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Sota P, Upontain S, Tangkawattana S, Punyapornwithaya V, Nakhapakorn K, Sripa B. Association between Opisthorchis viverrini infection in cats and humans: Non-spatial and spatial analyses. Vet Parasitol 2024; 327:110150. [PMID: 38422711 DOI: 10.1016/j.vetpar.2024.110150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 02/18/2024] [Accepted: 02/18/2024] [Indexed: 03/02/2024]
Abstract
Cats are recognized as significant reservoir hosts for human opisthorchiasis, particularly in areas with a high prevalence of infection. Despite this, the precise role of cats in the transmission of Opisthorchis viverrini between humans and felines remains unclear. This study investigates the association between these two hosts through both spatial and non-spatial analyses in the endemic Thanya sub-district of Thailand. A total of 105 owned cats were randomly sampled from 15 villages within the sub-district for stool examination. A questionnaire was administered to 66 cat owners to explore the human-pet relationship. Household locations were collected using GPS devices. Non-spatial analyses revealed a positive association between the two hosts (P= 0.011; OR 7, 95% CI: 1.6-30.9), highlighting two independent significant risk factors: cat owners consuming raw fish (P = 0.028; OR = 4.52, 95% CI: 1.25-19.45) and feeding cats raw fish (P = 0.011; OR = 16.41, 95% CI: 2.78-317.04) according to multivariate analysis. Spatial analysis provided further support to the non-spatial findings (p = 0.0123; OR = 3.45, 95% CI = 0.88-13.61). Multiple autologistic regression confirmed two significant risk factors: cat owners consuming raw fish (p = 0.054; OR = 3.37, 95% CI: 0.98-11.59) and feeding cats raw fish (p = 0.014; OR = 7.43, 95% CI: 1.49-37.05). Risk mapping identified the western part of the study site as a hotspot for O. viverrini infection. Hyper-endemic focusing revealed a union of human and cat buffers at 0.46 km², with an overlapping area of 0.22 km² (47.83%). This study underscores the impact of owners' behaviors, specifically consuming and feeding raw fish to cats, on the increased probability of infection in cats. It emphasizes the need for effective opisthorchiasis control through health education targeting cat owners in endemic areas.
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Affiliation(s)
- Pornphutthachat Sota
- Graduate School, Khon Kaen University, Khon Kaen 40002, Thailand; WHO Collaborating Centre for Research and Control of Opisthorchiasis (Southeast Asian Liver Fluke Disease), Tropical Disease Research Center, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Songkiad Upontain
- Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Sirikachorn Tangkawattana
- Faculty of Veterinary Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; WHO Collaborating Centre for Research and Control of Opisthorchiasis (Southeast Asian Liver Fluke Disease), Tropical Disease Research Center, Khon Kaen University, Khon Kaen 40002, Thailand.
| | | | - Kanchana Nakhapakorn
- Faculty of Environment and Resource Studies, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Banchob Sripa
- Department of Tropical Medicine, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; WHO Collaborating Centre for Research and Control of Opisthorchiasis (Southeast Asian Liver Fluke Disease), Tropical Disease Research Center, Khon Kaen University, Khon Kaen 40002, Thailand.
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Kamber L, Bürli C, Harbrecht H, Odermatt P, Sayasone S, Chitnis N. Modeling the persistence of Opisthorchis viverrini worm burden after mass-drug administration and education campaigns with systematic adherence. PLoS Negl Trop Dis 2024; 18:e0011362. [PMID: 38422118 DOI: 10.1371/journal.pntd.0011362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 03/12/2024] [Accepted: 01/23/2024] [Indexed: 03/02/2024] Open
Abstract
Opisthorchis viverrini is a parasitic liver fluke contracted by consumption of raw fish, which affects over 10 million people in Southeast Asia despite sustained control efforts. Chronic infections are a risk factor for the often fatal bile duct cancer, cholangiocarcinoma. Previous modeling predicted rapid elimination of O. viverrini following yearly mass drug administration (MDA) campaigns. However, field data collected in affected populations shows persistence of infection, including heavy worm burden, after many years of repeated interventions. A plausible explanation for this observation is systematic adherence of individuals in health campaigns, such as MDA and education, with some individuals consistently missing treatment. We developed an agent-based model of O. viverrini which allows us to introduce various heterogeneities including systematic adherence to MDA and education campaigns at the individual level. We validate the agent-based model by comparing it to a previously published population-based model. We estimate the degree of systematic adherence to MDA and education campaigns indirectly, using epidemiological data collected in Lao PDR before and after 5 years of repeated MDA, education and sanitation improvement campaigns. We predict the impact of interventions deployed singly and in combination, with and without the estimated systematic adherence. We show how systematic adherence can substantially increase the time required to achieve reductions in worm burden. However, we predict that yearly MDA campaigns alone can result in a strong reduction of moderate and heavy worm burden, even under systematic adherence. We predict latrines and education campaigns to be particularly important for the reduction in overall prevalence, and therefore, ultimately, elimination. Our findings show how systematic adherence can explain the observed persistence of worm burden; while emphasizing the benefit of interventions for the entire population, even under systematic adherence. At the same time, the results highlight the substantial opportunity to further reduce worm burden if patterns of systematic adherence can be overcome.
