Veterinary aspects of ecological monitoring: the natural history of emerging infectious diseases of humans,domestic animals and wildlife

Proliferation of disease pathogens capable of affecting humans, domestic livestock and wildlife increasingly threatens environmental security and biodiversity. Livestock and wild animals in proximity to human beings are often in the chain of transmission and infection. Globalization of industrial livestock production (especially poultry upon which so much of the burgeoning human population depends) often permits transcontinental disease spread. Rapidly expanding (and often illegal) international trade in wild and domestic animals and their products are increasingly involved in the emergence of new diseases that may have the ability to transmit among humans, livestock and wildlife. Rapidly increasing urbanization has led in many places to overcrowded townships that rely on “bushmeat” for sustenance and has contributed to the emergence of virulent zoonotic pathogens. The emergence and proliferation of pathogens are exacerbated by anthropogenic transformation of natural landscapes in order to increase agricultural and livestock production. This paper posits that data gathered by veterinary ecologists should be interpreted and used by other disciplines. The importance of a thorough knowledge of the “natural history” (ecology) of the disease agent and its human, domestic and wild hosts is stressed.     

Seroprevalence of brucellosis, tularemia, and yersiniosis in wild boars (Sus scrofa) from north-eastern Germany

Brucellosis and tularemia are classical zoonotic diseases transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonoses. The surveillance of the animal health status is strictly regulated for domestic animals, whereas systematic disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti-Brucella, anti-Francisella and anti-Yersinia antibodies in wild boars from North-Eastern Germany to assess public health risks. A total of 763 sera of wild boars from Mecklenburg-Western Pomerania hunted in 1995/1996 were tested using a commercially available Brucella suis ELISA, an in-house lipopolysaccharide (LPS)-based Francisella ELISA, and commercially available Western blot kits for the detection of anti-Francisella and anti-Yersinia antibodies. The Yersinia enterocolitica O:9 LPS is able to induce serological cross-reactions indistinguishable from brucellosis due to a similar immunodominant epitope in the Brucella O-polysaccharide. The Yersinia Western blot assay was, therefore, based on five recombinant Yersinia outer proteins which have been proved to be specific for the serodiagnosis of yersiniosis. Anti-Brucella, anti-Francisella and anti-Yersinia antibodies were detected in 22.0%, 3.1%, and 62.6% of the wild boars, respectively. The high seroprevalence of tularemia and brucellosis in wild boars indicates that natural foci of these zoonoses are present in wildlife in Germany. However, the impact of transmission of zoonotic pathogens from wildlife to livestock is unknown. Only careful and systematic monitoring will help to prevent the (re)emergence of these zoonotic diseases in domestic animals and consequently human infection.     

The devil is in the details—Host disease and co‐infections are associated with zoonotic pathogen carriage in Norway rats (Rattus norvegicus)

Traditionally, zoonotic pathogen ecology studies in wildlife have focused on the interplay among hosts, their demographic characteristics and their pathogens. But pathogen ecology is also influenced by factors that traverse the hierarchical scale of biological organization, ranging from within‐host factors at the molecular, cellular and organ levels, all the way to the host population within a larger environment. The influence of host disease and co‐infections on zoonotic pathogen carriage in hosts is important because these factors may be key to a more holistic understanding of pathogen ecology in wildlife hosts, which are a major source of emerging infectious diseases in humans. Using wild Norway rats (Rattus norvegicus) as a model species, the purpose of this study was to investigate how host disease and co‐infections impact the carriage of zoonotic pathogens. Following a systematic trap and removal study, we tested the rats for the presence of two potentially zoonotic bacterial pathogens (Bartonella tribocorum and Leptospira interrogans) and assessed them for host disease not attributable to these bacteria (i.e., nematode parasites, and macroscopic and microscopic lesions). We fitted multilevel multivariable logistic regression models with pathogen status as the outcome, lesions and parasites as predictor variables and city block as a random effect. Rats had significantly increased odds of being infected with B. tribocorum if they had a concurrent nematode infection in one or more organ systems. Rats with bite wounds, any macroscopic lesion, cardiomyopathy or tracheitis had significantly increased odds of being infected with L. interrogans. These results suggest that host disease may have an important role in the ecology and epidemiology of rat‐associated zoonotic pathogens. Our multiscale approach to assessing complex intrahost factors in relation to zoonotic pathogen carriage may be applicable to future studies in rats and other wildlife hosts.     

