Role of the Veterinarians and One Health in the Fight Against Zoonoses
K.P. Singh*1 and Praneeta Singh2
Government Veterinary Hospital, Deoranian, Bareilly,
Department of Animal Husbandry, Uttar Pradesh, India
1: Veterinary Officer, Government Veterinary Hospital, Deoranian, Bareilly, Uttar Pradesh Email: drkpsvet@rediffmail.com
2: Assistant Professor, Department of Livestock Products Technology, C.V.A.Sc., GBPUAT, Pantnagar, U.S.Nagar, Uttrakhand Email: vet_praneeta12@rediffmail.com
*Corresponding Author: Veterinary Officer, Government Veterinary Hospital, Deoranian, Bareilly, Uttar Pradesh Email: drkpsvet@rediffmail.com
Abstract
A zoonosis is an infectious disease that has jumped from a non-human animal to humans. The emergence and spread of zoonotic diseases like COVID-19 caused by SARS-CoV-2, indicates that veterinarians inhabit a central and primary position in the prevention of new and dangerous zoonoses that may impact human health. This is particularly true as this pandemic fits into the One Health concept, which considers the interactions between humans, animals, the environment and recognizes that human health is closely related to animal and environmental health. It is in these interfaces that veterinarians can play a relevant role in the prevention and detection of new zoonoses and determine which ones deserve at least some consideration. Veterinarians are especially important in wildlife surveillance, which becomes a fundamental parameter in the control of emerging zoonoses because ecological changes, molecular variations of infectious agents and wild animal-man interactions represent the main factors for the emergence of new pathogens.
Key Words: One health concept; Veterinarian; Zoonoses
Introduction
A zoonosis is an infectious disease that has jumped from a non-human animal to humans. Zoonotic pathogens may be bacterial, viral or parasitic or may involve unconventional agents and can spread to humans through direct contact or through food, water or the environment. They represent a major public health problem around the world due to our close relationship with animals in agriculture, as companions and in the natural environment. Zoonoses can also cause disruptions in the production and trade of animal products for food and other uses. Zoonoses comprise a large percentage of all newly identified infectious diseases as well as many existing ones. Some diseases, such as HIV, begin as a zoonosis but later mutate into human-only strains. Other zoonoses can cause recurring disease outbreaks, such as Ebola virus disease and salmonellosis. The others such as the novel coronavirus that causes COVID-19, have the potential to cause global pandemics.
We are currently living in an unusual pandemic, due to the spread of Coronavirus Disease in 2019 (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). This virus forms a sister clade to the prototype human and bat severe acute respiratory syndrome coronaviruses (SARS-CoVs) (Gorbalenya et al., 2020). SARS-CoV-2 belongs to the Coronavirinae subfamily, family Coronaviridae. Virions are spherical, displaying club-shaped projections. Enveloped by a lipid bilayer envelope, SARs-CoV-2 has a positive-sense single-stranded RNA that encodes four structural proteins [proteins S (spike protein), E (envelope), M (membrane) and N (nucleocapsid)] and 16 non-structural proteins (Tilocca et al., 2020).
The emergence and spread of zoonotic diseases like COVID-19 caused by SARS-CoV-2, indicates that veterinarians inhabit a central and primary position in the prevention of new and dangerous zoonoses that may impact human health. This is particularly true as this pandemic fits into the One Health concept, which considers the interactions between humans, animals, the environment and recognizes that human health is closely related to animal and environmental health (Bonilla-Aldana et al., 2020). It is in these interfaces that veterinarians can play a relevant role in the prevention and detection of new zoonoses and determine which ones deserve at least some consideration.
The Emerging Zoonoses
It has been proven that at least 75% of emerging diseases have a zoonotic origin, having diverse animal species as their primary reservoirs. Striking examples of these zoonoses include epidemics and/or pandemics such as the Spanish flu (Taubenberger and Morens, 2006), H1N1 (Nolting et al., 2019), SARS (Zhao, 2007), MERS (Paden et al., 2018) and Ebola (Pigott et al., 2017). All the etiological agents involved in those cases were originally found in animals and spread in humans. When a pathogen crosses species barrier, in most cases, the disease may not sustain or establish in the heterologous host. However, occasionally, there is a potential risk that it becomes more pathogenic and virulent, with consequences almost impossible to predict, as was experienced with the HIV virus (Peeters et al., 2017).
The number of potential human lives lost as well as the high morbidity and imminent risks of epidemics/pandemics converging to result in the emergence of new diseases makes it imperative and necessary to intensify studies, in which veterinarians have the responsibility to identify and reveal the risks, critical points and other epidemiological aspects involved in the transmission of an infectious agent from the animal, environment, and human interfaces.
