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Molecular Plant-microbe Interactions :... Mar 2011Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species... (Review)
Review
Over the years, agriculture across the world has been compromised by a succession of devastating epidemics caused by new viruses that spilled over from reservoir species or by new variants of classic viruses that acquired new virulence factors or changed their epidemiological patterns. Viral emergence is usually associated with ecological change or with agronomical practices bringing together reservoirs and crop species. The complete picture is, however, much more complex, and results from an evolutionary process in which the main players are ecological factors, viruses' genetic plasticity, and host factors required for virus replication, all mixed with a good measure of stochasticity. The present review puts emergence of plant RNA viruses into the framework of evolutionary genetics, stressing that viral emergence begins with a stochastic process that involves the transmission of a preexisting viral strain into a new host species, followed by adaptation to the new host.
Topics: Adaptation, Biological; Disease Reservoirs; Environment; Evolution, Molecular; Genetic Variation; Host-Derived Cellular Factors; Host-Pathogen Interactions; Mutation; Plant Diseases; Plant Immunity; Plant Viruses; Plants; RNA Viruses; Recombination, Genetic; Species Specificity
PubMed: 21294624
DOI: 10.1094/MPMI-09-10-0214 -
The Onderstepoort Journal of Veterinary... Apr 2014The global focus on wildlife as a major contributor to emerging pathogens and infectious diseases (EIDs) in humans and domestic animals is not based on field,...
The global focus on wildlife as a major contributor to emerging pathogens and infectious diseases (EIDs) in humans and domestic animals is not based on field, experimental or dedicated research, but mostly on limited surveys of literature, opinion and the assumption that biodiversity harbours pathogens. The perceived and direct impacts of wildlife, from being a reservoir of certain human and livestock pathogens and as a risk to health, are frequently overstated when compared to the Global burden of disease statistics available from WHO, OIE and FAO. However organisms that evolve in wildlife species can and do spill-over into human landscapes and humans and domestic animal population and, where these organisms adapt to surviving and spreading amongst livestock and humans, these emerging infections can have significant consequences. Drivers for the spill-over of pathogens or evolution of organisms from wildlife reservoirs to become pathogens of humans and domestic animals are varied but almost without exception poorly researched. The changing demographics, spatial distribution and movements, associated landscape modifications (especially agricultural) and behavioural changes involving human and domestic animal populations are probably the core drivers of the apparent increasing trend in emergence of new pathogens and infectious diseases over recent decades.
Topics: Animals; Animals, Wild; Biodiversity; Communicable Diseases, Emerging; Disease Reservoirs; Humans; Zoonoses
PubMed: 25005349
DOI: 10.4102/ojvr.v81i2.739 -
Parasites & Vectors Jan 2018Key aspects of 36 mosquito-borne arboviruses indigenous to Africa are summarized, including lesser or poorly-known viruses which, like Zika, may have the potential to... (Review)
Review
Key aspects of 36 mosquito-borne arboviruses indigenous to Africa are summarized, including lesser or poorly-known viruses which, like Zika, may have the potential to escape current sylvatic cycling to achieve greater geographical distribution and medical importance. Major vectors are indicated as well as reservoir hosts, where known. A series of current and future risk factors is addressed. It is apparent that Africa has been the source of most of the major mosquito-borne viruses of medical importance that currently constitute serious global public health threats, but that there are several other viruses with potential for international challenge. The conclusion reached is that increased human population growth in decades ahead coupled with increased international travel and trade is likely to sustain and increase the threat of further geographical spread of current and new arboviral disease.
Topics: Africa; Animals; Arbovirus Infections; Arboviruses; Disease Reservoirs; Humans; Mosquito Vectors
PubMed: 29316963
DOI: 10.1186/s13071-017-2559-9 -
Zoonoses and Public Health Feb 2019Rabies virus (RABV) does not persist in the environment as it is a very fragile agent. The primary hosts are mammalian species in the orders Carnivora and Chiroptera....