Zoological medicine and public health

Public-health issues regarding zoological collections and free-ranging wildlife have historically been linked to the risk of transmission of zoonotic diseases and accidents relating to bites or injection of venom or toxins by venomous animals. It is only recently that major consideration has been given worldwide to the role of the veterinary profession in contributing to investigating zoonotic diseases in free-ranging wildlife and integrating the concept of public health into the management activities of game preserves and wildlife parks. At the veterinary undergraduate level, courses in basic epidemiology, which should include outbreak investigation and disease surveillance, but also in population medicine, in infectious and parasitic diseases (especially new and emerging or re-emerging zoonoses), and in ecology should be part of the core curriculum. Foreign diseases, especially dealing with zoonotic diseases that are major threats because of possible agro-terrorism or spread of zoonoses, need to be taught in veterinary college curricula. Furthermore, knowledge of the principles of ecology and ecosystems should be acquired either during pre-veterinary studies or, at least, at the beginning of the veterinary curriculum. At the post-graduate level, master's degrees in preventive veterinary medicine, ecology and environmental health, or public health with an emphasis on infectious diseases should be offered to veterinarians seeking job opportunities in public health and wildlife management.     

A review of zoonotic disease surveillance supported by the Armed Forces Health Surveillance Center

The Armed Forces Health Surveillance Center (AFHSC), Division of Global Emerging Infections Surveillance and Response System conducts disease surveillance through a global network of US Department of Defense research laboratories and partnerships with foreign ministries of agriculture, health and livestock development in over 90 countries worldwide. In 2010, AFHSC supported zoonosis survey efforts were organized into four main categories: (i) development of field assays for animal disease surveillance during deployments and in resource limited environments, (ii) determining zoonotic disease prevalence in high-contact species which may serve as important reservoirs of diseases and sources of transmission, (iii) surveillance in high-risk human populations which are more likely to become exposed and subsequently infected with zoonotic pathogens and (iv) surveillance at the human-animal interface examining zoonotic disease prevalence and transmission within and between human and animal populations. These efforts have aided in the detection, identification and quantification of the burden of zoonotic diseases such as anthrax, brucellosis, Crimean Congo haemorrhagic fever, dengue fever, Hantaan virus, influenza, Lassa fever, leptospirosis, melioidosis, Q fever, Rift Valley fever, sandfly fever Sicilian virus, sandfly fever Naples virus, tuberculosis and West Nile virus, which are of military and public health importance. Future zoonotic surveillance efforts will seek to develop local capacity for zoonotic surveillance focusing on high risk populations at the human-animal interface.     

Seroprevalence of Brucellosis,Tularemia, and Yersiniosis in Wild Boars (Sus scrofa) from North‐Eastern Germany

Brucellosis and tularemia are classical zoonotic diseases transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonoses. The surveillance of the animal health status is strictly regulated for domestic animals, whereas systematic disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti‐Brucella, anti‐Francisella and anti‐Yersinia antibodies in wild boars from North‐Eastern Germany to assess public health risks. A total of 763 sera of wild boars from Mecklenburg‐Western Pomerania hunted in 1995/1996 were tested using a commercially available Brucella suis ELISA, an in‐house lipopolysaccharide (LPS)‐based Francisella ELISA, and commercially available Western blot kits for the detection of anti‐Francisella and anti‐Yersinia antibodies. The Yersinia enterocolitica O:9 LPS is able to induce serological cross‐reactions indistinguishable from brucellosis due to a similar immunodominant epitope in the Brucella O‐polysaccharide. The Yersinia Western blot assay was, therefore, based on five recombinant Yersinia outer proteins which have been proved to be specific for the serodiagnosis of yersiniosis. Anti‐Brucella, anti‐Francisella and anti‐Yersinia antibodies were detected in 22.0%, 3.1%, and 62.6% of the wild boars, respectively. The high seroprevalence of tularemia and brucellosis in wild boars indicates that natural foci of these zoonoses are present in wildlife in Germany. However, the impact of transmission of zoonotic pathogens from wildlife to livestock is unknown. Only careful and systematic monitoring will help to prevent the (re)emergence of these zoonotic diseases in domestic animals and consequently human infection.     

Zoonotic implications of the swine-transmitted protozoal infections

Pig production is an important part of the economy in many countries. Domestic and wild pigs (Sus scrofa) are susceptible to a wide range of infectious and parasitic diseases. Some of these diseases are specifically limited to pigs while some of the other diseases are shared with other species of wildlife and domestic livestock. As the numbers and geographic distribution of wild and domestic swines continue to increase, it is certain that the number of contacts between these swines and domestic livestock will also increase, as will the probability of human exposure to the parasites of swine directly or indirectly. Here, we will discuss the protozoal infections of pigs, which have the potential to infect humans and provide reasonable risk assessment for zoonotic transmission.     

