In only four decades, our world has suffered from at least six large-scale zoonotic disease outbreaks, including H1N1 flu, SARS, HIV, and coronavirus. These have collectively resulted in the deaths of millions and impacted the world economy. Research has revealed that zoonotic viruses account for 75% of all the emerging diseases we have today, making them one of the most critical areas of study when it comes to protecting public health.
However, after some of these outbreaks faded, there’s been relatively little effort to prevent the next ones. “We’ve suffered from a siloed approach, historically, and had a big emphasis on responding to health in emergencies but less of an emphasis on preventing those emergencies. Diseases in animals spill over into humans on a regular occurrence,” Mark Schipp, president of the World Organization for Animal Health, said.
While some zoonotic viruses are not dangerous, many are endemic globally. They place a burden on people who have contact with animals, especially livestock keepers. A recent study led by epidemiologist Christine Kreuder Johnson found that domesticated animals are responsible for a majority of viruses that have afflicted human beings after originating in animals.
According to The Verge, an American technology news website, the study used data from the USAID Emerging Pandemic Threat Predict program, which has collected over 140,000 biological samples from animals to identify 1,200 viruses that could one day pose another global threat. The findings revealed that the novel coronavirus is particularly dangerous because it made the leap from animals into humans and was able to be transmitted from human to human.
“The entire world population, for the most part, is naive to this new virus because none of us have been exposed to it before. And that’s what makes it especially dangerous. When they are transmitted human to human and everybody’s naive, we all get sick around the same time,” Johnson said.
The Role of Vets
Even if zoonic pathogens don’t get to infect humans, outbreaks of diseases among animal populations can impact food security and international livelihood. The 2018 African swine disease outbreak, for instance, decimated pork supplies and affected the diets of millions of people in China, where it is the major source of protein. According to Bloomberg, an online site that delivers business and markets news, data, analysis, and video to the world, it also affected a myriad of agricultural sectors, including pig farmers.
“The impact of not controlling non-zoonotic vaccine-preventable disease in animals is much larger than the zoonotic impact if it’s properly calculated,” Robyn Alders, senior technical advisor with the Centre for Global Health Security at Chatham House, said.
Scientists and medical professionals are doing everything they can, not only to address the COVID-19 pandemic but also to prevent another outbreak to happen. However, experts in the field of animal health have long been underestimated, even if they can greatly help in this crisis: veterinarians. Vets, as well as wildlife biologists, livestock farmers, and zookeepers, remain a largely untapped resource for combatting diseases that threaten people.
“There is still a very traditional divide among disciplines. We haven’t removed these barriers yet,” Jon Epstein, a wildlife veterinarian and disease ecologist for the EcoHealth Alliance in New York, said.
For years, vets have helped in discovering and diagnosing zoonotic outbreaks. In 1999, Tracey McNamara, then the chief veterinary pathologist at the Bronx Zoo, identified the first outbreak of the West Nile virus in North America. Its story is important because it is the same story of avian flu, rabies, MERS, HIV, SARS, anthrax, and Ebola—all diseases that can be passed from animals to humans. McNamara noticed that large numbers of crows were dying first, followed by flamingos, a cormorant, and an Asian pheasant. Eventually, several residents of New York City had contracted and died of a similar illness.
According to The Atlantic, an online site that covers news, politics, culture, technology, health, and more, through its articles, podcasts, videos, and flagship magazine, McNamara contacted the Centers for Disease Control and Prevention and the Agriculture Department to warn them but both just brushed her off. "The veterinarian cracked the case, and no one was interested in talking with her because she was a veterinarian," Laura H. Kahn, a physician and biodefense researcher at Princeton, said.
McNamara eventually proved she was right. Tests weeks later revealed that NYC was home to the first cases of West Nile virus ever reported in the Western hemisphere. The animal infections preceded the first human cases by at least one or two months, the US General Accounting Office (GAO) reported. “The West Nile events illustrate the value of communication between public and animal health communities,” the GAO said.
Vets Should Be Supported
Linda Saif, PhD, professor and coronavirus researcher from the Ohio State University College of Veterinary Medicine, said that vets should be involved in all aspects of zoonotic infections. “Veterinarians need to be part of identifying the animal reservoirs and the intermediate hosts for these diseases. This may focus on wildlife medicine, such as understanding the habitats and diversity of bat species as reservoirs for coronaviruses and multiple other viruses,” she said.
Vets have been proven useful in identifying zoonotic diseases. According to AVMA, an online site providing factual, up-to-date information and resources to support the veterinary community in delivering services, many experts believe that they should be working with other researchers to develop the most appropriate animal models for these diseases. Despite their huge benefit to the field, there has been little investment in veterinary services and veterinary public health in low- and middle- income countries. As a result, epidemics such as COVID-19 and zoonotic diseases have hindered the potential of individuals, communities, and whole nations.
Communities living in Africa, South Asia, and Latin America that depend on livestock for nutrition, water, income, or transportation have no access to veterinary services. “Livestock and Veterinary Services are chronically under-resourced against all comparative measures. Poor financial resources and inadequately staffed and organized Veterinary Services results in high livestock losses and uncontrolled epidemics,” the World Organization for Animal Health said.
One of the ways to prevent future pandemics and global health crises is to train more veterinary doctors and veterinary paravets as they can provide basic animal health care and advice to communities. They have been at the frontline of the fight against zoonotic disease through prevention, diagnosis, treatment, and surveillance.
“Veterinarians should be at the forefront of this research to investigate if a new disease can cause a reverse zoonosis and transmit from humans to pets and livestock,” Saif said.