Major trends in human parasitic diseases in China

Development and evaluation of a health literacy scale for parasitic diseases

BACKGROUND

Parasitic diseases remain a serious public health problem in China. Health education aimed at disseminating health-related knowledge and promoting healthy behaviours, plays a crucial role in the prevention and control of parasitic diseases. This study aims to develop a tool to measure the parasitic disease health literacy of residents in China.

METHODS

Scale development was based on qualitative and quantitative methods. Qualitative method included focus group discussions and Delphi consultations. A methodological design with multistage sampling and a pilot study was used to evaluate the questionnaire. The scale's reliability was tested using Cronbach's α and split-half reliability, while its construct validity was assessed using confirmatory factor analysis. The scale's passing score was determined using the receiver operating characteristic curve. A cross-sectional survey was conducted in six districts of the prefecture of Jiangsu and residents aged 14-69 years in the participating townships were randomly selected based on their location.

RESULTS

The health literacy indicator system for parasitic diseases included 3 first-level, 9 s-level and 23 third-level indicators. The 23-item questionnaire demonstrated good internal consistency (Cronbach's alpha = 0.774) and split-half reliability (Spearman-Brown coefficient = 0.778). The questionnaire's passing score was 60. A total of 990 valid questionnaires were collected from participants in three cities. The percentage of participants with health literacy regarding parasitic diseases was 15.8%. Their scores were influenced by age, income, employment, and educational level.

CONCLUSIONS

Health literacy of parasitic diseases is an integrated indicator rather than just knowledge or behavior information. The correlation between knowledge and behavior is weak. The capacity for healthy behavior of parasitic disease is associated with the location and culture of the city. For neglected diseases, it is important for people to talk positively about their behaviors with a doctor.

Emerging and Reemerging Parasitic Diseases in Taiwan: A Retrospective Study of Clinical Case Reports in 2001~2018

Emerging and re-emerging parasitic diseases can cause significant economic burdens at national and global levels. However, governments often underestimate or ignore these diseases, especially in developed countries. This retrospective, case-oriented study analyzed parasitic diseases reported in Taiwan between 2001 and 2018. One hundred and thirty-two eligible clinical profiles of Taiwanese patients obtained from the NCBI, Scopus, Google Scholar, and Web of Science databases and local journals according to age, sex, source of infection, symptoms, risk factors, and geographical regions were analyzed. The analysis results showed that the number/frequency of cases caused by nematodes (46.97%) or protozoa (37.88%) was significantly higher than that of trematodes (9.85%) or cestodes (5.30%) (p < 0.0001). Northern Taiwan (46.97%) had a significantly higher rate than Southern Taiwan (33.33%), Central Taiwan (8.33%), and Eastern Taiwan (5.30%) (p < 0.05). The 15-65 age group (68.94%) had a significantly higher rate than the 65-90 age group (22.73%) and the 0-15 age group (8.33%) (p < 0.0001). Males (70.46%) had a significantly higher number/frequency of cases than females (29.54%) (p < 0.0001). People who acquired the infection through the food/soil route (32.58%) or who had a low immune status (32.58%) had a higher rate than travel-related infections (15.15%) (p < 0.001). The present study showed that emerging/reemerging parasitic infections continue to be of great concern to the lives and health of Taiwanese citizens and, if ignored, will threaten the health of the Taiwanese people; therefore, the delineation of preventive measures by health authorities is urgently warranted.

PDDGCN: A Parasitic Disease-Drug Association Predictor Based on Multi-view Fusion Graph Convolutional Network

The precise identification of associations between diseases and drugs is paramount for comprehending the etiology and mechanisms underlying parasitic diseases. Computational approaches are highly effective in discovering and predicting disease-drug associations. However, the majority of these approaches primarily rely on link-based methodologies within distinct biomedical bipartite networks. In this study, we reorganized a fundamental dataset of parasitic disease-drug associations using the latest databases, and proposed a prediction model called PDDGCN, based on a multi-view graph convolutional network. To begin with, we fused similarity networks with binary networks to establish multi-view heterogeneous networks. We utilized neighborhood information aggregation layers to refine node embeddings within each view of the multi-view heterogeneous networks, leveraging inter- and intra-domain message passing to aggregate information from neighboring nodes. Subsequently, we integrated multiple embeddings from each view and fed them into the ultimate discriminator. The experimental results demonstrate that PDDGCN outperforms five state-of-the-art methods and four compared machine learning algorithms. Additionally, case studies have substantiated the effectiveness of PDDGCN in identifying associations between parasitic diseases and drugs. In summary, the PDDGCN model has the potential to facilitate the discovery of potential treatments for parasitic diseases and advance our comprehension of the etiology in this field. The source code is available at https://github.com/AhauBioinformatics/PDDGCN .

Preconceptional, pregnant, and postnatal exposure to outdoor air pollution and indoor environmental factors: Effects on childhood parasitic infections

BACKGROUND

Parasitic infections (PIs) are common and pose substantial health hazards in children globally, but the fundamental environmental variables exposure during crucial time window(s) are unclear.

OBJECTIVES

To identify key indoor and outdoor environmental factors leading to childhood PIs throughout critical time window(s).

METHODS

A combined cross-sectional and retrospective cohort study was performed on 8689 children residing in Changsha, China. Data was acquired pertaining to the health status and environmental exposure of the children in their homes. Personal exposure to outdoor air pollutants at the residential address during the preconceptional, perinatal, and postnatal periods was computed using data from ten air quality monitoring stations. An analysis of the relationships between childhood PIs and both indoor and outdoor factors was conducted using a multiple logistic regression model.

RESULTS

Childhood PIs were associated with outdoor CO and ozone (O3) exposure during the 10th-12th months prior to pregnancy, with ORs (95 % CI) of 1.68 (1.24-2.27) and 1.60 (1.15-2.22), respectively; childhood PIs were also associated with CO exposure during one year prior to pregnancy and the first trimester in utero [ORs = 1.57 (1.14-2.15) and 1.52 (1.17-1.97)]. Childhood PIs were found to be associated with PM2.5 exposure during pregnancy and the first year, with odds ratios of 1.51 (1.14-2.00) and 1.95 (1.22-3.12) per IQR increase in pollutant exposure, respectively. Exposures to smoke, renovation-related indoor air pollution (IAP), dampness and plant-related indoor allergens in the early life and past year were all associated with childhood PI, with odds ratios (95 % CI) ranging from 1.40 (1.01-1.95) for environmental tobacco smoke (ETS) during pregnancy to 1.63 (1.12-2.37) for mold/damp stains in the past year. In terms of PI risk, the early life and present periods were critical time windows for outdoor and indoor exposures, respectively. Certain individuals were more vulnerable to the PI risk associated with both indoor and outdoor exposures. Antibiotic use during child's lifetime and early years increased and decreased the PI risk of exposure to outdoor and indoor environments, respectively.

CONCLUSIONS

Exposure to outdoor air pollution in early life and indoor environments in the past year were found to be associated with childhood PI.