Zoonotic aspects of Mycobacterium bovis and Mycobacterium avium-intracellulare complex (MAC)

Pathogens that are transmitted between the environment, wildlife, livestock and humans represent major challenges for the protection of human and domestic animal health, the economic sustainability of agriculture, and the conservation of wildlife. Among such pathogens, the genus Mycobacterium is well represented by M. bovis, the etiological agent of bovine tuberculosis, M. avium ssp. paratuberculosis (Map) the etiological agent of Johne disease, M. avium ssp. avium (Maa) and in a few common cases by other emergent environmental mycobacteria. Epidemiologic surveys performed in Europe, North America and New Zealand have demonstrated the existence and importance of environmental and wildlife reservoirs of mycobacterial infections that limit the attempts of disease control programmes. The aim of this review is to examine the zoonotic aspects of mycobacteria transmitted from the environment and wildlife. This work is focused on the species of two main groups of mycobacteria classified as important pathogens for humans and animals: first, M. bovis, the causative agent of bovine tuberculosis, which belongs to the M. tuberculosis complex and has a broad host range including wildlife, captive wildlife, domestic livestock, non-human primates and humans; the second group examined, is the M. avium-intracellulare complex (MAC) which includes M. avium ssp. avium causing major health problems in AIDS patients and M. avium ssp. paratuberculosis the etiological agent of Johne disease in cattle and identified in patients with Crohn disease. MAC agents, in addition to a broad host range, are environmental mycobacteria found in numerous biotopes including the soil, water, aerosols, protozoa, deep litter and fresh tropical vegetation. This review examines the possible reservoirs of these pathogens in the environment and in wildlife, their role as sources of infection in humans and animals and their health impact on humans. The possibilities of control and management programmes for these mycobacterial infections are examined with regards to the importance of their natural reservoirs.     

Emerging and exotic zoonotic disease preparedness and response in the United States - coordination of the animal health component

For the response to a zoonotic disease outbreak to be effective, animal health authorities and disease specialists must be involved. Animal health measures are commonly directed at known diseases that threaten the health of animals and impact owners. The measures have long been applied to zoonotic diseases, including tuberculosis and brucellosis, and can be applied to emerging diseases. One Health (veterinary, public, wildlife and environmental health) and all-hazards preparedness work have done much to aid interdisciplinary understanding and planning for zoonotic diseases, although further improvements are needed. Actions along the prevention, preparedness, response and recovery continuum should be considered. Prevention of outbreaks consists largely of import controls on animals and animal products and biosecurity. Preparedness includes situational awareness, research, tool acquisition, modelling, training and exercises, animal movement traceability and policy development. Response would include detection systems and specialized personnel, institutions, authorities, strategies, methods and tools, including movement control, depopulation and vaccination if available and appropriate. The specialized elements would be applied within a general (nationally standardized) system of response. Recovery steps begin with continuity of business measures during the response and are intended to restore pre-event conditions. The surveillance for novel influenza A viruses in swine and humans and the preparedness for and response to the recent influenza pandemic illustrate the cooperation possible between the animal and public health communities.     

Yersinia pestis: examining wildlife plague surveillance in China and the USA

Plague is a zoonotic disease caused by the bacterium Yersinia pestis Lehmann and Neumann, 1896. Although it is essentially a disease of rodents, plague can also be transmitted to people. Historically, plague has caused massive morbidity and mortality events in human populations, and has recently been classified as a reemerging disease in many parts of the world. This public health threat has led many countries to set up wild and domestic animal surveillance programs in an attempt to monitor plague activity that could potentially spill over into human populations. Both China and the USA have plague surveillance programs in place, but the disease dynamics differ in each country. We present data on plague seroprevalence in wildlife and review different approaches for plague surveillance in the 2 countries. The need to better comprehend plague dynamics, combined with the fact that there are still several thousand human plague cases per year, make well-designed wildlife surveillance programs a critical part of both understanding plague risks to humans and preventing disease outbreaks in the future.     

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.     