Rabies virus (RABV) does not persist in the environment as it is a very fragile agent. The primary hosts are mammalian species in the orders Carnivora and Chiroptera. Since the late 1980s, RABV has been isolated from non-human primates, Callithrix jacchus (the white-tufted marmoset), in four coastal states (Rio Grande do Norte, Ceará, Piauí and Pernambuco) in north-eastern Brazil, where this species is indigenous. The original habitat of C. jacchus consisted of two Brazilian biomes, the Atlantic Forest and the Caatinga. However, these marmosets have since adapted to other ecosystems as a result of human activities. Between 1988 and 1989, RABV isolates were obtained from white-tufted marmosets in the state of Rio Grande do Norte, but antigenic and genetic identification studies were not conducted at that time. In the following years, three additional states reported cases (Ceará, Piauí and Pernambuco). In two of these states (Ceará and Piauí), human cases of rabies transmitted by marmosets were reported. According to Brazilian Health Ministry data, at least 19 human cases in which this species was the source of infection were registered in between 1990 and 2016. Recent findings in laboratory tests of 12 rabid samples from humans and marmosets and the regional transmission among these animals for over 20 years, together with the gradual increase in the affected geographic area, support the concept of the emergence of a new RABV reservoir. Regional tourism, the wild animal trade and the cultural practice of maintaining these animals as pets, particularly in coastal regions, appear to be major risk factors for the increase in human cases. Additional epidemiological and ecological studies are required to better understand local disease dynamics and to identify ideal opportunities for prevention and control of this fatal infection.
Topics: Amino Acid Substitution; Animals; Antigens, Viral; Brazil; Callithrix; Disease Reservoirs; Genome, Viral; Humans; Monkey Diseases; Phylogeny; Rabies; Rabies virus
PubMed: 30288933
DOI: 10.1111/zph.12527 -
Veterinary Research Feb 2012Numerous mammal species, including domestic and wild animals such as ruminants, dogs, cats and rodents, as well as humans, serve as reservoir hosts for various... (Review)
Review
Numerous mammal species, including domestic and wild animals such as ruminants, dogs, cats and rodents, as well as humans, serve as reservoir hosts for various Bartonella species. Some of those species that exploit non-human mammals as reservoir hosts have zoonotic potential. Our understanding of interactions between bartonellae and reservoir hosts has been greatly improved by the development of animal models for infection and the use of molecular tools allowing large scale mutagenesis of Bartonella species. By reviewing and combining the results of these and other approaches we can obtain a comprehensive insight into the molecular interactions that underlie the exploitation of reservoir hosts by Bartonella species, particularly the well-studied interactions with vascular endothelial cells and erythrocytes.
Topics: Animals; Bartonella; Bartonella Infections; Disease Reservoirs; Endothelial Cells; Erythrocytes; Mammals
PubMed: 22369683
DOI: 10.1186/1297-9716-43-15 -
Journal of Wildlife Diseases Oct 1970Present knowledge on reservoir hosts of Trypanosoma rhodesiense, T. gambiense and T. brucei in Africa and T. cruzi and T. rangeli in America and experimental... (Review)
Review
Present knowledge on reservoir hosts of Trypanosoma rhodesiense, T. gambiense and T. brucei in Africa and T. cruzi and T. rangeli in America and experimental transmission studies of T. cruzi in mammalian hosts and in lizards is discussed. The difficulty in differentiating the African species of human trypanosomes, which appear not to be host specific, is a major obstacle to epizootiological studies.
Topics: Animals; Animals, Wild; Chagas Disease; Disease Reservoirs; Host-Parasite Interactions; Humans; Species Specificity; Trypanosomiasis, African; Zoonoses
PubMed: 16512133
DOI: 10.7589/0090-3558-6.4.313 -
Zoonoses and Public Health Feb 2018Hepatitis E is a human disease mainly characterized by acute liver illness, which is caused by infection with the hepatitis E virus (HEV). Large hepatitis E outbreaks... (Review)
Review
Hepatitis E is a human disease mainly characterized by acute liver illness, which is caused by infection with the hepatitis E virus (HEV). Large hepatitis E outbreaks have been described in developing countries; however, the disease is also increasingly recognized in industrialized countries. Mortality rates up to 25% have been described for pregnant women during outbreaks in developing countries. In addition, chronic disease courses could be observed in immunocompromised transplant patients. Whereas the HEV genotypes 1 and 2 are mainly confined to humans, genotypes 3 and 4 are also found in animals and can be zoonotically transmitted to humans. Domestic pig and wild boar represent the most important reservoirs for these genotypes. A distinct subtype of genotype 3 has been repeatedly detected in rabbits and a few human patients. Recently, HEV genotype 7 has been identified in dromedary camels and in an immunocompromised transplant patient. The reservoir animals get infected with HEV without showing any clinical symptoms. Besides these well-known animal reservoirs, HEV-specific antibodies and/or the genome of HEV or HEV-related viruses have also been detected in many other animal species, including primates, other mammals and birds. In particular, genotypes 3 and 4 infections are documented in many domestic, wildlife and zoo animal species. In most cases, the presence of HEV in these animals can be explained by spillover infections, but a risk of virus transmission through contact with humans cannot be excluded. This review gives a general overview on the transmission pathways of HEV to humans. It particularly focuses on reported serological and molecular evidence of infections in wild, domestic and zoo animals with HEV or HEV-related viruses. The role of these animals for transmission of HEV to humans and other animals is discussed.
