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      Prevalence of and risk factors associated with Cryptosporidium infection in an underdeveloped rural community of southwest China

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          Abstract

          Background

          Cryptosporidium spp. is an important intestinal protozoan causing diarrhea in humans, livestock, and wild animals. Cryptosporidium infection remains a major public health issue, but its epidemiology in humans is still unclear, particularly in rural China. This study was designed to determine the prevalence of and risk factors associated with Cryptosporidium infection in a rural southwestern Chinese community.

          Methods

          A community-based cross-sectional survey was conducted among 687 residents of a small town in a Yi autonomous prefecture of southwest China in 2014. Blood samples were examined using a broad set of quality-controlled diagnostic methods for hepatitis B virus (HBV) and human immunodeficiency virus (HIV). Stool specimens were processed using the modified acid-fast staining method, and microscopically examined for Cryptosporidium infection. Univariable and multivariable analyses were performed to determine the risk factors associated with Cryptosporidium infection.

          Results

          The majority of the participants were Yi people with poor living conditions and unsatisfactory hygiene habits, and the study area was of very low socioeconomic status. Of the 615 individuals included in the analysis, 14 (2.3%) were HIV positive, 51 (8.3%) were infected with HBV, and 74 (12.0%) had Cryptosporidium infection. The prevalences of HIV/HBV, HIV/ Cryptosporidium, and HBV/ Cryptosporidium co-infections were 0.3%, 0.3%, and 1.8%, respectively. The prevalence of HBV infection was higher in individuals with Cryptosporidium infection ( χ 2 = 5.00, P = 0.03). Owning livestock or poultry was an important risk factor for Cryptosporidium infection (a OR = 2.27, 95% CI: 1.01–5.08, P < 0.05). Cryptosporidium infection was significantly associated with HBV infection (a OR = 3.42, 95% CI: 1.47–7.92, P < 0.01), but not with HIV infection (a OR = 0.57, 95% CI: 0.07–4.39, P = 0.59).

          Conclusions

          The prevalence of Cryptosporidium infection was high in the rural area of southwestern China that was investigated, and there was a significant association between HBV infection and Cryptosporidium infection. Further investigations are needed to determine the significance of Cryptosporidium infection in patients infected with HBV.

          Electronic supplementary material

          The online version of this article (doi:10.1186/s40249-016-0223-9) contains supplementary material, which is available to authorized users.

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          Most cited references 27

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          A review of the global burden, novel diagnostics, therapeutics, and vaccine targets for cryptosporidium.

          Cryptosporidium spp are well recognised as causes of diarrhoeal disease during waterborne epidemics and in immunocompromised hosts. Studies have also drawn attention to an underestimated global burden and suggest major gaps in optimum diagnosis, treatment, and immunisation. Cryptosporidiosis is increasingly identified as an important cause of morbidity and mortality worldwide. Studies in low-resource settings and high-income countries have confirmed the importance of cryptosporidium as a cause of diarrhoea and childhood malnutrition. Diagnostic tests for cryptosporidium infection are suboptimum, necessitating specialised tests that are often insensitive. Antigen-detection and PCR improve sensitivity, and multiplexed antigen detection and molecular assays are underused. Therapy has some effect in healthy hosts and no proven efficacy in patients with AIDS. Use of cryptosporidium genomes has helped to identify promising therapeutic targets, and drugs are in development, but methods to assess the efficacy in vitro and in animals are not well standardised. Partial immunity after exposure suggests the potential for successful vaccines, and several are in development; however, surrogates of protection are not well defined. Improved methods for propagation and genetic manipulation of the organism would be significant advances. Copyright © 2015 Elsevier Ltd. All rights reserved.
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            Zoonotic Cryptosporidium species and Enterocytozoon bieneusi genotypes in HIV-positive patients on antiretroviral therapy.

            Molecular diagnostic tools have been used increasingly in the characterization of the transmission of cryptosporidiosis and microsporidiosis in developing countries. However, few studies have examined the distribution of Cryptosporidium species and Enterocytozoon bieneusi genotypes in AIDS patients receiving antiretroviral therapy. In the present study, 683 HIV-positive patients in the National Free Antiretroviral Therapy Program in China and 683 matched HIV-negative controls were enrolled. Cryptosporidium species and subtypes and Enterocytozoon bieneusi genotypes were detected and differentiated by PCR and DNA sequencing. The infection rates were 1.5% and 0.15% for Cryptosporidium and 5.7% and 4.2% for E. bieneusi in HIV-positive and HIV-negative participants, respectively. The majority (8/11) of Cryptosporidium cases were infections by zoonotic species, including Cryptosporidium meleagridis (5), Cryptosporidium parvum (2), and Cryptosporidium suis (1). Prevalent E. bieneusi genotypes detected, including EbpC (39), D (12), and type IV (7), were also potentially zoonotic. The common occurrence of EbpC was a feature of E. bieneusi transmission not seen in other areas. Contact with animals was a risk factor for both cryptosporidiosis and microsporidiosis. The results suggest that zoonotic transmission was significant in the epidemiology of both diseases in rural AIDS patients in China.
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              HBV and the immune response.

