Emergence of "new" viral zoonoses]

In the last two to three decades a significant increase of viral zoonotic infections was observed. These zoonoses are not only newly (or previously unrecognized) emerging diseases, but also due to the reappearance of diseases thought to have been defeated (re-emerging diseases). "New" viral diseases can arise when viruses broaden their host-range (monkey poxvirus; equine morbillivirus), or can be a consequence of intrinsic properties of the virus itself, such as high mutation rates (influenza A virus). Most new or reemerging viral zoonoses are due to infections with hemorrhagic viruses. Many of them are transmitted by insects (arboviruses, e.g. yellow fever virus) or by rodents (e.g. Hanta viruses), others by contact with patients and nosocomial infections (e.g. Ebola virus). The emergence and increase of these diseases are a consequence of anthropogenic environmental changes, such as distortions of the ecological balance and changes in agriculture. In addition, the uncontrolled growth of the cities in tropical and subtropical regions without improvement of the public health measures and the increasing international animal trade and travel also favour the spread and recurrence of these diseases.     

Viral metagenomics as an emerging and powerful tool in veterinary medicine

New diseases continue to emerge in both human and animal populations, and the importance of animals, as reservoirs for viruses that can cause zoonoses are evident. Thus, an increased knowledge of the viral flora in animals, both in healthy and diseased individuals, is important both for animal and human health. Viral metagenomics is a culture-independent approach that is used to investigate the complete viral genetic populations of a sample. This review describes and discusses the different possible steps of a viral metagenomic study utilizing sequence-independent amplification, high-throughput sequencing, and bioinformatics to identify viruses. With this technology, multiple viruses can be detected simultaneously and novel and highly divergent viruses can be discovered and genetically characterized for the first time. This review also briefly discusses the applications of viral metagenomics in veterinary science and lists some of the viruses discovered within this field.     

Current problems in zoonosis research

New developments in the field of Zoonosis research are discussed. They include: 1. New emerging viral zoonosis 2. Multicausal zoonoses 3. Genetic aspects of the origin of new zoonoses 4. Transmission of zoonoses to man through foodstuffs of animal origin 5. The environment and zoonoses. Continuous zoonosis research with new molecular biological techniques is a necessity. In the final analysis, there are no true limits in the field of infectiology. Such research requires cooperation between ecologists, zoologists, botanists, molecular biologists, physicians and veterinarians.     

The "Friedrich-Loeffler-Institut": past, present and future of research in infectious diseases of animals

The Friedrich-Loeffler-Institut, founded in 1910 by Friedrich Loeffler, the discoverer of the first animal virus, foot-and-mouth disease virus, is the oldest virological research facility in the world. Beyond viruses, its area of competence has significantly expanded since its foundation and now also covers bacterial, parasitic and prion diseases of livestock, poultry and aquatic animals. Presently located at four sites within Germany (Insel Riems, Jena,Tübingen,Wusterhausen) the tasks of the institute as delineated in the Animal Disease Act encompass research on infectious animal diseases including zoonoses, import/export examinations, epidemiological studies in case of outbreaks of notifiable animal diseases, acting as reference laboratory for notifiable animal diseases and nationwide quality management of diagnosis of notifiable animal diseases. It is obliged to publish and maintain up-to-date diagnostic regimes for notifiable animal diseases, and it publishes a yearly report on animal health in Germany. With the increasing importance of infectious diseases of animals, in particular those potentially harmful to man (zoonoses), the Friedrich-Loeffler-Institut will be moving into new facilities including laboratories and animal facilities up to the highest biosafety level at its main site Insel Riems on the occasion of its 100th anniversary.     

