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Xu J.,National Institute of Parasitic Disease | Xu J.-F.,Center for Diseases Control and Prevention | Li S.-Z.,National Institute of Parasitic Disease | Zhang L.-J.,National Institute of Parasitic Disease | And 3 more authors.
Acta Tropica | Year: 2015

The prevalence of human schistosomiasis and soil-transmitted helminthiasis (STH) has decreased significantly in the People's Republic of China (P.R. China), particularly after 2005 when the national control programmes were reinforced by forming of integrated control strategies. Furthermore, social-economic development also contributed to the decrease of schistosome and soil-transmitted helminth infections. The prevalence of the zoonotic helminthiasis, including clonorchiasis and echinococcosis, on the other hand, is either underestimated or has in fact increased due to changes in social and environmental factors. In comparison with the control strategies in force and their effects on those four kinds of helminthiasis, the challenges and control priorities for the potential transfer from control to elimination of each disease is reviewed, to provide evidence for policy-makers to act upon. © 2013 Elsevier B.V.


Li Y.,Sun Yat Sen University | Xu H.,Sun Yat Sen University | Chen J.,Sun Yat Sen University | Gan W.,Sun Yat Sen University | And 3 more authors.
Parasitology Research | Year: 2012

Antigen 5 (Ag5) has been identified as a dominant component of cyst fluid of Echinococcus granulosus and is considered as a member of serine proteases family, which in other helminth, plays an important role in the egg hatch and larva invasion. However, whether Ag5 is expressed and secreted in all life stages is unknown. In this study, according to the sequence in GenBank, we cloned and sequenced the open reading frame (ORF) of Ag5 gene from the protoscolices of E. granulosus isolated from the sheep in Qinhai Province of China, and found several substitutions and a base insert and deletion in a short region near the stop code, leading to a frameshift mutation which is conserved with the homologue of other cestode. The ORF is 1,455 bp in length, encoding 484 amino acids with a secretory signal peptide. Bioinformatics analysis predicted several phosphorylation and myristoylation sites and a N-glycosylation site and a species-specific linear B epitope in the protein. The ORF was cloned into the plasmid pET28a(+) vector and expressed in Escherichia coli. The recombinant protein was purified by affinity chromatography. Anti-rEgAg5 antiserum was prepared in rats and used to analyze the localization of Ag5 in protoscolex and adult worm by immunofluorescence technique. Results demonstrated that the Ag5 is strongly expressed in the tegument of protoscolex and the embryonic membrane of egg and surface of oncosphere; meanwhile, it is also weakly expressed in tegument of the adult. This study showed that Ag5 is expressed in all stages of life cycle, secreted from the surface of the worm and may be anchored in membrane by its myristoylation sites; these characteristics make it a candidate antigen for diagnosis and vaccine for both intermediate and definitive hosts. © Springer-Verlag 2011.


Shan C.,York University | Zhou X.,National Institute of Parasitic Disease | Zhu H.,York University
Bulletin of Mathematical Biology | Year: 2014

We formulate and analyze a system of ordinary differential equations for the transmission of schistosomiasis japonica on the islets in the Yangtze River, China. The impact of growing islets on the spread of schistosomiasis is investigated by the bifurcation analysis. Using the projection technique developed by Hassard, Kazarinoff and Wan, the normal form of the cusp bifurcation of codimension 2 is derived to overcome the technical difficulties in studying the existence, stability, and bifurcation of the multiple endemic equilibria in high-dimensional phase space. We show that the model can also undergo transcritical bifurcations, saddle-node bifurcations, a pitchfork bifurcation, and Hopf bifurcations. The bifurcation diagrams and epidemiological interpretations are given. We conclude that when the islet reaches a critical size, the transmission cycle of the schistosomiasis japonica between wild rats Rattus norvegicus and snails Oncomelania hupensis could be established, which serves as a possible source of schistosomiasis transmission along the Yangtze River. © 2014 Society for Mathematical Biology.