Leptospira interrogans at the Human–Wildlife Interface in Northern Botswana: A Newly Identified Public Health Threat

Leptospirosis is the most widespread zoonosis in the world. In northern Botswana, humans live in close proximity to a diversity of wildlife and peridomestic rodents and may be exposed to a variety of zoonotic pathogens. Little is known regarding the occurrence and epidemiology of L. interrogans in Africa despite the recognized global importance of this zoonotic disease and the threat it poses to public health. In Botswana, banded mongooses (Mungos mungo) live in close proximity to humans across protected and unprotected landscapes and may be a useful sentinel species for assessing the occurrence of zoonotic organisms, such as L. interrogans. We utilized PCR to screen banded mongoose kidneys for leptospiral DNA and identified 41.5% prevalence of renal carriage of L. interrogans (exact binomial 95% CI 27.7–56.7%, n = 41). Renal carriage was also detected in one Selous' mongoose (Paracynictis selousi). This is the first published confirmation of carriage of L. interrogans in either species. This is also the first report of L. interrogans occurrence in northern Botswana and the only report of this organism in a wildlife host in the country. Pathogenic Leptospira are usually transmitted indirectly to humans through soil or water contaminated with infected urine. Other avenues, such as direct contact between humans and wildlife, as well as consumption of mongooses and other wildlife as bushmeat, may pose additional exposure risk and must be considered in public health management of this newly identified zoonotic disease threat. There is a critical need to characterize host species involvement and pathogen transmission dynamics, including human–wildlife interactions that may increase human exposure potential and infection risk. We recommend that public health strategy be modified to include sensitization of medical practitioners to the presence of L. interrogans in the region, the potential for human infection, and implementation of clinical screening. This study illustrates the need for increased focus on neglected zoonotic diseases as they present an important threat to public health.     

Marine Mammal Zoonoses: A Review of Disease Manifestations

Marine mammals evoke strong public affection as well as considerable scientific interest. However, the resultant close contact with marine wildlife poses human health risks, including traumatic injury and zoonotic disease transmission. The majority of zoonotic marine mammal diseases result in localized skin infections in man that resolve spontaneously or with appropriate medical therapy. However, other marine mammal zoonoses, if left untreated, induce life‐threatening systemic diseases that could pose public health risks. As the number of zoonotic diseases rises, the diagnosis of and treatment for these emerging pathogens pose special challenges requiring the expertise of physicians, veterinarians and wildlife biologists. Here, we provide a comprehensive review of the bacterial, viral and fungal marine mammal zoonotic diseases that we hope will be utilized by public health professionals, physicians, veterinarians and wildlife biologists to better understand, diagnose and prevent marine mammal zoonotic diseases.     

Developing vaccines to control protozoan parasites in ruminants: dead or alive?

Protozoan parasites are among some of the most successful organisms worldwide, being able to live and multiply within a very wide range of hosts. The diseases caused by these parasites cause significant production losses in the livestock sector involving reproductive failure, impaired weight gain, contaminated meat, reduced milk yields and in severe cases, loss of the animal. In addition, some protozoan parasites affecting livestock such as Toxoplasma gondii and Cryptosporidium parvum may also be transmitted to humans where they can cause serious disease. Data derived from experimental models of infection in ruminant species enables the study of the interactions between parasite and host. How the parasite initiates infection, becomes established and multiplies within the host and the critical pathways that may lead to a disease outcome are all important to enable the rational design of appropriate intervention strategies. Once the parasites invade the hosts they induce both innate and adaptive immune responses and the induction and function of these immune responses are critical in determining the outcome of the infection. Vaccines offer green solutions to control disease as they are sustainable, reducing reliance on pharmacological drugs and pesticides. The use of vaccines has multiple benefits such as improving animal health and welfare by controlling animal infections and infestations; improving public health by controlling zoonoses and food borne pathogens in animals; solving problems associated with resistance to acaricides, antibiotics and anthelmintics; keeping animals and the environment free of chemical residues and maintaining biodiversity. All of these attributes should lead to improved sustainability of animal production and economic benefit. Using different protozoan parasitic diseases as examples this paper will discuss various approaches used to develop vaccines to protect against disease in livestock and discuss the relative merits of using live versus killed vaccine preparations. A range of different vaccination targets and strategies will be discussed to help protect against: acute disease, congenital infection and abortion, persistence of zoonotic pathogens in tissues of food animals and passive transfer of immunity to neonates.     