Topics: Animals; Animals, Domestic; Animals, Wild; Animals, Zoo; Disease Reservoirs; Hepatitis E; Hepatitis E virus
PubMed: 28944602
DOI: 10.1111/zph.12405 -
Annals of the New York Academy of... Oct 2006Trypanosomosis is a major constraint on ruminant livestock production in Africa, Asia, and South America. The principal host species affected varies geographically, but... (Review)
Review
Trypanosomosis is a major constraint on ruminant livestock production in Africa, Asia, and South America. The principal host species affected varies geographically, but buffalo, cattle, camels, and horses are particularly sensitive. Natural infections with Trypanosoma congolense, T. vivax, T. brucei, and T. evansi have been described in goats. Trypanosomosis in goats produces acute, subacute, chronic, or subclinical forms, being T. vivax, T. congolense, and T. evansi, the most invasive trypanosomes for goats. However, the role of goats in the epidemiology of trypanosomosis is largely discussed and not well understood. Thus, it has commonly been assumed that trypanosomosis presents a subclinical course and that goats do not play an important role in the epidemiology of the disease. This can partially be due to parasitemia caused by trypanosomes which has been considered low in goats. However, this assumption is currently undergoing a critical reappraisal because of goats may also serve as a reservoir of trypanosome infection for other species, including the human beings in the case of T. brucei rhodesiense. The present article describes the current status of trypanosomosis in goats in Africa, Asia, and South America. Pathogenesis, clinical features, diagnosis, and treatment of the different trypanosomes are also described. The possible role in the epidemiology of the disease in the different areas is also discussed.
Topics: Animals; Disease Reservoirs; Goat Diseases; Goats; Insect Vectors; Phylogeny; Species Specificity; Trypanosoma; Trypanosomiasis; Tsetse Flies
PubMed: 17135529
DOI: 10.1196/annals.1373.040 -
Nature Reviews. Immunology Dec 2013Zoonotic viruses that emerge from wildlife and domesticated animals pose a serious threat to human and animal health. In many instances, mouse models have improved our... (Review)
Review
Zoonotic viruses that emerge from wildlife and domesticated animals pose a serious threat to human and animal health. In many instances, mouse models have improved our understanding of the human immune response to infection; however, when dealing with emerging zoonotic diseases, they may be of limited use. This is particularly the case when the model fails to reproduce the disease status that is seen in the natural reservoir, transmission species or human host. In this Review, we discuss how researchers are placing more emphasis on the study of the immune response to zoonotic infections in the natural reservoir hosts and spillover species. Such studies will not only lead to a greater understanding of how these infections induce variable disease and immune responses in distinct species but also offer important insights into the evolution of mammalian immune systems.
Topics: Animals; Disease Reservoirs; Host-Pathogen Interactions; Humans; Mice; Models, Animal; Physiology, Comparative; Zoonoses
PubMed: 24157573
DOI: 10.1038/nri3551 -
Viruses Apr 2011The aim of this manuscript is to describe how modern advances in our knowledge of viruses and viral evolution can be applied to the fields of disease ecology and... (Review)
Review
The aim of this manuscript is to describe how modern advances in our knowledge of viruses and viral evolution can be applied to the fields of disease ecology and conservation. We review recent progress in virology and provide examples of how it is informing both empirical research in field ecology and applied conservation. We include a discussion of needed breakthroughs and ways to bridge communication gaps between the field and the lab. In an effort to foster this interdisciplinary effort, we have also included a table that lists the definitions of key terms. The importance of understanding the dynamics of zoonotic pathogens in their reservoir hosts is emphasized as a tool to both assess risk factors for spillover and to test hypotheses related to treatment and/or intervention strategies. In conclusion, we highlight the need for smart surveillance, viral discovery efforts and predictive modeling. A shift towards a predictive approach is necessary in today's globalized society because, as the 2009 H1N1 pandemic demonstrated, identification post-emergence is often too late to prevent global spread. Integrating molecular virology and ecological techniques will allow for earlier recognition of potentially dangerous pathogens, ideally before they jump from wildlife reservoirs into human or livestock populations and cause serious public health or conservation issues.
Topics: Animals; Communicable Diseases, Emerging; Disease Reservoirs; Global Health; Humans; Virology; Virus Physiological Phenomena; Viruses; Zoonoses
PubMed: 21994738
DOI: 10.3390/v3040379