knowledge on transmission route, early symptoms, complications and carcinogenicity increased from 15.0% to 78.5% (p < 0.001), from 6.5% to 36.8% (p < 0.001), from 4.0% to 93.9% (p < 0.001) and from 4.5% to 49.4% (p < 0.001) after 12 months. In this school, 16 pupils (6.5%) had eaten raw freshwater fish during the year immediately before the baseline survey, a number that decreased to 3 (1.2%) (p = 0.002) 12 months later. The percentage of students had the belief on the ability not to eat raw freshwater fish in the future was 70.9% at the baseline and 97.2% 12 months later (p < 0.001). Although knowledge related to clonorchiasis also increased in the control school, the absolute percentage of changes was lower; in particular, practice and belief had not changed.

Rapid screening of Clonorchis sinensis infection: Performance of a method based on raw-freshwater fish-eating practice

Clonorchis sinensis infection is caused by ingestion of raw freshwater fish containing the infective larvae of Clonorchis sinensis. It is highly endemic in East Asia, especially in China. Selective chemotherapy of people who report habitual eating of raw freshwater fish is a control measure. As the performance of this screening technique has not yet been fully evaluated in China, a cross-sectional study was conducted, covering 17 counties in four major clonorchiasis-endemic provinces. About 1 000 participants were enrolled from each county. Fecal samples were collected and examined for helminth eggs and each person enrolled was asked about their practice with respect to eating raw freshwater fish. In total, 16 230 participants from 16 counties were finally included. The overall prevalence of C. sinensis infection was 10.8%, ranging from 0 to 53.7% in the 16 counties, while the percentage of inhabitants eating raw freshwater fish was 26.5%, ranging from 0 to 79.1%. The overall sensitivity and specificity of screening for C. sinensis infection in this approach was 82.3% and 80.3%, respectively, yielding a Youden's index of 0.6. The overall positive and negative likelihood ratios were 4.2 and 0.2, respectively, while the overall positive and negative predictive values were 33.5% and 97.4%, respectively. Furthermore, the sensitivity was higher with regard to high-intensity infections compared to light infections.

Contribution of NIPD-CTDR to the parasitic diseases control and elimination in China: Memory of the 70th anniversary for NIPD-CTDR

China has achieved a great success in control and elimination of key parasitic diseases. In 2007, the elimination of lymphatic filariasis was verified by WHO. The schistosomiasis incidence and snail-distributed areas have reduced to the lowest level in the history. The transmission and disease burden of echinococcosis have been contained largely, and the populations infected with soil-transmitted trematode and food-borne parasites have also shown a significantly declining trend. Because of rapid globalization and climate changes, however, many new challenges have arisen. In his paper, the 2020-2030 roadmaps towards the control and elimination of these key parasitic diseases are described. Moreover, China is actively implementing its global health strategy, and will be more and more engaged into global health affairs, in which a series of China-Africa health cooperation projects have been in planning with a wish of making a greater contribution to the SDGs.

Engagement of the National Institute of Parasitic Diseases in control of soil-transmitted helminthiasis in China

Soil-transmitted helminthiases (STHs) have been widely transmitted in China and the control of STHs was initiated by NIPD-CTDR since its foundation. Three national surveys on STHs have been carried out in China, and the infection rate has dropped from 53.58% in the first national survey (1988-92) to 4.49% in the third national survey (2014-16) due to strong interventions including mass drug administration, health education and environment improvement. National surveillance of STHs started in 2006 and has been implemented successively until now, which allows to understand the endemic status and trends of STHs prevalence in China. Surveillance has been expanded to 30 provinces of China since 2016. Integrated pilot programmes have been implemented between 2006 and 2009, in which an integrated strategy, with health education and control of infection sources as key components, was adopted. Since 2019, new control pilots have been started, which will be continued for five successive years to further explore appropriate control strategies in the current "new era". With the decline of infection rate of STHs, China is approaching the elimination stage for STHs. In order to achieve this final target, poverty alleviation programmes should be integrated with precise control measures, according to real situations.