Development of the WeChat Public Account I Love Parasitology and its Preliminary Application in the Teaching of Human Parasitology

OBJECTIVE

To better construct teaching resources, enhance real-time interaction and feedback between teachers and students in and out of class, and improve the teaching quality of parasitology, our team set up a WeChat public account I love Parasitology.

METHODS

The data sources were mainly from original pictures and multimedia materials of different parasites collected and produced by our team, as well as related materials collected from traditional publications and digital media. With the instant interactive platform, course schedules and corresponding teaching contents were sent by push notifications, case-based learning was carried out, and 2-way communication between students and teachers was achieved. Teaching effectiveness was assessed using a self-evaluation questionnaire.

RESULTS

A WeChat public account suitable for our daily teaching of parasitology was established. The second recursion and implementation of the learning resources allowed students to conduct in-depth reading and get unrestricted access to high-quality resources through the public account. In addition, all contents were in digital forms and made the original resources reborn, which would make up for our current and future shortage of physical teaching specimens. Moreover, the results from the questionnaire indicated that all these actions encouraged students to master theoretical knowledge, improved their abilities of case analysis and communication, and increased their knowledge of academic progress.

CONCLUSION

Our WeChat public account can provide excellent learning materials for students and is a good supplement to the routine education of human parasitology.

Novel study on the prevalence of Trichinella spiralis in farmed American minks (Neovison vison) associated with exposure to wild rats (Rattus norvegicus) in China

Minks and brown rats are reservoir hosts for many endoparasites including those of the genus Trichinella, a group of parasite nematodes with a worldwide distribution. However, little is known about the prevalence of Trichinella sp. infection in the American mink (Neovison vison) and rats (Rattus norvegicus) in China. Therefore, we aimed to examine the prevalence of Trichinella sp. infection in farmed minks in Weihai city, Shandong province, China and infer the possible route for Trichinella transmission to farmed American minks. In total, 289 muscle samples from minks and 102 carcasses of rats were collected from Weihai City. The appearance of Trichinella sp. was examined using the pooled artificial HCl-pepsin digestion method. The results showed that muscle larvae were detected in 20 of 289 minks (6.92%) and 2 of 102 synanthropic rats (1.96%). The larval density of Trichinella sp. in mink samples ranged from 0.025 to 0.815 larvae per gram (lpg), while the average larval burden in rats was 0.17 lpg. The isolates derived from minks and rats were identified at the species level using multiplex polymerase chain reaction (PCR), which revealed that the size of the two PCR products matched that of T. spiralis at 173 bp. Furthermore, sequence analysis showed 100% identity of the 5S rDNA inter-gene spacer regions of the two isolates to that of T. spiralis. This study presents a novel report of T. spiralis-mediated infection in minks and synanthropic rats in China. We highlight the vulnerability of farmed minks to Trichinella infection through exposure to synanthropic rats, which may raise a public health concern of potential zoonotic risks for domestic animals.

Estimating the population at risk with soil transmitted helminthiasis and annual drug requirements for preventive chemotherapy in Ogun State, Nigeria

Soil transmitted helminth (STH) infections are among the most common human infections worldwide with over 1 billion people affected. Many estimates of STH infection are often based on school-aged children (SAC). This study produced predictive risk-maps of STH on a more finite scale, estimated the number of people infected, and the amount of drug required for preventive chemotherapy (PC) in Ogun state, Nigeria. Georeferenced STH infection data obtained from a cross-sectional survey at 33 locations between July 2016 and November 2018, together with remotely-sensed environmental and socio-economic data were analyzed using Bayesian geostatistical modelling. Stepwise variable selection procedure was employed to select a parsimonious set of predictors to predict risk and spatial distribution of STH infections. The number of persons (pre-school ages children, SAC and adults) infected with STH were estimated, with the amount of tablets needed for preventive chemotherapy. An overall prevalence of 17.2% (95% CI 14.9, 19.5) was recorded for any STH infection. Ascaris lumbricoides infections was the most predominant, with an overall prevalence of 13.6% (95% CI 11.5, 15.7), while Hookworm and Trichuris trichiura had overall prevalence of 4.6% (95% CI 3.3, 5.9) and 1.7% (95% CI 0.9, 2.4), respectively. The model-based prevalence predictions ranged from 5.0 to 23.8% for Ascaris lumbricoides, from 2.0 to 14.5% for hookworms, and from 0.1 to 5.7% for Trichuris trichiura across the implementation units. The predictive maps revealed a spatial pattern of high risk in the central, western and on the border of Republic of Benin. The model identified soil pH, soil moisture and elevation as the main predictors of infection for A. lumbricoides, Hookworms and T. trichiura respectively. About 50% (10/20) of the implementation units require biannual rounds of mass drug administration. Approximately, a total of 1.1 million persons were infected and require 7.8 million doses. However, a sub-total of 375,374 SAC were estimated to be infected, requiring 2.7 million doses. Our predictive risk maps and estimated PC needs provide useful information for the elimination of STH, either for resource acquisition or identifying priority areas for delivery of interventions in Ogun State, Nigeria.

Foodborne Parasites Dominate Current Parasitic Infections in Hunan Province, China

Great progress has been made in the prevention and treatment of human parasitic diseases in China over the past six decades, but parasitic diseases are still one of the most serious public health problems in the world. The specific prevalence of parasitic diseases varies in different provinces due to their geographical environment and the dietary habits of people. In this study, a total of 4,428 patients suspected to have parasitic infection by clinicians or themselves from January 1, 2016, to December 31, 2020 were recommended to our laboratory for further testing. In total, 5,246 samples including fecal, blood, and other body fluids were detected by etiological and immunological methods. Approximately 15.20% (673/4,428) of all suspected patients were infected by at least one species of parasite, and the overall positive rate of suspected patients from Hunan Province was 15.10% (594/3,933). A total of 18 species of parasites, namely, nematodes (4 species), trematodes (5 species), cestodes (4 species), protozoa (2 species), and medical arthropods (3 species), and 3 of them were imported parasites outside of Hunan Province. There are 9 species of foodborne parasites, accounting for 89.92% (464/516) of patients infected by one species of parasite. Common parasites in Hunan Province include plerocercoid, Paragonimus westermani, Clonorchis sinensis, cysticercus, Toxoplasma gondii, and Schistosoma japonicum. In this study, we found that the incidence of soilborne nematode infections has decreased significantly. However, foodborne parasites gradually become the main parasitic infections as well as multiple infections are becoming more common. Therefore, we should not only continue the prevention and control of soil-derived nematodes but also focus on the prevention and control of foodborne parasites in the future.

A systematic review of flukes (Trematoda) of domestic goose (Anser anser dom.)