The socioeconomic burden of parasitic zoonoses: global trends

Diseases resulting from zoonotic transmission of parasites are common. Humans become infected through food, water, soil and close contact with animals. Most parasitic zoonoses are neglected diseases despite causing a considerable global burden of ill health in humans and having a substantial financial burden on livestock industries. This review aims to bring together the current data available on global burden estimates of parasitic zoonoses and indicate any changes in the trends of these diseases. There is a clear need of such information as interventions to control zoonoses are often in their animal hosts. The costs of such interventions together with animal health issues will drive the cost effectiveness of intervention strategies. What is apparent is that collectively, parasitic zoonoses probably have a similar human disease burden to any one of the big three human infectious diseases: malaria, tuberculosis or HIV in addition to animal health burden. Although the global burden for most parasitic zoonoses is not yet known, the major contributors to the global burden of parasitic zoonoses are toxoplasmosis, food borne trematode infections, cysticercosis, echinococcosis, leishmaniosis and zoonotic schistosomosis. In addition, diarrhoea resulting from zoonotic protozoa may have a significant impact.     

Cattle industry and zoonotic risk

The intensive farming of dairy and beef cattle has elicited a decrease in the herds and an increase in the number of animals per herd. The high concentration of cattle and the movement of the animals among herds has led to an increase in the health risks. In this context we have to consider the role of microbial agents of zoonoses, such as bacteria, parasites, and in some cases viruses. Notably, foodstuffs, such as meat, milk and dairy products, are the main sources of zoonoses of bovine origin. In particular, raw milk must be considered at high risk for trasmission of pathogens from cattle to humans. The European Regulation concerning food safety provides specific requirements for animal products and in bovine health management. Given the direct responsibility of the producer, the adoption of a self-regulation regimen on animal health, dairy and meat products must be planned by farmers.     

Cattle industry and zoonotic risk

The intensive farming of dairy and beef cattle has elicited a decrease in the herds and an increase in the number of animals per herd. The high concentration of cattle and the movement of the animals among herds has led to an increase in the health risks. In this context we have to consider the role of microbial agents of zoonoses, such as bacteria, parasites, and in some cases viruses. Notably, foodstuffs, such as meat, milk and dairy products, are the main sources of zoonoses of bovine origin. In particular, raw milk must be considered at high risk for trasmission of pathogens from cattle to humans. The European Regulation concerning food safety provides specific requirements for animal products and in bovine health management. Given the direct responsibility of the producer, the adoption of a self-regulation regimen on animal health, dairy and meat products must be planned by farmers.     

Viral networks and detection of potential zoonotic viruses in bats and rodents: A worldwide analysis

Bats and rodents are recognized to host a great diversity of viruses and several important viral zoonoses, but how this viral diversity is structured and how viruses are connected, shared and distributed among host networks is not well understood. To address this gap in knowledge, we compared the associative capacity of the host–virus networks in rodents and bats with the identification of those viruses with zoonotic potential. A virus database, detected by molecular methods, was constructed in the two taxonomic groups. We compiled 5,484 records: 825 in rodents and 4,659 in bats. We identified a total of 173 and 166 viruses, of which 53 and 40 are zoonotic viruses, in rodents and bats, respectively. Based on a network theory, a non‐directed bipartite host–virus network was built for each group. Subsequently, the networks were collapsed to represent the connections among hosts and viruses. We identified both discrete and connected communities. We observed a greater degree of connectivity in bat viruses and more discrete communities in rodents. The Coronaviridae recorded in bats have the highest values of degree, betweenness and closeness centralities. In rodents, higher degree positions were distributed homogeneously between viruses and hosts. At least in our database, a higher proportion of rodent viruses were zoonotic. Rodents should thus not be underestimated as important reservoirs of zoonotic disease. We found that viruses were more frequently shared among bats than in rodents. Network theory can reveal some macroecological patterns and identify risks that were previously unrecognized. For example, we found that parvovirus in megabats and Gbagroube virus in rodents may represent a zoonotic risk due to the proximity to humans and other zoonotic viruses. We propose that epidemiological surveillance programmes should consider the connectivity of network actors as a measure of the risks of dispersion and transmission.     