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Affiliation(s)
- Lars Kamber
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Christine Bürli
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Helmut Harbrecht
- Department of Mathematics and Computer Science, University of Basel, Basel, Switzerland
| | - Peter Odermatt
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
| | - Somphou Sayasone
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
- Lao Tropical and Public Health Institute, Vientiane, Lao People's Democratic Republic
| | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
- University of Basel, Basel, Switzerland
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Saijuntha W, Sithithaworn P, Wangboon C, Andrews RH, Petney TN. Liver Flukes: Clonorchis and Opisthorchis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1454:239-284. [PMID: 39008268 DOI: 10.1007/978-3-031-60121-7_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
Clonorchis sinensis, Opisthorchis viverrini and O. felineus are liver flukes of human and animal pathogens occurring across much of Europe and Asia. Nevertheless, they are often underestimated compared to other, better known neglected diseases in spite of the fact that many millions of people are infected and hundreds of millions are at risk. This is possibly because of the chronic nature of the infection and disease and that it takes several decades prior to a life-threatening pathology to develop. Several studies in the past decade have provided more information on the molecular biology of the liver flukes which clearly lead to better understanding of parasite biology, systematics and population genetics. Clonorchiasis and opisthorchiasis are characterized by a chronic infection that induces hepatobiliary inflammation, especially periductal fibrosis, which can be detected by ultrasonography. These chronic inflammations eventually lead to cholangiocarcinoma (CCA), a usually fatal bile duct cancer that develops in some infected individuals. In Thailand alone, opisthorchiasis-associated CCA kills up to 20,000 people every year and is therefore of substantial public health importance. Its socioeconomic impacts on impoverished families and communities are considerable. To reduce hepatobiliary morbidity and CCA, the primary intervention measures focus on control and elimination of the liver fluke. Accurate diagnosis of liver fluke infections in both human and other mammalian, snail and fish intermediate hosts is important for achieving these goals. While the short-term goal of liver fluke control can be achieved by praziquantel chemotherapy, a comprehensive health education package targeting school children is believed to be more beneficial for a long-term goal/solution. It is recommended that transdisciplinary research or multisectoral control approach including one health and/or eco health intervention strategy should be applied to combat the liver flukes and hence contribute to reduction of CCA in endemic areas.
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Affiliation(s)
| | - Paiboon Sithithaworn
- Department of Parasitology and Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
| | - Chompunoot Wangboon
- School of Preclinical Sciences, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, Thailand
| | - Ross H Andrews
- CASCAP, Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK
| | - Trevor N Petney
- CASCAP, Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
- Department of Paleontology and Evolution, State Museum of Natural History, Karlsruhe, Germany
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Borlase A, Prada JM, Crellen T. Modelling morbidity for neglected tropical diseases: the long and winding road from cumulative exposure to long-term pathology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220279. [PMID: 37598702 PMCID: PMC10440174 DOI: 10.1098/rstb.2022.0279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 07/13/2023] [Indexed: 08/22/2023] Open
Abstract
Reducing the morbidities caused by neglected tropical diseases (NTDs) is a central aim of ongoing disease control programmes. The broad spectrum of pathogens under the umbrella of NTDs lead to a range of negative health outcomes, from malnutrition and anaemia to organ failure, blindness and carcinogenesis. For some NTDs, the most severe clinical manifestations develop over many years of chronic or repeated infection. For these diseases, the association between infection and risk of long-term pathology is generally complex, and the impact of multiple interacting factors, such as age, co-morbidities and host immune response, is often poorly quantified. Mathematical modelling has been used for many years to gain insights into the complex processes underlying the transmission dynamics of infectious diseases; however, long-term morbidities associated with chronic or cumulative exposure are generally not incorporated into dynamic models for NTDs. Here we consider the complexities and challenges for determining the relationship between cumulative pathogen exposure and morbidity at the individual and population levels, drawing on case studies for trachoma, schistosomiasis and foodborne trematodiasis. We explore potential frameworks for explicitly incorporating long-term morbidity into NTD transmission models, and consider the insights such frameworks may bring in terms of policy-relevant projections for the elimination era. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Anna Borlase
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Joaquin M. Prada
- Faculty of Health and Medical Sciences, University of Surrey, Guildford GU2 7XH, UK
| | - Thomas Crellen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
- School of Biodiversity, One Health & Veterinary Medicine, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, Glasgow G12 8TA, UK
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Crellen T, Haswell M, Sithithaworn P, Sayasone S, Odermatt P, Lamberton PHL, Spencer SEF, Déirdre Hollingsworth T. Diagnosis of helminths depends on worm fecundity and the distribution of parasites within hosts. Proc Biol Sci 2023; 290:20222204. [PMID: 36651047 PMCID: PMC9845982 DOI: 10.1098/rspb.2022.2204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/16/2022] [Indexed: 01/19/2023] Open
Abstract
Helminth transmission and morbidity are dependent on the number of mature parasites within a host; however, observing adult worms is impossible for many natural infections. An outstanding challenge is therefore relating routine diagnostics, such as faecal egg counts, to the underlying worm burden. This relationship is complicated by density-dependent fecundity (egg output per worm reduces due to crowding at high burdens) and the skewed distribution of parasites (majority of helminths aggregated in a small fraction of hosts). We address these questions for the carcinogenic liver fluke Opisthorchis viverrini, which infects approximately 10 million people across Southeast Asia, by analysing five epidemiological surveys (n = 641) where adult flukes were recovered. Using a mechanistic model, we show that parasite fecundity varies between populations, with surveys from Thailand and Laos demonstrating distinct patterns of egg output and density-dependence. As the probability of observing faecal eggs increases with the number of mature parasites within a host, we quantify diagnostic sensitivity as a function of the worm burden and find that greater than 50% of cases are misdiagnosed as false negative in communities close to elimination. Finally, we demonstrate that the relationship between observed prevalence from routine diagnostics and true prevalence is nonlinear and strongly influenced by parasite aggregation.