Control of taeniasis and cysticercosis in China

National surveys suggest that the prevalence of taeniasis has considerably decreased in China, while reported cases indicated T. solium cysticercosis was historically highly endemic in northeastern, central and southwestern China. The high prevalence of taeniasis and cysticercosis there was driven by socio-ecological determinants. Cysticercosis may occur in the central nervous system, spinal cord, subcutaneous muscle, eyes, heart and oral cavity. Neurocysticercosis, the clinically most important type, causes epilepsy, increased intracranial pressure and neuropsychiatric symptoms. New molecular diagnostic techniques have been introduced for high sensitivity and discrimination of Taenia species. Immunological methods remain useful in the diagnosis of cysticercosis, especially neurocysticercosis. The introduction of imaging techniques including computed tomography and magnetic resonance imaging has significantly improved the diagnosis of neurocysticercosis. Recently, a combination of pumpkin seeds and areca nut has been explored against taeniasis, while praziquantel and albendazole are administrated simultaneously against cysticercosis, with promising efficacy and low side-effects. The widespread adoption of deworming protocols and techniques for inspection, management and treatment of pigs as well as improved sewage management has contributed to the significant decrease of taeniasis and cysticercosis in northern China. The positive results of these techniques should now be extended to highly endemic areas in western China to achieve the national elimination target for taeniasis and cysticercosis. Elimination of taeniasis and cysticercosis in China will not only benefit public health within China but also set an important example for less developed countries.

National surveillance on soil-transmitted helminthiasis in the People's Republic of China

Soil-transmitted helminths (STHs) are widely distributed and remain a public health problem in the People's Republic of China. Altogether, 301 counties across 30 regions were investigated during the national surveillance on STHs carried out in 2016 based on the modified Kato-Katz thick smear method to examine faecal samples. A total of 305 081 people were investigated with 7 366 (2.4%) found to be infected. The infection rates were the following: hookworm 1.4%, Ascaris lumbricoides 0.8% and Trichuris trichiura 0.5%. Having established that the STHs infection rate is relatively low, it is time to move towards elimination. The national surveillance system is essential for providing basic data and formulation of useful control strategies towards achieving this goal.

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.

Surveillance of clonorchiasis in China in 2016

Clonorchiasis is an important food-borne parasitic disease in China, and infection with C. sinensis can cause hepatobiliary diseases. Comprehensive and systematic prevention and control of clonorchiasis requires the establishment of an effective surveillance. A total of 301 surveillance points were set up in 30 provinces across China in 2016, and 1000 people were selected by cluster sampling at each surveillance point annually for C. sinensis infection screening using Kato-Katz thick smear method. C. sinensis infection was detected in 6226 people following screening of 305081 people at the 301 surveillance points in 2016. Infection rate was 2.04%; with C. sinensis infection detected in 70 counties spread across 15 provinces, 89.37% of the infected people were distributed in Jilin, Heilongjiang, Guangdong and Guangxi provinces. Highest infection rate was observed in Da'an city, Jilin Province (49%). The national infection rate in male and female was 2.70% and 1.40% respectively. Infection rate between male and female was significantly different (P <0.01). Disease prevalence increases with age in both male and female, reaches peak in age group 40-49. Result obtained indicate that major C. sinensis endemic areas are distributed in the north and south of China, and areas with high prevalence are distributed along the river system at county level. Result, also, shows that middle-aged men are at high-risk of infection. These results suggest that surveillance activities should be sustained nationwide and highlight the need for an integrated approach to control C. sinensis transmission in regions with high disease prevalence in China.

[National surveillance on Enterobius vermicularis infections among children at ages of 3 to 9 years in China from 2016 to 2018]

OBJECTIVE

To understand the epidemic status of Enterobius vermicularis infections among children aged 3 to 9 years in China, so as to provide scientific basis for the formulation of the prevention and control strategies for enterobiasis.