Risk groups
Zoonotic pathogens can spread to humans through any contact point with domestic, agricultural or wild animals. Markets selling the meat or by-products of wild animals are particularly high risk due to the large number of new or undocumented pathogens known to exist in some wild animal populations. Agricultural workers in areas with a high use of antibiotics for farm animals may be at increased risk of pathogens resistant to current antimicrobial drugs. People living adjacent to wilderness areas or in semi-urban areas with higher numbers of wild animals are at risk of disease from animals such as rats, foxes or raccoons. Urbanization and the destruction of natural habitats increase the risk of zoonotic diseases by increasing contact between humans and wild animals.
Role of The Veterinarian Professional
Considering the possible origin of the current pandemic, the intensification of studies in regions associated with high human activity alone and with intense contact with wildlife, should become a priority in the prevention of emerging diseases, as such hotspots are decisive in the emergence of new epidemics and pandemics. There are several regions in the world in which it is possible to identify the presence of these hotspots, including low and middle-income countries in South America and Africa. Therefore, potential new pandemics such as COVID-19 pose serious health threats in underdeveloped countries where these hotspots occur. This type of hotspot can also be seen in developed countries especially in places where there is a greater vulnerability in poor populations (Naranjo and Cosivi, 2021). Therefore, the consequences of contact between wildlife and human activities can have consequences in rich countries. It is necessary to reunite the forces and capacities of all of the involved actors and entities to avoid chaos and lack of control in the case of new emerging zoonotic diseases. The knowledge obtained through monitoring eventual ecological/epidemiological changes and the experience of previous studies in all knowledge areas will be effective tools to predict, prevent, and anticipate outbreaks by impacting zoonotic diseases such as COVID-19. This summarizes the veterinarian’s role in public health, framed in the One Health concept.
Emerging and re-emerging pathogens present challenges for public health systems worldwide. When considering animal interaction, the complexity of these challenges becomes even more evident. Despite the integration of the OIE and the WHO in the context of the One Health concept in 1960, the idea is still poorly explored in underdeveloped countries. Investment in studies that prioritize the investigation of the infectious agents present in wild animals associated with hotspots does not represent, at this moment a priority strategy for the prevention of pandemics by public health agencies. The implementation of this type of action would allow for the early identification of potential pathogens and the development of actions that could block and reduce opportunities for the pathogens to circulate freely and repeatedly among primary hosts and become highly infectious to humans.
Specific Actions
Veterinarians have experience in successfully managing outbreaks of diseases, such as brucellosis, tuberculosis, anthrax, foot-and-mouth disease and rabies, in addition to controlling zoonotic pathogens in foods of animal origin (Verteramo et al., 2019). Control measures, when strictly applied to animals, have resulted in a significant reduction of zoonoses in humans.
Practices such as zoobiquity and translational medicine are effectively applied in some countries with more stable economies for other diseases and would help to prevent zoonotic pandemics such as COVID-19. On the other hand, the exchange of experiences and the adoption of professional containment activities such as those which are customary in veterinary practice, like isolation and quarantine measures, could be useful. The latter, unlike in human medicine, are instances when veterinary practices are widely and rigorously used because they represent the main principles for preventing the entrance and spread of diseases in naïve animal populations.
Surveillance measures represent the main strategy, considering these preventive needs. Active surveillance is important in the investigation of the potential pathogens of animals and the potentials of possible emergence in humans. This type of control would allow the acquisition of rich databases that would support specific and effective measures to control zoonotic epidemics. High-risk behaviours could also be identified, and health education activities could be initiated to change habits that contribute to and hinder the adaptation and dissemination of the pathogens.
Veterinarians are especially important in wildlife surveillance, which becomes a fundamental parameter in the control of emerging zoonoses because ecological changes, molecular variations of infectious agents and wild animal-man interactions represent the main factors for the emergence of new pathogens. Therefore, the collaboration between veterinary communities linked to the monitoring of wildlife and human medical communities is crucial in the development of preventive strategies and must follow a double direction in the provision of early and specific information, which is not evident in most developing countries.
Microbiology studies combined with physiology, immunology and behavioural ecology must be applied to asymptomatic animal hosts. They can demonstrate which mechanisms could explain the absence of clinical signs and can provide effective and applicable responses to humans. At the same time, they are specific animal models, which provide ideal conditions for the reproduction of the disease showing similarity to human responses and should be used to carry out vaccine and treatment tests before being applied to humans. Besides, prior knowledge of the etiologic agent, its intrinsic characteristics and ecology can facilitate the faster development of vaccines and therapy drugs in cases of emergency and health risk.
