501
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Davies TJ, Pedersen AB. Phylogeny and geography predict pathogen community similarity in wild primates and humans. Proc Biol Sci 2008; 275:1695-701. [PMID: 18445561 DOI: 10.1098/rspb.2008.0284] [Citation(s) in RCA: 203] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
In natural systems, host species are often co-infected by multiple pathogen species, and recent work has suggested that many pathogens can infect a wide range of host species. An important question therefore is what determines the host range of a pathogen and the community of pathogens found within a given host species. Using primates as a model, we show that infectious diseases are more often shared between species that are closely related and inhabit the same geographical region. We find that host relatedness is the best overall predictor of whether two host species share the same pathogens. A higher frequency of pathogen host shifts between close relatives or inheritance of pathogens from a common ancestor may explain this result. For viruses, geographical overlap among neighbouring primate hosts is more important in determining host range. We suggest this is because rapid evolution within viral lineages allows host jumps across larger evolutionary distances. We also show that the phylogenetic pattern of pathogen sharing with humans is the same as that between wild primates. For humans, this means we share a higher proportion of pathogens with the great apes, including chimpanzees and gorillas, because these species are our closest relatives.
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Affiliation(s)
- T Jonathan Davies
- National Center for Ecological Analysis and Synthesis, 735 State Street, Santa Barbara, CA 93101, USA.
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502
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Muehlenbein MP, Martinez LA, Lemke AA, Ambu L, Nathan S, Alsisto S, Andau P, Sakong R. Perceived vaccination status in ecotourists and risks of anthropozoonoses. ECOHEALTH 2008; 5:371-378. [PMID: 18810550 DOI: 10.1007/s10393-008-0192-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 07/11/2008] [Accepted: 08/05/2008] [Indexed: 05/26/2023]
Abstract
Anthropozoonotic (human to nonhuman animal) transmission of infectious disease poses a significant threat to wildlife. A large proportion of travelers to tropical regions are not protected against vaccine-preventable illnesses, and a majority of these travelers demonstrate poor recall of actual vaccination status. Here we characterize self-perceived vaccination status among a large sample of ecotourists at the Sepilok Orangutan Rehabilitation Centre, Sabah, Malaysia. Despite their recognized travel itinerary to view endangered animals, tourists at wildlife sanctuaries are not adequately protected against vaccine-preventable illnesses. Of 633 surveys, over half reported being currently vaccinated against tuberculosis, hepatitis A, hepatitis B, polio, and measles. Fewer participants reported current vaccination status for influenza, rabies, and chickenpox. Despite the fact that the majority of visitors to Sepilok are from temperate regions where influenza is relatively more prevalent, 67.1% of those surveyed with medical-related occupations reported not being currently vaccinated for influenza. Ecotourists concerned about environmental protection are themselves largely unaware of their potential contribution to the spread of diseases to animals. The risks of negatively affecting animal populations must be communicated to all concerned parties, and this may begin by urging travelers to examine their actual vaccination status, particularly as the ecotourism industry continues its rapid expansion, and is seen increasingly as a possible tool to save great ape populations from extinction.
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Affiliation(s)
- Michael P Muehlenbein
- Department of Anthropology, Indiana University-Bloomington, 701 E. Kirkwood Avenue, Student Building 130, Bloomington, IN 47405, USA.
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503
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Parrish CR, Holmes EC, Morens DM, Park EC, Burke DS, Calisher CH, Laughlin CA, Saif LJ, Daszak P. Cross-species virus transmission and the emergence of new epidemic diseases. Microbiol Mol Biol Rev 2008; 72:457-70. [PMID: 18772285 PMCID: PMC2546865 DOI: 10.1128/mmbr.00004-08] [Citation(s) in RCA: 526] [Impact Index Per Article: 32.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Host range is a viral property reflecting natural hosts that are infected either as part of a principal transmission cycle or, less commonly, as "spillover" infections into alternative hosts. Rarely, viruses gain the ability to spread efficiently within a new host that was not previously exposed or susceptible. These transfers involve either increased exposure or the acquisition of variations that allow them to overcome barriers to infection of the new hosts. In these cases, devastating outbreaks can result. Steps involved in transfers of viruses to new hosts include contact between the virus and the host, infection of an initial individual leading to amplification and an outbreak, and the generation within the original or new host of viral variants that have the ability to spread efficiently between individuals in populations of the new host. Here we review what is known about host switching leading to viral emergence from known examples, considering the evolutionary mechanisms, virus-host interactions, host range barriers to infection, and processes that allow efficient host-to-host transmission in the new host population.
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Affiliation(s)
- Colin R Parrish
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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504
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White PCL, Böhm M, Marion G, Hutchings MR. Control of bovine tuberculosis in British livestock: there is no 'silver bullet'. Trends Microbiol 2008; 16:420-7. [PMID: 18706814 DOI: 10.1016/j.tim.2008.06.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2008] [Revised: 06/05/2008] [Accepted: 06/18/2008] [Indexed: 11/26/2022]
Abstract
Bovine tuberculosis (bTB; Mycobacterium bovis) is a bacterial infection of cattle that also affects certain wildlife species. Culling badgers (Meles meles), the principal wildlife host, results in perturbation of the badger population and an increased level of disease in cattle. Therefore, the priority for future management must be to minimize the risk of disease transmission by finding new ways to reduce the contact rate among the host community. At the farm level, targeting those individuals that represent an elevated risk of transmission might prove to be effective. At the landscape level, risk mapping can provide the basis for targeted surveillance of the host community. Here, we review the current evidence for bTB persistence in Britain and make recommendations for future management and research.
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Affiliation(s)
- Piran C L White
- Environment Department, University of York, Heslington, York, YO10 5DD, UK.
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505
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Lembo T, Hampson K, Haydon DT, Craft M, Dobson A, Dushoff J, Ernest E, Hoare R, Kaare M, Mlengeya T, Mentzel C, Cleaveland S. Exploring reservoir dynamics: a case study of rabies in the Serengeti ecosystem. J Appl Ecol 2008; 45:1246-1257. [PMID: 22427710 DOI: 10.1111/j.1365-2664.2008.01468.x] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Knowledge of infection reservoir dynamics is critical for effective disease control, but identifying reservoirs of multi-host pathogens is challenging. Here, we synthesize several lines of evidence to investigate rabies reservoirs in complex carnivore communities of the Serengeti ecological region in northwest Tanzania, where the disease has been confirmed in 12 carnivore species.Long-term monitoring data suggest that rabies persists in high-density domestic dog Canis familiaris populations (> 11 dogs km(-2)) and occurs less frequently in lower-density (< 5 dogs km(-2)) populations and only sporadically in wild carnivores.Genetic data show that a single rabies virus variant belonging to the group of southern Africa canid-associated viruses (Africa 1b) circulates among a range of species, with no evidence of species-specific virus-host associations.Within-species transmission was more frequently inferred from high-resolution epidemiological data than between-species transmission. Incidence patterns indicate that spill-over of rabies from domestic dog populations sometimes initiates short-lived chains of transmission in other carnivores.Synthesis and applications. The balance of evidence suggests that the reservoir of rabies in the Serengeti ecosystem is a complex multi-host community where domestic dogs are the only population essential for persistence, although other carnivores contribute to the reservoir as non-maintenance populations. Control programmes that target domestic dog populations should therefore have the greatest impact on reducing the risk of infection in all other species including humans, livestock and endangered wildlife populations, but transmission in other species may increase the level of vaccination coverage in domestic dog populations necessary to eliminate rabies.