METHODS

The national surveillance of enterobiasis was performed in 736 national surveillance sites (counties) from 30 provinces (municipalities/autonomous regions) in China from 2016 to 2018. All surveillance sites were classified into parts according to the geographical directions, including the eastern, western, southern, northern and middle parts, and a township was randomly selected from each part. Then, an administrative village was randomly selected from the township, and 200 permanent residents at ages of over 3 years living in the administrative village were randomly selected using the cluster sampling method. A total of 1 000 residents were examined in each surveillance site. E. vermicularis infections were detected among children at ages of 3 to 9 years using the modified Kato-Katz technique and the adhesive cellophane-tape perianal swab method, and the prevalence of infections was calculated and compared.

RESULTS

The prevalence of E. vermicularis infections was 2.50%, 2.84% and 2.46% among children at ages of 3 to 9 years in the 736 surveillance sites from 30 provinces (municipalities/autonomous regions) in China from 2016 to 2018, and there was no gender-specific prevalence of E. vermicularis infections (P > 0.05). Enterobiasis was main prevalent in the southern and southwestern part of China (Jiangxi, Guangxi, Guangdong, Sichuan, Fujian, Chongqing and Hainan), with 5.00% prevalence and greater, and the highest prevalence was seen in Jiangxi and Guangxi for successive 3 years. In addition, the prevalence of E. vermicularis infections was higher in children with the Han ethnicity than in those with the minority ethnicity, and a high prevalence was found in children at ages of 4 to 7 years, and a low prevalence seen in children at ages of 3, 8 and 9 years.

CONCLUSIONS

The prevalences of E. vermicularis infections have not changed much among children at ages of 3 to 9 years in China from 2016 to 2018, and high prevalence is seen in southern and southwestern China, which should be given a high priority.

From awareness to action: NIPD's engagement in the control of food-borne clonorchiasis

Clonorchiasis is caused by ingestion of raw freshwater fish containing infective larvae of Clonorchis sinensis. China harbours the largest number of people with C. sinensis infection. During the past three decades, the National Institute of Parasitic Diseases, affiliated to the Chinese Center for Disease Control and Prevention (NIPD) conducted many studies to facilitate the control on clonorchiasis. Three national surveys have shown the updated epidemiology of clonorchiasis in China. Recently, a national surveillance system has also been established, which will enable the production of high-resolution map. The evaluation of the disease burden has enhanced the awareness on clonorchiasis. Diverse diagnosis techniques including rapid screening by questionnaire, serological tests, faecal examination and a molecular method have been developed or evaluated. The NIPD also participated in the early evaluation of praziquantel against clonorchiasis, which enhanced its application in China. Also, the NIPD has verified the efficacy of tribendimidine against clonorchiasis. A new sustainable strategy is also being explored. However, more research is expected to further facilitate control of clonorchiasis in China, as well as international cooperation in fighting human liver fluke infections in Asia.

[Establishment of an evaluation system for the field assessment of the Kato-Katz technique in detection of soil-transmitted nematodiasis]

OBJECTIVE

To establish an evaluation system for the field assessment of the Kato-Katz technique in detecting soiltransmitted nematodes, so as to provide insights into the field application of the Kato-Katz technique.

METHODS

The initial evaluation indicators were determined through literature search, brainstorming and expert consultation. The evaluation indicatorswere improved and the weight of each indicator was decided through three rounds of expert consultation by using the Delphimethod. In addition, the expert authority coefficient and the coordination coefficient of each indicator were calculated at eachround of expert consultations.

