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Wang L, Wang Z, Qin M, Lei J, Cheng X, Yan J, Gavotte L, Frutos R. A regressive analysis of the main environmental risk factors of human echinococcosis in 370 counties in China. PLoS Negl Trop Dis 2024; 18:e0012131. [PMID: 38743784 PMCID: PMC11125469 DOI: 10.1371/journal.pntd.0012131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 05/24/2024] [Accepted: 03/31/2024] [Indexed: 05/16/2024] Open
Abstract
BACKGROUND Echinococcosis is a natural focal, highly prevalent disease in China. Factors influencing the spread of echinococcosis are not only related to personal exposure but also closely related to the environment itself. The purpose of this study was to explore the influence of environmental factors on the prevalence of human echinococcosis and to provide a reference for prevention and control of echinococcosis in the future. METHODS Data were collected from 370 endemic counties in China in 2018. By downloading Modis, DEM and other remote-sensing images in 2018. Data on environmental factors, i.e., elevation, land surface temperature (LST) and normalized difference vegetation index (NDVI) were collected. Rank correlation analysis was conducted between each environmental factor and the prevalence of echinococcosis at the county level. Negative binomial regression was used to analyze the impact of environmental factors on the prevalence of human echinococcosis at the county level. RESULTS According to rank correlation analysis, the prevalence of human echinococcosis in each county was positively correlated with elevation, negatively correlated with LST, and negatively correlated with NDVI in May, June and July. Negative binomial regression showed that the prevalence of human echinococcosis was negatively correlated with annual LST and summer NDVI, and positively correlated with average elevation and dog infection rate. The prevalence of human cystic echinococcosis was inversely correlated with the annual average LST, and positively correlated with both the average elevation and the prevalence rate of domestic animals. The prevalence of human alveolar echinococcosis was positively correlated with both NDVI in autumn and average elevation, and negatively correlated with NDVI in winter. CONCLUSION The prevalence of echinococcosis in the population is affected by environmental factors. Environmental risk assessment and prediction can be conducted in order to rationally allocate health resources and improve both prevention and control efficiency of echinococcosis.
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Affiliation(s)
- Liying Wang
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention; Chinese Centre for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Centre for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
- Cirad, UMR 17, Intertryp, Montpellier, France
- Espace-Dev, University of Montpellier, Montpellier, France
| | - Zhiyi Wang
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention; Chinese Centre for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Centre for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
| | - Min Qin
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention; Chinese Centre for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Centre for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
| | - Jiaxi Lei
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention; Chinese Centre for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Centre for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
| | - Xixi Cheng
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention; Chinese Centre for Tropical Diseases Research; WHO Collaborating Centre for Tropical Diseases; National Centre for International Research on Tropical Diseases, Ministry of Science and Technology; Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
| | - Jun Yan
- Chinese Centre for Disease Control and Prevention, Beijing, China
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Kui Y, Liu B, Wang X, Xue C, Xue J, Zhang Y, Zhang B, Dai Y, Han S, Wu W. Epidemiological Characteristics of Echinococcosis in Non-Endemic PLADs - China, 2017-2020. China CDC Wkly 2021; 3:1084-1088. [PMID: 34938586 PMCID: PMC8688752 DOI: 10.46234/ccdcw2021.262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 12/14/2021] [Indexed: 11/14/2022] Open
Abstract
What is already known about this topic? Echinococcosis, also known as hydatid disease, is a zoonotic parasitic disease caused by the larvae of Echinococcus granulosus. Western China has one of the most severe epidemics worldwide. Echinococcosis is endemic in 370 counties of 9 provincial-level administrative divisions (PLADs) including Inner Mongolia, Sichuan, Yunnan, Tibet, Shaanxi, Gansu, Qinghai, Ningxia, Xinjiang and Xinjiang Production and Construction Corps (XPCC).
What is added by this report? From 2017 to 2020, 244 cases were reported in 21 non-endemic PLADs. Of the cases reported in non-endemic PLADs, the majority were imported from endemic areas. Cases reported from non-endemic PLADs have been sporadic, and the number has increased in some areas. What are the implications for public health practice? Migrant workers and livestock from endemic areas may have contributed to the increased incidence of locally acquired infections in non-endemic PLADs, suggesting that health education among workers and livestock quarantine is important for the control of spread in non-endemic PLADs.
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Affiliation(s)
- Yan Kui
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Baixue Liu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Xu Wang
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Cuizhao Xue
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Jingbo Xue
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Yalan Zhang
- Henan Provincial Center for Disease Control and Prevention, Zhengzhou, Henan, China
| | - Benguang Zhang
- Shandong Institute of Parasitic Diseases, Jining, Shandong, China
| | - Yang Dai
- Jiangsu Institute of Parasitic Diseases, Wuxi, Jiangsu, China
| | - Shuai Han
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
| | - Weiping Wu
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); National Health Commission Key Laboratory of Parasite and Vector Biology; World Health Organization Collaborating Center for Tropical Diseases; National Center for International Research on Tropical Diseases, Shanghai, China
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3
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Fu MH, Wang X, Han S, Guan YY, Bergquist R, Wu WP. Advances in research on echinococcoses epidemiology in China. Acta Trop 2021; 219:105921. [PMID: 33878307 DOI: 10.1016/j.actatropica.2021.105921] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 04/10/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022]
Abstract
Echinococcoses are serious zoonotic diseases in China's vast, western and north-western pastoral areas that has one of the highest prevalence in the world. The two most common forms, cystic echinococcosis (CE) and alveolar echinococcosis (AE), are co-epidemic in some areas causing a grave threat to people's health and economic development. Echinococcus spp. are transmitted through domestic, sylvatic and mixed cycles involving many kinds of host. Successful transmission requires a favourable environment for the growth of the parasites and survival of their eggs, while the unique customs and religious beliefs in the endemic areas pose a challenge to the prevention and control of these parasites. Based on previous epidemiological studies, this paper reviews the particular factors affecting the transmission of Echinococcus parasites in China, with a focus on biological (parasite genotype and the species, age, sex and density of hosts), environmental (landscape and climate) and social (age, gender, ethnicity, education, occupation, life style, cultural customs, living conditions and hygiene practices of humans in the endemic areas). These three factors interact with each other and jointly determine the parasites' transmission intensity, the study of which supports the formulation of the strategies and measures that are significant for control of these infections.
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He W, Wang LY, Yu WJ, Zhang GJ, Zhong B, Liao S, Wang Q, Li RR, Yang L, Yao RX, Liu Y, Danba Z, Qin SC, Wang SA, Wang YX, Huang Y, Wang Q. Prevalence and spatial distribution patterns of human echinococcosis at the township level in Sichuan Province, China. Infect Dis Poverty 2021; 10:82. [PMID: 34090538 PMCID: PMC8180058 DOI: 10.1186/s40249-021-00862-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 05/19/2021] [Indexed: 12/04/2022] Open
Abstract
Background Echinococcosis is a global zoonotic parasitic disease caused by Echinococcus larvae. This disease is highly endemic in Sichuan Province, China. This study investigates the prevalence and spatial distribution characteristics of human echinococcosis at the township level in Sichuan Province, geared towards providing a future reference for the development of precise prevention and control strategies.
Methods Human prevalence of echinococcosis was evaluated using the B-ultrasonography diagnostic method in Sichuan Province between 2016 and 2019. All data were collected, collated, and analyzed. A spatial distribution map was drawn to intuitively analyze the spatial distribution features. Eventually, the spatial autocorrelation was specified and local indicators of spatial association (LISA) clustering map was drawn to investigate the spatial aggregation of echinococcosis at the township level in Sichuan Province. Results The prevalence of echinococcosis in humans of Sichuan Province was 0.462%, among which the occurrence of cystic echinococcosis (CE) was 0.221%, while that of alveolar echinococcosis (AE) was 0.244%. Based on the results of the spatial distribution map, a predominance of echinococcosis in humans decreased gradually from west to east and from north to south. The Global Moran’s I index was 0.77 (Z = 32.07, P < 0.05), indicating that the prevalence of echinococcosis in humans was spatially clustered, exhibiting a significant spatial positive correlation. Further, the findings of local spatial autocorrelation analysis revealed that the “high–high” concentration areas were primarily located in some townships in the northwest of Sichuan Province. However, the “low–low” concentration areas were predominantly located in some townships in the southeast of Sichuan Province.
Conclusions Our findings demonstrated that the prevalence of echinococcosis in humans of Sichuan Province follows a downward trend, suggesting that the current prevention and control work has achieved substantial outcomes. Nevertheless, the prevalence in humans at the township level is widely distributed and differs significantly, with a clear clustering in space. Therefore, precise prevention and control strategies should be formulated for clusters, specifically strengthening the “high–high” clusters at the township level. Graphic Abstract ![]()
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Affiliation(s)
- Wei He
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Li-Ying Wang
- National Institute of Parasitic Diseases, Chinese Centre for Disease Control and Prevention, Chinese Centre for Tropical Diseases Research, WHO Collaborating Centre for Tropical Diseases, National Centre for International Research On Tropical Diseases, Ministry of Science and Technology, NHC Key Laboratory of Parasite and Vector Biology (National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention), Shanghai, 200025, People's Republic of China.,Doctorate School of Chemical and Biological Sciences for Health (CBS2), University of Montpellier, 34395, Montpellier, France
| | - Wen-Jie Yu
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Guang-Jia Zhang
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Bo Zhong
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Sha Liao
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Qi Wang
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Rui-Rui Li
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Liu Yang
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Ren-Xin Yao
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Yang Liu
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China
| | - Zeli Danba
- Ganzi Prefectural Center for Disease Control and Prevention, No.139 Lucheng South Road, Ganzi Prefecture, 626000, People's Republic of China
| | - Sheng-Chao Qin
- Aba Prefectural Center for Disease Control and Prevention, No.178 Meigu Street, Aba Prefecture, 624000, People's Republic of China
| | - Shi-An Wang
- Liangshan Prefectural Center for Disease Control and Prevention, Section 2 of Hangtian Avenue, Liangshan Prefecture, 615000, People's Republic of China
| | - Yan-Xia Wang
- Ya'an Prefectural Center for Disease Control and Prevention, No.9 Fangcao Road, Daxing New District, Ya'an City, 625000, People's Republic of China
| | - Yan Huang
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China.
| | - Qian Wang
- Department of Parasitic Diseases, Sichuan Provincial Center for Disease Control and Prevention, No.6 Zhongxue Road, Chengdu, 610041, People's Republic of China.