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Affiliation(s)
- Tiziana Lembo
- Centre for Tropical Veterinary Medicine, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian EH25 9RG, UK
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506
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BAKER PHILIPJ, BOITANI LUIGI, HARRIS STEPHEN, SAUNDERS GLEN, WHITE PIRANCL. Terrestrial carnivores and human food production: impact and management. Mamm Rev 2008. [DOI: 10.1111/j.1365-2907.2008.00122.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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507
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Jones KE, Patel NG, Levy MA, Storeygard A, Balk D, Gittleman JL, Daszak P. Global trends in emerging infectious diseases. Nature 2008; 451:990-3. [PMID: 18288193 PMCID: PMC5960580 DOI: 10.1038/nature06536] [Citation(s) in RCA: 4227] [Impact Index Per Article: 264.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Accepted: 12/11/2007] [Indexed: 12/23/2022]
Abstract
Emerging infectious diseases are a major threat to health: AIDS, SARS, drug-resistant bacteria and Ebola virus are among the more recent examples. By identifying emerging disease 'hotspots', the thinking goes, it should be possible to spot health risks at an early stage and prepare containment strategies. An analysis of over 300 examples of disease emerging between 1940 and 2004 suggests that these hotspots can be accurately mapped based on socio-economic, environmental and ecological factors. The data show that the surveillance effort, and much current research spending, is concentrated in developed economies, yet the risk maps point to developing countries as the more likely source of new diseases. The origins of emerging infections diseases are significantly correlated with socio-economic, environmental and ecological factors. Emerging infectious diseases (EIDs) are a significant burden on global economies and public health1,2,3. Their emergence is thought to be driven largely by socio-economic, environmental and ecological factors1,2,3,4,5,6,7,8,9, but no comparative study has explicitly analysed these linkages to understand global temporal and spatial patterns of EIDs. Here we analyse a database of 335 EID ‘events’ (origins of EIDs) between 1940 and 2004, and demonstrate non-random global patterns. EID events have risen significantly over time after controlling for reporting bias, with their peak incidence (in the 1980s) concomitant with the HIV pandemic. EID events are dominated by zoonoses (60.3% of EIDs): the majority of these (71.8%) originate in wildlife (for example, severe acute respiratory virus, Ebola virus), and are increasing significantly over time. We find that 54.3% of EID events are caused by bacteria or rickettsia, reflecting a large number of drug-resistant microbes in our database. Our results confirm that EID origins are significantly correlated with socio-economic, environmental and ecological factors, and provide a basis for identifying regions where new EIDs are most likely to originate (emerging disease ‘hotspots’). They also reveal a substantial risk of wildlife zoonotic and vector-borne EIDs originating at lower latitudes where reporting effort is low. We conclude that global resources to counter disease emergence are poorly allocated, with the majority of the scientific and surveillance effort focused on countries from where the next important EID is least likely to originate.
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Affiliation(s)
- Kate E Jones
- Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK
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508
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509
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Hoberg EP, Polley L, Jenkins EJ, Kutz SJ, Veitch AM, Elkin BT. Integrated approaches and empirical models for investigation of parasitic diseases in northern wildlife. Emerg Infect Dis 2008; 14:10-7. [PMID: 18258071 PMCID: PMC2600137 DOI: 10.3201/eid1401.071119] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
A decade of research has yielded a multidisciplinary approach for detection, prediction, and potential mitigation measures. The North is a frontier for exploration of emerging infectious diseases and the large-scale drivers influencing distribution, host associations, and evolution of pathogens among persons, domestic animals, and wildlife. Leading into the International Polar Year 2007–2008, we outline approaches, protocols, and empirical models derived from a decade of integrated research on northern host–parasite systems. Investigations of emerging infectious diseases associated with parasites in northern wildlife involved a network of multidisciplinary collaborators and incorporated geographic surveys, archival collections, historical foundations for diversity, and laboratory and field studies exploring the interface for hosts, parasites, and the environment. In this system, emergence of parasitic disease was linked to geographic expansion, host switching, resurgence due to climate change, and newly recognized parasite species. Such integrative approaches serve as cornerstones for detection, prediction, and potential mitigation of emerging infectious diseases in wildlife and persons in the North and elsewhere under a changing global climate.
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Affiliation(s)
- Eric P Hoberg
- U.S. National Parasite Collection and Animal Parasitic Diseases Laboratory, U.S. Department of Agriculture Agricultural Research Service, Beltsville, MD 20705, USA.
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510
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Vial L, Wieland B, Jori F, Etter E, Dixon L, Roger F. African swine fever virus DNA in soft ticks, Senegal. Emerg Infect Dis 2008; 13:1928-31. [PMID: 18258050 PMCID: PMC2876773 DOI: 10.3201/eid1312.071022] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
African swine fever is a highly contagious disease of pigs in Africa. Although its persistence in Senegal may be caused by asymptomatic carriers involved in the domestic transmission cycle, we demonstrated that the soft tick Ornithodoros sonrai can be naturally infected with the causative agent.
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Affiliation(s)
- Laurence Vial
- French Agricultural Research Centre for International Development, Montpellier, France.
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511
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Pulliam JRC. Viral host jumps: moving toward a predictive framework. ECOHEALTH 2008; 5:80-91. [PMID: 18648800 PMCID: PMC7087992 DOI: 10.1007/s10393-007-0149-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 11/05/2007] [Accepted: 11/19/2007] [Indexed: 05/16/2023]
Abstract
In order to predict pathogen emergence, we must distinguish between emergence phenomena that occur via different processes. Focusing on the appearance of viral pathogens in new host species, I outline a framework that uses specific molecular characteristics to rank virus families by their expected a priori ability to complete each of three steps in the emergence process (encounter, infection, and propagation). I then discuss the degree to which the patterns expected, based solely on molecular-level structural characteristics, agree with observations regarding the ability of animal viruses to infect humans. This approach yields predictions consistent with empirical observations regarding the ability of specific viral families to infect novel host species but highlights the need for consideration of other factors, such as the ecology of host interactions and the determinants of cellular susceptibility and permissivity to specific virus groups, when trying to predict the frequency with which a virus will encounter a novel host species or the probability of propagation within a novel host species once infection has occurred.
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Affiliation(s)
- Juliet R C Pulliam
- Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA.
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512
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Abstract
The prevention and control of new pest and disease introductions is an agricultural challenge which is attracting growing public interest. This interest is in part driven by an impression that the threat is increasing, but there has been little analysis of the changing rates of biosecurity threat, and existing evidence is equivocal. Traditional biosecurity systems for animals and plants differ substantially but are beginning to converge. Bio-economic modelling of risk will be a valuable tool in guiding the allocation of limited resources for biosecurity. The future of prevention and management systems will be strongly influenced by new technology and the growing role of the private sector. Overall, today's biosecurity systems are challenged by changing national priorities regarding trade, by new concerns about environmental effects of biological invasions and by the question 'who pays?'. Tomorrow's systems may need to be quite different to be effective. We suggest three changes: an integration of plant and animal biosecurity around a common, proactive, risk-based approach; a greater focus on international cooperation to deal with threats at source; and a commitment to refocus biosecurity on building resilience to invasion into agroecosystems rather than building walls around them.
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Affiliation(s)
- J K Waage
- Centre for Environmental Policy, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
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513
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Roberts B. Influenza: Biology, Infection, and Control. EMERGING INFECTIONS IN ASIA 2008. [PMCID: PMC7120528 DOI: 10.1007/978-0-387-75722-3_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
The growth of the human population has profoundly affected the global ecosystem, influencing the animal population balance, the availability of fresh water, arable land, biotic production, and atmospheric gases. The human ecological impact has significantly accelerated the evolutionary change of numerous organisms. For example, the production of human medicine and food has resulted in the rapid evolution of drug-resistant pathogenic organisms as well as plants and insects resistant to pesticides (Palumbi, 2001). Recently, the nutritional support of the human population has relied on the vast monoculture of domestic mammals and birds, which has facilitated the emergence of pathogenic enzootic organisms that infect both animals and humans. This chapter will focus on the global threat to human health represented by the highly contagious enzootic virus influenza. It will also discuss current efforts and future improvements to protect humans from global influenza epidemics and pandemics.