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Affiliation(s)
- Thomas Crellen
- School of Biodiversity One Health and Veterinary Medicine, Graham Kerr Building, University of Glasgow, 82 Hillhead Street, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Melissa Haswell
- Office of the Deputy Vice Chancellor, Indigenous Strategy and Services and School of Geosciences, John Woolley Building, University of Sydney, Sydney, New South Wales 2050, Australia
- School of Public Health and Social Work, Kelvin Grove Campus, Queensland University of Technology, Brisbane City, Queensland 4000, Australia
| | - Paiboon Sithithaworn
- Department of Parasitology, Khon Kaen University, 123 Thanon Mittraphap, Khon Kaen 40002, Thailand
| | - Somphou Sayasone
- Lao Tropical and Public Health Institute, Samsenthai Road, Sisattanak district, Vientiane, Lao PDR
| | - Peter Odermatt
- Department of Public Health and Epidemiology, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil 4123, Switzerland
- University of Basel, Petersplatz 1, Basel 4001, Switzerland
| | - Poppy H. L. Lamberton
- School of Biodiversity One Health and Veterinary Medicine, Graham Kerr Building, University of Glasgow, 82 Hillhead Street, Glasgow G12 8QQ, UK
- Wellcome Centre for Integrative Parasitology, Sir Graeme Davies Building, University of Glasgow, 120 University Place, Glasgow G12 8TA, UK
| | | | - T. Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
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Khuntikeo N, Thinkhamrop B, Crellen T, Eamudomkarn C, Petney TN, Andrews RH, Sithithaworn P. Epidemiology and Control of Opisthorchis viverrini Infection: Implications for Cholangiocarcinoma Prevention. Recent Results Cancer Res 2023; 219:27-52. [PMID: 37660330 DOI: 10.1007/978-3-031-35166-2_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
It is known that Opisthorchis viverrini (OV) is the most significant risk factor for the development of cholangiocarcinoma (CCA); hence, it is also known as carcinogenic parasite. Effective control and elimination of OV infection should significantly reduce O. viverrini-related CCA. This chapter includes details of the three recently developed innovative tools, namely the Isan cohort database software, an OV-RDT for screening of O. viverrini, and an ultrasound telecommunication system. Past and current control programs, i.e., education, medication, and sanitation were discussed and stressed the need for a comprehensive control program which encompasses primary, secondary, and tertiary patient care programs for confirmation and management of suspected CCA cases. The approach of mathematical modeling for control of OV and CCA was also briefly described. Additionally, we highlighted the current progress toward control of OV and CCA in Thailand and potential for expansion into nearby countries in Southeast Asia.
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Affiliation(s)
- Narong Khuntikeo
- Department of Surgery, Faculty of Medicine, Khon Kaen University and Cholangiocarcinoma Research Institute, Khon Kaen, Thailand
| | - Bandit Thinkhamrop
- Faculty of Public Health, Khon Kaen University and Cholangiocarcinoma Research Institute, Khon Kaen, Thailand
| | - Thomas Crellen
- School of Biodiversity, One Health and Veterinary Medicine, University of Glasgow, G12 8QQ, Glasgow, United Kingdom
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7LF, London, UK
| | - Chatanun Eamudomkarn
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Trevor N Petney
- Evolution and Paleontology, State Museum of Natural History Karlsruhe, Erbprinzenstrasse 13, 76133, Karlsruhe, Germany
| | - Ross H Andrews
- Department of Surgery and Cancer, Faculty of Medicine, Imperial College, London, UK
| | - Paiboon Sithithaworn
- Department of Parasitology, Faculty of Medicine, Khon Kaen University and Cholangiocarcinoma Research Institute, Khon Kaen, Thailand.
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Foodborne Parasites and Their Complex Life Cycles Challenging Food Safety in Different Food Chains. Foods 2022; 12:foods12010142. [PMID: 36613359 PMCID: PMC9818752 DOI: 10.3390/foods12010142] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 12/20/2022] [Accepted: 12/21/2022] [Indexed: 12/29/2022] Open
Abstract
Zoonotic foodborne parasites often represent complex, multi host life cycles with parasite stages in the hosts, but also in the environment. This manuscript aims to provide an overview of important zoonotic foodborne parasites, with a focus on the different food chains in which parasite stages may occur. We have chosen some examples of meat-borne parasites occurring in livestock (Taenia spp., Trichinella spp. and Toxoplasma gondii), as well as Fasciola spp., an example of a zoonotic parasite of livestock, but transmitted to humans via contaminated vegetables or water, covering the 'farm to fork' food chain; and meat-borne parasites occurring in wildlife (Trichinella spp., Toxoplasma gondii), covering the 'forest to fork' food chain. Moreover, fish-borne parasites (Clonorchis spp., Opisthorchis spp. and Anisakidae) covering the 'pond/ocean/freshwater to fork' food chain are reviewed. The increased popularity of consumption of raw and ready-to-eat meat, fish and vegetables may pose a risk for consumers, since most post-harvest processing measures do not always guarantee the complete removal of parasite stages or their effective inactivation. We also highlight the impact of increasing contact between wildlife, livestock and humans on food safety. Risk based approaches, and diagnostics and control/prevention tackled from an integrated, multipathogen and multidisciplinary point of view should be considered as well.