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Khan A, Umhang G, Ullah Z, Boué F, Bastid V, Ullah I, Mahmood S, Afzal MS, Ahmed H. Investigation of Echinococcus multilocularis in foxes and dogs in Pakistan by detection of copro-DNA. Parasitol Res 2021; 120:731-737. [PMID: 33442815 DOI: 10.1007/s00436-020-07001-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 12/02/2020] [Indexed: 01/20/2023]
Abstract
Alveolar echinococcosis (AE) is a zoonosis caused by Echinococcus multilocularis, a heteroxenous parasite belonging to Cestoda class. AE is currently considered an important public health issue, but epidemiological and notably molecular data from several endemic countries, including Pakistan, are sparse. Here we report the first detection of Echinococcus multilocularis in wildlife from Pakistan after real-time PCR and sequencing confirmation in the faecal samples of three foxes from northern Kaghan and Siran regions. The occurrence is estimated at 4.4% (95% CI 0.9-12.4). In order to go further in the epidemiological investigations on E. multilocularis and due to the potential presence of other Echinococcus species, we suggest the need for further epidemiological surveys targeting E. multilocularis and E. granulosus sensu lato isolates from humans and intermediate hosts as well as definitive hosts from wildlife in Pakistan.
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Affiliation(s)
- Aisha Khan
- Department of Biosciences, COMSATS University Islamabad (CUI), Park Road, Chakh Shahzad, Islamabad, Pakistan
| | - Gérald Umhang
- ANSES LRFSN, Wildlife Surveillance and Eco-epidemiology Unit, National Reference Laboratory for Echinococcus spp., Malzéville, France.
| | - Zaib Ullah
- Department of Zoology, Hazara University Mansehra, Mansehra, Khyber Pakhtunkhwa, 21120, Pakistan
| | - Franck Boué
- ANSES LRFSN, Wildlife Surveillance and Eco-epidemiology Unit, National Reference Laboratory for Echinococcus spp., Malzéville, France
| | - Vanessa Bastid
- ANSES LRFSN, Wildlife Surveillance and Eco-epidemiology Unit, National Reference Laboratory for Echinococcus spp., Malzéville, France
| | - Ikram Ullah
- Department of Zoology, Hazara University Mansehra, Mansehra, Khyber Pakhtunkhwa, 21120, Pakistan
| | - Sajid Mahmood
- Department of Zoology, Hazara University Mansehra, Mansehra, Khyber Pakhtunkhwa, 21120, Pakistan
| | - Muhammad Sohail Afzal
- Department of Life Sciences, University of Management & Technology (UMT), Lahore, Pakistan
| | - Haroon Ahmed
- Department of Biosciences, COMSATS University Islamabad (CUI), Park Road, Chakh Shahzad, Islamabad, Pakistan.
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Wild H, Mendonsa E, Trautwein M, Edwards J, Jowell A, GebreGiorgis Kidanu A, Tschopp R, Barry M. Health interventions among mobile pastoralists: a systematic review to guide health service design. Trop Med Int Health 2020; 25:1332-1352. [PMID: 32881232 DOI: 10.1111/tmi.13481] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Mobile pastoralists are one of the last populations to be reached by health services and are frequently missed by health campaigns. Since health interventions among pastoralists have been staged across a range of disciplines but have not yet been systematically characterised, we set out to fill this gap. METHODS We conducted a systematic search in PubMed/MEDLINE, Scopus, Embase, CINAL, Web of Science, WHO Catalog, AGRICOLA, CABI, ScIELO, Google Scholar and grey literature repositories to identify records that described health interventions, facilitators and barriers to intervention success, and factors influencing healthcare utilisation among mobile pastoralists. No date restrictions were applied. Due to the heterogeneity of reports captured in this review, data were primarily synthesised through narrative analysis. Descriptive statistical analysis was performed for data elements presented by a majority of records. RESULTS Our search yielded 4884 non-duplicate records, of which 140 eligible reports were included in analysis. 89.3% of reports presented data from sub-Saharan Africa, predominantly in East Africa (e.g. Ethiopia, 30.0%; Kenya, 17.1%). Only 24.3% of reports described an interventional study, while the remaining 75.7% described secondary data of interest on healthcare utilisation. Only two randomised controlled trials were present in our analysis, and only five reports presented data on cost. The most common facilitators of intervention success were cultural sensitivity (n = 16), community engagement (n = 12) and service mobility (n = 11). CONCLUSION Without adaptations to account for mobile pastoralists' unique subsistence patterns and cultural context, formal health services leave pastoralists behind. Research gaps, including neglect of certain geographic regions, lack of both interventional studies and diversity of study design, and limited data on economic feasibility of interventions must be addressed to inform the design of health services capable of reaching mobile pastoralists. Pastoralist-specific delivery strategies, such as combinations of mobile and 'temporary fixed' services informed by transhumance patterns, culturally acceptable waiting homes, community-directed interventions and combined joint human-animal One Health design as well as the bundling of other health services, have shown initial promise upon which future work should build.
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Affiliation(s)
- Hannah Wild
- Stanford University School of Medicine, Stanford, CA, USA.,Department of Surgery, University of Washington, Seattle, WA, USA
| | | | - Micah Trautwein
- Department of Biology, Stanford University, Stanford, CA, USA
| | | | - Ashley Jowell
- Stanford University School of Medicine, Stanford, CA, USA
| | | | - Rea Tschopp
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Michele Barry
- Stanford University School of Medicine, Stanford, CA, USA.,The Center for Innovation in Global Health, Stanford University, Stanford, CA, USA
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Baumann S, Shi R, Liu W, Bao H, Schmidberger J, Kratzer W, Li W. Worldwide literature on epidemiology of human alveolar echinococcosis: a systematic review of research published in the twenty-first century. Infection 2019; 47:703-727. [PMID: 31147846 PMCID: PMC8505309 DOI: 10.1007/s15010-019-01325-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 05/20/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE Human alveolar echinococcosis (AE) is a potentially lethal zoonosis caused by the cestode Echinococcus multilocularis. The aim of this systematic review is to establish a comprehensive global AE literature overview taking into account the epidemiologically relevant AE research of the twenty-first century. METHODS We systematically searched the global literature published from 2001 through 2018 via MEDLINE, EMBASE, the Russian databases eLIBRARY.RU, CyberLeninka, the Chinese databases CNKI, VIP, Journals. RESEARCH ac.ir (Farsi language-based), Jordan E-Library (Arab language-based) and supplementary Google Scholar, in accordance with the PRISMA guidelines. QGIS software was used for the mapping of the affected countries. RESULTS We have listed 154 relevant publications in the final literature synopsis in consideration of our quality assessment. Including non-autochthonous cases, human AE was reported in 36 countries within the northern hemisphere from 2001 to 2018. The first publication of AE in Tajikistan, Pakistan, South Korea, Belgium, the Netherlands, Slovakia, Hungary, Lithuania, Latvia, Slovenia and Morocco occurred in this century; further first cases in Taiwan, Thailand, and Denmark were considered to be non-autochthonous by the authors. The highest total case numbers (n ≥ 100 in a single article) were reported in France, Germany, Switzerland, Poland, and Lithuania, including China and Kyrgyzstan with by far the highest prevalence figures. CONCLUSIONS Our paper emphasises the increasing spread of reported cases and the rise in its numbers in the literature of the twenty-first century, especially in western, northern and eastern Europe, as well as in central Asia. Epidemiological studies on human infections are lacking in many parts of the world.
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Affiliation(s)
- Sven Baumann
- Department of Internal Medicine I, Ulm University Hospital, Albert-Einstein-Allee 23, 89081, Ulm, Germany
| | - Rong Shi
- Department of Diagnostic and Interventional Radiology, Ulm University Hospital, Albert-Einstein-Allee 23, 89081, Ulm, Germany
| | - Wenya Liu
- Xinjiang Medical University, First Affiliated Hospital, WHO Collaborating Centre on Prevention and Care Management of Echinococcosis, Urumqi, 830000, Xinjiang Uyghur Autonomous Region, People's Republic of China
| | - Haihua Bao
- Qinghai University Affiliated Hospital, Qinghai University, Xining, 810001, Qinghai, People's Republic of China
| | - Julian Schmidberger
- Department of Internal Medicine I, Ulm University Hospital, Albert-Einstein-Allee 23, 89081, Ulm, Germany
| | - Wolfgang Kratzer
- Department of Internal Medicine I, Ulm University Hospital, Albert-Einstein-Allee 23, 89081, Ulm, Germany.
| | - Weixia Li
- Qinghai University Affiliated Hospital, Qinghai University, Xining, 810001, Qinghai, People's Republic of China
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Craig PS, Giraudoux P, Wang ZH, Wang Q. Echinococcosis transmission on the Tibetan Plateau. ADVANCES IN PARASITOLOGY 2019; 104:165-246. [PMID: 31030769 DOI: 10.1016/bs.apar.2019.03.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Since the mid-1990s detailed studies and field investigations on the Tibetan Plateau have revealed human echinococcosis to be an under-reported major public health problem, particularly in the dominant pastoral communities in the eastern and central regions. Human prevalence surveys showed that cystic echinococcosis (CE, caused by Echinococcus granulosus) and alveolar echinococcosis (AE, caused by Echinococcus multilocularis) are co-endemic with higher burdens of each disease than other endemic world regions. Epidemiological investigations identified some major risk factors for human CE and AE including dog ownership, husbandry practices and landscape features. Dogs appear to be the major zoonotic reservoir for both E. granulosus and E. multilocularis, but the latter is also transmitted in complex wildlife cycles. Small mammal assemblages especially of vole and pika species thrive on the Plateau and contribute to patterns of E. multilocularis transmission which are influenced by landscape characteristics and anthropogenic factors. Tibetan foxes are a principal definitive host for both E. multilocularis and E. shiquicus. In 2006 a national echinococcosis control programme was initiated in Tibetan communities in northwest Sichuan Province and rolled out to all of western China by 2010, and included improved surveillance (and treatment access) of human disease and regular deworming of dogs with annual copro-testing. Control of echinococcosis in Tibetan pastoral communities poses a difficult challenge for delivery and sustainability.