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514
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Host specificity under molecular and experimental scrutiny. Trends Parasitol 2008; 24:24-8. [DOI: 10.1016/j.pt.2007.10.002] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 05/07/2007] [Accepted: 10/04/2007] [Indexed: 11/22/2022]
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515
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Boyard C, Vourc'h G, Barnouin J. The relationships between Ixodes ricinus and small mammal species at the woodland-pasture interface. EXPERIMENTAL & APPLIED ACAROLOGY 2008; 44:61-76. [PMID: 18247140 DOI: 10.1007/s10493-008-9132-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Accepted: 01/22/2008] [Indexed: 05/25/2023]
Abstract
Ixodes ricinus, as vector, and small mammals, as reservoirs, are implicated in pathogen transmission between wild fauna, domestic animals and humans at the woodland-pasture interface. The ecological relationship between ticks and small mammals was monitored in 2005 on four bocage (enclosed pastureland) sites in central France, where questing ticks were collected by dragging and small mammals were trapped. Questing I. ricinus tick and small mammal locations in the environment were assessed through correspondence analysis. I. ricinus larval burden on small mammals was modeled using a negative binomial law. The correspondence analyses underlined three landscape features: grassland, hedgerow, and woodland. Seven small mammal species were trapped, while questing ticks were all I. ricinus, with the highest abundance in woodland and the lowest in pasture. The small mammals were overall more abundant in hedgerow, less present in woodland and sparse in grassland. They carried mainly I. ricinus, and secondarily I. acuminatus and I. trianguliceps. The most likely profile for a tick-infested small mammal corresponded to a male wood mouse (Apodemus sylvaticus) in woodland or hedgerow during a dry day. A. sylvaticus, which was the only species captured in grassland, but was also present in hedgerow and woodland, may be a primary means of transfer of I. ricinus larvae from woodland to pasture.
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Affiliation(s)
- Chloé Boyard
- INRA (Institut National de la Recherche Agronomique), UR346 Epidémiologie Animale, 63122 Saint Genes Champanelle, France
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516
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French NP, Gemmell NJ, Buddle BM. Advances in biosecurity to 2010 and beyond: towards integrated detection, analysis and response to exotic pest invasions. N Z Vet J 2007; 55:255-63. [PMID: 18059642 DOI: 10.1080/00480169.2007.36779] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In order to limit the number and impact of exotic pest invasions, leading-edge technologies must be embraced and embedded within integrated national and international biosecurity systems. Outlined here are recent advances in the detection of exotic pests, and prospects for the early recognition of disease. Applications of new tools are described, using our understanding of the genomes of pathogens and vectors. In addition, the role of mathematical and simulation models to aid both biosecurity planning, and decision making in the face of an epidemic, are discussed, and recent attempts to unify epidemiology and evolutionary dynamics are outlined. Given the importance of emerging diseases and zoonoses, the need to align human and veterinary surveillance within fully integrated systems is underlined.
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Affiliation(s)
- N P French
- Institute of Veterinary, Animal, and Biomedical Sciences, Massey University Private Bag 11222 Palmerston North, New Zealand.
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517
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Brooks DR, Hoberg EP. How will global climate change affect parasite–host assemblages? Trends Parasitol 2007; 23:571-4. [DOI: 10.1016/j.pt.2007.08.016] [Citation(s) in RCA: 229] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2007] [Revised: 08/08/2007] [Accepted: 08/10/2007] [Indexed: 11/27/2022]
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518
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Lembo T, Haydon DT, Velasco-Villa A, Rupprecht CE, Packer C, Brandão PE, Kuzmin IV, Fooks AR, Barrat J, Cleaveland S. Molecular epidemiology identifies only a single rabies virus variant circulating in complex carnivore communities of the Serengeti. Proc Biol Sci 2007; 274:2123-30. [PMID: 17609187 PMCID: PMC2279181 DOI: 10.1098/rspb.2007.0664] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Understanding the transmission dynamics of generalist pathogens that infect multiple host species is essential for their effective control. Only by identifying those host populations that are critical to the permanent maintenance of the pathogen, as opposed to populations in which outbreaks are the result of 'spillover' infections, can control measures be appropriately directed. Rabies virus is capable of infecting a wide range of host species, but in many ecosystems, particular variants circulate among only a limited range of potential host populations. The Serengeti ecosystem (in northwestern Tanzania) supports a complex community of wild carnivores that are threatened by generalist pathogens that also circulate in domestic dog populations surrounding the park boundaries. While the combined assemblage of host species appears capable of permanently maintaining rabies in the ecosystem, little is known about the patterns of circulation within and between these host populations. Here we use molecular phylogenetics to test whether distinct virus-host associations occur in this species-rich carnivore community. Our analysis identifies a single major variant belonging to the group of southern Africa canid-associated viruses (Africa 1b) to be circulating within this ecosystem, and no evidence for species-specific grouping. A statistical parsimony analysis of nucleoprotein and glycoprotein gene sequence data is consistent with both within- and between-species transmission events. While likely differential sampling effort between host species precludes a definitive inference, the results are most consistent with dogs comprising the reservoir of rabies and emphasize the importance of applying control efforts in dog populations.
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Affiliation(s)
- T Lembo
- Wildlife and Emerging Diseases Section, Centre for Tropical Veterinary Medicine, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush Veterinary Centre, Roslin, Midlothian, Edinburgh EH25 9RG, UK.
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519
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Pedersen AB, Jones KE, Nunn CL, Altizer S. Infectious diseases and extinction risk in wild mammals. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2007; 21:1269-79. [PMID: 17883492 PMCID: PMC7202242 DOI: 10.1111/j.1523-1739.2007.00776.x] [Citation(s) in RCA: 196] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2007] [Accepted: 05/01/2007] [Indexed: 05/17/2023]
Abstract
Parasite-driven declines in wildlife have become increasingly common and can pose significant risks to natural populations. We used the IUCN Red List of Threatened and Endangered Species and compiled data on hosts threatened by infectious disease and their parasites to better understand the role of infectious disease in contemporary host extinctions. The majority of mammal species considered threatened by parasites were either carnivores or artiodactyls, two clades that include the majority of domesticated animals. Parasites affecting host threat status were predominantly viruses and bacteria that infect a wide range of host species, including domesticated animals. Counter to our predictions, parasites transmitted by close contact were more likely to cause extinction risk than those transmitted by other routes. Mammal species threatened by parasites were not better studied for infectious diseases than other threatened mammals and did not have more parasites or differ in four key traits demonstrated to affect parasite species richness in other comparative studies. Our findings underscore the need for better information concerning the distribution and impacts of infectious diseases in populations of endangered mammals. In addition, our results suggest that evolutionary similarity to domesticated animals may be a key factor associated with parasite-mediated declines; thus, efforts to limit contact between domesticated hosts and wildlife could reduce extinction risk.
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Affiliation(s)
- Amy B Pedersen
- Odum School of Ecology, University of Georgia, Athens, GA 30602, USA.
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520
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Böhm M, White PCL, Chambers J, Smith L, Hutchings MR. Wild deer as a source of infection for livestock and humans in the UK. Vet J 2007; 174:260-76. [PMID: 17258479 DOI: 10.1016/j.tvjl.2006.11.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Revised: 08/31/2006] [Accepted: 11/03/2006] [Indexed: 10/23/2022]
Abstract
Wild deer can feature in the epidemiology of a wide range of livestock and human diseases in the United Kingdom by representing a source of disease via various transmission routes. This review highlights current and possible future infections of deer in the UK which may have an impact on livestock and/or human health. Increases in deer abundance as well as range expansion are likely to exacerbate the potential for disease persistence due to the formation of multi-species deer assemblages, which may act as disease reservoirs. Climatic changes are likely to have a direct impact on the presence and abundance of various pathogens and their vectors, so that with a warming climate exotic diseases may play a role in future UK livestock and wildlife disease management. This paper highlights the need for a monitoring strategy for wildlife diseases, in particular infections in wild deer, in the UK.