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Rinaldo A, Rodriguez-Iturbe I. Ecohydrology 2.0. RENDICONTI LINCEI. SCIENZE FISICHE E NATURALI 2022; 33:245-270. [PMID: 35673327 PMCID: PMC9165276 DOI: 10.1007/s12210-022-01071-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 03/27/2022] [Indexed: 11/23/2022]
Abstract
This paper aims at a definition of the domain of ecohydrology, a relatively new discipline borne out of an intrusion-as advertised by this Topical Collection of the Rendiconti Lincei-of hydrology and geomorphology into ecology (or vice-versa, depending on the reader's background). The study of hydrologic controls on the biota proves, in our view, significantly broader than envisioned by its original focus that was centered on the critical zone where much of the action of soil, climate and vegetation interactions takes place. In this review of related topics and contributions, we propose a reasoned broadening of perspective, in particular by firmly centering ecohydrology on the fluvial catchment as its fundamental control volume. A substantial unity of materials and methods suggests that our advocacy may be considered legitimate.
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Affiliation(s)
- Andrea Rinaldo
- Accademia Nazionale dei Lincei, Rome, Italy
- Laboratory of Ecohydrology ENAC/IIE/ECHO, École Polytechinque Fédérale de Lausanne, Lausanne, Switzerland
- Dipartimento ICEA, Università degli studi di Padova, Padua, Italy
| | - Ignacio Rodriguez-Iturbe
- Department of Ocean Engineering, Texas A&M University, College Station, TX USA
- Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX USA
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Current status of human liver fluke infections in the Greater Mekong Subregion. Acta Trop 2021; 224:106133. [PMID: 34509453 DOI: 10.1016/j.actatropica.2021.106133] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 12/12/2022]
Abstract
The Greater Mekong Subregion (GMS) is a trans-national region of the Mekong River basin in Southeast Asia comprising Cambodia, the People's Republic of China (specifically Yunnan Province and Guangxi Zhuang Autonomous Region), Lao People's Democratic Republic (Lao PDR), Myanmar, Thailand, and Vietnam home to more than 340 million people or almost 4.5% of the global population. Human liver fluke infections caused by Opisthorchis viverrini and Clonorchis sinensis have been major public health problems in this region for decades. Opisthorchiasis caused by O. viverrini is prevalent in Thailand, Lao PDR, Cambodia and central-southern Vietnam with more than 12 million people infected. Clonorchiasis caused by C. sinensis is endemic in northern Vietnam and Guangxi with estimated 3.5 -5 million infected. The infections can cause several liver and biliary diseases such as cholangitis, periductal fibrosis, gallstones, and cholangiocarcinoma (CCA), a fatal bile duct cancer. Key determinants of the geographical distribution differences of the two liver fluke species are snail species and geographic barriers. Main risk behaviour of the infections is the culture of eating raw fish "the raw attitude" of people in the GMS, especially the Tai/Dai/Thai/Laos ethnic groups, the major population in the GMS. Over the past 20 years, there is a big change in prevalence of the infections. Opisthorchiasis has long been endemic, particularly in northern and northeastern Thailand and Lao PDR with over 8-10 million cases estimated. However, after several rounds of national campaign against opisthorchiasis using integrated control approach in Thailand over the past three decades, the prevalence of O. viverrini infection has reduced from over 15% in 1996 to 2.2% in 2019. High prevalence of O. viverrini infection continues in Lao PDR and central Vietnam. Emerging high prevalence, up to a maximum of 47.5%, has been noted in Cambodia during the past 10 years possibly due to more studies being conducted rather than increasing prevalence. O. viverrini infection has now also been reported in Lower Myanmar in recent years. Clonorchiasis has been known in northern Vietnam and southern China for a long time. Several surveys have reported infections in Guangxi in the last 10 years, and until now liver fluke infected cases have not been reported in Yunnan. Overall, nowadays, there is a shift in high risk areas for GMS liver fluke infection from northeastern Thailand to Lao PDR, Cambodia, Vietnam, Myanmar, and Guangxi P.R. China. Urgent systematic disease mapping and integrated liver fluke control using One Health approaches should be implemented nationwide in GMS countries.