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Affiliation(s)
- Phil S Craig
- School of Environment and Life Sciences, University of Salford, Greater Manchester, United Kingdom.
| | - Patrick Giraudoux
- Department of Chrono-Environment, UMR UFC/CNRS, Université de Franche-Comté, Besancon, France; Laboratory of Wildlife Management and Ecosystem Health, Yunnan University of Finance and Economics, Kunming, China.
| | - Zheng Huan Wang
- School of Life Sciences, and Shanghai Key Laboratory of Urbanization and Ecological Restoration, East China Normal University, Shanghai, China; Joint Translational Science and Technology Research Institute, Shanghai, China
| | - Qian Wang
- Sichuan Provincial Center for Disease Control and Prevention, Chengdu, China
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Malkamäki S, Näreaho A, Oksanen A, Sukura A. Berries as a potential transmission vehicle for taeniid eggs. Parasitol Int 2019; 70:58-63. [PMID: 30711641 DOI: 10.1016/j.parint.2019.01.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Revised: 01/29/2019] [Accepted: 01/30/2019] [Indexed: 11/28/2022]
Abstract
Potential role of wild forest berries as a transmission vehicle for taeniid eggs was examined using non-zoonotic Taenia laticollis eggs as a model. The berries studied were bilberries (Vaccinium myrtillus) (1 m2 plot, n = 10) and lingonberries (Vaccinium vitis-idaea) (1 m2 plot, n = 11). The plots in the managed forest were evenly sprayed with 30,000 or 60,000 T. laticollis eggs suspended in water, and berries were collected 24 h after spraying. The berries were rinsed with water, and the water was sieved through a 1-mm and a 63-μm sieve to remove coarse material and through a 20-μm sieve to collect possible eggs. A small proportion of the sieved material was examined by microscopy after treatment with fluorescent Calcofluor White stain, which binds to eggshell chitin. In the recovery tests in artificially spiked samples, the detection limit was 5 eggs in 100 g of commercial frozen bilberries and lingonberries. Taeniid eggs were detected in all of the 10 experimentally contaminated bilberry samples and in 10 of 11 lingonberry samples. The sieved debris was also analyzed for T. laticollis DNA using semi-quantitative PCR. All samples were positive in quantitative SYBR Green real-time PCR using a T. laticollis-specific primer pair amplifying a short fragment of mitochondrial NADH dehydrogenase subunit 1 gene. This indicates that forest berries contaminated in shrubs contained T. laticollis eggs, and that berries can serve as a vehicle for taeniid eggs and may pose a possible risk to humans.
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Affiliation(s)
- Sanna Malkamäki
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki (FINPAR), Finland.
| | - Anu Näreaho
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki (FINPAR), Finland
| | - Antti Oksanen
- Finnish Food Safety Authority Evira (FINPAR), Oulu, Finland
| | - Antti Sukura
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, University of Helsinki (FINPAR), Finland
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Childhood suffering: hyper endemic echinococcosis in Qinghai-Tibetan primary school students, China. Infect Dis Poverty 2018; 7:71. [PMID: 29996900 PMCID: PMC6042437 DOI: 10.1186/s40249-018-0455-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 06/19/2018] [Indexed: 11/17/2022] Open
Abstract
Background As part of an ongoing program that aims to use early detection and timely treatment to improve the control of echinococcosis, especially in younger age groups, we undertook a series of active surveys among Qinghai-Tibetan children in the Qinghai Province of Northwestern China in 2011 and 2012. The significant outcomes that resulted from this study emphasize the need to draw attention to echinococcosis, both alveolar echinococcosis (AE) and cystic echinococcosis (CE), so that policy development is promoted and suitable avenues for control are identified in the highly endemic areas on the Tibetan Plateau. Methods A total of 19 629 primary school students, aged 6–18 years, with a dominant Tibetan background underwent abdominal ultrasound examination, and 86.4% of the compliant students donated 2–5 ml of venous blood for serological tests. All the abnormal ultrasound results were recorded. If identified as echinococcosis, the disease lesion was assessed according to the WHO-Informal Working Group on Echinococcosis (WHO-IWGE) classification for AE and CE. Among the surveyed students, the prevalence by school was compared among geo-locations, sex and age groups. The clinical image presentations were analyzed according to lesion number, size, the location in the liver and the classification stage. Statistical significance was set at P-value < 0.05 for comparisons among groups. Results A total of 341 students (1.7%) were identified by ultrasound as having either CE (119, 0.6%) or AE (222, 1.1%). The highest prevalence rates of childhood AE cases occurred in the Tehetu (12.1%) and Moba (11.8%) townships in Dari County. There was a high seropositive rate (37.0%) and a heterogeneous distribution of cases, with a prevalence ranged from 0 to 12.1% for AE and 0–2.9% for CE. Moreover, the seropositive rate ranged from 0.7–45.1% across different schools. Conclusions The high prevalence of echinococcosis in Qinghai-Tibetan primary school students reflects a lack of knowledge about Echinococcus spp. transmission. The combination of systematic education for children and regularly performed anthelmintic treatment for dogs could achieve the goal of sustainable hydatidosis control. Electronic supplementary material The online version of this article (10.1186/s40249-018-0455-y) contains supplementary material, which is available to authorized users.
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Cadavid Restrepo AM, Yang YR, McManus DP, Gray DJ, Barnes TS, Williams GM, Soares Magalhães RJ, Clements ACA. Environmental risk factors and changing spatial patterns of human seropositivity for Echinococcus spp. in Xiji County, Ningxia Hui Autonomous Region, China. Parasit Vectors 2018. [PMID: 29523176 PMCID: PMC5845300 DOI: 10.1186/s13071-018-2764-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Background Human echinococcoses are parasitic helminth infections that constitute a serious public health concern in several regions across the world. Cystic (CE) and alveolar echinococcosis (AE) in China represent a high proportion of the total global burden of these infections. This study was conducted to predict the spatial distribution of human seropositivity for Echinococcus species in Xiji County, Ningxia Hui Autonomous Region (NHAR), with the aim of identifying communities where targeted prevention and control efforts are required. Methods Bayesian geostatistical models with environmental and demographic covariates were developed to predict spatial variation in the risk of human seropositivity for Echinococcus granulosus (the cause of CE) and E. multilocularis (the cause of AE). Data were collected from three cross-sectional surveys of school children conducted in Xiji County in 2002–2003, 2006–2007 and 2012–2013. Environmental data were derived from high-resolution satellite images and meteorological data. Results The overall seroprevalence of E. granulosus and E. multilocularis was 33.4 and 12.2%, respectively, across the three surveys. Seropositivity for E. granulosus was significantly associated with summer and winter precipitation, landscape fragmentation variables and the extent of areas covered by forest, shrubland, water and bareland/artificial surfaces. Seropositivity for E. multilocularis was significantly associated with summer and winter precipitations, landscape fragmentation variables and the extent of shrubland and water bodies. Spatial correlation occurred over greater distances for E. granulosus than for E. multilocularis. The predictive maps showed that the risk of seropositivity for E. granulosus expanded across Xiji during the three surveys, while the risk of seropositivity for E. multilocularis became more confined in communities located in the south. Conclusions The identification of high-risk areas for seropositivity for these parasites, and a better understanding of the role of the environment in determining the transmission dynamics of Echinococcus spp. may help to guide and monitor improvements in human echinococcosis control strategies by allowing targeted allocation of resources.
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Affiliation(s)
- Angela M Cadavid Restrepo
- Research School of Population Health, The Australian National University, Canberra, Australian Capital Territory, 0200, Australia.
| | - Yu Rong Yang
- Ningxia Medical University, 692 Shengli St, Xingqing, Yinchuan, Ningxia Hui Autonomous Region, China.,Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, 4006, Australia
| | - Donald P McManus
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, 4006, Australia
| | - Darren J Gray
- Research School of Population Health, The Australian National University, Canberra, Australian Capital Territory, 0200, Australia.,Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, 4006, Australia
| | - Tamsin S Barnes
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.,The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Gatton, Queensland, 4343, Australia
| | - Gail M Williams
- The University of Queensland, School of Public Health, Brisbane, Queensland, 4006, Australia
| | - Ricardo J Soares Magalhães
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.,Children's Health and Environment Programme, Queensland Children's Medical Research Institute, The University of Queensland, Brisbane, Queensland, 4101, Australia
| | - Archie C A Clements
- Research School of Population Health, The Australian National University, Canberra, Australian Capital Territory, 0200, Australia
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Cadavid Restrepo AM, Yang YR, McManus DP, Gray DJ, Barnes TS, Williams GM, Soares Magalhães RJ, Hamm NAS, Clements ACA. Spatiotemporal patterns and environmental drivers of human echinococcoses over a twenty-year period in Ningxia Hui Autonomous Region, China. Parasit Vectors 2018; 11:108. [PMID: 29471844 PMCID: PMC5824458 DOI: 10.1186/s13071-018-2693-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 02/02/2018] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Human cystic (CE) and alveolar (AE) echinococcoses are zoonotic parasitic diseases that can be influenced by environmental variability and change through effects on the parasites, animal intermediate and definitive hosts, and human populations. We aimed to assess and quantify the spatiotemporal patterns of human echinococcoses in Ningxia Hui Autonomous Region (NHAR), China between January 1994 and December 2013, and examine associations between these infections and indicators of environmental variability and change, including large-scale landscape regeneration undertaken by the Chinese authorities. METHODS Data on the number of human echinococcosis cases were obtained from a hospital-based retrospective survey conducted in NHAR for the period 1 January 1994 through 31 December 2013. High-resolution imagery from Landsat 4/5-TM and 8-OLI was used to create single date land cover maps. Meteorological data were also collected for the period January 1980 to December 2013 to derive time series of bioclimatic variables. A Bayesian spatio-temporal conditional autoregressive model was used to quantify the relationship between annual cases of CE and AE and environmental variables. RESULTS Annual CE incidence demonstrated a negative temporal trend and was positively associated with winter mean temperature at a 10-year lag. There was also a significant, nonlinear effect of annual mean temperature at 13-year lag. The findings also revealed a negative association between AE incidence with temporal moving averages of bareland/artificial surface coverage and annual mean temperature calculated for the period 11-15 years before diagnosis and winter mean temperature for the period 0-4 years. Unlike CE risk, the selected environmental covariates accounted for some of the spatial variation in the risk of AE. CONCLUSIONS The present study contributes towards efforts to understand the role of environmental factors in determining the spatial heterogeneity of human echinococcoses. The identification of areas with high incidence of CE and AE may assist in the development and refinement of interventions for these diseases, and enhanced environmental change risk assessment.