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Affiliation(s)
- Monika Böhm
- Environment Department, University of York, Heslington, York YO10 5DD, UK
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521
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Barros de Freitas R, Durigon EL, Oliveira DDS, Romano CM, Castro de Freitas MR, Linhares ADC, Melo FL, Walshkeller L, Barbosa ML, Huatuco EMM, Holmes EC, Zanotto PMDA. The "pressure pan" evolution of human erythrovirus B19 in the Amazon, Brazil. Virology 2007; 369:281-7. [PMID: 17698162 DOI: 10.1016/j.virol.2007.07.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/02/2007] [Accepted: 07/03/2007] [Indexed: 11/22/2022]
Abstract
To understand the evolutionary dynamics of human parvovirus B19, we analyzed VP1 and VP2 gene sequences of B19 sampled from Belém (Amazon), the city of São Paulo, Brazil and globally. Our analysis revealed a strikingly different pattern of evolutionary change for those viral lineages introduced into Belém, which exhibited a higher rate of nonsynonymous substitutions compared to those viruses sampled from other locations. We propose that difference this is due to the high prevalence of B19 in Belém (up to 85%) compared to other locations (prevalences of approximately 50%), which imposes a more intense selection pressure. Hence, those B19 lineages introduced into Belém experienced an elevated rate of amino acid change, driven by positive selection, in order to generate serial re-infections in a small web of transmission, which can be thought of as an evolutionary "pressure pan".
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Affiliation(s)
- Ronaldo Barros de Freitas
- Seção de Virologia, Instituto Evandro Chagas, Secretaria de Vigilância em Saúde, Ministério da Saúde, Belém, Brazil
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522
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Chua KB, Crameri G, Hyatt A, Yu M, Tompang MR, Rosli J, McEachern J, Crameri S, Kumarasamy V, Eaton BT, Wang LF. A previously unknown reovirus of bat origin is associated with an acute respiratory disease in humans. Proc Natl Acad Sci U S A 2007; 104:11424-9. [PMID: 17592121 PMCID: PMC1899191 DOI: 10.1073/pnas.0701372104] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Indexed: 01/19/2023] Open
Abstract
Respiratory infections constitute the most widespread human infectious disease, and a substantial proportion of them are caused by unknown etiological agents. Reoviruses (respiratory enteric orphan viruses) were first isolated from humans in the early 1950s and so named because they were not associated with any known disease. Here, we report a previously unknown reovirus (named "Melaka virus") isolated from a 39-year-old male patient in Melaka, Malaysia, who was suffering from high fever and acute respiratory disease at the time of virus isolation. Two of his family members developed similar symptoms approximately 1 week later and had serological evidence of infection with the same virus. Epidemiological tracing revealed that the family was exposed to a bat in the house approximately 1 week before the onset of the father's clinical symptoms. Genome sequence analysis indicated a close genetic relationship between Melaka virus and Pulau virus, a reovirus isolated in 1999 from fruit bats in Tioman Island, Malaysia. Screening of sera collected from human volunteers on the island revealed that 14 of 109 (13%) were positive for both Pulau and Melaka viruses. This is the first report of an orthoreovirus in association with acute human respiratory diseases. Melaka virus is serologically not related to the different types of mammalian reoviruses that were known to infect humans asymptomatically. These data indicate that bat-borne reoviruses can be transmitted to and cause clinical diseases in humans.
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Affiliation(s)
- Kaw Bing Chua
- *National Public Health Laboratory, Selangor 4700, Malaysia; and
| | - Gary Crameri
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | - Alex Hyatt
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | - Meng Yu
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | | | - Juliana Rosli
- *National Public Health Laboratory, Selangor 4700, Malaysia; and
| | - Jennifer McEachern
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | - Sandra Crameri
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | | | - Bryan T. Eaton
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
| | - Lin-Fa Wang
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, Australian Animal Health Laboratory and Australian Biosecurity Cooperative Research Center for Emerging Infectious Diseases, Geelong, Victoria 3220, Australia
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523
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Altizer S, Nunn CL, Lindenfors P. Do threatened hosts have fewer parasites? A comparative study in primates. J Anim Ecol 2007; 76:304-14. [PMID: 17302838 DOI: 10.1111/j.1365-2656.2007.01214.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
1. Parasites and infectious diseases have become a major concern in conservation biology, in part because they can trigger or accelerate species or population declines. Focusing on primates as a well-studied host clade, we tested whether the species richness and prevalence of parasites differed between threatened and non-threatened host species. 2. We collated data on 386 species of parasites (including viruses, bacteria, protozoa, helminths and arthropods) reported to infect wild populations of 36 threatened and 81 non-threatened primate species. Analyses controlled for uneven sampling effort and host phylogeny. 3. Results showed that total parasite species richness was lower among threatened primates, supporting the prediction that small, isolated host populations harbour fewer parasite species. This trend was consistent across three major parasite groups found in primates (helminths, protozoa and viruses). Counter to our predictions, patterns of parasite species richness were independent of parasite transmission mode and the degree of host specificity. 4. We also examined the prevalence of selected parasite genera among primate sister-taxa that differed in their ranked threat categories, but found no significant differences in prevalence between threatened and non-threatened hosts. 5. This study is the first to demonstrate differences in parasite richness relative to host threat status. Results indicate that human activities and host characteristics that increase the extinction risk of wild animal species may lead simultaneously to the loss of parasites. Lower average parasite richness in threatened host taxa also points to the need for a better understanding of the cascading effects of host biodiversity loss for affiliated parasite species.
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Affiliation(s)
- Sonia Altizer
- Institute of Ecology, University of Georgia, Athens, GA 30602, USA.
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524
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Anderson PK, Cunningham AA, Patel NG, Morales FJ, Epstein PR, Daszak P. Emerging infectious diseases of plants: pathogen pollution, climate change and agrotechnology drivers. Trends Ecol Evol 2007; 19:535-44. [PMID: 16701319 DOI: 10.1016/j.tree.2004.07.021] [Citation(s) in RCA: 719] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2004] [Revised: 07/19/2004] [Accepted: 07/30/2004] [Indexed: 11/20/2022]
Abstract
Emerging infectious diseases (EIDs) pose threats to conservation and public health. Here, we apply the definition of EIDs used in the medical and veterinary fields to botany and highlight a series of emerging plant diseases. We include EIDs of cultivated and wild plants, some of which are of significant conservation concern. The underlying cause of most plant EIDs is the anthropogenic introduction of parasites, although severe weather events are also important drivers of disease emergence. Much is known about crop plant EIDs, but there is little information about wild-plant EIDs, suggesting that their impact on conservation is underestimated. We conclude with recommendations for improving strategies for the surveillance and control of plant EIDs.
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525
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Goater CP, Colwell DD. EPIDEMIOLOGICAL CHARACTERISTICS OF AN INVADING PARASITE: DICROCOELIUM DENDRITICUM IN SYMPATRIC WAPITI AND BEEF CATTLE IN SOUTHERN ALBERTA, CANADA. J Parasitol 2007; 93:491-4. [PMID: 17626339 DOI: 10.1645/ge-1060r.1] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Previous surveys of wild ungulates indicate that the liver fluke, Dicrocoelium dendriticum, was rare in the Cypress Hills area of southeastern Alberta. However, 41 of 59 wapiti (Cervus elaphus) sampled during the 2003 and 2004 hunting seasons from this region were infected, with 7 hosts containing >1,000 worms. Prevalence and mean intensity were similarly high in sympatric beef cattle and mule deer. Worm abundance in wapiti was age related, with calves containing significantly higher numbers of worms (mean +/- SD abundance = 825 +/- 1098) than adults (107 +/- 259). This pattern with host age was not evident in beef cattle, although the smaller sample sizes may be a contributing factor. These results indicate that D. dendriticum is now well established in Cypress Hills Park, circulating between at least 3 species of sympatric ungulates, including beef cattle.
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Affiliation(s)
- Cameron P Goater
- Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta, T1K 3M4 Canada.