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Simakova AV, Chitnis N, Babkina IB, Fedorova OS, Fedotova MM, Babkin AM, Khodkevich NE. Abundance of Opisthorchis felineus Metacercariae in cyprinid fish in the middle Ob River basin (Tomsk region, Russia). Food Waterborne Parasitol 2021; 22:e00113. [PMID: 33681491 PMCID: PMC7930129 DOI: 10.1016/j.fawpar.2021.e00113] [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: 10/29/2020] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 11/16/2022] Open
Abstract
Infection with the liver fluke, Opisthorchis felineus, caused by the consumption of infected raw or undercooked cyprinid fish is common in humans and carnivores in the middle Ob River basin (Tomsk region, Russia) and can lead to diseases in humans. The goal of this study was the status of fish infection with O. felineus metacercariae in order to assess the role of fish in the infection of the human population in the middle Ob River basin. Of the 14 Cyprinidae species recorded in the middle Ob River basin, we examined 6 cyprinid species for prevalence and intensity of infection with O. felineus metacercariae. Five of these species (Leuciscus idus, Leuciscus leuciscus, Rutilus rutilus, Abramis brama, and Carassius gibelio) are of commercial value, while the common bleak is an object of amateur fishing. In addition, we conducted a survey of the fish consumption habits as part of a community-based cross-sectional study in the rural Shegarsky district, Tomsk region, Russian Federation. O. felineus metacercariae were observed in muscles of all examined species except for the Prussian carp. The ide is the main infection source in the Ob River (prevalence of infection, 100%, and intensity, 50.5 metacercariae per fish) and the common dace in the Tom River (91.1% and 12.7 metacercariae). Although the two alien species (bream and common bleak) are susceptible to infection with O. felineus metacercariae, the prevalence of infection in these fish and in the roach did not exceed 3%. The prevalence and intensity of infection in fish increased with age and size. The infection characteristics of fish in different water flows were different. The cyprinid species account on average for 69.8% of the commercial fish harvested in the Tomsk region. According to epidemiological survey, among 600 participants, 87.5% (n = 525) of respondents consumed river fish, with the most popular fish being cyprinids including Prussian carp, dace, ide and bream, followed by pike and perch. Thus, the epizootological state of the water flows in the middle Ob River basin is adverse with respect to opisthorchiasis, as indicated by high infection rates of liver fluke metacercariae in ide and common dace, which are abundant species of high commercial value. An extremely high prevalence of infection suggests a strong transmission cycle with a high rate of infection from infected humans and/or animal reservoir hosts to snails and fish. In addition to treating humans, there should be a strong focus on identifying these potential reservoir hosts to reduce subsequent infection in humans. Furthermore, since the intensity of infection in humans is determined by the presence of fish species such as ide and dace in the diet, they should be included in a dietary change campaign by eliminating the consumption of raw fish. Commercial cyprinid species play the key role in maintaining opisthorchiasis foci. The ide and common dace are the main source of human and animal infection. Measures to control Opisthorchis felineus should target these two species of fish. The invasion of fish increases with their age and size.
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Affiliation(s)
- Anastasia V Simakova
- Biological Institute, Tomsk State University, Tomsk, Russian Federation.,Department of Integrated Environmental Projects, Tomsk Oil and Gas Research and Design Institute, Tomsk, Russian Federation
| | - Nakul Chitnis
- Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Irina B Babkina
- Biological Institute, Tomsk State University, Tomsk, Russian Federation
| | - Olga S Fedorova
- Department of Faculty Pediatrics, Federal State Budget Educational Institution of Higher Education, Siberian State Medical University, Ministry of Healthcare of Russian Federation, Tomsk, Russian Federation
| | - Marina M Fedotova
- Department of Faculty Pediatrics, Federal State Budget Educational Institution of Higher Education, Siberian State Medical University, Ministry of Healthcare of Russian Federation, Tomsk, Russian Federation
| | - Alexandr M Babkin
- Biological Institute, Tomsk State University, Tomsk, Russian Federation
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11
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Crellen T, Sithithaworn P, Pitaksakulrat O, Khuntikeo N, Medley GF, Hollingsworth TD. Towards Evidence-based Control of Opisthorchis viverrini. Trends Parasitol 2021; 37:370-380. [PMID: 33516657 DOI: 10.1016/j.pt.2020.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 12/18/2020] [Accepted: 12/25/2020] [Indexed: 01/21/2023]
Abstract
Transmission of the carcinogenic liver fluke Opisthorchis viverrini is ongoing across Southeast Asia. Endemic countries within the region are in different stages of achieving control. However, evidence on which interventions are the most effective for reducing parasite transmission, and the resulting liver cancer, is currently lacking. Quantitative modelling can be used to evaluate different control measures against O. viverrini and assist the design of clinical trials. In this article we evaluate the epidemiological parameters that underpin models of O. viverrini and the data necessary for their estimation, with the aim of developing evidence-based strategies for parasite control at a national or regional level.
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Affiliation(s)
- Thomas Crellen
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK.
| | - Paiboon Sithithaworn
- Department of Parasitology, Khon Kaen University, Khon Kaen 40002, Thailand; Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Opal Pitaksakulrat
- Department of Parasitology, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Narong Khuntikeo
- Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen 40002, Thailand; Department of Surgery, Khon Kaen University, Khon Kaen 40002, Thailand
| | - Graham F Medley
- Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London, WC1H 9SH, UK
| | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7LF, UK
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Huang XH, Qian MB, Zhu GH, Fang YY, Hao YT, Lai YS. Assessment of control strategies against Clonorchis sinensis infection based on a multi-group dynamic transmission model. PLoS Negl Trop Dis 2020; 14:e0008152. [PMID: 32218570 PMCID: PMC7156112 DOI: 10.1371/journal.pntd.0008152] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Revised: 04/14/2020] [Accepted: 02/18/2020] [Indexed: 12/21/2022] Open
Abstract
Clonorchiasis is one of the most important food-borne trematodiases affecting millions of people. Strategies were recommended by different organizations and control programmes were implemented but mostly in short-time periods. It's important to assess the long-term benefits and sustainability of possible control strategies on morbidity control of the disease. We developed a multi-group transmission model to describe the dynamics of C. sinensis transmission among different groups of people with different raw-fish-consumption behaviors, based on which, a full model with interventions was proposed and three common control measures (i.e., preventive chemotherapy, information, education, and communication (IEC) and environmental modification) and their possible combinations were considered. Under a typical setting of C. sinensis transmission, we simulated interventions according to different strategies and with a series of values of intervention parameters. We found that combinations of measures were much beneficial than those singly applied; higher coverages of measures had better effects; and strategies targeted on whole population performed better than that on at-risk population with raw-fish-consumption behaviors. The strategy recommended by the government of Guangdong Province, China shows good and sustainable effects, under which, the infection control (with human prevalence <5%) could be achieved within 7.84 years (95% CI: 5.78-12.16 years) in our study setting (with original observed prevalence 33.67%). Several sustainable strategies were provided, which could lead to infection control within 10 years. This study makes the effort to quantitatively assess the long-term effects of possible control strategies against C. sinensis infection under a typical transmission setting, with application of a multi-group dynamic transmission model. The proposed model is easily facilitated with other transmission settings and the simulation outputs provide useful information to support the decision-making of control strategies on clonorchiasis.