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Affiliation(s)
| | - Yu Rong Yang
- Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, People's Republic of China
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Donald P McManus
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Darren J Gray
- Research School of Population Health, The Australian National University, Canberra, ACT, Australia
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Tamsin S Barnes
- School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Gatton, QLD, Australia
| | - Gail M Williams
- School of Public Health, The University of Queensland, Brisbane, QLD, Australia
| | - Ricardo J Soares Magalhães
- School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
- Children's Health and Environment Program, Child Health Research Centre, The University of Queensland, Brisbane, QLD, Australia
| | - Nicholas A S Hamm
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands
| | - Archie C A Clements
- Research School of Population Health, The Australian National University, Canberra, ACT, Australia
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Barnes AN, Davaasuren A, Baasandagva U, Gray GC. A systematic review of zoonotic enteric parasitic diseases among nomadic and pastoral people. PLoS One 2017; 12:e0188809. [PMID: 29190664 PMCID: PMC5708844 DOI: 10.1371/journal.pone.0188809] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/25/2017] [Indexed: 12/31/2022] Open
Abstract
Introduction Zoonotic enteric parasites are ubiquitous and remain a public health threat to humans due to our close relationship with domestic animals and wildlife, inadequate water, sanitation, and hygiene practices and diet. While most communities are now sedentary, nomadic and pastoral populations still exist and experience unique exposure risks for acquiring zoonotic enteric parasites. Through this systematic review we sought to summarize published research regarding pathogens present in nomadic populations and to identify the risk factors for their infection. Methods Using systematic review guidelines set forth by PRISMA, research articles were identified, screened and summarized based on exclusion criteria for the documented presence of zoonotic enteric parasites within nomadic or pastoral human populations. A total of 54 articles published between 1956 and 2016 were reviewed to determine the pathogens and exposure risks associated with the global transhumance lifestyle. Results The included articles reported more than twenty different zoonotic enteric parasite species and illustrated several risk factors for nomadic and pastoralist populations to acquire infection including; a) animal contact, b) food preparation and diet, and c) household characteristics. The most common parasite studied was Echinococcosis spp. and contact with dogs was recognized as a leading risk factor for zoonotic enteric parasites followed by contact with livestock and/or wildlife, water, sanitation, and hygiene barriers, home slaughter of animals, environmental water exposures, household member age and sex, and consumption of unwashed produce or raw, unprocessed, or undercooked milk or meat. Conclusion Nomadic and pastoral communities are at risk of infection with a variety of zoonotic enteric parasites due to their living environment, cultural and dietary traditions, and close relationship to animals. Global health efforts aimed at reducing the transmission of these animal-to-human pathogens must incorporate a One Health approach to support water, sanitation, and hygiene development, provide education on safe food handling and preparation, and improve the health of domestic animals associated with these groups, particularly dogs.
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Affiliation(s)
- Amber N. Barnes
- Institute of Veterinary Medicine, Ulaanbaatar, Mongolia
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, NC, United States of America
- * E-mail:
| | - Anu Davaasuren
- Institute of Veterinary Medicine, Ulaanbaatar, Mongolia
- National Center for Communicable Disease, Ulaanbaatar, Mongolia
| | - Uyanga Baasandagva
- Institute of Veterinary Medicine, Ulaanbaatar, Mongolia
- National Center for Zoonotic Disease, Ulaanbaatar, Mongolia
| | - Gregory C. Gray
- Division of Infectious Diseases, School of Medicine, Duke University, Durham, NC, United States of America
- Global Health Institute, Duke University, Durham, NC, United States of America
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Cai DM, Wang HY, Wang XL, Jiang Y, Luo Y, Li YZ. Ultrasonographic findings of small lesion of hepatic alveolar echinococcosis. Acta Trop 2017; 174:165-170. [PMID: 26892870 DOI: 10.1016/j.actatropica.2016.01.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/06/2016] [Accepted: 01/29/2016] [Indexed: 02/05/2023]
Abstract
OBJECTIVE To investigate the features of small lesions of hepatic alveolar echinococcsis paragonimiasis (AE) on conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) imaging. METHODS This retrospective study was approved by the Institutional Review Board, and the requirement for informed consent was waived. US and CEUS features of seventeen lesions histopathologically proven hepatic AE were retrospectively reviewed. Nine patients with seventeen hepatic AE lesions who were admitted to our hospital between January 2008 and June 2015 were enrolled. All hepatic AE lesions were small (≤3cm). The US and CEUS examinations were performed with a Philips IU22 scanner with a 1-5-MHz convex transducer. After US was completed, the CEUS study was performed. Pulse-inversion harmonic imaging was used for CEUS. A bolus injection of 2.4mL of a sulfur-hexafluoride-filled microbubble contrast agent (SonoVue) was administered. The features of the lesions by US and CEUS were retrospectively reviewed. RESULTS In total, all lesions were detected by US and CEUS. The mean size of the lesions was 1.8±0.7cm (range: 1.0-3.0cm). Five patients (55.6%, 5/9) had a lesion in the right hepatic lobe; two (22.2%, 2/9) had two lesions in the left hepatic lobe; and two patients (22.2%, 2/9) had four lesions in the right lobe. Seven lesions (41.2%, 7/17) were hypoechoic nodules and ten (58.8%, 10/17) were hyperechoic nodules. Nine lesions (52.3%, 9/17) were of mixed echogenicity type. Ten lesions (58.8%, 10/17) had a regular shape. Nine lesions (52.3%, 9/27) had a sharp margin and six (35.3%, 6/17) had indistinct margins. Four lesions (57.1%, 4/7) with hypoechoic nodule had small dotted calcifications, none was found in hyperechoic nodule. Seven nodules (41.2%, 7/17) showed short striated blood-flow signals surrounding the margin, on color Doppler flow imaging. By CEUS, All the lesions were hypoechoic with mixed content (). 12 lesions (70.1%, 12/17) were rim enhanced with irregular piece-like nonenhanced internal areas and showed nonhomogeneous hypo-enhancement during the arterial phase, with mixed echogenicity. The main pathological findings included: (1) (1) coagulative or liquefactive necrosis within the lesion with sporadic distribution of wizened alveolar hydatid cysts; and (2) hyperplasia of granulomatous and fibrous tissue around the lesion. CONCLUSION Hyperechogenicity, mixed echogenicity type, dotted calcification with hypoechogenicity, sharp margin, rim enhancement and piece-like nonenhanced areas could be seen as the main ultrasonographic features of small lesion of hepatic alveolar echinococcosis.
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Potential risk factors associated with human alveolar echinococcosis: Systematic review and meta-analysis. PLoS Negl Trop Dis 2017; 11:e0005801. [PMID: 28715408 PMCID: PMC5531747 DOI: 10.1371/journal.pntd.0005801] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 07/27/2017] [Accepted: 07/12/2017] [Indexed: 12/28/2022] Open
Abstract
Background Human alveolar echinococcosis (AE) is a severe zoonotic disease caused by the metacestode stage of Echinococcus multilocularis. AE is commonly associated with a long incubation period that may last for more than ten years. The objective of this systematic literature review was to identify and summarize the current knowledge on statistically relevant potential risk factors (PRFs) associated with AE in humans. Methodology/Principal findings Six bibliographic databases were searched, generating a total of 1,009 publications. Following the removal of duplicate records and the exclusion of papers that failed to meet the criteria of a previously agreed a priori protocol, 23 publications were retained; however, 6 of these did not contain data in a format that allowed their inclusion in the meta-analysis. The remaining 17 publications (6 case-control and 11 cross-sectional studies) were meta-analysed to investigate associations between AE and PRFs. Pooled odds ratios (OR) were used as a measure of effect and separately analysed for case-control and cross-sectional studies. In the case-control studies, the following PRFs for human AE showed higher odds of outcome: “dog ownership”, “cat ownership”, “have a kitchen garden”, “occupation: farmer”, “haymaking in meadows not adjacent to water”, “went to forests for vocational reasons”, “chewed grass” and “hunting / handling foxes”. In the cross-sectional studies, the following PRFs showed higher odds of outcome: “dog ownership”, “play with dogs”, “gender: female”, “age over 20 years”, “ethnic group: Tibetan”, “low income”, “source of drinking water other than well or tap”, “occupation: herding” and “low education”. Our meta-analysis confirmed that the chance of AE transmission through ingestion of food and water contaminated with E. multilocularis eggs exists, but showed also that food- and water-borne PRFs do not significantly increase the risk of infection. Conclusions/significance This systematic review analysed international peer-reviewed articles that have over the years contributed to our current understanding of the epidemiology of human AE. The identification of potential risk factors may help researchers and decision makers improve surveillance and/or preventive measures that aim at decreasing human infection with E. multilocularis. More primary studies are needed to confirm potential risk factors and their role in the epidemiology of human AE. Human alveolar echinococcosis is a severe zoonotic disease caused by the metacestode stage of the tapeworm Echinococcus multilocularis. The objective of this systematic literature review was to identify and summarize the current knowledge on potential risk factors associated with human alveolar echinococcosis. The categories of potential risk factors included dog-related factors such as dog ownership or play with dogs; vocational factors like being a farmer or handling foxes; human habits such as chewing grass; gender (being female) and socio-cultural factors like being Tibetan or having a low income or poor education, which may be relevant only in particular endemic areas. The identification of potential risk factors may help identify strategies that aim to decrease human infection with E. multilocularis.