RESULTS

The recovery rates of the questionnaire were 100.00%, 100.00% and 89.29% at the firstto the third round of the expert consultations, respectively, and the expert authority coefficients were all more than 0.85 at eachround. The final evaluation system included 4 first-level indicators and 15 second-level indicators. In the first-level indicators, "detecting effect" and "funds investment" had the mean weighted value of 4.53 and 4.49, which were relatively higher than that of"person-time investment" and "operability" (both 4.34). Among the second-level indicators under each first-level indicator, thefour most significant indicators included "ability of personnel in egg discrimination", "cooperation of village cadres and doctors","Person-time on testing" and "organizational start-up cost", with the mean weighted values of 4.74, 4.43, 4.39 and 4.17, respectively. The coordination coefficients were 0.39 to 0.65, 0.28 to 0.58 and 0.45 to 0.65 at the first to the third round of the expertconsultations, respectively, and there were significant differences in the coordination coefficients at all three rounds of the consultations (all P < 0.05).

CONCLUSIONS

An evaluation system for the field assessment of the Kato-Katz technique in detecting soiltransmitted nematodes is successfully established, among which "ability of personnel in egg discrimination" and "cooperation ofvillage cadres and doctors" have the greatest mean weighted values of the significance.

Neglected tropical diseases in the People's Republic of China: progress towards elimination

Since the founding of the People’s Republic of China in 1949, considerable progress has been made in the control and elimination of the country’s initial set of 11 neglected tropical diseases. Indeed, elimination as a public health problem has been declared for lymphatic filariasis in 2007 and for trachoma in 2015. The remaining numbers of people affected by soil-transmitted helminth infection, clonorchiasis, taeniasis, and echinococcosis in 2015 were 29.1 million, 6.0 million, 366 200, and 166 100, respectively. In 2017, after more than 60 years of uninterrupted, multifaceted schistosomiasis control, has seen the number of cases dwindling from more than 10 million to 37 600. Meanwhile, about 6000 dengue cases are reported, while the incidence of leishmaniasis, leprosy, and rabies are down at 600 or fewer per year. Sustained social and economic development, going hand-in-hand with improvement of water, sanitation, and hygiene provide the foundation for continued progress, while rigorous surveillance and specific public health responses will consolidate achievements and shape the elimination agenda. Targets for poverty elimination and strategic plans and intervention packages post-2020 are important opportunities for further control and elimination, when remaining challenges call for sustainable efforts.

Improving diagnostic performance of the Kato-Katz method for Clonorchis sinensis infection through multiple samples

BACKGROUND

Clonorchiasis is caused by eating of raw or undercooked freshwater fish containing the larvae of Clonorchis sinensis; the Kato-Katz method is widely applied in diagnosis. The improvement of repeated Kato-Katz smears from multiple stool samples has been well illuminated in many helminths other than C. sinensis.

METHODS

A cross-sectional investigation was implemented to capture the epidemiology and risk factors of clonorchiasis among middle school students in Qiyang county, China. Students with complete data of six Kato-Katz thick smears from two stool samples were included in this analysis. Data on the habits of eating raw freshwater fish were also collected and compared.

RESULTS

Altogether, 397 students had complete information of six smears, out of which 394 reported the information on eating habits. According to the 'gold' standard by six smears, 77 students (19.4%) were detected with C. sinensis. However, only 45 (11.3%) were detected using a single smear, with an underestimation of 41.6% compared to the 'gold' standard. However, the geometric mean of eggs per gram of feces in detected cases was 126.4 in a single smear, overestimated by 105.2% compared to 61.6 by the 'gold' standard. The linear relationship between prevalence and infection intensity of detected cases based on different smears was significantly negative. The habits of eating raw freshwater fish in the false negative cases was similar to those in the detected cases, but these two groups had significantly higher levels for habits of eating raw freshwater fish than negative individuals.

CONCLUSIONS

In low endemicity situations, underestimation of C. sinensis infection could not be avoided based on a limited number of Kato-Katz smears. Thus, repeated smears from at least two stool samples should be considered when an individual eats raw freshwater fish, drug efficacy is evaluated or elimination of C. sinensis is verified. Additionally, when logistics are insufficient for multiple samples to be taken for diagnosis for survey and surveillance in the areas or populations of low endemicity, prevalence accuracy needs to be corrected.