Trematodes are one of the most numerous and widespread groups of parasitic invertebrates among helminths, characterized by a complex life cycle. As the final host, digenetic flukes parasitize vertebrates, including domestic waterfowl. Infection of hosts with parasitic digenetic worms causes huge economic damage to poultry. But trematode fauna of domestic geese are presented mainly only for individual regions. Despite the fact that there is already a systematic review of tapeworms and acanthocephala of domestic birds – geese and ducks, there are, unfortunately, no review articles on the taxonomy of digenetic flukes for geese (Anser anser dom.). Taking into account the relevance of the topic, based on our own and extensive literature data, we set the task to determine the general species composition of digenetic flukes (Trematoda), parasitizing in domestic geese which have been recorded in the world until 2020. Each Trematoda species is provided with the following data: scientific name, authority and year, first, second intermediate, auxiliary and final hosts, site in the host body, collecting localities and geographic distribution, and literature sources. Currently it is established that there are 149 species of helminths parasitising domestic geese. The taxonomic composition of the class Trematoda registered in domestic geese consists of 2 classes, 14 families, 30 genera and 65 species. Of all the species of trematodes parasitizing in domestic geese, 44 species have been recorded in Europe, 26 species in Asia, 6 species in North America, 1 species in South America, 1 species in Africa and 2 species in Oceania. Three species are registered in domestic geese (Echinoparyphium recurvatum, Echinostoma revolutum, Prosthogonimus ovatus) are cosmopolitan parasites. The biggest species diversity is characterized by the families Echinostomatidae (17 species) and Notocotylidae (12 species). There are 11 species of digenetic flukes recorded in domestic geese Cyclocoelum mutabile, Echinostoma grande, E. paraulum, E. revolutum, E. robustum, Hypoderaeum conoideum, Paryphostomum novum, P. pentalobum, Catatropis verrucosa, Notocotylus attenuatus, N. parviovatus) on the territory of Azerbaijan. Four of them (Echinostoma revolutum, Hypoderaeum conoideum, Paryphostomum novum, Notocotylus attenuatus) were also noted in the course of our helminthological studies. The trematode Cyclocoelum mutabile was recorded in domestic ducks only in Azerbaijan. Most species of trematodes were found in the north-eastern part (total 9 species) and southern part (total 5 species) of Azerbaijan. This is due to the widespread distribution of molluscs – intermediate hosts of digenetic flukes, in these regions. Eighteen species of digenetic flukes parasitize both birds and mammals (Rodentia, Carnivora, Lagomorpha, Artiodactyla). And eleven species of trematodes are of medical importance, registered in humans.

Taxonomy of Echinostoma revolutum and 37-Collar-Spined Echinostoma spp.: A Historical Review

Echinostoma flukes armed with 37 collar spines on their head collar are called as 37-collar-spined Echinostoma spp. (group) or 'Echinostoma revolutum group'. At least 56 nominal species have been described in this group. However, many of them were morphologically close to and difficult to distinguish from the other, thus synonymized with the others. However, some of the synonymies were disagreed by other researchers, and taxonomic debates have been continued. Fortunately, recent development of molecular techniques, in particular, sequencing of the mitochondrial (nad1 and cox1) and nuclear genes (ITS region; ITS1-5.8S-ITS2), has enabled us to obtain highly useful data on phylogenetic relationships of these 37-collar-spined Echinostoma spp. Thus, 16 different species are currently acknowledged to be valid worldwide, which include E. revolutum, E. bolschewense, E. caproni, E. cinetorchis, E. deserticum, E. lindoense, E. luisreyi, E. mekongi, E. miyagawai, E. nasincovae, E. novaezealandense, E. paraensei, E. paraulum, E. robustum, E. trivolvis, and Echinostoma sp. IG of Georgieva et al., 2013. The validity of the other 10 species is retained until further evaluation, including molecular analyses; E. acuticauda, E. barbosai, E. chloephagae, E. echinatum, E. jurini, E. nudicaudatum, E. parvocirrus, E. pinnicaudatum, E. ralli, and E. rodriguesi. In this review, the history of discovery and taxonomic debates on these 26 valid or validity-retained species are briefly reviewed.

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

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

Acute shock caused by Clonorchis sinensis infection: a case report

Background

Clonorchiasis, caused by Clonorchis sinensis (C. sinensis) infection, is a serious food-borne zoonotic disease that is often asymptomatic or shows only mild symptoms, which leads to delayed treatment and chronic clonorchiasis and results in various complications, such as cholelithiasis, cholangitis, cholecystitis and cholangiocarcinoma. However, acute shock caused by C. sinensis infection has not been reported. Here, for the first time, we describe a fatal case of acute shock caused by C. sinensis infection.

Case presentation

A patient with a history of eating raw or undercooked freshwater fish was hospitalized with acute shock caused by severe abdominal pain. Physical examination suggested acute abdomen with severe abdominal pain and rigidity. Computed tomography (CT) detection indicated acute cholecystitis and cholelithiasis. After cholecystectomy, several liver flukes were found in the drainage tube. Furthermore, morphological analysis and polymerase chain reaction (PCR) identified the pathogen as C. sinensis. The liver gradually restored normal function after anthelmintic therapy with praziquantel.

Conclusions

In this fatal case, C. sinensis infection was the cause of acute shock, which is rarely found in the clinic environment. This report aims to increase awareness of the hazards and complications related to clonorchiasis. The PCR diagnosis method used in this report might be helpful in reducing the misdiagnosis of clonorchiasis and unnecessary cholecystectomy.

Repeated Peritoneal Catheter Blockage Caused by Neurocysticercosis Following Ventriculoperitoneal Shunt Placement for Hydrocephalus

Cerebral cysticercosis is common, but the possibility for repeated occurrence of peritoneal catheter blockage caused by neurocysticercosis (NCC) after two revisions following ventriculoperitoneal shunt placement for hydrocephalus is unusual. Herein, we describe one rare case in which peritoneal catheter revision was performed two times unsuccessfully. Endoscopic cysternostomy rather than peritoneal catheter adjustment was performed successfully, and histopathological examination of excised cystic samples confirmed NCC in our hospital. The present case highlights the need for awareness of NCC as a possible etiology of hydrocephalus, especially in developing countries. Uncommon findings in both lateral ventricles following low-field magnetic resonance imaging scans as well as the rarity of this infection involved in unusual location play important roles in misdiagnosis and incorrect treatment for hydrocephalus; thus, endoscopic cysternostomy, rather than multiple shunt adjustment of the peritoneal end, is recommended in the selected patient. To the best of our knowledge, this is the first report describing the misdiagnosis and inappropriate treatment of hydrocephalus caused by cerebral cysticercosis in China.

Intestinal Parasite Infections among Inhabitants in Yanbian Prefecture, Jilin Province, China

To investigate the prevalence of intestinal parasite infections in Yanbian Prefecture, Jilin Province, China, epidemiological surveys were conducted on a collaboration basis between the Korean Centers for Disease Control and Prevention and the Yanbian Center for Disease Control and Prevention. A total of 8,396 (males 3,737 and females 4,659) stool samples were collected from 8 localities and examined with the formalin-ether sedimentation technique, and additionally examined with the cellotape anal swab to detect Enterobius vermicularis eggs. The overall rate of intestinal parasites was 1.57%. The prevalence of Ascaris lumbricoides was the highest (0.80%), followed by Entamoeba spp. (0.23%), heterophyid flukes (0.15%), Clonorchis sinensis (0.08%), Enterobius vermicularis (0.07%), hookworms (0.06%), Trichostrongylus spp. (0.06%), Giardia lamblia (0.04%), Paragonimus spp. (0.02%), Diphyllobothrium spp. (0.02%), Trichuris trichiura (0.02%). The prevalence by sex was similar, 1.58% (n=59) in males and 1.57% (n=73) in females. By the present study, it is partly revealed that the prevalences of intestinal parasite infections are relatively low among the inhabitants of Yanbian Prefecture, Jilin Province, China.