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526
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Affiliation(s)
- Mariah E. Hopkins
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA 94720‐3114, USA,
| | - Charles L. Nunn
- Max Planck Institute for Evolutionary Anthropology, D‐04103 Leipzig, Germany,
- Department of Integrative Biology, Berkeley, University of California, CA 94720‐3140, USA
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527
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Cleaveland S, Mlengeya T, Kaare M, Haydon D, Lembo T, Laurenson MK, Packer C. The conservation relevance of epidemiological research into carnivore viral diseases in the serengeti. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2007; 21:612-22. [PMID: 17531040 DOI: 10.1111/j.1523-1739.2007.00701.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Recent outbreaks of rabies and canine distemper in wildlife populations of the Serengeti show that infectious disease constitutes a significant cause of mortality that can result in regional extirpation of endangered species even within large, well-protected areas. Nevertheless, effective management of an infectious disease depends critically on understanding the epidemiological dynamics of the causative pathogen. Pathogens with short infection cycles cannot persist in small populations in the absence of a more permanent reservoir of infection. Development of appropriate interventions requires detailed data on transmission pathways between reservoirs and wildlife populations of conservation concern. Relevant data can be derived from long-term population monitoring, epidemic and case-surveillance patterns, genetic analyses of rapidly evolving pathogens, serological surveys, and intervention studies. We examined studies of carnivore diseases in the Serengeti. Epidemiological research contributes to wildlife conservation policy in terms of management of endangered populations and the integration of wildlife conservation with public health interventions. Long-term, integrative, cross-species research is essential for formulation of effective policy for disease control and optimization of ecosystem health.
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Affiliation(s)
- Sarah Cleaveland
- Wildlife and Emerging Diseases Section, Centre for Tropical Veterinary Medicine, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin, Midlothian, EH25 9RG, United Kingdom.
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528
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McCarthy ND, Colles FM, Dingle KE, Bagnall MC, Manning G, Maiden MCJ, Falush D. Host-associated genetic import in Campylobacter jejuni. Emerg Infect Dis 2007; 13:267-72. [PMID: 17479890 PMCID: PMC2063414 DOI: 10.3201/eid1302.060620] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
C. jejuni genomes have a host signature that enables attribution of isolates to animal sources. Establishing sources of human infection supports effective disease control measures. Host association with Campylobacter jejuni was analyzed by using multilocus sequence typing data for 713 isolates from chickens and bovids (cattle and sheep). Commonly used summary measures of genotypes (sequence type and clonal complex) showed poor accuracy, but a method using the full allelic profile showed 80% accuracy in distinguishing isolates from these 2 host groups. We explored the biologic basis of more accurate results with allelic profiles. Strains isolated from specific hosts have imported a substantial number of alleles while circulating in those host species. These results imply that 1) although Campylobacter moves frequently between hosts, most transmission is within species, and 2) lineages can acquire a host signature and potentially adapt to the host through recombination. Assignment using this signature enables improved prediction of source for pathogens that undergo frequent genetic recombination.
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Affiliation(s)
- Noel D McCarthy
- Department of Zoology, University of Oxford, Oxford, United Kingdom.
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529
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Abstract
TOC Summary: The discovery of SARS-like coronaviruses in horseshoe bats highlights the possibility of future outbreaks caused by different coronaviruses of bat origin. Bats have been identified as a natural reservoir for an increasing number of emerging zoonotic viruses, including henipaviruses and variants of rabies viruses. Recently, we and another group independently identified several horseshoe bat species (genus Rhinolophus) as the reservoir host for a large number of viruses that have a close genetic relationship with the coronavirus associated with severe acute respiratory syndrome (SARS). Our current research focused on the identification of the reservoir species for the progenitor virus of the SARS coronaviruses responsible for outbreaks during 2002–2003 and 2003–2004. In addition to SARS-like coronaviruses, many other novel bat coronaviruses, which belong to groups 1 and 2 of the 3 existing coronavirus groups, have been detected by PCR. The discovery of bat SARS-like coronaviruses and the great genetic diversity of coronaviruses in bats have shed new light on the origin and transmission of SARS coronaviruses.
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Affiliation(s)
- Lin-Fa Wang
- Australian Animal Health Laboratory, Geelong, Victoria, Australia.
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530
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Abstract
Wildlife and exotic pets represent large reservoirs for emerging zoonoses. Most emerging infectious diseases are zoonotic; wildlife constitutes a large and often unknown reservoir. Wildlife can also be a source for reemergence of previously controlled zoonoses. Although the discovery of such zoonoses is often related to better diagnostic tools, the leading causes of their emergence are human behavior and modifications to natural habitats (expansion of human populations and their encroachment on wildlife habitat), changes in agricultural practices, and globalization of trade. However, other factors include wildlife trade and translocation, live animal and bushmeat markets, consumption of exotic foods, development of ecotourism, access to petting zoos, and ownership of exotic pets. To reduce risk for emerging zoonoses, the public should be educated about the risks associated with wildlife, bushmeat, and exotic pet trades; and proper surveillance systems should be implemented.
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Affiliation(s)
- Bruno B Chomel
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California 95616, USA.
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531
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Farm husbandry and the risks of disease transmission between wild and domestic mammals: a brief review focusing on bovine tuberculosis in badgers and cattle. ACTA ACUST UNITED AC 2007. [DOI: 10.1017/asc2006102] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractWhere wildlife act as a reservoir of disease for domestic mammals, measures solely based on management of either in isolation are unlikely to resolve the problem. Many such diseases can have serious economic implications for farmers and the economy and their management can present considerable challenges. Traditionally, wildlife populations have been culled in attempts to reduce the risks of disease transmission to livestock (e.g. bovine tuberculosis in European badgers and brushtail possums). However, this may be both undesirable and potentially counter-productive in some circumstances. Consequently, in recent years increasing attention has focused on changing livestock husbandry and farm management practices so as to reduce risks of disease transmission from wildlife to livestock. Here we present a brief review of husbandry and farm management practices that may influence disease transmission risks from wild to domestic mammals, with particular attention to bovine tuberculosis in the UK. We conclude that the manipulation of farming practices could potentially make a significant contribution to disease risk management. However, there are currently scant empirical data on risk reduction methods and further information will undoubtedly be required to inform husbandry best-practice.
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532
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Abstract
In field experiments manipulating generalist pathogens and host community composition, the presence of a highly susceptible reservoir species drove disease dynamics in multiple nonreservoir species, sometimes decreasing their abundance through apparent competition. The dynamics of generalist pathogens in multispecies host communities remain a major frontier for disease ecology. Of particular interest are how host community structure controls pathogen transmission and how disease spread feeds back to influence the host community. Pathogen spillover occurs when epidemics in a host population are driven not by transmission within that population but by transmission from a reservoir population. Here we review examples of spillover in pathogens infecting humans, domesticated animals, and crops, noting that most empirical evidence for spillover results from nonmanipulative, observational studies. We then present results from two field experiments utilizing an experimentally tractable model system of annual wild grasses and a generalist virus, the barley yellow dwarf virus. In these experiments, the presence of a highly susceptible reservoir species, Avena fatua (wild oats), greatly increased pathogen prevalence in several other species. This result demonstrates pathogen spillover and illustrates the crucial role of host community structure in controlling the dynamics of generalist pathogens. Further, pathogen spillover from A. fatua decreased the abundance of two other host species through pathogen-mediated apparent competition. Thus, our results provide experimental support for theoretical predictions of strong feedbacks between host community structure and generalist disease dynamics.
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Affiliation(s)
- Alison G Power
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York 14853, USA.
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533
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Childs JE, Mackenzie JS, Richt JA. Introduction: conceptualizing and partitioning the emergence process of zoonotic viruses from wildlife to humans. Curr Top Microbiol Immunol 2007; 315:1-31. [PMID: 17848058 PMCID: PMC7122288 DOI: 10.1007/978-3-540-70962-6_1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
This introduction provides a telegraphic overview of the processes of zoonotic viral emergence, the intricacies of host-virus interactions, and the distinct role of biological transitions and modifying factors. The process of emergence is conceptualized as two transition stages which are common and required for all disease emergence, (1) human contact with the infectious agent and (2) cross-species transmission of the agent, and two transition stages which are not required for emergence and appear unavailable to many zoonotic pathogens, (3) sustained human-to-human transmission and (4) genetic adaptation to the human host. The latter two transitions are presumably prerequisites for the pandemic emergence of a pathogen. The themes introduced herein are amplified and explored in detail by the contributors to this volume. Each author explores the mechanisms and unique circumstances by which evolution, biology, history, and current context have contrived to drive the emergence of different zoonotic agents by a series of related events; although recognizable similarities exist among the events leading to emergence the details and circumstances are never repetitive.