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Deplazes P, Rinaldi L, Alvarez Rojas CA, Torgerson PR, Harandi MF, Romig T, Antolova D, Schurer JM, Lahmar S, Cringoli G, Magambo J, Thompson RCA, Jenkins EJ. Global Distribution of Alveolar and Cystic Echinococcosis. ADVANCES IN PARASITOLOGY 2017; 95:315-493. [PMID: 28131365 DOI: 10.1016/bs.apar.2016.11.001] [Citation(s) in RCA: 559] [Impact Index Per Article: 79.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Alveolar echinococcosis (AE) and cystic echinococcosis (CE) are severe helminthic zoonoses. Echinococcus multilocularis (causative agent of AE) is widely distributed in the northern hemisphere where it is typically maintained in a wild animal cycle including canids as definitive hosts and rodents as intermediate hosts. The species Echinococcus granulosus, Echinococcus ortleppi, Echinococcus canadensis and Echinococcus intermedius are the causative agents of CE with a worldwide distribution and a highly variable human disease burden in the different endemic areas depending upon human behavioural risk factors, the diversity and ecology of animal host assemblages and the genetic diversity within Echinococcus species which differ in their zoonotic potential and pathogenicity. Both AE and CE are regarded as neglected zoonoses, with a higher overall burden of disease for CE due to its global distribution and high regional prevalence, but a higher pathogenicity and case fatality rate for AE, especially in Asia. Over the past two decades, numerous studies have addressed the epidemiology and distribution of these Echinococcus species worldwide, resulting in better-defined boundaries of the endemic areas. This chapter presents the global distribution of Echinococcus species and human AE and CE in maps and summarizes the global data on host assemblages, transmission, prevalence in animal definitive hosts, incidence in people and molecular epidemiology.
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Affiliation(s)
- P Deplazes
- University of Zürich, Zurich, Switzerland
| | - L Rinaldi
- University of Naples Federico II, Napoli, Italy
| | | | | | - M F Harandi
- Research centre of Hydatid Disease in Iran, Kerman University of Medical Sciences, Kerman, Iran
| | - T Romig
- University of Hohenheim, Stuttgart, Germany
| | - D Antolova
- Institute of Parasitology SAS, Kosice, Slovak Republic
| | - J M Schurer
- University of Saskatchewan, Saskatoon, SK, Canada; University of Washington, Seattle, WA, United States
| | - S Lahmar
- National School of Veterinary Medicine, Sidi Thabet, Tunisia
| | - G Cringoli
- University of Naples Federico II, Napoli, Italy
| | - J Magambo
- Meru University of Science and Technology, Meru, Kenya
| | | | - E J Jenkins
- University of Saskatchewan, Saskatoon, SK, Canada
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Cadavid Restrepo AM, Yang YR, McManus DP, Gray DJ, Giraudoux P, Barnes TS, Williams GM, Soares Magalhães RJ, Hamm NAS, Clements ACA. The landscape epidemiology of echinococcoses. Infect Dis Poverty 2016; 5:13. [PMID: 26895758 PMCID: PMC4759770 DOI: 10.1186/s40249-016-0109-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 02/15/2016] [Indexed: 12/29/2022] Open
Abstract
Echinococcoses are parasitic diseases of major public health importance globally. Human infection results in chronic disease with poor prognosis and serious medical, social and economic consequences for vulnerable populations. According to recent estimates, the geographical distribution of Echinococcus spp. infections is expanding and becoming an emerging and re-emerging problem in several regions of the world. Echinococcosis endemicity is geographically heterogeneous and over time it may be affected by global environmental change. Therefore, landscape epidemiology offers a unique opportunity to quantify and predict the ecological risk of infection at multiple spatial and temporal scales. Here, we review the most relevant environmental sources of spatial variation in human echinococcosis risk, and describe the potential applications of landscape epidemiological studies to characterise the current patterns of parasite transmission across natural and human-altered landscapes. We advocate future work promoting the use of this approach as a support tool for decision-making that facilitates the design, implementation and monitoring of spatially targeted interventions to reduce the burden of human echinococcoses in disease-endemic areas.
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Affiliation(s)
- Angela M Cadavid Restrepo
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
| | - Yu Rong Yang
- Ningxia Medical University, Yinchuan, Ningxia Hui Autonomous Region, P. R. China.
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Donald P McManus
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Darren J Gray
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
- Molecular Parasitology Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
| | - Patrick Giraudoux
- Chrono-environment lab, UMR6249, University of Bourgogne Franche-Comté/CNRS, Besançon, France.
- Institut Universitaire de France, Paris, France.
| | - Tamsin S Barnes
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.
- The University of Queensland, Queensland Alliance for Agriculture and Food Innovation, Gatton, Queensland, Australia.
| | - Gail M Williams
- School of Public Health, The University of Queensland, Brisbane, Queensland, Australia.
| | - Ricardo J Soares Magalhães
- The University of Queensland, School of Veterinary Science, Gatton, Queensland, Australia.
- Child Health Research Centre, The University of Queensland, Brisbane, Queensland, Australia.
| | - Nicholas A S Hamm
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, Enschede, The Netherlands.
| | - Archie C A Clements
- Research School of Population Health, The Australian National University, Canberra, New South Wales, Australia.
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Marston CG, Danson FM, Armitage RP, Giraudoux P, Pleydell DRJ, Wang Q, Qui J, Craig PS. A random forest approach for predicting the presence of Echinococcus multilocularis intermediate host Ochotona spp. presence in relation to landscape characteristics in western China. APPLIED GEOGRAPHY (SEVENOAKS, ENGLAND) 2014; 55:176-183. [PMID: 25386042 PMCID: PMC4223806 DOI: 10.1016/j.apgeog.2014.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Understanding distribution patterns of hosts implicated in the transmission of zoonotic disease remains a key goal of parasitology. Here, random forests are employed to model spatial patterns of the presence of the plateau pika (Ochotona spp.) small mammal intermediate host for the parasitic tapeworm Echinococcus multilocularis which is responsible for a significant burden of human zoonoses in western China. Landsat ETM+ satellite imagery and digital elevation model data were utilized to generate quantified measures of environmental characteristics across a study area in Sichuan Province, China. Land cover maps were generated identifying the distribution of specific land cover types, with landscape metrics employed to describe the spatial organisation of land cover patches. Random forests were used to model spatial patterns of Ochotona spp. presence, enabling the relative importance of the environmental characteristics in relation to Ochotona spp. presence to be ranked. An index of habitat aggregation was identified as the most important variable in influencing Ochotona spp. presence, with area of degraded grassland the most important land cover class variable. 71% of the variance in Ochotona spp. presence was explained, with a 90.98% accuracy rate as determined by 'out-of-bag' error assessment. Identification of the environmental characteristics influencing Ochotona spp. presence enables us to better understand distribution patterns of hosts implicated in the transmission of Em. The predictive mapping of this Em host enables the identification of human populations at increased risk of infection, enabling preventative strategies to be adopted.
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Affiliation(s)
- Christopher G Marston
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool. L3 3AF, UK. Tel: +441512312401
| | - F Mark Danson
- School of Environment and Life Sciences, University of Salford, Manchester. M5 4WT, UK. , ,
| | - Richard P Armitage
- School of Environment and Life Sciences, University of Salford, Manchester. M5 4WT, UK. , ,
| | - Patrick Giraudoux
- Department of Chrono-environment and Institut Universitaire de France, University of Franche-Comté, Place Leclerc, 25030 Besançon cedex, France.
| | - David R J Pleydell
- INRA, UMR-1351 CMAEE, Domaine Duclos, Prise D'eau, 97122 Petit Bourg, Guadeloupe.
| | - Qian Wang
- Sichuan Centers for Disease Control and Prevention, Chengdu 610041, Sichuan, China. ,
| | - Jiamin Qui
- Sichuan Centers for Disease Control and Prevention, Chengdu 610041, Sichuan, China. ,
| | - Philip S Craig
- School of Environment and Life Sciences, University of Salford, Manchester. M5 4WT, UK. , ,
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Wang Q, Huang Y, Huang L, Yu W, He W, Zhong B, Li W, Zeng X, Vuitton DA, Giraudoux P, Craig PS, Wu W. Review of risk factors for human echinococcosis prevalence on the Qinghai-Tibet Plateau, China: a prospective for control options. Infect Dis Poverty 2014; 3:3. [PMID: 24475907 PMCID: PMC3910240 DOI: 10.1186/2049-9957-3-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 01/22/2014] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE Echinococcosis is a major parasitic zoonosis of public health importance in western China. In 2004, the Chinese Ministry of Health estimated that 380,000 people had the disease in the region. The Qinghai-Tibet Plateau is highly co-endemic with both alveolar echinococcosis (AE) and cystic echinococcosis (CE). In the past years, the Chinese government has been increasing the financial support to control the diseases in this region. Therefore, it is very important to identify the significant risk factors of the diseases by reviewing studies done in the region in the past decade to help policymakers design appropriate control strategies. REVIEW Selection criteria for which literature to review were firstly defined. Medline, CNKI (China National Knowledge Infrastructure), and Google Scholar were systematically searched for literature published between January 2000 and July 2011. Significant risk factors found by single factor and/or multiple factors analysis were listed, counted, and summarized. Literature was examined to check the comparability of the data; age and sex specific prevalence with same data structures were merged and used for further analysis.A variety of assumed social, economical, behavioral, and ecological risk factors were studied on the Plateau. Those most at risk were Tibetan herdsmen, the old and female in particular. By analyzing merged comparable data, it was found that females had a significant higher prevalence, and a positive linearity relationship existed between echinococcosis prevalence and increasing age. In terms of behavioral risk factors, playing with dogs was mostly correlated with CE and/or AE prevalence. In terms of hygiene, employing ground water as the drinking water source was significantly correlated with CE and AE prevalence. For definitive hosts, dog related factors were most frequently identified with prevalence of CE or/and AE; fox was a potential risk factor for AE prevalence only. Overgrazing and deforestation were significant for AE prevalence only. CONCLUSION Tibetan herdsmen communities were at the highest risk of echinococcosis prevalence and should be the focus of echinococcosis control. Deworming both owned and stray dogs should be a major measure for controlling echinococcosis; treatment of wild definitive hosts should also be considered for AE endemic areas. Health education activities should be in concert with the local people's education backgrounds and languages in order to be able to improve behaviors. Further researches are needed to clarify the importance of wild hosts for AE/CE prevalence, the extent and range of the impacts of ecologic changes (overgrazing and deforestation) on the AE prevalence, and risk factors in Tibet.