Extensive disseminated cysticercosis: a case report in Yunnan province, China

BACKGROUND

Cysticercosis is spreading all over the world and it is a major health problem in most countries of Latin America, Africa, and Asia. Extensive disseminated cysticercosis is relatively rare and fewer than 120 case have been reported in the worldwide. We reported a rare case of extensive disseminated cysticercosis in Yunan province, China.

CASE PRESENTATION

A rare case of extensive disseminated cysticercosis, in a 61-year-old male Chinese was detected from Yunnan province in 2018. Clinical and etiological examination was performed, as well as the epidemiological investigation.

CONCLUSION

The life cycle of T. solium in the area where the case came from is complete. We expect this case could raise the attentions to the control of Taenia solium infection and subsequent cysticercosis there.

Assessment of health education products aimed at controlling and preventing helminthiases in China

BACKGROUND

Helminthiases have placed a huge burden of disease on the population in China. However, widespread control activities have led to significant achievements. As health education has been widely disseminated and plays an important role in the control and elimination of these diseases, we collected health education products aimed at controlling and preventing helminthiases in China. We analyzed their characteristics and assessed their quality.

METHODS

Firstly, health education products aimed at controlling and preventing helminthiases were collected from a diverse range of organizations. Secondly, the expert brainstorming and Delphi methods were applied to establish an evaluation system, which was then used to assess the collected products systematically. Those deemed excellent were awarded. Characteristics - including type, source, targeted disease(s), targeted population, and languages - of the collected products and the awarded products were presented here.

RESULTS

In total, 96 health education products on helminthiases were collected from 53 organizations. Most products belonged to either the graphic design (47) or daily-use (24) category. Seventy were collected from Centers for Disease Control and Prevention and 20 from institutes or control stations of parasitic diseases, primarily at the provincial and county levels. Regarding disease targets of the products, 67 focused on a single helminthiasis, 25 on multiple helminthiases, and the remaining four on non-specific diseases. Of the 67 single helminthiasis-focused products, most targeted schistosomiasis (37), followed by echinococcosis (16). The majority of products (79) targeted the general population, while 11 targeted students specifically. Regarding languages, 86 products were only in Chinese, while the other ten were in both Chinese and the minority languages of China. Out of these ten products, one targeted schistosomiasis and the other nine targeted echinococcosis. Thirty-four products were awarded. The characteristics of the awarded products were similar to those of the collected products.

CONCLUSIONS

A diverse range of health education products have been designed and applied for the prevention and control of helminthiases in China. Many products have good features such as specifying the targeted diseases and populations. However, there are significant gaps in terms of both the quantity and quality of products pertaining to some of the diseases. Experiences from the awarded products could be drawn upon to design more products aimed at a range of different helminthiases.

[Establishment and role of national clonorchiasis surveillance system in China]

Clonorchiasis is one key food-borne parasitic disease in China. Owing to several years'efforts and preparation, the national clonorchiasis surveillance system in China has been established preliminarily since 2016. In this article, the necessity to establish the national clonorchiasis surveillance system is explained. Then, the structure, content and corresponding methods of the surveillance system are briefly introduced. Key points in the surveillance are summarized and the development of surveillance in future is discussed. Furthermore, the contribution of clonorchiasis surveillance in China to the world is also analyzed.

Performance evaluation of existing immunoassays for Clonorchis sinensis infection in China

BACKGROUND

Clonorchiasis ranks among the most important food-borne parasitic diseases in China. However, due to low compliance to traditional fecal examination techniques in the general population and medical personnel, immunodiagnosis is expected. This study evaluated, in parallel, the performance of four immunodiagnostic kits detecting clonorchiasis in China.