All creatures great and minute: a public policy primer for companion animal zoonoses

Approximately 63% of US households have at least one pet, a large percentage of which are considered family members. Pet owners can derive substantial physical and psychological benefits from interaction with companion animals. However, pet ownership is not without risks; zoonotic diseases are increasingly drawing the attention of healthcare professionals, policy makers and the general public. While zoonoses of 'traditional' pets are widely recognized and their prevention and treatment factors are generally known, the growing popularity of 'non-traditional' pets has the potential to facilitate human exposure to novel zoonoses. However, the greatest risk of zoonoses probably arises from animals taken directly from the wild to serve as pets. Non-governmental organizations, state veterinary associations and others have been calling for increased regulation of animal imports, some proposing that all 'exotics' be banned from the pet trade. Because zoonotic diseases of companion animals are influenced by interacting factors of ecological, technical, socio-economic, and political origin, efforts to minimize their impact need be multi-dimensional, simultaneously addressing both the ecological and socio-political drivers of disease emergence and transmission. This study is intended to serve as a primer for animal care professionals seeking to engage with policy makers and the pet industry on the prevention of companion animal zoonoses. We provide background on the human-animal bond, risks of zoonoses associated with groups of companion animals, and the public policy context, as well as identify the factors needed to build a comprehensive approach to companion animal zoonoses risk management. Also included are examples of innovative, non-regulatory initiatives designed to limit the spread and impact of companion animal zoonoses, including a reptile salmonella poster, the National Reptile Improvement Plan, Habitattitude campaign, Pet Zoonoses Committee, and a wildlife disease surveillance initiative known as Project TripWire.     

6th International Conference on Emerging Zoonoses

The 6th International Conference on Emerging Zoonoses, held at Cancun, Mexico, 24-27 February 2011, offered 84 participants from 18 countries, a snapshot of current research in numerous zoonoses caused by viruses, bacteria or prions. Co-chaired by Professors Heinz Feldmann and Jürgen Richt, the conference explored 10 topics: (i) The ecology of emerging zoonotic diseases; (ii) The role of wildlife in emerging zoonoses; (iii) Cross-species transmission of zoonotic pathogens; (iv) Emerging and neglected influenza viruses; (v) Haemorrhagic fever viruses; (vi) Emerging bacterial diseases; (vii) Outbreak responses to zoonotic diseases; (viii) Food-borne zoonotic diseases; (ix) Prion diseases; and (x) Modelling and prediction of emergence of zoonoses. Human medicine, veterinary medicine and environmental challenges are viewed as a unity, which must be considered under the umbrella of 'One Health'. Several presentations attempted to integrate the insights gained from field data with mathematical models in the search for effective control measures of specific zoonoses. The overriding objective of the research presentations was to create, improve and use the tools essential to address the risk of contagions in a globalized society. In seeking to fulfil this objective, a three-step approach has often been applied: (i) use cultured cells, model and natural animal hosts and human clinical models to study infection; (ii) combine traditional histopathological and biochemical approaches with functional genomics, proteomics and computational biology; and (iii) obtain signatures of virulence and insights into mechanisms of host defense response, immune evasion and pathogenesis. This meeting review summarizes 39 of the conference presentations and mentions briefly the 16 articles in this Special Supplement, most of which were presented at the conference in earlier versions. The full affiliations of all presenters and many colleagues have been included to facilitate further inquiries from readers.     

Zoonoses as a risk when associating with livestock or animal products

The risk of zoonotic disease transmission when handling livestock or animal products is substantial. In industrialized countries, the classical zoonotic diseases such as tuberculosis or brucellosis are no longer in the foreground. Latent zoonoses such as salmonellosis and campylobacteriosis can cause serious disease in humans and have become a major public health problem during the past years. Since animals infected with these pathogens show only mild transient disease or no clinical signs at all, new concepts in the entire production line ("stable to table") are necessary in order to avoid human infection. Two emerging viruses with zoonotic potential--avian influenza virus and Nipah virus--have been found in Asia in 1997 and 1999. Both diseases had a major impact on disease control and public health in the countries of origin. In order to cope threats from infectious diseases, in particular those of public health relevance, a combined effort among all institutions involved will be necessary. The proposed "European Center for Infectious Diseases" and the "Swiss center for zoonotic diseases" could be a potential approach in order to achieve this goal.     