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Affiliation(s)
- James E. Childs
- Department of Epidemiology and Public Health and Center for Eco-Epidemiolog, Yale University School of Medicine, 60 College St, 208034, 06520-8034 New Haven, CT USA
| | - John S. Mackenzie
- Centre for Emerging Infectious Diseases, Australian Biosecurity Cooperative Research Centre, Curtin University of Technology, U1987, 6845 Perth, WA Australia
| | - Jürgen A. Richt
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center USDA, 2300 Dayton Ave Ames, 50010 IA USA
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534
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Abstract
Despite the wealth of data describing the ecological factors that underpin viral emergence, little is known about the evolutionary processes that allow viruses to jump species barriers and establish productive infections in new hosts. Understanding the evolutionary basis to virus emergence is therefore a key research goal and many of the debates in this area can be considered within the rigorous theoretical framework established by evolutionary genetics. In particular, the respective roles played by natural selection and genetic drift in shaping genetic diversity are also of fundamental importance for understanding the nature of viral emergence. Herein, we discuss whether there are evolutionary rules to viral emergence, and especially whether certain types of virus, or those that infect a particular type of host species, are more likely to emerge than others. We stress the complex interplay between rates of viral evolution and the ability to recognize cell receptors from phylogenetically divergent host species. We also emphasize the current lack of convincing data as to whether viral emergence requires adaptation to the new host species during the early stages of infection, or whether it is largely a chance process involving the transmission of a viral strain with the necessary genetic characteristics.
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Affiliation(s)
- James E. Childs
- Department of Epidemiology and Public Health and Center for Eco-Epidemiolog, Yale University School of Medicine, 60 College St, 208034, 06520-8034 New Haven, CT USA
| | - John S. Mackenzie
- Centre for Emerging Infectious Diseases, Australian Biosecurity Cooperative Research Centre, Curtin University of Technology, U1987, 6845 Perth, WA Australia
| | - Jürgen A. Richt
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center USDA, 2300 Dayton Ave Ames, 50010 IA USA
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535
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Bastolla U, Porto M, Roman HE, Vendruscolo M. Genetic Variability in RNA Viruses: Consequences in Epidemiology and in the Development of New Stratgies for the Extinction of Infectivity. STRUCTURAL APPROACHES TO SEQUENCE EVOLUTION 2007. [PMCID: PMC7123777 DOI: 10.1007/978-3-540-35306-5_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Ugo Bastolla
- Fac. de Ciencias, Universidad Autonoma Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Markus Porto
- Institut für Festkörperphysik, TU Darmstadt, Hochschulstr. 8, 64289 Darmstadt, Germany
| | - H. Eduardo Roman
- Dipartimento di Fisica, Universita di Milano-Bicocca, Piazza della Scienza 3, 29126 Milano, Italy
| | - Michele Vendruscolo
- Department of Chemistry, University of Cambridge, Lensfield Road, CB2 1EW Cambridge, UK
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536
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Craig PS, Budke CM, Schantz PM, Li T, Qiu J, Yang Y, Zeyhle E, Rogan MT, Ito A. Human Echinococcosis: A Neglected Disease? Trop Med Health 2007. [DOI: 10.2149/tmh.35.283] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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537
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Childs JE, Mackenzie JS, Richt JA. Pre-spillover prevention of emerging zoonotic diseases: what are the targets and what are the tools? Curr Top Microbiol Immunol 2007; 315:389-443. [PMID: 17848073 PMCID: PMC7120954 DOI: 10.1007/978-3-540-70962-6_16] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The uneven standards of surveillance, human- or animal-based, for zoonotic diseases or pathogens maintained and transmitted by wildlife H(R)s, or even domestic species, is a global problem, readily apparent even within the United States, where investment in public health, including surveillance systems, has a long and enviable history. As of 2006, there appears to be little scientific, social, or political consensus that animal-based surveillance for zoonoses merits investment in international infrastructure, other than the fledgling efforts with avian influenza, or targeted nontraditional avenues of surveillance and research. National institutions charged with strategic planning for emerging diseases or intentional releases of zoonotic agents have emphasized improving diagnostic capabilities for detecting human infections, modifying the immune status of human or domestic animals through vaccines, producing better antiviral or antibacterial drugs, and enhancing human-based surveillance as an early warning system. With the possible exception of extensive human vaccination, each of these approaches target post-spillover events and none of these avenues of research will have the slightest impact on reducing the risk of additional emergence of viruses or other pathogens from wildlife. Novel schemes of preventing spillover of human pathogens from animal H(R)s can only spring from improving our understanding of the ecological context and biological interactions of pathogen maintenance among H(R)s. Although the benefit derived from investments to improve surveillance and knowledge of zoonotic pathogens circulating among wildlife H(R) populations is uncertain, our experience with HIV and the looming threat of pandemic avian influenza A inform us of the outcomes we can expect by relying on detection of post-spillover events among sentinel humans.
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Affiliation(s)
- James E. Childs
- Department of Epidemiology and Public Health and Center for Eco-Epidemiolog, Yale University School of Medicine, 60 College St, 208034, 06520-8034 New Haven, CT USA
| | - John S. Mackenzie
- Centre for Emerging Infectious Diseases, Australian Biosecurity Cooperative Research Centre, Curtin University of Technology, U1987, 6845 Perth, WA Australia
| | - Jürgen A. Richt
- Virus and Prion Diseases of Livestock Research Unit, National Animal Disease Center USDA, 2300 Dayton Ave Ames, 50010 IA USA
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538
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Pioz M, Loison A, Gibert P, Dubray D, Menaut P, Le Tallec B, Artois M, Gilot-Fromont E. Transmission of a pestivirus infection in a population of Pyrenean chamois. Vet Microbiol 2007; 119:19-30. [PMID: 17092662 DOI: 10.1016/j.vetmic.2006.09.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2006] [Revised: 09/04/2006] [Accepted: 09/05/2006] [Indexed: 11/24/2022]
Abstract
Outbreaks of a previously unrecorded disease have recently affected Pyrenean chamois (Rupicapra pyrenaica pyrenaica) populations across the mountain range. A pestivirus was hypothesized to be the cause of this emerging disease and this type of virus can cross the species barrier and be transmitted to or from wildlife. Using an epidemiological survey conducted from 1995 to 2004 at Orlu, France, we characterized the virus and analyzed its transmission. A phylogenetic analysis of viral sequences and virus neutralization tests showed that the virus belonged to the newly described border disease virus-4 group. The increase of seroprevalence with age indicated that infection can occur at any age and resulted in lifelong immunity. Overall, 70.3% of 323 samples were positive for anti-p80 antibodies and 10.2% of 167 samples showed viremia, as demonstrated by either positive ELISA antigen test or RT-PCR. Infection has thus been widespread in this population since 1995, whereas no mass mortality or clinical signs have been observed. Incidence and seroprevalence varied seasonally and according to number of individuals aged less than 2 years old in the population, so viral transmission was dependent on host population age structure. We propose that the virus is now endemic in this population and is likely detrimental for reproduction and juveniles. Further investigation is needed to estimate the impact of pestivirus on host population dynamics and the risk of cross-transmission to farm animals.