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Affiliation(s)
- Xiao-Hong Huang
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
| | - Men-Bao Qian
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai, People’s Republic of China
- WHO Collaborating Centre for Tropical Diseases, Key Laboratory of Parasite and Vector Biology, Ministry of Health, Shanghai, People’s Republic of China
| | - Guang-Hu Zhu
- Department of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin, Guangxi, People’s Republic of China
| | - Yue-Yi Fang
- Institute of Parasitic Diseases, Guangdong Provincial Center for Disease Control and Prevention, Guangzhou, Guangdong, People’s Republic of China
| | - Yuan-Tao Hao
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
- Sun Yat-sen Global Health Institute, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
| | - Ying-Si Lai
- Department of Medical Statistics, School of Public Health, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
- Sun Yat-sen Global Health Institute, Sun Yat-sen University, Guangzhou, Guangdong, People’s Republic of China
- * E-mail:
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Betson M, Alonte AJI, Ancog RC, Aquino AMO, Belizario VY, Bordado AMD, Clark J, Corales MCG, Dacuma MG, Divina BP, Dixon MA, Gourley SA, Jimenez JRD, Jones BP, Manalo SMP, Prada JM, van Vliet AHM, Whatley KCL, Paller VGV. Zoonotic transmission of intestinal helminths in southeast Asia: Implications for control and elimination. ADVANCES IN PARASITOLOGY 2020; 108:47-131. [PMID: 32291086 DOI: 10.1016/bs.apar.2020.01.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intestinal helminths are extremely widespread and highly prevalent infections of humans, particularly in rural and poor urban areas of low and middle-income countries. These parasites have chronic and often insidious effects on human health and child development including abdominal problems, anaemia, stunting and wasting. Certain animals play a fundamental role in the transmission of many intestinal helminths to humans. However, the contribution of zoonotic transmission to the overall burden of human intestinal helminth infection and the relative importance of different animal reservoirs remains incomplete. Moreover, control programmes and transmission models for intestinal helminths often do not consider the role of zoonotic reservoirs of infection. Such reservoirs will become increasingly important as control is scaled up and there is a move towards interruption and even elimination of parasite transmission. With a focus on southeast Asia, and the Philippines in particular, this review summarises the major zoonotic intestinal helminths, risk factors for infection and highlights knowledge gaps related to their epidemiology and transmission. Various methodologies are discussed, including parasite genomics, mathematical modelling and socio-economic analysis, that could be employed to improve understanding of intestinal helminth spread, reservoir attribution and the burden associated with infection, as well as assess effectiveness of interventions. For sustainable control and ultimately elimination of intestinal helminths, there is a need to move beyond scheduled mass deworming and to consider animal and environmental reservoirs. A One Health approach to control of intestinal helminths is proposed, integrating interventions targeting humans, animals and the environment, including improved access to water, hygiene and sanitation. This will require coordination and collaboration across different sectors to achieve best health outcomes for all.
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Affiliation(s)
- Martha Betson
- University of Surrey, Guildford, Surrey, United Kingdom.
| | | | - Rico C Ancog
- University of the Philippines Los Baños, Laguna, Philippines
| | | | | | | | - Jessica Clark
- University of Surrey, Guildford, Surrey, United Kingdom
| | | | | | - Billy P Divina
- University of the Philippines Los Baños, Laguna, Philippines
| | | | | | | | - Ben P Jones
- University of Surrey, Guildford, Surrey, United Kingdom
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Mathematical Global Dynamics and Control Strategies on Echinococcus multilocularis Infection. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2019; 2019:3569528. [PMID: 31281409 PMCID: PMC6594268 DOI: 10.1155/2019/3569528] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/09/2019] [Accepted: 05/14/2019] [Indexed: 01/22/2023]
Abstract
Echinococcus multilocularis, a major cause of echinococcosis in human, is a parasitic sylvatic disease between two major hosts in a predator-prey relation. A new model for the transmission dynamics of Echinococcus multilocularis in the population of red foxes and voles with environment as a source of infection is formulated and rigorously analyzed. The model is used to access the impact of treatment on red foxes and environmental disinfection as control strategies on the disease dynamics. The control reproduction number is computed and is used to rigorously prove the local and global dynamics of models' equilibria. Using available data on Echinococcus, elasticity indices and partial rank correlation coefficients of control reproduction number and cumulative new cases in red foxes and voles are computed. Parameters that have high influence locally and globally are identified. Numerical experiments indicate that administering disinfection of environment only induces more positive impact than applying treatment only on red foxes in controlling the infection. Generally, interventions towards treating red foxes and environmental disinfection could be sufficient in tackling transmission of disease in the populations.