Caliciviruses: an overview.

Several caliciviruses are known to cause diseases in animal and man. Amongst them are vesicular exanthema virus of swine (VESV), feline calicivirus, rabbit hemorrhagic disease virus (RHDV), and Norwalk and Sapporo-like viruses; the latter viruses cause gastroenteritis in man. In this paper, an overview of caliciviruses is presented, with particular emphasis on the molecular aspects. The unique properties as compared to other related families of positive-stranded RNA viruses will be discussed. Many findings about the molecular biology of caliciviruses came from systems that are difficult to work with, such as RHDV, which can thus far only be propagated either in animals or in primary rabbit hepatocyte cultures. Therefore, the review will concentrate on RHDV.     

Recent data on the epidemiology and prophylaxis of human rabies in France

Rabies is an animal disease which is transmitted to man only by accident, most often through the bite (more rarely after scratches or licks of mucosa) of a rabid animal, domestic or wild. A good knowledge of the epizootiology of animal rabies is therefore necessary to establish, on solid grounds, the prophylaxis of human rabies. Inter-human transmission of rabies being an exceptional event which will be considered separately, the epidemiology of human rabies mainly studies the sources and circumstances of human exposure to rabid animals, which differ according to the epizootiology of animal rabies in a given country: either enzootic (or hyperenzootic) canine rabies, or enzootic selvatic rabies. It appears that the risk of human rabies is higher in the first situation for two reasons: (i) rabies viruses show an increased virulence due to numerous serial passages in dogs (viruses with short incubation period) and (ii) high frequency of dog-man contacts due to the high density of both populations.     

Avian influenza viruses in wild birds: a moving target

The long-standing evolutionary and ecological relationships between wild birds and influenza A viruses has created a broad pool of viral genetic diversity and a reservoir of potentially transmissible viruses. An understanding of these relationships can help us identify and modify critical control points to reduce transmission of avian influenza viruses into animal and human populations.     

甲型流感病毒多功能蛋白质NS1的研究进展

近年来大量的研究结果表明,甲型流感病毒的非结构蛋白质1(NS1)是在感染病毒期间具有多个辅助功能的毒力因子,为揭示该人畜共患病毒的致病性机理提供重要参考价值。这篇文章综述了该病毒蛋白质一些最新研究进展,包括NS1的合成、结构、亚细胞定位及在病毒复制机制、宿主天然免疫应答或/和适应性免疫应答、细胞信号传导中发挥各种作用。作者重点阐述了NS1-RNA之间和NS1-蛋白质之间的相互作用,因为它们都是上述功能和过程的基础。同时突出不同毒株NS1蛋白可能特有的特性,鉴于此,也讨论了NS1对人和动物甲型流感病毒致病性的某些作用。最后概述NS1可能应用于流感疫苗的研制、新抗病毒药物的研发等。同时比较了乙、丙型流感病毒NS1研究新进展。     

Influenza virus infections in mammals

The natural reservoir of all known subtypes of influenza A viruses are aquatic birds, mainly of the orders Anseriformes and Charadriiformes in which the infection is asymptomatic and the viruses stay at an evolutionary equilibrium. However, mammals may occasionally contract influenza A virus infections from this pool. This article summarizes: (i) natural infections in mammals including pigs, horses, marine mammals, ferrets, minks; (ii) results from experimental infections in several animal models including mice, ferrets, primates, rats, minks, hamsters and (iii) evidence for the increased pathogenicity of the current influenza A H5N1/Asia viruses for mammals. Several reports have shown that a number of mammalian species, including pigs, cats, ferrets, minks, whales, seals and finally also man are susceptible to natural infection with influenza A viruses of purely avian genetic make up. Among the mammalian species naturally susceptible to avian influenza virus the pig and the cat might exert the greatest potential public health impact. Despite numerous studies in animal and cell culture models, the basis of the extended host spectrum and the unusual pathogenicity of the influenza A H5N1 viruses for mammals is only beginning to be unraveled. Recently, also the transmission of equine influenza A virus to greyhound racing dogs has been documented.     