Duo-quan W.,National Institute of Parasitic Disease | Lin-hua T.,National Institute of Parasitic Disease | Heng-hui L.,U.S. Center for Disease Control and Prevention | Zhen-cheng G.,National Institute of Parasitic Disease | Xiang Z.,National Institute of Parasitic Disease
PLoS ONE | Year: 2013

Objective:To identify the major ecological drivers for malaria vector density using the structural equation model (SEM) in the Three Gorges Reservoir.Method:An 11-year longitudinal surveillance of malaria vector as well as its related ecological factors was carried out in the Three Gorges Reservoir. The Delphi method was used to identify associated ecological factors. The structural equation model was repeatedly corrected and improved by the corrected index, combined with the actual situation. The final model was defined by relative simplicity, best fitting as well as the practicality.Result:The final model indicated that the direct effects of temperature, livestock, humidity, and breeding on the vector were 0.015, -0.228, 0.450, 0.516 respectively, their total effects on the vector were 0.359, -0.112, 0.850, and 0.043 through different pathways.Conclusion:SEM was effective and convenient in elucidating the mechanism by which malaria vector dynamics operated in this study. It identified that the breeding had the highest direct effect on vector and played a key role for mediating effect of temperature and humidity. © 2013 Duo-quan et al.


PubMed | Guangxi Zhuang Autonomous Region Center for Disease Prevention and Control, Guangxi Medical University, National Institute of Parasitic Disease and Chinese National Institute for Viral Disease Control and Prevention
Type: Journal Article | Journal: The Korean journal of parasitology | Year: 2016

The nitric oxide (NO) formation and intrinsic nitrosation may be involved in the possible mechanisms of liver fluke-associated carcinogenesis. We still do not know much about the responses of inducible NO synthase (iNOS) induced by Clonorchis sinensis infection. This study was conducted to explore the pathological lesions and iNOS expressions in the liver of mice with different infection intensity levels of C. sinensis. Extensive periductal inflammatory cell infiltration, bile duct hyperplasia, and fibrosis were commonly observed during the infection. The different pathological responses in liver tissues strongly correlated with the infection intensity of C. sinensis. Massive acute spotty necrosis occurred in the liver parenchyma after a severe infection. The iNOS activity in liver tissues increased, and iNOS-expressing cells with morphological differences were observed after a moderate or severe infection. The iNOS-expressing cells in liver tissues had multiple origins.


Yang B.,Fudan University | Chen Y.,National Institute of Parasitic Disease | Wu L.,Fudan University | Xu L.,National Institute of Parasitic Disease | And 2 more authors.
American Journal of Tropical Medicine and Hygiene | Year: 2012

The seroprevalence of Entamoeba histolytica infection in the residents of seven provinces in China was examined by using an enzyme-linked immunosorbent assay with a crude antigen and a recombinant surface antigen, C-Igl, of the parasites. A total of 1,312 serum samples were investigated. The positivity rates for these two antigens were 11.05% and 6.25%, respectively. There was no significant difference in the seropositivity to E. histolytica between men and women. We used a logistic regression model and maximal-likelihood methods to estimate the prevalence of E. histolytica infection from sequential serologic data. Seropositivity in Sichuan, Guizhou, and Sinkiang Provinces was higher than that in Beijing, Shanghai, and Qinghai Provinces. The present study provides an overview of seropositivity to E. histolytica infection in seven provinces in China and use the logistic regression model estimation method to achieve a more accurate measure of amebiasis prevalence. Copyright © 2012 by The American Society of Tropical Medicine and Hygiene.


Chen S.H.,National Institute of Parasitic Disease
PLoS neglected tropical diseases | Year: 2010

BACKGROUND: Pentastomiasis is a rare parasitic infection of humans. Pentastomids are dioecious obligate parasites requiring multiple hosts to complete their lifecycle. Despite their worm-like appearance, they are commonly placed into a separate sub-class of the subphylum Crustacea, phylum Arthropoda. However, their systematic position is not uncontested and historically, they have been considered as a separate phylum. METHODOLOGY/PRINCIPAL FINDINGS: An appraisal of Armillifer agkistrodontis was performed in terms of morphology and genetic identification after its lifecycle had been established in a multi-host model, i.e., mice and rats as intermediate hosts, and snakes (Agkistrodon acutus and Python molurus) as definitive hosts. Different stages of the parasite, including eggs, larvae and adults, were isolated and examined morphologically using light and electron microscopes. Phylogenetic and cluster analysis were also undertaken, focusing on the 18S rRNA and the Cox1 gene. The time for lifecycle completion was about 14 months, including 4 months for the development of eggs to infectious larvae in the intermediate host and 10 months for infectious larvae to mature in the final host. The main morphological difference between A. armillatus and Linguatula serrata is the number of abdominal annuli. Based on the 18S rRNA sequence, the shortest hereditary distance was found between A. agkistrodontis and Raillietiella spp. The highest degree of homology in the Cox 1 nucleic acid sequences and predicted amino acid sequences was found between A. agkistrodontis and A. armillatus. CONCLUSION: This is the first time that a multi-host model of the entire lifecycle of A. agkistrodontis has been established. Morphologic and genetic analyses supported the notion that pentastomids should be placed into the phylum Arthropoda.


