Emerging zoonoses: the challenge for public health and biodefense

The concept of new and emerging diseases has captured the public interest and has revitalized the public health infectious disease research community. This interest has also resulted in competition for funding and turf wars between animal health and public health scientists and public officials and, in some cases, has delayed and hindered progress toward effective prevention, control and biodefense. There is a dynamic list of outbreaks causing substantial morbidity and mortality in humans and often in the reservoir animal species. Some agents have the potential to grow into major epidemics. There are many determinants that influence the emergence of diseases of concern that require the use of current understanding of the nature of agent persistence and spread. Additional factors that are global must be added to plans for prevention and control. To this complex mix has been added the potential for accidental or malicious release of agents. The nature of emerging infectious agents and their impact is largely unpredictable. Models that strive to predict the dynamics of agents may be useful but can also blind us to increasing disease risks if it does not match a specific model. Field investigations of early events will be critical and should drive prevention and control actions. Many disease agents have developed strategies to overcome extremes of reservoir qualities like population size and density. Every infectious agent spreads easier when its hosts are closer together. Zoonoses must be dealt with at the interface of human and animal health by all available information. Lessons learned from the emergence of and response to agents like West Nile virus, H5N1 avian influenza, SARS and bovine spongiform encephalopathy, the cause of new-variant Creutzfeldt-Jakob disease in humans, must be used to create better plans for response and meet the challenge for public health and biodefense.     

Emerging viral zoonoses: frameworks for spatial and spatiotemporal risk assessment and resource planning

Spatial epidemiological tools are increasingly being applied to emerging viral zoonoses (EVZ), partly because of improving analytical methods and technologies for data capture and management, and partly because the demand is growing for more objective ways of allocating limited resources in the face of the emerging threat posed by these diseases. This review documents applications of geographical information systems (GIS), remote sensing (RS) and spatially-explicit statistical and mathematical models to epidemiological studies of EVZ.Landscape epidemiology uses statistical associations between environmental variables and diseases to study and predict their spatial distributions. Phylogeography augments epidemiological knowledge by studying the evolution of viral genetics through space and time. Cluster detection and early warning systems assist surveillance and can permit timely interventions. Advanced statistical models can accommodate spatial dependence present in epidemiological datasets and can permit assessment of uncertainties in disease data and predictions. Mathematical models are particularly useful for testing and comparing alternative control strategies, whereas spatial decision-support systems integrate a variety of spatial epidemiological tools to facilitate widespread dissemination and interpretation of disease data. Improved spatial data collection systems and greater practical application of spatial epidemiological tools should be applied in real-world scenarios.     

Emerging and re-emerging viruses of the honey bee (Apis mellifera L.)

Until the late 1980s, specific viral infections of the honey bee were generally considered harmless in all countries. Then, with the worldwide introduction of the ectoparasite mite Varroa destructor, beekeepers encountered increasing difficulties in maintaining their colonies. Epidemiological surveys and laboratory experiments have demonstrated that the newly acquired virulence of several viruses belonging to the family Dicistroviridae (acute bee paralysis virus, Kashmir bee virus and Israeli acute paralysis virus) in Europe and the USA had been observed in relation with V. destructor acting as a disseminator of these viruses between and within bee colonies and as an activator of virus multiplication in the infected individuals: bee larvae and adults. Equal emphasis is given to deformed wing virus (DWV) belonging to the Iflaviridae. Overt outbreaks of DWV infections have been shown to be linked to the ability of V. destructor to act not only as a mechanical vector of DWV but also as a biological vector. Its replication in mites prior to its vectoring into pupae seemed to be necessary and sufficient for the induction of a overt infection in pupae developing in non-viable bees with deformed wings. DWV in V. destructor infested colonies is now considered as one of the key players of the final collapse. Various approaches for combating bee viral diseases are described: they include selection of tolerant bees, RNA interference and prevention of new pathogen introduction. None of these approaches are expected to lead to enhanced bee-health in the short term.     

Emerging issues and parasite zoonoses in the SE Asian and Australasian region

Parasite zoonoses are common in the SE Asian region. However, recent case reports and surveillance activities have revealed a number of emerging issues that threaten both biosecurity and ongoing control efforts. In all cases, the application of molecular tools has contributed to the identification of new foci of infection, novel aetiological agents and epidemiological investigations. These emerging issues are discussed with reference to trypanosomes, Toxoplasma, fish-borne flukes, cysticercosis and hookworm.     