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Affiliation(s)
- Qian Wang
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Yan Huang
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Liang Huang
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Wenjie Yu
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Wei He
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Bo Zhong
- Sichuan Provincial Center for Diseases Control and Prevention, Chengdu, Sichuan, China
| | - Wei Li
- Ganzi Prefecture Center for Diseases Control and Prevention, Kangding, Sichuan, China
| | - Xiangman Zeng
- Institute of Parasitic Diseases, China Center for Diseases Control and Prevention, Shanghai, China
| | - Dominique A Vuitton
- WHO Collaborating Center for Prevention and Treatment of Human Echinococcosis, University Hospital and University of Franche-Comté, 25030 Besançon, France
| | - Patrick Giraudoux
- Department of Chrono-Environment, UMR UFC/CNRS 6249 aff. INRA, University of Franche-Comté, Besançon, France
| | - Philip S Craig
- Cestode Zoonoses Research Group, Bioscience Research Institute and School of Environment and Life Sciences, University of Salford, Great Manchester M5 4WT, UK
| | - Weiping Wu
- Institute of Parasitic Diseases, China Center for Diseases Control and Prevention, Shanghai, China
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Reinfection studies of canine echinococcosis and role of dogs in transmission of Echinococcus multilocularis in Tibetan communities, Sichuan, China. Parasitology 2013; 140:1685-92. [PMID: 23985352 PMCID: PMC3806043 DOI: 10.1017/s0031182013001200] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the eastern Tibetan plateau both human cystic and alveolar echinococcosis (AE) caused by infection with Echincoccus granulosus or Echinococcus multilocularis, respectively are highly endemic. The domestic dog plays a key role in zoonotic transmission in this region. Our primary objective was to investigate the role of domestic dogs in maintaining transmission of E. multilocularis in Shiqu county, Sichuan. A cohort of 281 dogs was followed up over one year after a single treatment with praziquantel followed by re-infection surveillance at 2, 5 and 12 months post-treatment. Faecal samples were tested by an Echinococcus genus-specific coproantigen ELISA and two species-specific copro-PCR tests. Total Echinococcus coproantigen prevalence in Shiqu at baseline was 21% and 9·6% after 2 months. E. multilocularis copro-PCR was positive in 11·2% of dogs before treatment (vs 3·6% with E. granulosus copro-DNA), 2·9% at 2 months post-treatment, and 0% at 5 month and 12 months. The results suggest that dogs may have the potential to maintain E. multilocularis transmission within local pastoral communities, and thus dog dosing could be an effective strategy to reduce transmission of E. multilocularis as well as E. granulosus in these co-endemic Tibetan communities.
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Abstract
From continental to regional scales, the zoonosis alveolar echinococcosis (AE) (caused by Echinococcus multilocularis) forms discrete patches of endemicity within which transmission hotspots of much larger prevalence may occur. Since the late 80s, a number of hotspots have been identified in continental Asia, mostly in China, wherein the ecology of intermediate host communities has been described. This is the case in south Gansu, at the eastern border of the Tibetan plateau, in south Ningxia, in the western Tian Shan of Xinjiang, and in the Alay valley of south Kyrgyzstan. Here we present a comparative natural history and characteristics of transmission ecosystems or ecoscapes. On this basis, regional types of transmission and their ecological characteristics have been proposed in a general framework. Combining climatic, land cover and intermediate host species distribution data, we identified and mapped 4 spatially distinct types of transmission ecosystems typified by the presence of one of the following small mammal ‘flagship’ species: Ellobius tancrei, Ochotona curzoniae, Lasiopodomys brandtii or Eospalax fontanierii. Each transmission ecosystem had its own characteristics which can serve as a reference for further in-depth research in the transmission ecology of E. multilocularis. This approach may be used at fine spatial scales to characterize other poorly known transmission systems of the large Eurasian endemic zone, and help in consideration of surveillance systems and interventions.
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Atkinson JAM, Gray DJ, Clements ACA, Barnes TS, McManus DP, Yang YR. Environmental changes impacting Echinococcus transmission: research to support predictive surveillance and control. GLOBAL CHANGE BIOLOGY 2013; 19:677-688. [PMID: 23504826 DOI: 10.1111/gcb.12088] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/27/2012] [Accepted: 10/29/2012] [Indexed: 06/01/2023]
Abstract
Echinococcosis, resulting from infection with tapeworms Echinococcus granulosus and E. multilocularis, has a global distribution with 2-3 million people affected and 200,000 new cases diagnosed annually. Costs of treatment for humans and economic losses to the livestock industry have been estimated to exceed $2 billion. These figures are likely to be an underestimation given the challenges with its early detection and the lack of mandatory official reporting policies in most countries. Despite this global burden, echinococcosis remains a neglected zoonosis. The importance of environmental factors in influencing the transmission intensity and distribution of Echinococcus spp. is increasingly being recognized. With the advent of climate change and the influence of global population expansion, food insecurity and land-use changes, questions about the potential impact of changing temperature, rainfall patterns, increasing urbanization, deforestation, grassland degradation and overgrazing on zoonotic disease transmission are being raised. This study is the first to comprehensively review how climate change and anthropogenic environmental factors contribute to the transmission of echinococcosis mediated by changes in animal population dynamics, spatial overlap of competent hosts and the creation of improved conditions for egg survival. We advocate rigorous scientific research to establish the causal link between specific environmental variables and echinococcosis in humans and the incorporation of environmental, animal and human data collection within a sentinel site surveillance network that will complement satellite remote-sensing information. Identifying the environmental determinants of transmission risk to humans will be vital for the design of more accurate predictive models to guide cost-effective pre-emptive public health action against echinococcosis.
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Affiliation(s)
- Jo-An M Atkinson
- School of Population Health, University of Queensland, Brisbane, Australia.
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Role of dog behaviour and environmental fecal contamination in transmission ofEchinococcus multilocularisin Tibetan communities. Parasitology 2011; 138:1316-29. [DOI: 10.1017/s0031182011000874] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYOn the Eastern Tibetan Plateau region (Sichuan province, China) dogs are regarded as important definitive hosts ofEchinococcus multilocularis. We studied dog spatial behaviour in 4 Tibetan villages in order to determine the role of dogs in environmental contamination and their potential interactions with small mammal intermediate hosts. We identified definitive host species andEchinococcusspp. infection status of feces collected in the field by PCR methods and analysed the spatial distribution of canid feces. Nocturnal space utilization of GPS collared dogs in and around villages was also undertaken.E. multilocularisDNA was amplified in 23% of dog feces (n=142) and in 15% of fox feces (n=13) but this difference was not significant. However, dog feces were more frequently observed (78% of collected feces) than fox feces and are therefore assumed to largely contribute to human environment contamination. Feces were mainly distributed around houses of dog owners (0–200 m) where collared dogs spent the majority of their time. Inside villages, the contamination was aggregated in some micro-foci where groups of dogs defecated preferentially. Finally, small mammal densities increased from the dog core areas to grasslands at the periphery of villages occasionally used by dogs; male dogs moving significantly farther than females. This study constitutes a first attempt to quantify in a spatially explicit way the role of dogs inE. multilocularisperi-domestic cycles and to identify behavioural parameters required to modelE. multilocularistransmission in this region.
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Torgerson PR, Keller K, Magnotta M, Ragland N. The global burden of alveolar echinococcosis. PLoS Negl Trop Dis 2010; 4:e722. [PMID: 20582310 PMCID: PMC2889826 DOI: 10.1371/journal.pntd.0000722] [Citation(s) in RCA: 309] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2010] [Accepted: 04/29/2010] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Human alveolar echinococcosis (AE) is known to be common in certain rural communities in China whilst it is generally rare and sporadic elsewhere. The objective of this study was to provide a first estimate of the global incidence of this disease by country. The second objective was to estimate the global disease burden using age and gender stratified incidences and estimated life expectancy with the disease from previous results of survival analysis. Disability weights were suggested from previous burden studies on echinococcosis. METHODOLOGY/PRINCIPAL FINDINGS We undertook a detailed review of published literature and data from other sources. We were unable to make a standardised systematic review as the quality of the data was highly variable from different countries and hence if we had used uniform inclusion criteria many endemic areas lacking data would not have been included. Therefore we used evidence based stochastic techniques to model uncertainty and other modelling and estimating techniques, particularly in regions where data quality was poor. We were able to make an estimate of the annual global incidence of disease and annual disease burden using standard techniques for calculation of DALYs. Our studies suggest that there are approximately 18,235 (CIs 11,900-28,200) new cases of AE per annum globally with 16,629 (91%) occurring in China and 1,606 outside China. Most of these cases are in regions where there is little treatment available and therefore will be fatal cases. Based on using disability weights for hepatic carcinoma and estimated age and gender specific incidence we were able to calculate that AE results in a median of 666,434 DALYs per annum (CIs 331,000-1.3 million). CONCLUSIONS/SIGNIFICANCE The global burden of AE is comparable to several diseases in the neglected tropical disease cluster and is likely to be one of the most important diseases in certain communities in rural China on the Tibetan plateau.
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Affiliation(s)
- Paul R Torgerson
- Ross University School of Veterinary Medicine, St. Kitts, West Indies.
