Role of Veterinarians and One Health in the Fight against Zoonosis
Dr. Abhilakh Singh kushwah1, Dr. Anand k Yadav2
(PG scholar)1,2
Department of veterinary Gynaecology & obstetrics Jabalpur1,2
College of Veterinary Science & Animal Husbandry Jabalpur, NDVSU Jabalpur M.P. – 482001
Corresponding Author: Abhilakh825@gmail.com
INTRODUCTION
Zoonoses are diseases and infections that are naturally transmitted between vertebrate animals and humans. Approximately 60% of all human pathogens are zoonotic, all types of potential pathogenic agents, including bacteria, viruses, parasites, and fungi, can cause these zoonotic infections. Veterinarians are trained to help prevent the transmission of zoonotic diseases by recognizing and treating diseases in companion and food animals, these professionals play an essential role in promoting public health by educating clients about disease transmission from animals to humans. We are presently 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) . 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 .
The pathogen has spread around the world within a short period of time. In 8 months (from December 2019 to August 2020) it has reached more than 19 million cases with ∼728 thousand deaths in more than 215 countries/territories/areas of the world. In addition to the challenges it poses to public health, it has provoked economic and social consequences due to the pandemic control measures, which are based on social distancing and the different quarantine concepts implemented throughout the world .The pandemic originated in the city of Wuhan, in the south of China, where rapid economic growth promoted a high demand for animal protein and included regional eating habits, like consumption of exotic animals such as bats, snakes, and pangolins, which are normally traded in local food markets. 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, and 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. One Health (OH) is a collaborative, multisectoral, coordinated, and transdisciplinary approach – working at the local, regional, national, and global levels – with the goal of achieving optimal health outcomes by recognizing the interconnection between people, animals, plants, and their shared environment. With the increase in population, industrialization, and geopolitical problems, global changes are increasing which damage the biodiversity, ecosystems, and migratory movements of both humankind and species in general. Rapid climate and environmental changes have led to the emergence and re-emergence of infectious and noninfectious diseases [figure].
Magnitude of zoonotic disease
the new identified zoonotic agents , most are viruses, In particular, RNA viruses. For example it is estimated that the ocean alone contain somewhere around 4×1030 viruses. This number is higher than the number of stars in the observable universe. Enormous numbers of viral particles can exist on land. For example, one duck can excrete billions of avian influenza (AI) virus particles. Given the enormity of the numbers of emerging viruses as well as the growing challenges of drug-resistant bacteria, the medical and veterinary communities must work together to better understand and contain them.
THE CONTEXT OF EMERGING ZOONOSES
It has been proven that at least 75% of emerging diseases have a zoonotic origin, having various animal species as their primary reservoirs. Striking examples of these zoonoses include epidemics and/or pandemics such as the Spanish flu, H1N1 , SARS, MERS , and Ebola . 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 become more pathogenic and virulent, with consequences almost impossible to predict, as was experienced with the HIV virus . 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.
Examples of zoonotic diseases
Let me give you a few examples of zoonotic diseases research and control in which the zoonoses group in WHO is either involved or which illustrate the current situation as to zoonotic diseases in the world.
- Rabies is certainly one of the most important zoonotic diseases. This does not become obvious when looking at the major causes of death worldwide . Rabies is present in large areas of the northern hemisphere in many different wild animal species (e.g. fox, skunk, raccoon, raccoon dog, mongoose). Although only a small number of human deaths are reported there, rabies remains a permanent public health hazard, represents a major obstacle to the free movements of people and their pets and is at the origin of important spending for the public health sector and the general public (costs of post-exposure treatments, days of work lost). Dog rabies is still present in 87 countries and territories (with a total population at risk of about 2.4 billion persons) where between 35 000 and 50 000 human deaths due to rabies are estimated to occur each year. In these areas a total of 6.5 million persons receive rabies post-exposure treatment. Comprehensive programmes for the control of the disease in dogs have been shown to cost 25-52% less than a programme for improved post-exposure delivery in human beings.
- Echinococcosis/Hydatidosis is an important problem in many parts of the world especially in countries of the middle-east and north Africa where the reported incidence varies from 2 to 89.5 cases per 100 000 inhabitants . In Maghreb countries alone, minimum spending and losses in the human and animal health sectors are estimated at US$ 60 million annually.
- Leptospirosis is found worldwide and most of the cases are diagnosed in professionally-exposed groups such as slaughterhouse workers, veterinarians, livestock breeders, sewer workers, and in some countries in groups representing a large part of the total population, i.e. paddy-field and sugarcane workers. Cases are also associated with recreational activities such as swimming and fishing. In countries where rice cultivation is common, large numbers of farmers involved in water rice paddy field work throughout the year are affected with leptospirosis.
INCLUSION 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. 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 . 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 reemerging 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.
The benefits of One Health
The benefits of a One Health approach include:
- Improving animal and human health globally through collaboration among all the health sciences, especially between the veterinary and human medical professions, to address critical needs.
- Meeting new global challenges head-on through collaboration among multiple professions—veterinary medicine, human medicine, environmental health, wildlife health, and public health.
- Developing centers of excellence for education and training in specific areas through enhanced collaboration among colleges and schools of veterinary medicine, human medicine, and public health.
- Increasing professional opportunities for veterinarians.
- Adding to our scientific knowledge to create innovative programs to improve health.
SOME SPECIFIC ACTIONS
in economic systems worldwide due to COVID-19 was at times the result of disobedience and non-compliance with the guidelines of preventive medicine, which outline the best strategies for containing the spread of the disease. Despite the knowledge and experience gained in previous epidemics, most governmental institutions are still not convinced of the veterinarian’s role in this context. 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 . Control measures, when strictly applied to animals, have resulted in a significant reduction of zoonoses in humans. Some of the specific actions of the veterinary profession are shown in Figure1
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 behaviors 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.
FIGURE 1 | Examples of specific actions by the veterinarians to combat the emergence of zoonotic diseases. (A) – Studies to monitor multiple factors
(environmental, temporal, and others) available in Geographic Information Systems that allow indicating changes for the modeling and forecasting of diseases. (B) – Environmental control that indirectly interferes in the control of vectors and/or hosts amplifying agents that transmit zoonotic diseases. (C) – Monitoring of wildlife through research that evaluates changes in the host and potential pathogens. (D) – In vitro investigation regarding the evolution of the characteristics of infectious agents over time. (E)-Health education through clarification to the population about the risks and care to be taken in human-animal contact. (F) – Production of diagnostic tests and vaccines using animal models based on comparative medicine. (G) – Application of translational medicine and zoobiquity in the exchange of experiences between teams of multi health professionals. (H) – Sanitary control in pets and production animals. (I) – Inspection and control of food of animal origin.
Veterinary epidemiology allows alignment with disease forecasting and modeling 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. have demonstrated the preliminary efficacy of a vaccine tested on mice and Rhesus macaques against SARS-CoV-2 in partnership with a multiprofessional 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. The authors 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. 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. have reported intense research performed with veterinarians in the development of vaccines and effective therapies against Ebola. Maki et al. 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.
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. Despite being the weakest link, 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 reemerging zoonoses.