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Affiliation(s)
- Maryline Pioz
- Laboratoire de Biométrie et Biologie Evolutive (UMR 5558), CNRS, Université Claude Bernard Lyon 1, 43 Boulevard 11 Nov 1918, 69622 Villeurbanne Cedex, France
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539
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Zoonosis emergentes. un reto interdisciplinar. GACETA MÉDICA DE BILBAO 2007. [PMCID: PMC7148768 DOI: 10.1016/s0304-4858(07)74559-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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540
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Malpica JM, Sacristán S, Fraile A, García-Arenal F. Association and host selectivity in multi-host pathogens. PLoS One 2006; 1:e41. [PMID: 17183670 PMCID: PMC1762347 DOI: 10.1371/journal.pone.0000041] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2006] [Accepted: 10/02/2006] [Indexed: 11/21/2022] Open
Abstract
The distribution of multi-host pathogens over their host range conditions their population dynamics and structure. Also, host co-infection by different pathogens may have important consequences for the evolution of hosts and pathogens, and host-pathogen co-evolution. Hence it is of interest to know if the distribution of pathogens over their host range is random, or if there are associations between hosts and pathogens, or between pathogens sharing a host. To analyse these issues we propose indices for the observed patterns of host infection by pathogens, and for the observed patterns of co-infection, and tests to analyse if these patterns conform to randomness or reflect associations. Applying these tests to the prevalence of five plant viruses on 21 wild plant species evidenced host-virus associations: most hosts and viruses were selective for viruses and hosts, respectively. Interestingly, the more host-selective viruses were the more prevalent ones, suggesting that host specialisation is a successful strategy for multi-host pathogens. Analyses also showed that viruses tended to associate positively in co-infected hosts. The developed indices and tests provide the tools to analyse how strong and common are these associations among different groups of pathogens, which will help to understand and model the population biology of multi-host pathogens.
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Affiliation(s)
- José M. Malpica
- Departamento de Biotecnología, Instituto Nacional de Investigación Agraria y AlimentariaMadrid, Spain
| | - Soledad Sacristán
- Departamento de Biotecnología y Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
| | - Aurora Fraile
- Departamento de Biotecnología y Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
| | - Fernando García-Arenal
- Departamento de Biotecnología y Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de MadridMadrid, Spain
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541
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Bradley CA, Altizer S. Urbanization and the ecology of wildlife diseases. Trends Ecol Evol 2006; 22:95-102. [PMID: 17113678 PMCID: PMC7114918 DOI: 10.1016/j.tree.2006.11.001] [Citation(s) in RCA: 421] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 09/28/2006] [Accepted: 11/07/2006] [Indexed: 01/29/2023]
Abstract
Urbanization is intensifying worldwide, with two-thirds of the human population expected to reside in cities within 30 years. The role of cities in human infectious disease is well established, but less is known about how urban landscapes influence wildlife–pathogen interactions. Here, we draw on recent advances in wildlife epidemiology to consider how environmental changes linked with urbanization can alter the biology of hosts, pathogens and vectors. Although urbanization reduces the abundance of many wildlife parasites, transmission can, in some cases, increase among urban-adapted hosts, with effects on rarer wildlife or those living beyond city limits. Continued rapid urbanization, together with risks posed by multi-host pathogens for humans and vulnerable wildlife populations, emphasize the need for future research on wildlife diseases in urban landscapes.
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542
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Telfer S, Begon M, Bennett M, Bown KJ, Burthe S, Lambin X, Telford G, Birtles R. Contrasting dynamics of Bartonella spp. in cyclic field vole populations: the impact of vector and host dynamics. Parasitology 2006; 134:413-25. [PMID: 17096870 PMCID: PMC2952920 DOI: 10.1017/s0031182006001624] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 09/12/2006] [Accepted: 09/13/2006] [Indexed: 11/07/2022]
Abstract
Many zoonotic disease agents are transmitted between hosts by arthropod vectors, including fleas, but few empirical studies of host-vector-microparasite dynamics have investigated the relative importance of hosts and vectors. This study investigates the dynamics of 4 closely related Bartonella species and their flea vectors in cyclic populations of field voles (Microtus agrestis) over 3 years. The probability of flea infestation was positively related to field vole density 12 months previously in autumn, but negatively related to more recent host densities, suggesting a dilution effect. The 4 Bartonella species exhibited contrasting dynamics. Only B. grahamii, showed a distinct seasonal pattern. Infection probability increased with field vole density for B. doshiae, B. taylorii and BGA (a previously unidentified species) and with density of coexisting wood mice for B. doshiae and B. grahamii. However, only the infection probability of BGA in spring was related to flea prevalence. B. doshiae and BGA were most common in older animals, but the other 2 were most common in non-reproductive hosts. Generally, host density rather than vector abundance appears most important for the dynamics of flea-transmitted Bartonella spp., possibly reflecting the importance of flea exchange between hosts. However, even closely related species showed quite different dynamics, emphasising that other factors such as population age structure can impact on zoonotic risk.
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Affiliation(s)
- S Telfer
- School of Biological Sciences, University of Liverpool, Biosciences Building, Liverpool L69 7LB, UK.
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543
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Cowen P, Garland T, Hugh-Jones ME, Shimshony A, Handysides S, Kaye D, Madoff LC, Pollack MP, Woodall J. Evaluation of ProMED-mail as an electronic early warning system for emerging animal diseases: 1996 to 2004. J Am Vet Med Assoc 2006; 229:1090-9. [PMID: 17014355 DOI: 10.2460/javma.229.7.1090] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To identify emerging animal and zoonotic diseases and associated geographic distribution, disease agents, animal hosts, and seasonality of reporting in the Program for Monitoring Emerging Diseases (ProMED)-mail electronic early warning system. DESIGN Retrospective study. SAMPLE POPULATION 10,490 disease reports. PROCEDURES Descriptive statistics were collated for all animal disease reports appearing on the ProMED-mail system from January 1, 1996, to December 31, 2004. RESULTS Approximately 30% of reports concerned events in the United States; reports were next most common in the United Kingdom, Canada, Australia, Russia, and China. Rabies, bovine spongiform encephalopathy, and anthrax were reported consistently over the study period, whereas avian influenza, Ebola virus, and Hantavirus infection were reported frequently in approximately half of the study years. Reports concerning viral agents composed more than half of the postings. Humans affected by zoonotic disease accounted for a third of the subjects. Cattle were affected in 1,080 reports, and wildlife species were affected in 825 reports. For the 10,490 postings studied, there was a retraction rate of 0.01 and a correction rate of 0.02. CONCLUSIONS AND CLINICAL RELEVANCE ProMED-mail provided global coverage, but gaps in coverage for individual countries were detected. The value of a global electronic reporting system for monitoring emerging diseases over a 9-year period illustrated how new technologies can augment disease surveillance strategies. The number of animal and zoonotic diseases highlights the importance of animals in the study of emerging diseases.
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Affiliation(s)
- Peter Cowen
- ProMED-mail, International Society of Infectious Diseases, 181 Longwood Ave, Boston, MA 02115-2577, USA
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544
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Lee MH, Kwon HA, Kwon DY, Park H, Sohn DH, Kim YC, Eo SK, Kang HY, Kim SW, Lee JH. Antibacterial activity of medicinal herb extracts against Salmonella. Int J Food Microbiol 2006; 111:270-5. [PMID: 16876280 DOI: 10.1016/j.ijfoodmicro.2006.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2006] [Revised: 05/19/2006] [Accepted: 06/02/2006] [Indexed: 12/26/2022]
Abstract
The therapeutic potentials of twenty-two medicinal herb species traditionally used in Korea to treat gastrointestinal infections were evaluated for the treatment of salmonellosis. Candidates were primarily screened using the disk-agar method for antibacterial activity against three different Salmonella serotypes. Of the herbs tested, the aqueous and methanolic extracts of Schizandrae Fructus exhibited antibacterial activity against all three Salmonella. The extracts of this herb were further tested against 13 additional Salmonella strains of 6 different serotypes. All of these strains were also affected by these extracts, though the methanolic extract had slightly higher activity. The MIC values of this extract against the 16 Salmonella strains varied from 15.6 to 125 microg/ml. Nine of the 16 strains tested had MIC values of <31.3 microg/ml for the methanolic extract of Schizandrae Fructus. The in vivo antibacterial activity of Schizandrae Fructus extract was examined in a S. Typhimurium infection mouse model. Mice were initially infected with S. Typhimurium, and then administered with Schizandrae Fructus extract. The extract was found to have major effects on mortality and on the numbers of viable S. Typhimurium recovered from feces. Clinical signs and histological damages were rarely observed in the treated mice, whereas the untreated controls showed clinical signs, e.g., lethargy, and histological damage in the kidney, liver, intestine, and spleen. We conclude that Schizandrae Fructus has the potential to provide an effective treatment for salmonellosis.