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McManus DP. Echinococcosis with Particular Reference to Southeast Asia. ADVANCES IN PARASITOLOGY 2010; 72:267-303. [DOI: 10.1016/s0065-308x(10)72010-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Vaniscotte A, Pleydell D, Raoul F, Quéré JP, Jiamin Q, Wang Q, Tiaoying L, Bernard N, Coeurdassier M, Delattre P, Takahashi K, Weidmann JC, Giraudoux P. Modelling and spatial discrimination of small mammal assemblages: an example from western Sichuan (China). Ecol Modell 2009; 220:1218-1231. [PMID: 20161274 PMCID: PMC2702787 DOI: 10.1016/j.ecolmodel.2009.02.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We investigate the relationship between landscape heterogeneity and the spatial distribution of small mammals in two areas of Western Sichuan, China. Given a large diversity of species trapped within a large number of habitats, we first classified small mammal assemblages and then modelled the habitat of each in the space of quantitative environmental descriptors. Our original two step "classify then model" procedure is appropriate for the frequently encountered study scenario: trapping data collected in remote areas with sampling guided by expert field knowledge.In the classification step, we defined assemblages by grouping sites of similar species composition and relative densities using an expert-class-merging procedure which reduced redundancy in the habitat factor used within a multinomial logistic regression predicting species trapping probabilities. Assemblages were thus defined as mixtures of small mammal frequency distributions in discrete groups of sampled sites.In the modelling step, assemblages' habitats and environments of the two sampled areas were discriminated in the space of remotely sensed environmental descriptors. First, we compared the discrimination of assemblage/study areas by linear and non-linear forms of Discriminant Analysis (Linear Discriminant Analysis versus Mixture Discriminant Analysis) and of Multiple Regression (Generalized Linear Models versus Multiple Adaptive Regression Splines). The "best" predictive modelling technique was then used to quantify the contribution of each environmental variable in discriminations of assemblages and areas.Mixtures of Gaussians provided a more efficient model of assemblage coverage in environmental space than a single Gaussian cluster model. However, non-linearity in assemblage response to environmental gradients was consistently predicted with lower deviance and misclassification error by Multiple Adaptive Regression Splines. The two study areas were mainly discriminated along vegetation indices. However, although the Normalized Difference Vegetation Index (NDVI) could discriminate forested from non-forested habitats, its power to discriminate assemblages in Maerkang, where a greater diversity of forest habitat was observed, was seen to be limited, and in this case NDVI was outperformed by the Enhanced Vegetation Index (EVI). Our analyses highlight previously unobserved differences between the environments and small mammal communities of two fringe areas of the Tibetan plateau and suggests that a biogeograph-ical approach is required to elucidate ecological processes in small mammal communities and to reduce extrapolation uncertainty in distribution mapping.
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Affiliation(s)
- Amélie Vaniscotte
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
| | - David Pleydell
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
| | - Francis Raoul
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
| | - Jean Pierre Quéré
- Campus International de Baillarguet, INRA, CBGP-UMR 1062, CS 30016 Montferrier sur Lez, 34988 Saint Gély du Fesc cedex, France
| | - Qiu Jiamin
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Qian Wang
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Li Tiaoying
- Institute of Parasitic Diseases, Sichuan Center for Disease Control and Prevention, Chengdu 610041, Sichuan, China
| | - Nadine Bernard
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
| | - Michael Coeurdassier
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
| | - Pierre Delattre
- Campus International de Baillarguet, INRA, CBGP-UMR 1062, CS 30016 Montferrier sur Lez, 34988 Saint Gély du Fesc cedex, France
| | - Kenichi Takahashi
- Hokkaido Institute of Public Health, Kita 19, Nishi 12, 060-0819 Sapporo, Japan
| | | | - Patrick Giraudoux
- Department of Chrono-environment, UMR UFC/CNRS 6249, USC INRA, Université de Franche-comté, 25030 Besançon cedex, France
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Kamiya M. Collaborative control initiatives targeting zoonotic agents of alveolar echinococcosis in the northern hemisphere. J Vet Sci 2008; 8:313-21. [PMID: 17993743 PMCID: PMC2868145 DOI: 10.4142/jvs.2007.8.4.313] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Alveolar echinococcosis is one of the most important lethal zoonotic helminth infections in the northern hemisphere. Currently, the threat to public health is increasing, as evidenced by the rising prevalence rate of alveolar echinococcosis, as well as the invasion of urban areas by infected wild foxes. This threat is further increased due to the involvement of pet dogs, and probably cats, as emerging sources of infection. These increased threats to public health also have associated economic risks; therefore, there is a need for effective and sustainable methods of control. In this paper, initiatives to control alveolar echinococcosis by targeting its definitive hosts through anthelmintic baiting campaigns initiated by local residents who used local resources for bait production, distribution and collection of fecal samples for diagnosis are described. Further, when such distribution programs are coupled with the use of GIS-based maps, the optimum distribution of bait was obtained. These programs have also included the use of intravital diagnostic analyses of infection rates, which have been overseen by the Forum on Environment and Animals (FEA), and also allowed a nationwide monitoring of echinococcosis in difinitive hosts. In addition, a government initiative requiring mandatory reporting of echinococcosis in dogs to health authorities was recently initiated in Japan. Overall, the results of this study have shown that use of collaborative control initiatives targeting zoonotic agents of alveolar echinococcosis can be an effective method for reducing the threat of lethal echinococcosis in the northern hemisphere.
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Affiliation(s)
- Masao Kamiya
- OIE Reference Laboratory for Echinococcosis and Laboratory of Environmental Zoology, Department of Biosphere and Environmental Sciences, Faculty of Environmental Systems, Rakuno Gakuen University, Hokkaido 069-8501, Japan.
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Yang YR, Craig PS, Vuitton DA, Williams GM, Sun T, Liu TX, Boufana B, Giraudoux P, Teng J, Li Y, Huang L, Zhang W, Jones MK, McManus DP. Serological prevalence of echinococcosis and risk factors for infection among children in rural communities of southern Ningxia, China. Trop Med Int Health 2008; 13:1086-94. [DOI: 10.1111/j.1365-3156.2008.02101.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Wang Z, Wang X, Liu X. Echinococcosis in China, a review of the epidemiology of Echinococcus spp. ECOHEALTH 2008; 5:115-126. [PMID: 18787915 DOI: 10.1007/s10393-008-0174-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2007] [Revised: 03/25/2008] [Accepted: 03/27/2008] [Indexed: 05/26/2023]
Abstract
Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are highly significant infectious diseases occurring worldwide and caused by metacestodes of tapeworms Echinococcus granulosus and E. multilocularis, respectively. Both human CE and AE have highest prevalence rates in western and northwestern China. Livestock is the main intermediate host of E. granulosus, and wild small mammal are the main intermediate hosts of E. multilocularis. Since they range freely in pastoral areas, prey on wild small mammals and offal of livestock after slaughter, and have close relationships with humans, domestic dogs are the most important definitive host of both Echinococcus spp. with the highest risk of transmitting CE and AE to humans. Pastoralism is the occupation with the highest risk of being infected with the both kinds of echinococcosis due to the proximity of livestock, dogs, and wildlife host species. In this review, we summarize the epidemiology of human echinococcosis, the situation of parasite transmission in animal hosts, and possible transmission patterns in China. In addition, human activities and their potential influence on the transmission of echinococcosis are also discussed.
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Affiliation(s)
- Zhenghuan Wang
- School of Life Science, East China Normal University, 200062 Shanghai, China
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Kamiya M, Trinipil Lagapa J, Oku Y. Research on targeting sources of alveolar echinococcosis in Japan. Comp Immunol Microbiol Infect Dis 2007; 30:427-48. [PMID: 17662388 DOI: 10.1016/j.cimid.2007.05.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Accepted: 05/16/2007] [Indexed: 11/19/2022]
Abstract
Echinococcus multilocularis is a fatal zoonotic parasite in the Northern Hemisphere. Recently, it has become endemic in many countries in Asia, especially in the northern island of Hokkaido in Japan. The increasing threat of public health due to alveolar echinococcosis has compelled researches for sensitive diagnosis and effective control. This paper reviews on the epidemiology, diagnosis and control of echinococcosis specifically in Japan. International collaborative responses by researchers and government initiatives such as mandatory reporting system for veterinarians who diagnose echinococcosis in dogs are presented. Successful control measures in Japan using anthelmintic fortified baits for foxes are described. Assessment of prevalence rates during control campaigns is analyzed favoring the use of intravital diagnosis rather than the traditional necropsy method from hunting or trapping activities of wild foxes. The novel concept of "endogenous development" by local resident volunteers towards sustainable control of echinococcosis is stressed.
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Affiliation(s)
- Masao Kamiya
- OIE Reference Laboratory for Echinococcosis and Laboratory of Environmental Zoology, Department of Biosphere and Environmental Sciences, Rakuno Gakuen University, Bunkyodai-midorimachi 582, Ebetsu, Hokkaido 069-8501, Japan.
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Romig T, Thoma D, Weible AK. Echinococcus multilocularis--a zoonosis of anthropogenic environments? J Helminthol 2007; 80:207-12. [PMID: 16768864 DOI: 10.1079/joh2006347] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Transmission of the fox tapeworm Echinococcus multilocularis, the causative agent of human alveolar echinococcosis, is known to depend on various environmental factors which are subject to human influence. Epidemiological data suggest that in most endemic regions anthropogenic landscape changes (e.g. deforestation and agricultural practices) have led to more favourable conditions for the parasite's animal hosts, especially arvicolid rodents, thereby increasing the risk for parasite transmission and human disease. Examples are the conversion of forests or crop fields into meadows and pastures in Europe, China and North America, and overgrazing of natural grassland in central Asia. Other anthropogenic factors include interference with host population densities by wildlife disease control, changing hunting pressure and provision of new habitats, e.g. in urban areas. Domestic dogs may, under certain conditions, get involved in the otherwise largely wildlife-based transmission, and thereby greatly increase the infection pressure to humans. The introduction of neozootic host species may increase transmission, or even initiate the parasite's life-cycle in previously non-endemic regions. Lastly, the parasite itself may be accidentally introduced into non-endemic areas, if suitable host populations are present (e.g. in northern Japan).
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Affiliation(s)
- T Romig
- Department of Parasitology, University of Hohenheim, Emil-Wolff-Str. 34, 75099 Stuttgart, Germany.
