Veterinarian response to the COVID-19 crisis : Animal health
- Part 1 -

Dr K Rashbehari Singh *

The Coronaviruses have characteristic 'corona' (crown) of spike proteins which surround their lipid envelope, and hence called coronaviruses. Coronavirus (CoV) infections are common in both animals and humans and some coronavirus strains can cause zoonotic diseases (infectious diseases that can be transmitted between humans and animals).

Coronaviruses can cause illness ranging from the common cold to more severe diseases such as Middle East Respiratory Syndrome (caused by MERS-CoV) and Severe Acute Respiratory Syndrome (caused by SARS-CoV) in humans. It was demonstrated that MARS-CoV and SARS-CoV viruses were transmitted to humans from dromedary camels and civets respectively.

A novel coronavirus disease 2019 (COVID-19), classified as zoonotic disease, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2 ) was identified from humans in Wuhan, China in 2019 and quickly led to a global pandemic and has subsequently devastated economies and healthcare systems worldwide.

Covid-19 is a new infection and time is the key to understand how it will evolve. As per WHO report (2006), about 61 per cent of human pathogens are zoonotic in origin, while zoonoses account for a whopping 80 percent of the global emerging diseases in humans in the past three decades. COVID-19 is a zoonotic disease, originated from animals, jumped to humans, and spread by person to person transmission.

WILDLIFE VIRAL SURVEILLANCE

Through the years veterinary epidemiologists and virologists have been dealing with the circulation of pathogenic viruses among wild animals. Studies on the virus evolution, spread and pathogenesis in domestic and wild animals provided essential inputs for the integrated surveillance studies on the etiology of viral zoonoses and their impact on the health of animals, humans, and the ecosystem.

Coronaviruses appear to have origins in a variety of bat species and, to date, over 200 novel coronaviruses have been identified in bats. But they need intermediate hosts before jumping to humans. Indeed, coronaviruses are very keen to jump species barriers (inter-species transmission), to evolve, and to find new ecological niches.

This spill-over was confirmed for SARS-CoV and MARS-CoV, with masked palm civets and dromedary camels as an intermediate host, respectively. However, the zoonotic source of SARS-CoV-2 remains unidentified to date. The surveillance of coronavirus in wild life, notably in hot spots marked by risky human-animal interfaces, need to be integrated with human medicine with the aim to advance interdisciplinary research studies, to understand and predict potential spill-over phenomena and to prevent or limit future human pandemics.

VETERINARIANS AND ANIMAL INFECTIOUS EPIDEMICS

Veterinarians have gained extensive field experience in the control of past epidemics of infectious and contagious diseases of animals and zoonotic diseases, transmissible from animals to humans. Veterinary epidemiologists have successfully applied a variety of surveillance methods to understand the ways in which viral agents spread, and to support evidence-based, effective, sustainable and timely measures for the reduction of the level of prevalence or the elimination of infectious diseases in animal populations.

The human health system, traditionally, focuses on the treatment of the individual patients and rarely the measures are directed to the whole population. In veterinary medicine, on the contrary, the health control strategy is directed to the whole animal population (e.g. livestock and poultry), since epizootic diseases cause high costs for general agriculture and livestock sectors, though with limited risk to public health.

Controlling an infectious outbreak requires understanding of the nature, scale, and dynamics of the epidemic, with the aim to reduce the disease prevalence and to provide swift evidence to the decision-makers for implementing measures able to mitigate the economic and animal health burden.

Considering the experience gained by the veterinarians in the epidemiology of animal diseases within populations, using active and passive surveillance systems and risk analysis, veterinary medicine might provide a valuable contribution of knowledge to public health for the control of infection in the human population.

In natural settings when in contact with infected humans, and through experimental infection, several animal species have demonstrated susceptibility to the virus. There is also evidence that infected animals can transmit the virus to other animals in natural settings through contact, such as mink to mink transmission, and mink to cat transmission. Cats and ferrets are highly susceptible to SARS-CoV-2; dogs have low susceptibility; and cattle, pigs, chicken, and ducks are not susceptible to the virus.

Worldwide, a small number of pets including cats and dogs have been reported to be infected with COVID-19 virus, mostly after close contact with people with COVID-19. Infected pets might get sick or they might not have any symptoms. The sick pets had only mild illness and fully recovered. Serious illness in pets appears to be extremely rare.

Many are worried about the safety of the pet animals from the coronavirus pandemic and whether or not the virus can be transmitted to/from their pets. Multiple international and domestic human and animal health organizations and infectious disease experts agree that at this time there is no evidence that domestic animals, including pets and livestock, can spread COVID-19 to people.There are dog-specific and cat-specific corona viruses that have been around for years and these viruses infect only dogs and cats, but not humans.

The larger concern is spreading of COVID-19 to pets from humans and not the reverse. There are additional risks when handling a large number of animals in the farm, susceptible to infection with SARS-CoV-2, as the animals are kept in close contact.

There is no evidence that the virus can spread to people from the skin, fur, or hair of pets. Do not wipe or bath the pets with chemical disinfectants, alcohol, hydrogen peroxide or other products such as hand sanitizer or other industrial or surface cleaners. Consult a veterinarian for appropriate products for bathing or cleaning the pets.

Several animals in zoos and sanctuaries have tested positive for SARS-CoV-2, including big cats (lions, tigers, pumas, cougars, snow leopard) and non-human primates (gorillas) after showing signs of illness. It is suspected that these animals became sick after being exposed to an animal caretaker with COVID-19.

SARS-CoV-2 has been reported in mink farms in multiple countries. Infected workers were likely introduced to the virus to mink on the farms and spread can occur between minks as well as from mink to other animals on the firm (dogs, cats) Respiratory disease and increases in mink deaths have been reported on most affected mink farms in the United States. Some infected mink might also appear healthy.

At present, there is no evidence that mink are playing a significant role in the spread of SARS-CoV-2 to people. But, there is a possibility of mink spreading SARS-CoV-2 to people on mink farms. Mink to human spread of the virus has been reported in the Netherlands, Denmark and Poland.

The waste from human activity can significantly influence marine mammal health. Human contact with marine animals does occur, with both captive animals and sometimes during field studies. Any direct contact poses some risk of transmitting pathogens in either direction. Infection of captive marine mammals from humans is of limited concern, at least beyond the individual animals in a collection.

The risk posed by marine mammals to people is likely negligible. The risk to human-to-animal transmission can't be ignored. Facilities with captive marine mammals should limit contact with them, and obviously there should be no contact with people who are infected or quarantined.

FIGHTING ANIMAL DISEASES IN TIMES OF COVID-19

Animal diseases continue to spread worldwide, despite the devastating impacts of COVID-19 which have led to global movement restrictions. Transboundary animal diseases have been spreading in recent years due to several factors, leading to epidemic situations, many of which still persist. There is a worldwide increase of African Swine Fever (ASF) cases in recent years.

There is no effective vaccine for controlling the deadly pig disease. The disease has triggered a major crisis in the pork industry, causing massive pig losses and detrimental social economic impacts. Highly Pathogenic Avian Influenza (HPAI) is also another challenge to veterinary and public health services.

It has been one of the most reported animal diseases in recent years, due to its serious consequences for livelihoods and international trades. Avian Influenza strains have a potential zoonotic impact and they have the ability to mutate and evolve quickly.

In times of COVID-19 pandemic, the OIE (World Organization for Animal Health) calls countries to continue their efforts to implement prevention and control measures for animal diseases. It is essential to sustain veterinary activities to avoid the detrimental impacts of animal diseases, which could exacerbate the current sanitary and socio-economic crisis.


(To be continued)