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Khieu V, Fürst T, Miyamoto K, Yong TS, Chai JY, Huy R, Muth S, Odermatt P. Is Opisthorchis viverrini Emerging in Cambodia? ADVANCES IN PARASITOLOGY 2019; 103:31-73. [PMID: 30878058 DOI: 10.1016/bs.apar.2019.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Opisthorchis viverrini infection is widely prevalent in Southeast Asia. In Cambodia information on this helminth infection is scare. Recent reports suggest that O. viverrini is an emerging public health problem. We aimed to synthesize all information in relation to the infection, epidemiology, and morbidity of O. viverrini in Cambodia; from published as well as thus far unpublished sources. First reports on O. viverrini date back to 1995. In 2006 an O. viverrini initiative was launched by the national helminth control program. Since then O. viverrini has been reported in all - except two - provinces. Villages with high prevalences (>20%) were found in provinces from Preah Vihear to Takeo. The infection has a highly focal distribution. In many villages no infections were detected. O. viverrini infection was also reported in cats, dogs and intermediate hosts. No report on morbidity associated with O. viverrini was found. The current evidence suggests that O. viverrini infection remains underreported in Cambodia. It is likely that the transmission will further increase in the future with potentially serious consequences for human health.
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Affiliation(s)
- Virak Khieu
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Thomas Fürst
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland; School of Public Health, Imperial College London, London, United Kingdom
| | - Kazuko Miyamoto
- School of Nursing, Faculty of Medicine & Center for International Education and Exchange, Yamanashi University, Yamanashi, Japan
| | - Tai-Soon Yong
- Department of Environmental Biology, Institute of Tropical Medicine, and Arthropods of Medical Importance Resource Bank, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Jong-Yil Chai
- Institute of Parasitic Diseases, Korea Association of Health Promotion, Seoul, Republic of Korea; Department of Parasitology and Tropical Medicine, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Rekol Huy
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Sinuon Muth
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Peter Odermatt
- Swiss Tropical and Public Health Institute, Basel, Switzerland; University of Basel, Basel, Switzerland
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16
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Nawrocki CC, Kiatsopit N, Namsanor J, Sithithaworn P, Carlton EJ. Culture of fecal indicator bacteria from snail intestinal tubes as a tool for assessing the risk of Opisthorchis viverrini infection in Bithynia snail habitat. Parasit Vectors 2019; 12:66. [PMID: 30700304 PMCID: PMC6354346 DOI: 10.1186/s13071-019-3313-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 01/13/2019] [Indexed: 11/10/2022] Open
Abstract
Background Like many trematodes of human health significance, the carcinogenic liver fluke, Opisthorchis viverrini, is spread via fecal contamination of snail habitat. Methods for assessing snail exposure to fecal waste can improve our ability to identify snail infection hotspots and potential sources of snail infections. We evaluated the feasibility of culturing fecal indicator bacteria from Bithynia snail intestinal tubes as a method for assessing snail exposure to fecal waste. Snails and water samples were collected from a site with a historically high prevalence of O. viverrini infected snails (“hotspot” site) and a site with historically no infected snails (“non-hotspot” site) on two sampling days. Snails were tested for O. viverrini and a stratified random sample of snails from each site was selected for intestinal tube removal and culture of gut contents for the fecal indicator bacteria, Escherichia coli. Water samples were tested for E. coli and nearby households were surveyed to assess sources of fecal contamination. Results At the hotspot site, 26 of 2833 Bithynia siamensis goniomphalos snails were infected with O. viverrini compared to 0 of 1421 snails at the non-hotspot site. A total of 186 snails were dissected and cultured. Escherichia coli were detected in the guts of 20% of uninfected snails, 4% of O. viverrini-positive snails and 8% of snails not examined for cercarial infection at the hotspot site. Only one of 75 snails from the non-hotspot site was positive for E. coli. Accounting for sampling weights, snails at the hotspot site were more likely to have gut E. coli than snails from the non-hotspot site. The concentration of fecal indicator bacteria in surface water was higher at the hotspot vs non-hotspot site on only the first sampling day. Conclusions Fecal indicator bacteria can be detected in the intestinal tubes of Bithynia snails. The presence of fecal indicator bacteria in Bithynia snail guts may indicate risk of O. viverrini infection in snail populations. This method has the potential to aid in identifying locations and time windows of peak snail infection risk and may be applicable to other trematodes of human-health significance. Electronic supplementary material The online version of this article (10.1186/s13071-019-3313-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Courtney C Nawrocki
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA
| | - Nadda Kiatsopit
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.,Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Jutamas Namsanor
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.,Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Paiboon Sithithaworn
- Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.,Cholangiocarcinoma Research Institute, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Elizabeth J Carlton
- Department of Environmental and Occupational Health, Colorado School of Public Health, University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
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17