RESULTS

A bank with 475 sera was established in this study. Except for the low performance of the kit detecting IgM, the other three kits detecting IgG showed sensitivities ranging from 81.51% (194/238) to 99.16% (236/238). Higher sensitivity was presented in heavy infection intensity [89.47% (68/76) to 100% (76/76)]. Among the four kits, the overall specificity varied from 73.42% (174/237) to 87.34% (207/237). It was observed that the specificity was lower in the sera of the participants living in clonorchiasis-endemic areas but without any parasite infection [67.5% (81/120) to 90% (108/120)], as compared to those from the non-endemic area [94% (47/50) to 98% (49/50)]. The cross-reaction rate varied from 14.93% (10/67) to 31.34% (21/67). Youden's index was -0.022, 0.689, 0.726, and 0.802 for kits T1, T2, T3 and T4, respectively. Repeatability was high in all four kits.

CONCLUSIONS

Three immunodiagnosis kits targeting IgG antibody had high performance on detecting chronic Clonorchis sinensis infection, but that detecting IgM antibody had not. The kits detecting IgG antibody also showed high sensitivity in heavy infection intensity. Research on immunological diagnosis of clonorchiasis is expected to be strengthened to improve the sensitivity in light infection and specificity.

Combating echinococcosis in China: strengthening the research and development

Echinococcosis is a neglected zoonotic disease, causing great morbidity and mortality due to the wide distribution of its endemic areas. China holds a high percentage in the global burden of both cystic and alveolar echinococcosis. A national survey conducted between 2012 and 2016 showed that an estimated 50 million people are at risk of contracting the disease in western China, of whom about 0.17 million are cases with echinococcosis.

Despite this, research and development on echinococcosis in China is greatly inadequate compared to that in other countries. In this paper, we argue that there is a need for more research and work to be conducted in China on echinococcosis, including researching techniques in regards to diagnosis, treatment, and vaccination, and developing products through technical transformation and piloting strategies to control and even elimination.

However, great opportunities exist for China to strengthen the research and development on this disease through initiatives such as Health China 2030, the Belt and Road Initiative, the China-Africa cooperation, as well as through further cooperation between China and the World Health Organization. All of these can bring us closer to controlling echinococcosis in China as well as in other countries. One element of crucial importance will be the training and development of professionals, which can be strengthened through international cooperation.

Neglected tropical diseases and global burden of disease in China

Recently, the mortality of 240 causes in China including a subnational analysis during 1990–2013 was published in The Lancet. This comprehensive analysis will undoubtedly impact policymaking regarding public health in China. However, it is unfavourable in some degree to neglected tropical diseases, which is the subject of this Letter to the Editor. Policymakers, especially those in less developed provinces of China, should fully consider the burden of neglected tropical diseases, which will benefit the control and final elimination of these diseases in the country.

Clonorchiasis

On Aug 21, 1875, James McConnell published in The Lancet his findings from a post-mortem examination of a 20-year-old Chinese man--undertaken at the Medical College Hospital in Calcutta, India--in whom he found Clonorchis sinensis in the bile ducts. Now, exactly 140 years later, we have a sound understanding of the lifecycle of this liver fluke, including key clinical, diagnostic, and epidemiological features. Developments in the so-called -omics sciences have not only advanced our knowledge of the biology and pathology of the parasite, but also led to the discovery of new diagnostic, drug, and vaccine targets. C sinensis infection is primarily related to liver and biliary disorders, especially cholangiocarcinoma. Clonorchiasis mainly occurs in east Asia, as a result of the region's social-ecological systems and deeply rooted cultural habit of consuming raw freshwater fish. The Kato-Katz technique, applied on fresh stool samples, is the most widely used diagnostic approach. Praziquantel is the treatment of choice and has been considered for preventive chemotherapy. Tribendimidine showed good safety and therapeutic profiles in phase 2 trials and warrants further investigation. Still today, the precise distribution, the exact number of infected people, subtle morbidities and pathogenesis, and the global burden of clonorchiasis are unknown. Integrated control strategies, consisting of preventive chemotherapy; information, education, and communication; environmental management; and capacity building through intersectoral collaboration should be advocated.