在“同一个健康”框架下,加强兽医与人医合作,有效监测和应对人畜共患病和新发传染病

新发传染病主要是人畜共患病,是世界经济和公共健康的沉重负担。这就要求加强检测、鉴别和监视传染病的能力方面投入。高致病禽流感H5N1、新甲型流感("猪流感")H1N1、非典型性肺炎、西尼罗河病毒、地方流行性狂犬病、布鲁氏菌病以及发展中国家暴发的其它人畜共患病及近期猪抗甲氧西林金黄色葡萄球菌,是人类、动物及其环境相互作用的典型范例。面临中国动物和人类常见的新发传染病坚持"同一个健康"战略,这就要求业已存在的兽医和人医及公共卫生机构的通力合作。人的疾病控制系统与动物疾病控制系统虽然都已经建立,但人畜共患病的暴发表明兽医机构和人医机构密切合作的重要性。在保证环境健康的同时,通过动物疾病和人类疾病监测系统的密切合作,中国就一定能够控制人畜共患病。以这种方式进行疾病预防、监测与应对,各层面及各动物生产部门间有效的兽医推广是加强和保持健康生态环境中人和动物健康的有效办法。中国还需大量努力才能达到从制度上保证预防和消灭疾病。透明而准确的人与动物疾病监督通常会产生经济且可持续的预防疾病方法。加拿大在兽医、公共健康、食品安全和人畜共患病预防方面所发挥的作用就是与中国农业部合作,促进必要的、可持续的兽医监督网络的建设。     

野生动物隐孢子虫的种类和基因型

隐孢子虫病（Cryptosporidiosis）是一种全球性的人兽共患原虫病,具有广泛的宿主范围,可以感染鸟类、哺乳类、鱼类、爬行类、两栖类以及人在内的240多种动物。野生动物隐孢子虫做为人隐孢子虫病感染的重要传播来源,对其进行生物学研究具有重要的公共卫生意义。本文分别叙述了野生动物隐孢子虫的种类及基因型,为进一步研究野生动物的隐孢子虫病提供了有效的参考。     

A survey of the transmission of infectious diseases/infections between wild and domestic ungulates in Europe

ABSTRACT: The domestic animals/wildlife interface is becoming a global issue of growing interest. However, despite studies on wildlife diseases being in expansion, the epidemiological role of wild animals in the transmission of infectious diseases remains unclear most of the time. Multiple diseases affecting livestock have already been identified in wildlife, especially in wild ungulates. The first objective of this paper was to establish a list of infections already reported in European wild ungulates. For each disease/infection, three additional materials develop examples already published, specifying the epidemiological role of the species as assigned by the authors. Furthermore, risk factors associated with interactions between wild and domestic animals and regarding emerging infectious diseases are summarized. Finally, the wildlife surveillance measures implemented in different European countries are presented. New research areas are proposed in order to provide efficient tools to prevent the transmission of diseases between wild ungulates and livestock.     

Opportunities and obstacles to collecting wildlife disease data for public health purposes: results of a pilot study on Vancouver Island, British Columbia

Existing sources of wildlife morbidity and mortality data were evaluated and 3 pilot active surveillance projects were undertaken to compare and contrast methods for collecting wildlife disease data on Vancouver Island for public health purposes. Few organizations could collect samples for diagnostic evaluation, fewer still maintained records, and none regularly characterized or reported wildlife disease for public health purposes. Wildlife rehabilitation centers encountered the greatest variety of wildlife from the largest geographic area and frequently received submissions from other organizations. Obstacles to participation included the following: permit restrictions; financial disincentives; staff safety; no mandate to collect relevant data; and lack of contact between wildlife and public health agencies. Despite these obstacles, modest investments in personnel allowed novel pathogens of public health concern to be tracked. Targeted surveillance for known pathogens in specific host species, rather than general surveys for unspecified pathogens, was judged to be a more effective and efficient way to provide useful public health data.     

Cryptosporidiosis in People: It's Not Just About the Cows

Cryptosporidiosis is one of the most common causes of infectious diarrhea in people. Although dairy calves are high-risk hosts, the role of other livestock, pets, and humans in the disease should not be underestimated. Some Cryptosporidium species and strains are specific to people, others are specific to animals while some are zoonotic pathogens. Cryptosporidium hominis is the species responsible for the majority of human cases in the United States, Sub-Saharan Africa, and Asia, while Cryptosporidium parvum accounts for more human cases in Europe and particularly in the United Kingdom. A deeper understanding of Cryptosporidium host range, reservoirs, and transmission is needed to develop preventive strategies to protect the general public.     

The transmissible spongiform encephalopathies: disease risks for North America.

Transmissible spongiform encephalopathies exotic to North America (BSE and associated diseases) are unlikely to be introduced or to persist should they be introduced into the United States [2]. Domestic TSEs (scrapie, CWD, and TME) seem to be relatively restricted in their host range, and none of these diseases is known to naturally cause disease in cattle. It is important that surveillance for TSEs continues, however, particularly in cattle because of the extreme consequences to the livestock industries, and potentially, public health, if BSE becomes established. Because the TSEs have implications beyond effects on their natural host species, adequate surveillance, control, and even eradication of these diseases should be goals for the livestock industries, wildlife managers, and animal health agencies in the United States.