               Carlo Ferrari (2015)
              Hepatitis B virus (HBV) infection acquired in adult life is generally self-limited while chronic persistence of the virus is the prevalent outcome when infection is acquired perinatally. Both control of infection and liver cell injury are strictly dependent upon protective immune responses, because hepatocyte damage is the price that the host must pay to get rid of intracellular virus. Resolution of acute hepatitis B is associated with functionally efficient, multispecific antiviral T-cell responses which are preceded by a poor induction of intracellular innate responses at the early stages of infection. Persistent control of infection is provided by long-lasting protective memory, which is probably sustained by continuous stimulation of the immune system by trace amounts of virus which are never totally eliminated, persisting in an occult episomic form in the nucleus of liver cells even after recovery from acute infection. Chronic virus persistence is instead characterized by a lack of protective T-cell memory maturation and by an exhaustion of HBV-specific T-cell responses. Persistent exposure of T cells to high antigen loads is a key determinant of functional T-cell impairment but also other mechanisms can contribute to T-cell inhibition, including the tolerogenic effect of the liver environment. The degree of T-cell impairment is variable and its severity is related to the level of virus replication and antigen load. The antiviral T-cell function is more efficient in patients who can control infection either partially, such as inactive HBsAg carriers with low levels of virus replication, or completely, such as patients who achieve HBsAg loss either spontaneously or after antiviral therapy. Thus, understanding the features of the immune responses associated with control of infection is needed for the successful design of novel immune modulatory therapies based on the reconstitution of efficient antiviral responses in chronic HBV patients.
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                Author and article information

                Contributors
                yayang14@fudan.edu.cn
                z_yibiao@hotmail.com
                xiaopl90@163.com
                13211020008@fudan.edu.cn
                yue.chen@uottawa.ca
                songliang@ufl.edu
                lwucdc@163.com
                xxsong@fudan.edu.cn
                jiangqw@fudan.edu.cn
                Journal
                Infect Dis Poverty
                Infect Dis Poverty
                Infectious Diseases of Poverty
                BioMed Central (London )
                2049-9957
                9 January 2017
                9 January 2017
                2017
                : 6
                Affiliations
                [1 ]ISNI 0000 0001 0125 2443, GRID grid.8547.e, School of Public Health, , Fudan University, ; Building 8, 130 Dong’an Road, Xuhui District, Shanghai, 200032 China
                [2 ]ISNI 0000 0001 0125 2443, GRID grid.8547.e, Key Laboratory of Public Health Safety, , Fudan University, Ministry of Education, ; Building 8, 130 Dong’an Road, Xuhui District, Shanghai, 200032 China
                [3 ]ISNI 0000 0001 0125 2443, GRID grid.8547.e, Center for Tropical Disease Research, , Fudan University, ; Building 8, 130 Dong’an Road, Xuhui District, Shanghai, 200032 China
                [4 ]ISNI 0000 0001 2182 2255, GRID grid.28046.38, School of Epidemiology, Public Health and Preventive Medicine, Faculty of Medicine, , University of Ottawa, ; 451 Smyth Road, Ottawa, ON K1H 8M5 Canada
                [5 ]ISNI 0000 0004 1936 8091, GRID grid.15276.37, Department of Environmental and Global Health, College of Public Health and Health Professions, , University of Florida, ; 2055 Mowry Road, Gainesville, FL 32611 USA
                [6 ]ISNI 0000 0004 1936 8091, GRID grid.15276.37, Emerging Pathogens Institute, , University of Florida, ; 2055 Mowry Road, Gainesville, FL 32611 USA
                [7 ]Puge Center for Disease Prevention and Control, 6 Qingnian Road, Puge County, Sichuan, 615300 China
                Article
                223
                10.1186/s40249-016-0223-9
                5267368
                28126012
                © The Author(s). 2017

                Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

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                © The Author(s) 2017

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