警惕和关注人与猪的细菌性共患病

据有关文献记载,动物传染病有200余种,其中有半数以上可以传染给人类。在人类历史上,一些人畜共患病曾造成了巨大的灾难,构成对人类健康的巨大威胁。2002年底至2003年席卷我国及东南亚、加拿大等国的SARS、给全球养禽业带来毁灭性打击的禽流感给各国人民造成了极大的恐慌,夺去了许多人的生命,对经济造成了严重的冲击。近些年来,某些人畜共患病又有所抬头。今年在四川成都发生的人—猪链球菌病,造成了重大的经济损失和社会灾害,给予了人们许多启示,它显示了疫病对人类生命的威胁时刻存在;人与动物疫病关系密切;改变错误认识和陋习,提高人、畜卫生保健水平是当务之急。猪的饲养数量大、分布广,与人接触密切,而我国又是一个以猪肉为主要肉食的国家,所以警惕和关注人与猪之间传播的共患病更为重要。     

Backyard poultry: legislation,zoonoses and disease prevention

In law, backyard poultry are “food‐producing animals” and “farmed animals” and are subject to regulations regarding welfare, prescribing, banned procedures, disposal of carcases, feeding bans, notifiable diseases and disease surveillance in addition to those applying to most other pets. Many owners and some veterinary surgeons are unclear about the requirements of these regulations. Backyard poultry are also associated with some different zoonotic disease risks to mammalian pets. Because a high proportion of poultry morbidity and mortality relates to infectious diseases, the health of backyard poultry is amenable to improvement through basic husbandry, biosecurity, hygiene and preventive medicine measures that can be incorporated into a simple “flock‐health plan”. This article reviews these topics.     

Buffalopox: an emerging and re-emerging zoonosis

Outbreaks of buffalopox or pox-like infections affecting buffaloes, cows and humans have been recorded in many parts of the world. Since the first outbreak in India, a large number of epidemics have occurred. Unlike in the previous years, generalized forms of the disease are now rare; however, there are severe local forms of the disease affecting the udder and teats, leading to mastitis thereby undermining the productivity of milk animals. The causative agent buffalopox virus (BPXV) is a member of the Orthopoxvirus, and is closely related to Vaccinia virus (VACV), the type-species of the genus. Earlier studies with restriction fragment length polymorphism and recent investigations involving sequencing of the genes that are essential in viral pathogenesis have shown that BPXV is phylogenetically very closely related to VACV and may be considered as a clade of the latter. The review discusses the epidemiology, novel diagnostic methods for the disease, and molecular biology of the virus, and infers genetic relationships of BPXV with other members of the genus.     

Knowledge and perceptions of dog-associated zoonoses: Brazos County,Texas, USA

In order to assess the knowledge and perceptions of dog-associated zoonoses in Brazos County, Texas, random digit dialing was used to select 922 households for participation in a cross-sectional telephone survey. The interviews were completed during June 2008 and yielded a response rate of 55% (922/1691). Fifty-six percent of the respondents who completed the questionnaire owned dogs. Eighty-six percent of the respondents indicated they would report being bitten by a dog that they did not own. Five factors were shown to be significantly associated with such reporting. Those respondents who believed that rabies could be transmitted by bats were 5.5 times more likely (95% CI: 1.6, 18.6) to report a dog bite compared to people who did not hold this belief. Respondents who would seek emergency treatment if they believed they had been exposed to rabies were 3.1 times more likely to report a bite (95% CI: 1.8, 5.4). Those who were over 60 years of age were 2.3 times more likely (95% CI: 1.2, 4.4) to report being bitten when compared to respondents who were under the age of 60. Living inside the city limits also increased the chance that the respondent would report being bitten by a dog (OR 2.3, 95% CI: 1.4, 3.9). Females were 2.3 times more likely (95% CI: 1.3, 3.7) to report being bitten than their male counterparts. Dog ownership did not have a significant impact on reporting. Only 85% of respondents stated that they would seek emergency treatment if they believed that they may have been exposed to rabies. In addition, only 59% of respondents were aware that exposure to rabies without treatment could lead to death. While 98% of respondents had heard of rabies and knew that it was possible to get it from a dog, only 54% of respondents knew that worms could be transmitted from dogs to people. This study demonstrated that many people surveyed lacked knowledge about dog-associated zoonotic diseases, which could seriously impact their health and the health of their families. It is important to find a method of getting information out to the public in order to correct this deficiency.     