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Affiliation(s)
- Mi-Hyang Lee
- College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Chonju, 561-756, Republic of Korea
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545
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Pickup RW, Rhodes G, Bull TJ, Arnott S, Sidi-Boumedine K, Hurley M, Hermon-Taylor J. Mycobacterium avium subsp. paratuberculosis in lake catchments, in river water abstracted for domestic use, and in effluent from domestic sewage treatment works: diverse opportunities for environmental cycling and human exposure. Appl Environ Microbiol 2006; 72:4067-77. [PMID: 16751517 PMCID: PMC1489623 DOI: 10.1128/aem.02490-05] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mycobacterium avium subsp. paratuberculosis from infected animals enters surface waters and rivers in runoff from contaminated pastures. We studied the River Tywi in South Wales, United Kingdom, whose catchment comprises 1,100 km2 containing more than a million dairy and beef cattle and more than 1.3 million sheep. The River Tywi is abstracted for the domestic water supply. Between August 2002 and April 2003, 48 of 70 (68.8%) twice-weekly river water samples tested positive by IS900 PCR. In river water, the organisms were associated with a suspended solid which was depleted by the water treatment process. Disposal of contaminated slurry back onto the land established a cycle of environmental persistence. A concentrate from 100 liters of finished water tested negative, but 1 of 54 domestic cold water tanks tested positive, indicating the potential for these pathogens to access domestic outlets. In the separate English Lake District region, with hills up to 980 m, tests for M. avium subsp. paratuberculosis in the high hill lakes and sediments were usually negative, but streams and sediments became positive lower down the catchment. Sediments from 9 of 10 major lakes receiving inflow from these catchments were positive, with sediment cores indicating deposition over at least 40 to 50 years. Two of 12 monthly 1-liter samples of effluent and a single 100-liter sample from the Ambleside sewage treatment works were positive for M. avium subsp. paratuberculosis. Since Lake Ambleside discharges into Lake Windermere, which is available for domestic supply, there is a potential for these organisms to cycle within human populations.
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Affiliation(s)
- R W Pickup
- Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA21 4AP, United Kingdom.
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546
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Macdonald DW, Laurenson MK. Infectious disease: Inextricable linkages between human and ecosystem health. BIOLOGICAL CONSERVATION 2006; 131:143-150. [PMID: 32287338 PMCID: PMC7111083 DOI: 10.1016/j.biocon.2006.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Affiliation(s)
- David W Macdonald
- Wildlife Conservation Research Unit, Zoology Department, University of Oxford, Tubney House, Abingdon Road, Tubney, Oxon OX13 5QL, United Kingdom
- Frankfurt Zoological Society, P.O. Box 14935, Arusha, Tanzania and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin Midlothian, EH25 9RG, United Kingdom
| | - M Karen Laurenson
- Frankfurt Zoological Society, P.O. Box 14935, Arusha, Tanzania and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Roslin Midlothian, EH25 9RG, United Kingdom
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547
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Bender JB, Hueston W, Osterholm M. Recent Animal Disease Outbreaks and Their Impact on Human Populations. J Agromedicine 2006; 11:5-15. [PMID: 16893833 DOI: 10.1300/j096v11n01_02] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Over the past 20 years, headlines have documented an increasing number of emerging diseases; most have an animal source (zoonoses). Recent examples include West Nile virus, severe acute respiratory syndrome (SARS), avian influenza, and monkeypox. While some emerging diseases occur among both humans and animals, others affect only animals or only humans. Nevertheless, all these new or reemerging infections have societal implications, often tied to local and national economies. It is important to understand the implications of emerging animal diseases and encourage stronger collaboration of veterinary and medical practitioners, especially in rural areas. Illnesses in agricultural workers may be the index cases for newly emerging diseases.
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548
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Jones-Engel L, Engel GA, Heidrich J, Chalise M, Poudel N, Viscidi R, Barry PA, Allan JS, Grant R, Kyes R. Temple monkeys and health implications of commensalism, Kathmandu, Nepal. Emerg Infect Dis 2006; 12:900-6. [PMID: 16707044 PMCID: PMC3373059 DOI: 10.3201/eid1206.060030] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Humans in contact with macaques risk exposure to enzootic primateborne viruses. The threat of zoonotic transmission of infectious agents at monkey temples highlights the necessity of investigating the prevalence of enzootic infectious agents in these primate populations. Biological samples were collected from 39 rhesus macaques at the Swoyambhu Temple and tested by enzyme-linked immunosorbent assay, Western blot, polymerase chain reaction, or combination of these tests for evidence of infection with rhesus cytomegalovirus (RhCMV), Cercopithecine herpesvirus 1 (CHV-1), simian virus 40 (SV40), simian retrovirus (SRV), simian T-cell lymphotropic virus (STLV), simian immunodeficiency virus (SIV), and simian foamy virus (SFV). Antibody seroprevalence was 94.9% to RhCMV (37/39), 89.7% to SV40 (35/39), 64.1% to CHV-1 (25/39), and 97.4% to SFV (38/39). Humans who come into contact with macaques at Swoyambhu risk exposure to enzootic primateborne viruses. We discuss implications for public health and primate management strategies that would reduce contact between humans and primates.
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Affiliation(s)
- Lisa Jones-Engel
- University of Washington--National Primate Research Center, Seattle, Washington 98195, USA.
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549
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Nuño M, Chowell G, Wang X, Castillo-Chavez C. On the role of cross-immunity and vaccines on the survival of less fit flu-strains. Theor Popul Biol 2006; 71:20-9. [PMID: 16930653 DOI: 10.1016/j.tpb.2006.07.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2006] [Revised: 06/14/2006] [Accepted: 07/03/2006] [Indexed: 11/17/2022]
Abstract
A pathogen's route to survival involves various mechanisms including its ability to invade (host's susceptibility) and its reproductive success within an invaded host ("infectiousness"). The immunological history of an individual often plays an important role in reducing host susceptibility or it helps the host mount a faster immunological response de facto reducing infectiousness. The cross-immunity generated by prior infections to influenza A strains from the same subtype provide a significant example. The results of this paper are based on the analytical study of a two-strain epidemic model that incorporates host isolation (during primary infection) and cross-immunity to study the role of invasion mediated cross-immunity in a population where a precursor related strain (within the same subtype, i.e. H3N2, H1N1) has already become established. An uncertainty and sensitivity analysis is carried out on the ability of the invading strain to survive for given cross-immunity levels. Our findings indicate that it is possible to support coexistence even in the case when invading strains are "unfit", that is, when the basic reproduction number of the invading strain is less than one. However, such scenarios are possible only in the presence of isolation. That is, appropriate increments in isolation rates and weak cross-immunity can facilitate the survival of less fit strains. The development of "flu" vaccines that minimally enhance herd cross-immunity levels may, by increasing genotype diversity, help facilitate the generation and survival of novel strains.
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Affiliation(s)
- M Nuño
- Department of Biostatistics, Harvard School of Public Health, Boston, MA 02115, USA.
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550
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Abstract
Many of the emerging infectious diseases, including those caused by bioterrorist agents, are zoonoses. Since zoonoses can infect both animals and humans, the medical and veterinary communities should work closely together in clinical, public health, and research settings. In the clinical setting, input from both professions would improve assessments of the risk-benefit ratios of pet ownership, particularly for pet owners who are immunocompromised. In public health, human and animal disease surveillance systems are important in tracking and controlling zoonoses such as avian influenza virus, West Nile virus, and foodborne pathogens. Comparative medicine is the study of disease processes across species, including humans. Physician and veterinarian comparative medicine research teams should be promoted and encouraged to study zoonotic agent-host interactions. These efforts would increase our understanding of how zoonoses expand their host range and would, ultimately, improve prevention and control strategies.
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Affiliation(s)
- Laura H Kahn
- Princeton University, Princeton, New Jersey 08542, USA.
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