Parasitology should not be abandoned: data from outpatient parasitological testing in Guangdong, China

Over the past six decades, the Chinese government made parasitoses with a high disease burden, including soil-transmitted nematode infections, malaria, leishmaniasis, filariasis, and schistosomiasis, a public health priority because they were seen to be crucial impediments to the development of rural areas. As a result, these debilitating parasitic diseases that used to be widely prevalent have been well controlled or eliminated. Consequently, less attention has been paid to parasitic infection during the rapid development of the economy, especially in developed areas. However, our investigations conducted in the parasitological laboratory of Sun Yat-sen University (Guangzhou, Guangdong, China) show that emerging parasitic diseases still threaten many people's health, with 340 of 880 outpatients (38.6%) receiving a diagnosis of parasitic disease, among whom 201 (59.1%) had clonorchiasis and 120 (35.3%) had taeniasis/cysticercosis. Furthermore, our doctors are not equipped with sufficient parasitology knowledge because this discipline is not able to maintain attraction. Many parasitic infections that result in severe consequences are treatable and preventable, but the phenomena of misdiagnosis and missed diagnosis are common and merit attention.

Fishborne zoonotic heterophyid infections: An update

Fishborne heterophyid trematodes infecting humans are at least 29 species worldwide and belong to 13 genera. Its global burden is much more than 7 million infected people. They include Metagonimus (M. yokogawai, M. takahashii, M. miyatai, M. minutus, and M. katsuradai), Heterophyes (H. heterophyes, H. nocens, H. dispar, and H. aequalis), Haplorchis (H. taichui, H. pumilio, H. yokogawai, and H. vanissimus), Pygidiopsis (P. summa and P. genata), Heterophyopsis (H. continua), Stellantchasmus (S. falcatus), Centrocestus (C. formosanus, C. armatus, C. cuspidatus, and C. kurokawai), Stictodora (S. fuscata and S. lari), Procerovum (P. varium and P. calderoni), Acanthotrema (A. felis), Apophallus (A. donicus), Ascocotyle (A. longa), and Cryptocotyle (C. lingua). Human infections are scattered around the world but the major endemic areas are located in Southeast Asia. The source of human infection is ingestion of raw or improperly cooked fish. The pathogenicity, host-parasite relationships, and clinical manifestations in each species infection are poorly understood; these should be elucidated particularly in immunocompromised hosts. Problems exist in the differential diagnosis of these parasitic infections because of close morphological similarity of eggs in feces and unavailability of alternative methods such as serology. Molecular diagnostic techniques are promising but they are still at an infant stage. Praziquantel has been proved to be highly effective against most of the patients infected with heterophyid flukes. Epidemiological surveys and detection of human infections are required for better understanding of the geographical distribution and global burden of each heterophyid species. In this review, the most updated knowledge on the morphology, biology, epidemiology, pathogenesis and pathology, immunology, clinical manifestations, diagnosis and treatment, and prevention and control of fishborne zoonotic heterophyid infections is provided.

Current Research of Trichinellosis in China

Trichinellosis, caused by Trichinella, is an emerging or re-emerging zoonotic parasitic disease, which is distributed worldwide with major socio-economic importance in some developing countries. In particular, it has been calculated that more than 40 million people are at risk of Trichinella infection in China. This review summarizes the current information on the epidemiology, laboratory diagnosis and vaccines of trichinellosis in China. Moreover, study of the treatment potential of using Trichinella for immune-related diseases and cancer, as well as the transcription and post-transcription modification of Trichinella were also collected, providing viewpoints for future investigations. Current advances in research will help us to develop new strategies for the prevention and control of trichinellosis and may potentially yield biological agents for treating other diseases.

The Impact of Emerging Infectious Diseases on Chinese Blood Safety

Emerging infectious diseases (EIDs) have always been one of the major threats to public health. Although the implementation of mandatory testing for 4 classical transfusion-transmitted infectious-human immunodeficiency virus, hepatitis B virus, hepatitis C virus, and syphilis-has reduced the transfusion risk of these pathogens, the potential threat of various EID agents and their constantly evolving variants to blood safety in China is not fully understood. This review presents 9 representative EID agents that are autochthonous and epidemic nationally or regionally in China. The epidemiologic status and distribution of these EID agents among donors and/or healthy populations are summarized. The potential risks of these EID agents to blood safety are discussed. The review also explores strategies to strengthen hemovigilance systems and studies to further evaluate the impact of EID agents on blood safety.

Clonorchis sinensis, an oriental liver fluke, as a human biological agent of cholangiocarcinoma: a brief review

Parasitic diseases remain an unarguable public health problem worldwide. Liver fluke Clonorchis sinensis is a high risk pathogenic parasitic helminth which is endemic predominantly in Asian countries, including Korea, China, Taiwan, Vietnam, and the far eastern parts of Russia, and is still actively transmitted. According to the earlier 8^th National Survey on the Prevalence of Intestinal Parasitic Infections in 2012, C. sinensis was revealed as the parasite with highest prevalence of 1.86% in general population among all parasite species surveyed in Korea. This fluke is now classified under one of the definite Group 1 human biological agents (carcinogens) by International Agency of Research on Cancer (IARC) along with two other parasites, Opisthorchis viverrini and Schistosoma haematobium. C. sinensis infestation is mainly linked to liver and biliary disorders, especially cholangiocarcinoma (CCA). For the purposes of this mini-review, we will only focus on C. sinensis and review pathogenesis and carcinogenesis of clonorchiasis, disease condition by C. sinensis infestation, and association between C. sinensis infestation and CCA. In this presentation, we briefly consider the current scientific status for progression of CCA by heavy C. sinensis infestation from the food-borne trematode and development of CCA.

Major parasitic diseases of poverty in mainland China: perspectives for better control

Significant progress has been made in the prevention, control, and elimination of human parasitic diseases in China in the past 60 years. However, parasitic diseases of poverty remain major causes of morbidity and mortality, and inflict enormous economic costs on societies.In this article, we review the prevalence rates, geographical distributions, epidemic characteristics, risk factors, and clinical manifestations of parasitic diseases of poverty listed in the first issue of the journal Infectious Diseases of Poverty on 25 October 2012. We also address the challenges facing control of parasitic diseases of poverty and provide suggestions for better control.

Painless Jaundice Caused by Clonorchis sinensis Infection: A Case Report

A man with only yellowing of the skin and eye sclera was diagnosed with clonorchiasis, which rarely manifested jaundice as the initial symptom. However, because of a lack of evidence for a diagnostic gold standard, the time until definitive diagnosis was more than a week. The diagnostic process relied on inquiring about the patient's history, including the place of residence, dietary habits, and symptoms, as well as on serological findings, an imaging examination, and pathological findings. MRCP and CT results showed mild dilatation of intrahepatic ducts and increased periductal echogenicity. The eggs were ultimately found in stool by water sedimentation method after the negative report through direct smear. DNA sequencing of PCR production of the eggs demonstrated 98-100% homology with ITS2 of Clonorchis sinensis. After anti-parasite medical treatment, the patient's symptoms were gradually relieved. Throughout the diagnostic procedure, besides routine examinations, the sedimentation method or concentration method could be used as a sensitive way for both light and heavy C. sinensis infection in the definite diagnosis.