Chen Y.D.,National Institute of Parasitic Disease | Chen Y.D.,Collaborative Center for Malaria | Zhou C.H.,National Institute of Parasitic Disease | Zhou C.H.,Collaborative Center for Malaria | And 2 more authors.
Biomedical and Environmental Sciences | Year: 2012

Objective: To examine Clonorchis sinensis infection in China and evaluate the effectiveness of efforts to prevent and control it, two nationwide surveys were undertaken in 31 provinces, autonomous regions, and municipalities (PAMs) during 1988-92 (the 1990 survey) and during 2001-04 (the 2003 survey). Methods: During the period 2001-04, two sampling methods were applied. The first method repeated the stratified cluster random sampling used in the 1990 survey; the second method applied two-characteristic stratified cluster random sampling in 27 PAMs-the 2003 endemic area (EA) survey. The Kato-Katz thick smear method was used for the nationwide survey. Results: The infection rates of Clonorchis sinensis in the 1990 and 2003 surveys were 0.311 and 0.579, respectively. The infection rate was 2.40 in the 2003 EA survey, and it was estimated that 12.49 million people in China were infected with Clonorchis sinensis. Conclusion: The 2003 survey showed that the standardized infection rate of Clonorchis sinensis increased by 74.85 compared with the 1990 survey. The infection rate in males was higher than in females; the infection rate among people eating raw fish or eating out frequently was higher than among those who did not. © 2012 The Editorial Board of Biomedical and Environmental Sciences.


Wang D.Q.,National Institute of Parasitic Disease | Tang L.H.,National Institute of Parasitic Disease | Gu Z.C.,National Institute of Parasitic Disease | Zheng X.,National Institute of Parasitic Disease | Jiang W.K.,National Institute of Parasitic Disease
Biomedical and Environmental Sciences | Year: 2013

Objective: To define and evaluate the malaria transmission potential in the Yangtze River, following construction of the Three Gorges Reservoir. Methods: Six villages, namely, Kaixian, Fengjie, Wanzhou, Fuling, Yubei, and Zigui were selected for investigating the malaria transmission potential in the reservoir. Transmission potential was estimated by mathematical modeling and evaluation of the local malaria situation. Factors that influenced the transmission potential were analyzed using Poisson regression analysis in combination with Grey Systematic Theory (based on evaluation by the Delphi method). Results: Indirect fluorescent antibody data and the incidence of malaria in the local population were consistent with the malaria transmission potential calculated for the area. Multivariate Poisson regression analysis showed a statistically significant association between the riparian zone and the man-biting rate. Conclusion: The risk of a malaria epidemic can be forecasted using the malaria transmission potential parameters investigated here which was closely correlated with the riparian zone. Copyright © 2013 by China CDC.


Duo-quan W.,National Institute of Parasitic Disease | Lin-hua T.,National Institute of Parasitic Disease | Zhen-cheng G.,National Institute of Parasitic Disease | Xiang Z.,National Institute of Parasitic Disease | And 2 more authors.
PLoS ONE | Year: 2012

The mosquito sampling efficiency of light-trap catches and electric motor mosquito catches were compared with that of human biting catches in the Three Gorges Reservoir. There was consistency in the sampling efficiency between light-trap catches and human biting catches for Anopheles sinensis (r = 0.82, P<0.01) and light-trap catches were 1.52 (1.35-1.71) times that of human biting catches regardless of mosquito density (r = 0.33, P>0.01), while the correlation between electric motor mosquito catches and human biting catches was found to be not statistically significant (r = 0.43, P>0.01) and its sampling efficiency was below that of human biting catches. It is concluded that light-traps can be used as an alternative to human biting catches of Anopheles sinensis in the study area and is a promising tool for sampling malaria vector populations. © 2012 Duo-quan et al.

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