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Impact of overgrazing on the transmission of Echinococcus multilocularis in Tibetan pastoral communities of Sichuan Province, China. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200702010-00013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) regarding the assessment of the risk of Echinococcosis introduction into the UK, Ireland, Sweden, Malta and Finland as a consequence of abandoning national rules. EFSA J 2007. [DOI: 10.2903/j.efsa.2007.441] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Opinion of the Panel on additives and products or substances used in animal feed (FEEDAP) on the safety and efficacy of the product Bonvital, a preparation of Enterococcus faecium, as a feed additive for piglets and pigs for fattening in accordance with R. EFSA J 2007. [DOI: 10.2903/j.efsa.2007.440] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
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Wang Q, Vuitton DA, Xiao Y, Budke CM, Campos-Ponce M, Schantz PM, Raoul F, Yang W, Craig PS, Giraudoux P. Pasture types and Echinococcus multilocularis, Tibetan communities. Emerg Infect Dis 2006; 12:1008-10. [PMID: 16707064 PMCID: PMC3373058 DOI: 10.3201/eid1206.041229] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Our study showed that open pastures had more small mammal burrows than fenced pastures in Tibetan pastoralist communities in 2003. This characteristic was linked to a higher prevalence of Echinococcus multilocularis in dogs and indicates that pasture type may affect E. multilocularis transmission.
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Affiliation(s)
- Qian Wang
- Sichuan Provincial Center for Disease Control and Prevention, Chengdu, Sichuan, People's Republic of China.
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Jenkins DJ, Romig T, Thompson RCA. Emergence/re-emergence of Echinococcus spp.--a global update. Int J Parasitol 2006; 35:1205-19. [PMID: 16157340 DOI: 10.1016/j.ijpara.2005.07.014] [Citation(s) in RCA: 248] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2005] [Revised: 07/28/2005] [Accepted: 07/28/2005] [Indexed: 12/28/2022]
Abstract
This review provides an update of the biological aspects of the genus Echinococcus and focuses on newly recognized endemic areas. Infection with the intermediate cystic stage of all species of Echinococcus causes disease and incapacity in animals and humans, and in the most serious cases, death of the host. Transmission of Echinococcus to new continents has occurred during European colonisation and the parasite has often taken advantage of Echinococcus-naive wildlife populations in these new environments, incorporating them into its transmission pattern. Echinococcus granulosus consists of a complex of 10 strains. Host specificities of these strains have important implications for transmission and control. As a result of human behaviour and/or political instability in a number of countries Echinococcus is re-emerging as an important public health issue. The importance of wildlife reservoirs in perpetuating transmission and as a source of infection for domestic animals and humans is addressed. The review also refers to the transmission pattern of a recently described new species, Echinococcus shiquicus, from China.
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Affiliation(s)
- D J Jenkins
- Australian Hydatid Control and Epidemiology Program, 12 Mildura Street, Fyshwick, ACT 2609, Australia.
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Tiaoying L, Jiamin Q, Wen Y, Craig PS, Xingwang C, Ning X, Ito A, Giraudoux P, Wulamu M, Wen Y, Schantz PM. Echinococcosis in Tibetan populations, western Sichuan Province, China. Emerg Infect Dis 2006; 11:1866-73. [PMID: 16485472 PMCID: PMC3367622 DOI: 10.3201/eid1112.050079] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This area has the highest prevalences of both forms of this disease in the world. We screened 3,199 people from Shiqu County, Sichuan Province, China, for abdominal echinococcosis (hydatid disease) by portable ultrasound combined with specific serodiagnostic tests. Both cystic echinococcosis (CE) (Echinococcus granulosus infection) and alveolar echinococcosis (AE) (E. multilocularis) were co-endemic in this area at the highest village prevalence values recorded anywhere in the world: 12.9% were infected with one or the other form (6.8% CE and 6.2% AE). Prevalences of both CE and AE were significantly higher in female than male patients and increased with the age of the person screened. Pastoral herdsmen were at highest risk for infection (prevalence 19.0%). Prevalence of CE varied in 5 townships from 0% to 12.1%, whereas AE prevalence ranged from 0% to 14.3%. Risk factors associated with both infections included the number of owned dogs, frequency of contact with dogs, and sources of drinking water.
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Affiliation(s)
- Li Tiaoying
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
| | - Qiu Jiamin
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
| | - Yang Wen
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
| | | | - Chen Xingwang
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
| | - Xiao Ning
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
- Asahikawa Medical College, Asahikawa, Japan
| | - Akira Ito
- Asahikawa Medical College, Asahikawa, Japan
| | - Patrick Giraudoux
- World Health Organization Collaborating Centre for the Prevention and Treatment of Alveolar Echinococcosis, Université de Franche-Comté, Besancon, France
| | | | - Yu Wen
- Sichuan Centers for Disease Control and Prevention, Chengdu, Sichuan Province, People's Republic of China
| | - Peter M. Schantz
- Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Schantz PM. Progress in diagnosis, treatment and elimination of echinococcosis and cysticercosis. Parasitol Int 2006; 55 Suppl:S7-S13. [PMID: 16386944 DOI: 10.1016/j.parint.2005.11.050] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Here I review the current status of geographical occurrence and public health significance of echinococcosis (Echinococcus spp. infections) and cysticercosis (Taenia solium infection) with special emphasis on the remarkable technologic progress achieved in recent decades that has led to greater understanding of the biology and epidemiology of these cestode infections. The greatest remaining challenges are to apply this knowledge and technology to improved medical management and prevention of these infections.
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Affiliation(s)
- Peter M Schantz
- Division of Parasitic Diseases, Coordinating Center for Infectious Diseases, Centers For Disease Control and Prevention, Atlanta, GA 30341, USA.
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Giraudoux P, Pleydell D, Raoul F, Quéré JP, Wang Q, Yang Y, Vuitton DA, Qiu J, Yang W, Craig PS. Transmission ecology of Echinococcus multilocularis: what are the ranges of parasite stability among various host communities in China? Parasitol Int 2005; 55 Suppl:S237-46. [PMID: 16361111 DOI: 10.1016/j.parint.2005.11.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A striking feature of the transmission ecology of Echinococcus multilocularis in China is the diversity of hosts that contribute to the parasite cycle. Considering the population dynamics of key reservoir intermediate hosts and the ratio of their preferred habitat in a landscape (ROMPA) is essential to understanding transmission, but the numerous communities in which the parasite cycles and the extent of those communities is currently far from being fully documented. On the Tibetan plateau grassland management influences intermediate host species populations and the sheer size of the area could be a major contributing factor to sustaining transmission in the region. In Southern Gansu and Southern Ningxia the processes of deforestation have temporarily provided optimal habitat for key reservoir intermediate hosts of E. multilocularis, resulting in high transmission and human disease, however currently the parasite may be extinct locally. Faced with this pattern of potentially transient transmission in a diversity of communities the question of the dispersal potential of the parasite arises. The reforestation program currently active across much of Western China has the potential to give rise to a massive increase in habitat favourable to suitable intermediate hosts and emergence or re-emergence of the zoonosis alveolar echinococcosis in many areas. This potential epidemic could be mitigated by both natural and human induced parasite dispersal mechanisms including fox migration and the sale of infected dogs originating from stable endemic foci on the Tibetan plateau. However, currently the degree of genetic exchange between discrete transmission foci is unknown and it is expected that genetic techniques could provide crucial information regarding this important question.
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Affiliation(s)
- Patrick Giraudoux
- Department of Environmental Biology-EA3184-usc INRA, Université de Franche-Comté, Place Leclerc, 25030 Besançon cedex, France.
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Abstract
Globally human alveolar echinococcosis (AE) is a rare zoonotic helminthic disease confined to the Northern Hemisphere as sporadic infections in rural populations, principally in some areas of North America, west-central Europe, the Near East, Siberia, Central Asia, Japan and China. In China the first human cases were reported from western regions in the 1960s, but most hospital records remain fragmented and inadequate. From the mid-1990s mass screening surveys using portable ultrasound scanners recorded higher prevalences (up to 6% by county) than in any other areas of the world with some village rates as high as 15%. Risk factors identified for AE cases included ethnicity, sex, age and occupation. The role of the dog in transmission of Echinococcus multilocularis to humans now appears to be significant and may be one of the most important risk factor, in combination with landscape/land-use features conducive to maintaining wildlife host populations.
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Affiliation(s)
- Philip S Craig
- Bioscience Research Institute, University of Salford, Salford, Greater Manchester, M54WT, UK.
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Budke CM, Jiamin Q, Craig PS, Torgerson PR. Modeling the transmission of Echinococcus granulosus and Echinococcus multilocularis in dogs for a high endemic region of the Tibetan plateau. Int J Parasitol 2005; 35:163-70. [PMID: 15710437 DOI: 10.1016/j.ijpara.2004.10.026] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2004] [Revised: 10/22/2004] [Accepted: 10/29/2004] [Indexed: 11/17/2022]
Abstract
Echinococcus granulosus and Echinococcus multilocularis abundance and prevalence data, for domestic dogs of Shiqu County, Sichuan Province, People's Republic of China, were fitted to mathematical models to evaluate transmission parameters. Abundance models, assuming the presence and absence of immunity, were fit for both E. granulosus and E. multilocularis using Bayesian priors, maximum likelihood, and Monte Carlo sampling techniques. When the models were compared, using the likelihood ratio test for nested models, the model assuming the presence of immunity was the best fit for E. granulosus infection, with a purgation based prevalence of 8% (true prevalence interval of 8-19% based on the sensitivity of purgation) and a mean abundance of 80 parasites per dog, with an average infection pressure of 560 parasites per year. In contrast, the model assuming the absence of immunity was the best fit for E. multilocularis infection, with a purgation based prevalence of 12% (true prevalence interval of 13-33% based on the sensitivity of purgation) and a mean abundance of 131 parasites per dog, with an average infection pressure of 334 or 533 parasites per year assuming a 5 or 3 month parasite life expectancy, respectively. The prevalence data for both parasites was then fit to a set of differential equations modeling the transition between infection states in order to determine number of infectious insults per year. Infection pressure was 0.21, with a 95% credibility interval of 0.12 to 0.41, infections per year for E. granulosus and 0.52, with a 95% credibility interval of 0.29-0.77, infections per year for E. multilocularis assuming a 5 month parasite lifespan or 0.85, with a 95% credibility interval of 0.47-1.25 infections per year, assuming a 3 month E. multilocularis lifespan in dogs.
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Affiliation(s)
- Christine M Budke
- Institute of Parasitology, University of Zürich, Winterthurerstrasse 266a, CH-8057, Zürich, Switzerland.
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