Comparative medicine also covers field studies in the prevention of zoonosis. A good example of this is the monitoring of diseases that occur naturally in animal populations that can signal potential threats to human health. The use of sentinel animals, which have greater susceptibility, environmental exposure, or shorter life span has been very useful. The double meaning in interventions must be attributed to the One Health approach considering the risks shared between humans and animals.
Veterinary epidemiology allows alignment with disease forecasting and modelling studies through the application of georeferencing software that associates environmental variables such as temperature, humidity, soil type, vector density, pathogen, host, exposure and transit of animals and people. The convergence of factors that include the availability of these geocoded multi-temporal data and multi-professional collaborations worldwide would allow for the production of a sophisticated Geographic Information System under a holistic perspective for the development of research related to the control of zoonosis.
The molecular evolutionary aspects of zoonotic or potential pathogens must be constantly monitored. Genomic plasticity is a factor widely identified in viruses and bacteria within animal hosts and in hostile environmental conditions, such as thermal, oxidative, nutritional and chemical stress, which could favour the selection pressure of more adapted, resistant, and/or pathogenic agents.
Several recent studies have highlighted the fundamental importance of the veterinarian’s performance in the context of One Health. Van Doremalen et al. (2020) have demonstrated the preliminary efficacy of a vaccine tested on mice and Rhesus macaques against SARS-CoV-2 in partnership with a multi-professional team that includes veterinarians. In Chile, another multidisciplinary group, including veterinarians, developed an improved procedure to produce nanobodies using alpacas (Lama pacos) as donor species. Nieto et al. (2020) reported an optimized, fast, efficient, inexpensive and simple density gradient method for nanobody selection and a sub-nanomolar affinity nanobody against the Spike receptor binding domain of SARS-CoV2. This proposed methodology may help in the generation of diagnostic and potentially therapeutic measures against COVID-19 and other infectious and emergent viruses. Sun et al. (2020) reported a variant of H1N1 from pigs with the greatest pathogenic potential in humans. Their experimental work was carried out in veterinary laboratories in the USA. In India, Dhama et al. (2018) have reported intense research performed with veterinarians in the development of vaccines and effective therapies against Ebola. Maki et al. (2017) reported that the monitoring of wildlife allowed the implementation of control strategies such as the use of bait vaccines to control wild rabies.
Epidemics such as those already experienced and uncontrolled pandemics such as the current COVID-19 will continue to happen, not only because of the high capacity of zoonotic pathogens to carry out mutation, reassortment and recombination processes that allow them to overcome barriers between species, geographical limitations and adverse conditions but also due to the severe deficiency in the surveillance systems.
These factors coupled with few globalized and unified combat actions and the low interaction of the pillars of One Health focus, which involves the medical, veterinary and environmental communities and increases the risk of new emergencies in public health worldwide.
Prevention and control of Zoonotic Diseases
Prevention methods for zoonotic diseases differ for each pathogen. However, several practices are recognized as effective in reducing risk at the community and personal levels. Safe and appropriate guidelines for animal care in the agricultural sector help to reduce the potential for foodborne zoonotic disease outbreaks through foods such as meat, eggs, dairy or even some vegetables. Standards for clean drinking water and waste removal, as well as protections for surface water in the natural environment are also important and effective. Education campaigns to promote handwashing after contact with animals and other behavioural adjustments can reduce community spread of zoonotic diseases when they occur. Antimicrobial resistance is a complicating factor in the control and prevention of zoonoses. The use of antibiotics in animals raised for food is widespread and increases the potential for drug-resistant strains of zoonotic pathogens capable of spreading quickly in animal and human populations.
People can come in contact with animals in many places. This includes at home and away from home, in places like petting zoos, fairs, schools, stores, and parks. Insects, like mosquitoes and fleas, and ticks bite people and animals’ day and night. Thankfully, there are things you can do to protect yourself and your family from zoonotic diseases.
Conclusion
Variations in behaviour and different human activities, such as the consumption and sale of wild animals, the poor application of food security rules, the advance of urbanization into rural areas and constant direct contact with animal reservoirs are recognized as the main risk factors that lead to outbreaks. All these factors can be tackled with preventive actions from a veterinary perspective, which are the resolutive competencies of this profession. To avoid future emerging zoonoses, it is necessary to be prepared. The most effective way may be to maintain the natural barriers between animals that are reservoirs and human society, applying the conceptualization of the One Health doctrine in these actions. The veterinarian must assume a position of leadership in research and actions that primarily involve prevention and surveillance, which must be undertaken as an important part of maintaining public health, especially related to emerging and re-emerging zoonoses.
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