Cytokine modulation of human blood viscosity from vivax malaria patients

Malaria is a major infectious disease in several countries and is caused by protozoa of the genus Plasmodium. In vivax malaria patients, inflammatory processes occur, as well as changes in cytokines and blood flow. The present study analyzed the cytokine modulation of blood viscosity from patients infected with Plasmodium vivax (P. vivax). Blood samples were collected from 42 non-infected individuals (control group) and 37 individuals infected with P. vivax. The IL-2, IL-4, IL-6, IL-10, TNFα, TGF-β and IL-17 cytokine concentrations in the serum were assessed, and the blood rheological properties were determined. The analysis of blood viscosity for shear rates revealed that the blood viscosity of the infected patients was significantly greater than that of the non-infected individuals. The viscosity of the blood was greater in the infected individuals than in the non-infected subjects. The serum from individuals with P. vivax infections exhibited higher IFN-γ and IL-17 concentrations and lower TGF-β levels. Incubation of the blood from infected individuals with IL-17 or IL-17 associated with IFN-γ reduced the viscosity to rates equivalent to the blood from non-infected individuals. Independently of cytokine modulation, no correlation was found between the parasitemia and blood viscosity of the infected patients. These data suggest that the alterations of blood viscosity are relevant as an auxiliary tool for the clinical diagnosis of disease. In malaria, erythrocytes are more sensitive to osmotic shock, and the reduction of viscosity by IL-17 may be related to a possible immunomodulator agent during infection.

The role of evolutionary biology in research and control of liver flukes in Southeast Asia

Stimulated largely by the availability of new technology, biomedical research at the molecular-level and chemical-based control approaches arguably dominate the field of infectious diseases. Along with this, the proximate view of disease etiology predominates to the exclusion of the ultimate, evolutionary biology-based, causation perspective. Yet, historically and up to today, research in evolutionary biology has provided much of the foundation for understanding the mechanisms underlying disease transmission dynamics, virulence, and the design of effective integrated control strategies. Here we review the state of knowledge regarding the biology of Asian liver Fluke-host relationship, parasitology, phylodynamics, drug-based interventions and liver Fluke-related cancer etiology from an evolutionary biology perspective. We consider how evolutionary principles, mechanisms and research methods could help refine our understanding of clinical disease associated with infection by Liver Flukes as well as their transmission dynamics. We identify a series of questions for an evolutionary biology research agenda for the liver Fluke that should contribute to an increased understanding of liver Fluke-associated diseases. Finally, we describe an integrative evolutionary medicine approach to liver Fluke prevention and control highlighting the need to better contextualize interventions within a broader human health and sustainable development framework.

Co-endemicity of Pulmonary Tuberculosis and Intestinal Helminth Infection in the People's Republic of China

Both pulmonary tuberculosis (PTB) and intestinal helminth infection (IHI) affect millions of individuals every year in China. However, the national-scale estimation of prevalence predictors and prevalence maps for these diseases, as well as co-endemic relative risk (RR) maps of both diseases' prevalence are not well developed. There are co-endemic, high prevalence areas of both diseases, whose delimitation is essential for devising effective control strategies. Bayesian geostatistical logistic regression models including socio-economic, climatic, geographical and environmental predictors were fitted separately for active PTB and IHI based on data from the national surveys for PTB and major human parasitic diseases that were completed in 2010 and 2004, respectively. Prevalence maps and co-endemic RR maps were constructed for both diseases by means of Bayesian Kriging model and Bayesian shared component model capable of appraising the fraction of variance of spatial RRs shared by both diseases, and those specific for each one, under an assumption that there are unobserved covariates common to both diseases. Our results indicate that gross domestic product (GDP) per capita had a negative association, while rural regions, the arid and polar zones and elevation had positive association with active PTB prevalence; for the IHI prevalence, GDP per capita and distance to water bodies had a negative association, the equatorial and warm zones and the normalized difference vegetation index had a positive association. Moderate to high prevalence of active PTB and low prevalence of IHI were predicted in western regions, low to moderate prevalence of active PTB and low prevalence of IHI were predicted in north-central regions and the southeast coastal regions, and moderate to high prevalence of active PTB and high prevalence of IHI were predicted in the south-western regions. Thus, co-endemic areas of active PTB and IHI were located in the south-western regions of China, which might be determined by socio-economic factors, such as GDP per capita.

The Adaptive Change of HLA-DRB1 Allele Frequencies Caused by Natural Selection in a Mongolian Population That Migrated to the South of China

Pathogen-driven balancing selection determines the richness of human leukocyte antigen (HLA) alleles. Changes in the pathogen spectrum may cause corresponding changes in HLA loci. Approximately 700 years ago, a Mongolian population moved from the north of China to the Yunnan region in the south of China. The pathogen spectrum in the south of China differs from that in the north. In this study, changes in the HLA genes in the Yunnan Mongolian population, as well as the underlying mechanism, were investigated. A sequence-based typing method (SBT) was used to genotype HLA-DRB1 in 470 individuals from two Mongolian populations and another five ethnic groups. Meanwhile, 10 autosomal short tandem repeats (STRs) were genotyped to assess the influence of genetic background on HLA-DRB1 frequencies. The frequencies of certain alleles changed significantly in the Mongolian population that migrated to Yunnan. For example, DRB1*12:02:01 increased from 6.1% to 35.4%. STR analysis excluded the possibility of a recent bottleneck and indicated that 50% of the genetic consistency between northern and southern Mongolians; Tajima's D value for HLA-DRB1 exon2 and dN/dS analysis showed that the HLA-DRB1 genes in both Mongolian populations were under balancing selection. However, the sites under natural selection changed. We proposed that the dramatically change of HLA frequencies in southern Mongolian was caused by a combination of inter-population gene flow and natural selection. Certain diseases specific to the south of China, such as malaria, may be the driving force behind the enhanced DRB1*12:02:01 frequency.

Association between Liver Fluke Infection and Hepatobiliary Pathological Changes: A Systematic Review and Meta-Analysis

OBJECTIVE

To provide information about the role of liver fluke infection as a risk factor for hepatobiliary pathological changes and promote awareness among the people living in endemic areas, a systematic review and meta-analysis based on published studies was conducted to examine the association between liver fluke infection and hepatobiliary pathological changes.

METHODS

Relevant original literature was searched in multiple literature databases, including PubMed, Cochrane, Clinical Evidence, Trip Database, Clinical Trials, Current Controlled Trials, Web of Science, the China National Knowledge Infrastructure (CNKI) database, and the Wanfang academic journal full-text database. Studies were selected based on strict screening with inclusion and exclusion criteria. Tests of heterogeneity, sensitivity and publication bias were performed with the Review Manager software, version 5.3, and meta-regression analyses were performed with the Stata software, version 11.0 (Stata Corporation, College Station, TX, USA). Pooled risk ratios (RRs) and odds ratios (ORs) with their 95% confidence intervals (95% CIs) were calculated and used to evaluate the risk of hepatobiliary pathological changes resulting from liver fluke infection. Linear trend analyses were conducted to determine the dose-response relationship using IBM SPSS Statistics 20.0.