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Saijuntha W, Sithithaworn P, Kiatsopit N, Andrews RH, Petney TN. Liver Flukes: Clonorchis and Opisthorchis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1154:139-180. [PMID: 31297762 DOI: 10.1007/978-3-030-18616-6_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Clonorchis sinensis, Opisthorchis viverrini, and O. felineus are liver flukes of human and animal pathogens occurring across much of Europe and Asia. Nevertheless, they are often underestimated compared to other, better known neglected diseases in spite of the fact that many millions of people are infected and hundreds of millions are at risk. This is possibly because of the chronic nature of the infection and disease and that it takes several decades prior to a life-threatening pathology to develop. Several studies in the past decade have provided more information on the molecular biology of the liver flukes which clearly lead to better understanding of parasite biology, systematics, and population genetics. Clonorchiasis and opisthorchiasis are characterized by a chronic infection that induces hepatobiliary inflammation, especially periductal fibrosis, which can be detected by ultrasonography. These chronic inflammations eventually lead to cholangiocarcinoma (CCA), a usually fatal bile duct cancer that develops in some infected individuals. In Thailand alone, opisthorchiasis-associated CCA kills up to 20,000 people every year and is therefore of substantial public health importance. Its socioeconomic impacts on impoverished families and communities are considerable. To reduce hepatobiliary morbidity and CCA, the primary intervention measures focus on control and elimination of the liver fluke. Accurate diagnosis of liver fluke infections in both human and other mammalian, snail and fish intermediate hosts, are important for achieving these goals. While the short-term goal of liver fluke control can be achieved by praziquantel chemotherapy, a comprehensive health education package targeting school children is believed to be more beneficial for a long-term goal/solution. It is recommended that a transdisciplinary research or multisectoral control approach including one health and/or eco health intervention strategy should be applied to combat the liver flukes, and hence contribute to reduction of cholangiocarcinoma in endemic areas.
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Affiliation(s)
- Weerachai Saijuntha
- Walai Rukhavej Botanical Research Institute, Mahasarakham University, Maha Sarakham, Thailand
| | - Paiboon Sithithaworn
- Department of Parasitology, Faculty of Medicine, Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen, Thailand.
| | - Nadda Kiatsopit
- Department of Parasitology, Faculty of Medicine, Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen, Thailand
| | - Ross H Andrews
- CASCAP, Faculty of Medicine, Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen, Thailand.,Faculty of Medicine, St Mary's Campus, Imperial College London, London, UK
| | - Trevor N Petney
- CASCAP, Faculty of Medicine, Cholangiocarcinoma Research Institute, Khon Kaen University, Khon Kaen, Thailand.,Department of Paleontology and Evolution, State Museum of Natural History, Karlsruhe, Germany
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18
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Bürli C, Harbrecht H, Odermatt P, Sayasone S, Chitnis N. Analysis of interventions against the liver fluke, opisthorchis viverrini. Math Biosci 2018; 303:115-125. [DOI: 10.1016/j.mbs.2018.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 06/05/2018] [Accepted: 06/25/2018] [Indexed: 01/23/2023]
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Integrative EcoHealth/One Health Approach for Sustainable Liver Fluke Control: The Lawa Model. ADVANCES IN PARASITOLOGY 2018; 102:115-139. [PMID: 30442307 DOI: 10.1016/bs.apar.2018.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The Lawa model is a successful integrative and sustainable means of controlling opisthorchiasis in Thailand. The model integrates the EcoHealth and One Health holistic approaches with systems thinking to target the interruption of Opisthorchis viverrini transmission. Using the six principles of EcoHealth and emphasizing the three domains of One Health (human-animal-ecosystem), the program targets each step of the parasite life cycle, thus maximizing the chances of interrupting the life cycle of the parasite. The main drivers of success are the village health volunteers and health-promoting hospitals, together with the support of the government and academia. The success of the model has led to continuous expansion, adoption nationally and internationally and application to the control of other neglected tropical diseases as well as noncommunicable diseases.
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Tangkawattana S, Tangkawattana P. Reservoir Animals and Their Roles in Transmission of Opisthorchis viverrini. ADVANCES IN PARASITOLOGY 2018; 101:69-95. [PMID: 29907256 DOI: 10.1016/bs.apar.2018.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Although any fish-eating mammals could be potential definitive hosts of Opisthorchis viverrini, only a few, especially cats and dogs, are actually known reservoir hosts for this parasite. Both animals usually get infected via consuming raw or undercooked contaminated fish, fish dishes or food remains from households. The infected animals sustain parasite egg spread via open environment defecation. Cats are the most important reservoir with higher prevalence rates of O. viverrini infection than dogs in endemic areas. Usually Opisthorchis-infected animals do not exhibit apparent clinical symptoms or specific abnormalities in laboratory examinations. Pathological findings in these animal reservoirs are basically similar to those seen in humans and experimental animals, namely periductal inflammation, biliary hyperplasia and periductal fibrosis. However, O. viverrini-associated cholangiocarcinoma has not yet been reported in the reservoir animals at present. Praziquantel is a treatment of choice not only for humans but also for animal reservoirs. Integrated control of opisthorchiasis in animal reservoirs is based on holistic approaches such as EcoHealth/One Health concepts. In fact integrated control of opisthorchiasis in humans in ecosystem has also proved successful, for example, the Lawa model for opisthorchiasis control in the endemic area of Khon Kaen, Thailand. Other feral and wild animals in endemic areas might also be potential reservoirs, and this requires more investigation. In addition, genetic diversity and evolution of the flukes might also influence zoonotic capability.
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