Perspectives on emerging zoonotic disease research and capacity building in Canada

Zoonoses are fundamental determinants of community health. Preventing, identifying and managing these infections must be a central public health focus. Most current zoonoses research focuses on the interface of the pathogen and the clinically ill person, emphasizing microbial detection, mechanisms of pathogenicity and clinical intervention strategies, rather than examining the causes of emergence, persistence and spread of new zoonoses. There are gaps in the understanding of the animal determinants of emergence and the capacity to train highly qualified individuals; these are major obstacles to preventing new disease threats. The ability to predict the emergence of zoonoses and their resulting public health and societal impacts are hindered when insufficient effort is devoted to understanding zoonotic disease epidemiology, and when zoonoses are not examined in a manner that yields fundamental insight into their origin and spread. Emerging infectious disease research should rest on four pillars: enhanced communications across disciplinary and agency boundaries; the assessment and development of surveillance and disease detection tools; the examination of linkages between animal health determinants of human health outcomes; and finally, cross-disciplinary training and research. A national strategy to predict, prevent and manage emerging diseases must have a prominent and explicit role for veterinary and biological researchers. An integrated health approach would provide decision makers with a firmer foundation from which to build evidence-based disease prevention and control plans that involve complex human/animal/environmental systems, and would serve as the foundation to train and support the new cadre of individuals ultimately needed to maintain and apply research capacity in this area.     

Simultaneous detection and differentiation of Newcastle disease and avian influenza viruses using oligonucleotide microarrays

Newcastle disease (ND) and avian influenza (AI) are two of the most important zoonotic viral diseases of birds throughout the world. These two viruses often have a great impact upon the poultry industry. Both viruses are associated with transmission from wild to domestic birds, and often display similar signs that need to be differentiated. A rapid surveillance among wild and domestic birds is important for early disease detection and intervention, and is the basis for what measures should be taken. The surveillance, thus, should be able to differentiate the diseases and provide a detailed analysis of the virus strains. Here, we described a fast, simultaneous and inexpensive approach to the detection of Newcastle disease virus (NDV) and avian influenza virus (AIV) using oligonucleotide microarrays. The NDV pathotypes and the AIV haemagglutinin subtypes H5 and H7 were determined at the same time. Different probes on a microarray targeting the same gene were implemented in order to encompass the diversified virus strains or provide multiple confirmations of the genotype. This ensures good sensitivity and specificity among divergent viruses. Twenty-four virus isolates and twenty-four various combinations of the viruses were tested in this study. All viruses were successfully detected and typed. The hybridization results on microarrays were clearly identified with the naked eyes, with no further imaging equipment needed. The results demonstrate that the detection and typing of multiple viruses can be performed simultaneously and easily using oligonucleotide microarrays. The proposed method may provide potential for rapid surveillance and differential diagnosis of these two important zoonoses in both wild and domestic birds.     

Comparative antiviral and proviral factors in semen and vaccines for preventing viral dissemination from the male reproductive tract and semen

Many animal and human viruses are disseminated via semen, but there is little information on how to measure and stimulate protective antiviral immunity in the male reproductive tract and semen. This information is important since successful vaccination through the stimulation of protective immune responses could be a mechanism to prevent viral contamination of semen and subsequent wide spread viral dissemination. Even control of the infection by shortening the duration of viral shedding and lowering the viral load in semen would lessen the chances of viral dissemination through this route. This review will highlight the current knowledge of immunity in the male reproductive tract and summarize 'antiviral' as well as 'proviral' factors in semen such as cytokines, cells, antibodies, antimicrobial peptides, enzymes, hormones and growth factors. These factors must provide a fine balance between 'immunosuppression' in semen needed to protect sperm viability and 'immunocompetency' to prevent pathogen contamination. The review will also suggest continuing challenges to researchers for preventing viral dissemination via semen and propose a large animal model for continued research in this important area.