RESULT

A total of 36 studies were included in the meta-analysis. Significant associations were found between liver fluke infection and cholangitis or cholecystitis (RR: 7.80, P<0.001; OR: 15.98, P<0.001), cholelithiasis (RR: 2.42, P = 0.03; OR: 4.96, P = 0.03), hepatocellular carcinoma (OR: 4.69, P<0.001) and cholangiocarcinoma (RR: 10.43, P<0.001; OR: 4.37, P<0.001). In addition, heavier infection was significantly associated with higher incidence of hepatobiliary pathological changes (P<0.05). However, cirrhosis was not significantly associated with liver fluke infection (RR: 3.50, P = 0.06; OR: 5.79, P = 0.08). The statistical heterogeneity was significant, no significant difference was observed in the sensitivity analysis, and no publication bias was found.

CONCLUSION

The meta-analysis found that liver fluke infection was significantly associated with cholangitis, cholecystitis, cholelithiasis, hepatocellular carcinoma and cholangiocarcinoma and that more severe infection was associated with higher incidence. However, the association between liver fluke infection and cirrhosis was not significant.

Geostatistical modelling of soil-transmitted helminth infection in Cambodia: do socioeconomic factors improve predictions?

Soil-transmitted helminth infections are intimately connected with poverty. Yet, there is a paucity of using socioeconomic proxies in spatially explicit risk profiling. We compiled household-level socioeconomic data pertaining to sanitation, drinking-water, education and nutrition from readily available Demographic and Health Surveys, Multiple Indicator Cluster Surveys and World Health Surveys for Cambodia and aggregated the data at village level. We conducted a systematic review to identify parasitological surveys and made every effort possible to extract, georeference and upload the data in the open source Global Neglected Tropical Diseases database. Bayesian geostatistical models were employed to spatially align the village-aggregated socioeconomic predictors with the soil-transmitted helminth infection data. The risk of soil-transmitted helminth infection was predicted at a grid of 1×1km covering Cambodia. Additionally, two separate individual-level spatial analyses were carried out, for Takeo and Preah Vihear provinces, to assess and quantify the association between soil-transmitted helminth infection and socioeconomic indicators at an individual level. Overall, we obtained socioeconomic proxies from 1624 locations across the country. Surveys focussing on soil-transmitted helminth infections were extracted from 16 sources reporting data from 238 unique locations. We found that the risk of soil-transmitted helminth infection from 2000 onwards was considerably lower than in surveys conducted earlier. Population-adjusted prevalences for school-aged children from 2000 onwards were 28.7% for hookworm, 1.5% for Ascaris lumbricoides and 0.9% for Trichuris trichiura. Surprisingly, at the country-wide analyses, we did not find any significant association between soil-transmitted helminth infection and village-aggregated socioeconomic proxies. Based also on the individual-level analyses we conclude that socioeconomic proxies might not be good predictors at an aggregated large-scale analysis due to their large between- and within-village heterogeneity. Specific information of both the infection risk and potential predictors might be needed to obtain any existing association. The presented soil-transmitted helminth infection risk estimates for Cambodia can be used for guiding and evaluating control and elimination efforts.

Cross-strait parasitological research priorities arrived at by historical tracking and advanced dialogue

To further enhance dialogue and promote cross-strait cooperation in the prevention and control of parasitic diseases, this paper reviewed the progress and current challenges in the cross-strait control and research of parasitic infections, based on three cross-strait meetings on parasitological research in the last decade. The major outcome of the 3rd Meeting of Cross-Strait Parasitological Research held in April 2013 was identifying the research priorities for parasitological research.

Surveillance systems for neglected tropical diseases: global lessons from China's evolving schistosomiasis reporting systems, 1949-2014

Though it has been a focus of the country’s public health surveillance systems since the 1950s, schistosomiasis represents an ongoing public health challenge in China. Parallel, schistosomiasis-specific surveillance systems have been essential to China’s decades-long campaign to reduce the prevalence of the disease, and have contributed to the successful elimination in five of China’s twelve historically endemic provinces, and to the achievement of morbidity and transmission control in the other seven. More recently, an ambitious goal of achieving nation-wide transmission interruption by 2020 has been proposed. This paper details how schistosomiasis surveillance systems have been structured and restructured within China’s evolving public health system, and how parallel surveillance activities have provided an information system that has been integral to the characterization of, response to, and control of the disease. With the ongoing threat of re-emergence of schistosomiasis in areas previously considered to have achieved transmission control, a critical examination of China’s current surveillance capabilities is needed to direct future investments in health information systems and to enable improved coordination between systems in support of ongoing control. Lessons drawn from China’s experience are applied to the current global movement to reduce the burden of helminthiases, where surveillance capacity based on improved diagnostics is urgently needed.

Mosquito surveillance revealed lagged effects of mosquito abundance on mosquito-borne disease transmission: a retrospective study in Zhejiang, China

Mosquito-borne diseases (MBDs) are still threats to public health in Zhejiang. In this study, the associations between the time-lagged mosquito capture data and MBDs incidence over five years were used to examine the potential effects of mosquito abundance on patterns of MBDs epidemiology in Zhejiang during 2008–2012. Light traps were used to collect adult mosquitoes at 11 cities. Correlation tests with and without time lag were performed to investigate the correlations between MBDs incidence rates and mosquito abundance by month. Selected MBDs consisted of Japanese encephalitis (JE), dengue fever (DF) and malaria. A Poisson regression analysis was performed by using a generalized estimating equations (GEE) approach, and the most parsimonious model was selected based on the quasi-likelihood based information criterion (QICu). We identified five mosquito species and the constituent ratio of Culex pipiens pallens, Culex tritaeniorhynchus, Aedes albopictus, Anopheles sinensis and Armigeres subalbatus was 66.73%, 21.47%, 6.72%, 2.83% and 2.25%, respectively. The correlation analysis without and with time lag showed that Culex mosquito abundance at a lag of 0 or 1 month was positively correlated with JE incidence during 2008–2012, Ae. albopictus abundance at a lag of 1 month was positively correlated with DF incidence in 2009, and An. sinensis abundance at a lag of 0–2 months was positively correlated with malaria incidence during 2008–2010. The Poisson regression analysis showed each 0.1 rise of monthly mosquito abundance corresponded to a positive increase of MBD cases for the period of 2008–2012. The rise of mosquito abundance with a lag of 0–2 months increased the risk of human MBDs infection in Zhejiang. Our study provides evidence that mosquito monitoring could be a useful early warning tool for the occurrence and transmission of MBDs.