Tick-borne zoonoses: Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever

The primary health risk for veterinary staff and companion pet owners is exposure to ticks in the wooded/pasture areas or to ticks brought indoors by their pets. There are no proven cases of direct animal to human transmission for Lyme disease, ehrlichiosis, or Rocky Mountain spotted fever. Direct inoculation of blood from a bacteremic animal, eg, by needle stick is a theoretical, but, so far, undocumented health risk. However, veterinarians should record needle sticks or other inoculation-type injuries that occur in their practices. Prevention of Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, and other tick-borne diseases depends on the avoidance of tick-infested areas and proper use of repellents and acaricides.     

The future role of the veterinarian in the control of zoonoses

Developments in the rearing and the health status of meat animals is presented. Attention is drawn to the increase in latent infections, most of which are zoonotic diseases. Such infections escape official ante-mortem and post-mortem inspection as it is presently conducted in industrialised countries, which still rely on the classical rules established by Robert von Ostertag. This examination is thus in need of reform. Proposals submitted to the EEC Commission consist of a stepwise inclusion of the major herds of meat animals in systematic health control aimed at effective control of zoonoses and thus improved consumer protection. It is thus expected that the importance of meat inspection on the basis of pathological-anatomical changes will decrease the importance of establishing the health status during the animal's lifetime will increase. Nevertheless, there will be no complete substitution of classical meat inspection because there are numerous changes in the meat specific to the individual animal which can be detected only by meat inspection, and must be detected if the concept of consumer protection is properly applied. The reform of meat inspection which has become necessary will entail a variety of new tasks for research.     

The future role of the veterinarian in the control of zoonoses

Summary

Developments in the rearing and the health status of meat animals is presented. Attention is drawn to the increase in latent infections, most of which are zoonotic diseases. Such infections escape official ante‐mortem and post‐mortem inspection as it is presently conducted in industrialised countries, which still rely on the classical rules established by Robert von Ostertag. This examination is thus in need of reform.

Proposals submitted to the EEC Commission consist of a stepwise inclusion of the major herds of meat animals in systematic health control aimed at effective control of zoonoses and thus improved consumer protection. It is thus expected that the importance of meat inspection on the basis of pathological‐anatomical changes will decrease the importance of establishing the health status during the animal's lifetime will increase.

Nevertheless, there will be no complete substitution of classical meat inspection because there are numerous changes in the meat specific to the individual animal which can be detected only by meat inspection, and must be detected if the concept of consumer protection is properly applied. The reform of meat inspection which has become necessary will entail a variety of new tasks for research.     

Outlook for control of current zoonoses in swine--an issue on consumer health protection

With the development of a uniform European strategy for the control of zoonoses the European Commission has placed the main emphasis on the protection of consumer health. This direction is clearly marked by the White Paper on Food Safety and the attached proposals for directives and regulations. The present article considers the peculiarities of the epidemiological situation of the agents Campylobacter spp. and Yersinia enterocolitica in pork production. The situation of zoonoses in Europe is used as an opportunity to present the distinctive characteristics of these agents, results of epidemiological studies available, and the risk to consumer health in light of the literature. For the approaching transfer of the responsibility for food safety to the primary producers, i.e. the farmers, the most interesting data concern the prevalence, distribution and risk factors. But as there is a strong need for clarification of further questions about the main ways of entry of these agents on farms and into the production chain before a successful preventive strategy can be developed on pig farms, these issues are considered in more detail here.     

Zoonoses and potential zoonoses of bears

Captive and free‐ranging wild bears can carry and transmit several zoonotic pathogens. A review of nearly 90 years of scientific publications concerning confirmed and potential zoonotic diseases that can be present in any of the eight species of bears in the world was conducted. The findings were organized amongst the following disease sections: bacterial, viral, protozoal, mycotic, helminth and arthropod‐borne. The most commonly reported pathogens of concern were of parasitic (Trichinella, Toxoplasma) and bacterial (Francisella, Brucella) origin.     

Vector-borne parasitic zoonoses: emerging scenarios and new perspectives

Changing climate is not the only driver for alterations in the dynamic interaction between arthropod vectors of zoonotic parasites and their hosts, including humans. A suite of other factors ranging from urbanization and deforestation to changing demographics in both developing and developed countries, the impact of the recent economic crisis, increased global movement of people and animals and follow-on effects of major catastrophes. This article reviews the most important vector-borne parasites of zoonotic concern that are changing/expanding their distribution patterns in both endemic and/or previously non-endemic areas. We include the discussion of the changing aspects of malaria, leishmaniasis, babesiosis, Chagas disease as well as of some spirurid and filarioid nematodes.