Major emerging and re-emerging zoonoses in China: a matter of global health and socioeconomic development for 1.3 billion

Emerging and re-emerging zoonoses are a significant public health concern and cause considerable socioeconomic problems globally. The emergence of severe acute respiratory syndrome (SARS), highly pathogenic avian influenza (HPAI) H5N1, avian influenza H7N9, and severe fever with thrombocytopenia syndrome (SFTS), and the re-emergence of rabies, brucellosis, and other zoonoses have had a significant effect on the national economy and public health in China, and have affected other countries. Contributing factors that continue to affect emerging and re-emerging zoonoses in China include social and environmental factors and microbial evolution, such as population growth, urbanization, deforestation, livestock production, food safety, climate change, and pathogen mutation. The Chinese government has devised new strategies and has taken measures to deal with the challenges of these diseases, including the issuing of laws and regulations, establishment of disease reporting systems, implementation of special projects for major infectious diseases, interdisciplinary and international cooperation, exotic disease surveillance, and health education. These strategies and measures can serve as models for the surveillance and response to continuing threats from emerging and re-emerging zoonoses in other countries.

Congenital malaria in China

Abstract

Background

Congenital malaria, in which infants are directly infected with malaria parasites from their mother prior to or during birth, is a potentially life-threatening condition that occurs at relatively low rates in malaria-endemic regions. It is recognized as a serious problem in Plasmodium falciparum–endemic sub-Saharan Africa, where recent data suggests that it is more common than previously believed. In such regions where malaria transmission is high, neonates may be protected from disease caused by congenital malaria through the transfer of maternal antibodies against the parasite. However, in low P. vivax–endemic regions, immunity to vivax malaria is low; thus, there is the likelihood that congenital vivax malaria poses a more significant threat to newborn health. Malaria had previously been a major parasitic disease in China, and congenital malaria case reports in Chinese offer valuable information for understanding the risks posed by congenital malaria to neonatal health. As most of the literature documenting congenital malaria cases in China are written in Chinese and therefore are not easily accessible to the global malaria research community, we have undertaken an extensive review of the Chinese literature on this subject.

Methods/Principal Findings

Here, we reviewed congenital malaria cases from three major searchable Chinese journal databases, concentrating on data from 1915 through 2011. Following extensive screening, a total of 104 cases of congenital malaria were identified. These cases were distributed mainly in the eastern, central, and southern regions of China, as well as in the low-lying region of southwest China. The dominant species was P. vivax (92.50%), reflecting the malaria parasite species distribution in China. The leading clinical presentation was fever, and other clinical presentations were anaemia, jaundice, paleness, diarrhoea, vomiting, and general weakness. With the exception of two cases, all patients were cured with antimalarial drugs such as chloroquine, quinine, artemether, and artesunate.

Conclusions

The symptoms of congenital malaria vary significantly between cases, so clear and early diagnosis is difficult. We suggest that active surveillance might be necessary for neonates born to mothers with a history of malaria.

Bayesian geostatistical modelling of soil-transmitted helminth survey data in the People's Republic of China

BACKGROUND

Soil-transmitted helminth infections affect tens of millions of individuals in the People's Republic of China (P.R. China). There is a need for high-resolution estimates of at-risk areas and number of people infected to enhance spatial targeting of control interventions. However, such information is not yet available for P.R. China.

METHODS

A geo-referenced database compiling surveys pertaining to soil-transmitted helminthiasis, carried out from 2000 onwards in P.R. China, was established. Bayesian geostatistical models relating the observed survey data with potential climatic, environmental and socioeconomic predictors were developed and used to predict at-risk areas at high spatial resolution. Predictors were extracted from remote sensing and other readily accessible open-source databases. Advanced Bayesian variable selection methods were employed to develop a parsimonious model.

RESULTS

Our results indicate that the prevalence of soil-transmitted helminth infections in P.R. China considerably decreased from 2005 onwards. Yet, some 144 million people were estimated to be infected in 2010. High prevalence (>20%) of the roundworm Ascaris lumbricoides infection was predicted for large areas of Guizhou province, the southern part of Hubei and Sichuan provinces, while the northern part and the south-eastern coastal-line areas of P.R. China had low prevalence (<5%). High infection prevalence (>20%) with hookworm was found in Hainan, the eastern part of Sichuan and the southern part of Yunnan provinces. High infection prevalence (>20%) with the whipworm Trichuris trichiura was found in a few small areas of south P.R. China. Very low prevalence (<0.1%) of hookworm and whipworm infections were predicted for the northern parts of P.R. China.

CONCLUSIONS

We present the first model-based estimates for soil-transmitted helminth infections throughout P.R. China at high spatial resolution. Our prediction maps provide useful information for the spatial targeting of soil-transmitted helminthiasis control interventions and for long-term monitoring and surveillance in the frame of enhanced efforts to control and eliminate the public health burden of these parasitic worm infections.

Delineation of the Structural Elements of Oriental Liver Fluke PLA2 Isoforms for Potent Drug Designing

Clonorchis sinensis or the Chinese liver fluke is one of the most prevalent parasites affecting a major population in the oriental countries. The parasite lacks lipid generating mechanisms but is exposed to fatty acid rich bile in the liver. A secretory phospholipase A2, an enzyme that breaks down complex lipids, is important for the growth of the parasite. The enzyme is also implicated in the pathogenesis leading up to the hepatic fibrosis and its complications including cancer. The five isoforms of this particular enzyme from the parasite therefore qualify as potential drug targets. In this study, a detailed structural and ligand binding analysis of the isoforms has been done by modeling. The overall three dimensional structures of the isoforms are well conserved with three helices and a β-wing stabilized by four disulfide bonds. There are characteristic differences at the calcium binding loop, hydrophobic channel and the C-terminal domain that can potentially be exploited for drug binding. But the most significant feature pertains to the catalytic site where the isoforms exhibit three variations of either a histidine-aspartate-tyrosine or histidine-glutamate-tyrosine or histidine-aspartate-phenylalanine. Molecular docking studies show that isoform specific residues and their conformations in the substrate binding hydrophobic channel make unique interactions with certain inhibitor molecules resulting in a perfect tight fit. The proposed ligand molecules have a predicted affinity in micro-molar to nano-molar range. Interestingly, few of the ligand binding interaction patterns is in accordance to the phylogenetic studies to thereby establish the usefulness of evolutionary mechanisms in aiding ligand design. The molecular diversity of the parasitic PLA2 described in this study provides a platform for personalized medicine in the therapeutics of clonorchiasis.

Systematic teaching method to enhance the effectiveness of training for paragonimiasis

The clinical symptoms of human paragonimiasis are complex and variable, and patients can easily be misdiagnosed. Pagumogonimus skrjabini is the species causing this disease found only in China. A 2002 epidemiological survey showed that the rate of paragonimiasis was 21·96% in the migration areas of the Three-Gorge Reservoir, Chongqing, China. Therefore, there is a need to train medical workers to treat individuals in these areas. The Third Military Medical University (TMMU) in Chongqing built a comprehensive and systematic teaching method, which included teaching students about the basic biology of the organism, guiding students to use appropriate diagnostic tests and participate in scientific research to develop diagnostic kits, and visiting endemic areas to provide on-site teaching. The use of on-site teaching is an innovative approach for training undergraduate medical students in human parasitology. Three improvements were implemented during the on-site teaching component of the program: (1) systematizing the learning process; (2) integrating formal knowledge with clinical experience; and (3) enhancing students' knowledge of medical ethics. Based on a survey, 95% of students believed that this systematic teaching system gave them a more comprehensive grasp of knowledge on P. skrjabini, and graduate students were able to provide early diagnosis of P. skrjabini cases in this remote region. Students also participated in the research and development of a P. skrjabini diagnostic kit, for which a patent has been applied, and during the on-site teaching process, data were collected for the government and health sector to assist in public-health planning and decision-making for this disease.

Retrotransposon-microsatellite amplified polymorphism, an electrophoretic approach for studying genetic variability among Schistosoma japonicum geographical isolates

In the present study, retrotransposon-microsatellite amplified polymorphism (REMAP) was used to examine genetic variability among Schistosoma japonicum isolates from different endemic provinces in mainland China, using S. japonicum from Japan and the Philippines for comparison. Of the 50 primer combinations screened, eight produced highly reproducible REMAP fragments. Using these primers, 190 distinct DNA fragments were generated in total, of which 147 (77.37%) were polymorphic, indicating considerable genetic variation among the 43 S. japonicum isolates examined. The percentage of polymorphic bands (PPB) among S. japonicum isolates from mainland China, Japan, and the Philippines was 77.37%; PPB values of 18.42% and 53.68% were found among isolates from southwestern (SW) China and the lower Yangtze/Zhejiang province in eastern (E) China, respectively. Based on REMAP profiles, unweighted pair-group method with arithmetic averages (UPGMA) dendrogram analysis revealed that all of the S. japonicum samples grouped into three distinct clusters: parasites from mainland China, Japan, and the Philippines were clustered in each individual clade. Within the mainland China cluster, SW China isolates (from Sichuan and Yunnan provinces) grouped together, whereas worms from E China (Zhejiang, Anhui, Jiangxi, Jiangsu, Hunan, and Hubei provinces) grouped together. These results demonstrated that the REMAP marker system provides a reliable electrophoretic technique for studying genetic diversity and population structures of S. japonicum isolates from mainland China, and could be applied to other pathogens of human and animal health significance.

Soil-transmitted helminth infections and correlated risk factors in preschool and school-aged children in rural Southwest China

We conducted a survey of 1707 children in 141 impoverished rural areas of Guizhou and Sichuan Provinces in Southwest China. Kato-Katz smear testing of stool samples elucidated the prevalence of ascariasis, trichuriasis and hookworm infections in pre-school and school aged children. Demographic, hygiene, household and anthropometric data were collected to better understand risks for infection in this population. 21.2 percent of pre-school children and 22.9 percent of school aged children were infected with at least one of the three types of STH. In Guizhou, 33.9 percent of pre-school children were infected, as were 40.1 percent of school aged children. In Sichuan, these numbers were 9.7 percent and 6.6 percent, respectively. Number of siblings, maternal education, consumption of uncooked meat, consumption of unboiled water, and livestock ownership all correlated significantly with STH infection. Through decomposition analysis, we determined that these correlates made up 26.7 percent of the difference in STH infection between the two provinces. Multivariate analysis showed that STH infection is associated with significantly lower weight-for-age and height-for-age z-scores; moreover, older children infected with STHs lag further behind on the international growth scales than younger children.

Canine and feline parasitic zoonoses in China

Canine and feline parasitic zoonoses have not been given high priority in China, although the role of companion animals as reservoirs for zoonotic parasitic diseases has been recognized worldwide. With an increasing number of dogs and cats under unregulated conditions in China, the canine and feline parasitic zoonoses are showing a trend towards being gradually uncontrolled. Currently, canine and feline parasitic zoonoses threaten human health, and cause death and serious diseases in China. This article comprehensively reviews the current status of major canine and feline parasitic zoonoses in mainland China, discusses the risks dogs and cats pose with regard to zoonotic transmission of canine and feline parasites, and proposes control strategies and measures.

The second transcribed spacer rDNA sequence: an effective genetic marker for inter-species phylogenetic analysis of trematodes in the order Strigeata

In the present study, the second nuclear internal transcribed spacer (ITS-2) rDNA of Schistosoma japonicum isolates in mainland China was amplified, sequenced, and assessed for inferring the intra- and inter-species phylogenetic relationships of trematodes in the order Strigeata. The fragment containing ITS-2 rDNA was obtained from 24 S. japonicum isolates from eight epidemic provinces in mainland China. The length polymorphisms were observed among these ITS-2 rDNA sequences, ranging from 343 to 346 bp, and the intra- and inter-population variations in ITS-2 sequence were 0.0-2.1% among S. japonicum isolates in China. Phylogenetic analyses using the maximum parsimony and maximum likelihood methods revealed that the ITS-2 rDNA sequence is not a suitable marker for studying inter- and intra-population variation in S. japonicum. However, phylogenetic analysis of trematodes in the order Strigeata indicated that the ITS-2 rDNA sequence provides an effective molecular marker for studying inter-species phylogenetic relationships among trematodes in this order.

High prevalence of Opisthorchis viverrini infection in a riparian population in Takeo Province, Cambodia

Opisthorchis viverrini infection was found to be highly prevalent in 3 riverside villages (Ang Svay Chek A, B, and C) of the Prey Kabas District, Takeo Province. This area is located in the southern part of Cambodia, where the recovery of adult O. viverrini worms was recently reported. From May 2006 until May 2010, fecal examinations were performed on a total of 1,799 villagers using the Kato-Katz thick smear technique. In the 3 villages, the overall positive rate for helminth eggs ranged from 51.7 to 59.0% (av. 57.4%), and the percentage positive for O. viverrini was 46.4-50.6% (47.5%). Other helminths detected included hookworms (13.2%), echinostomes (2.9%), Trichuris trichiura (1.3%), Ascaris lumbricoides (0.6%), and Taenia spp. (0.06%). The prevalence of O. viverrini eggs appeared to reflect a lower infection in younger individuals (<20 years) than in the adult population (>20 years). Men (50.4%) revealed a significantly higher (P=0.02) prevalence than women (44.3%). The Ang Svay Chek villages of the Prey Kabas District, Takeo Province, Cambodia have been confirmed to be a highly endemic area for human O. viverrini infection.

Teaching human parasitology in China

China has approximately one-fifth of the world's population. Despite the recent success in controlling major parasitic diseases, parasitic diseases remain a significant human health problem in China. Hence, the discipline of human parasitology is considered as a core subject for undergraduate and postgraduate students of the medical sciences. We consider the teaching of human parasitology to be fundamental to the training of medical students, to the continued research on parasitic diseases, and to the prevention and control of human parasitic diseases. Here, we have summarized the distribution of educational institutions in China, particularly those that teach parasitology. In addition, we have described some existing parasitology courses in detail as well as the teaching methods used for different types of medical students. Finally, we have discussed the current problems in and reforms to human parasitology education. Our study indicates that 304 regular higher education institutions in China offer medical or related education. More than 70 universities have an independent department of parasitology that offers approximately 10 different parasitology courses. In addition, six universities in China have established excellence-building courses in human parasitology.