Pioneers of the One Health movement to blend human, veterinary and environmental health are gaining respect, epidemic by epidemic, but capturing the attention of the human health care establishment remains a challenge.
“You have to take the long view,” acknowledged Laura H. Kahn, MD, MPH, of the One Health Initiative team. “It took people over a century to realize the significance of basic sanitation, and lots of countries don’t even have that.”
In 1847, human physician Dr. Ignaz Semelweis came up with the idea that if doctors in Viennese maternity wards would wash their hands between patient exams, fewer women would die of childbed fever. The medical community considered his theory outlandish and he died a pariah.
But subsequent research by Louis Pasteur and Joseph Lister proved Semelweis was onto something, and today surgical hygiene is universally accepted.
In 2006, Dr. Kahn, a physician and research scholar at Princeton University, penned an article for the U.S. Centers for Disease Control and Prevention titled “Confronting Zoonoses: Linking Human and Veterinary Medicine.”
“It caught the attention of a number of veterinarians who were very enthusiastic,” she recalled. “One of them was Dr. Bruce Kaplan, who formerly worked in epidemic intelligence for the CDC. He asked me, ‘What are you going to do about this?’”
In 2007, the American Veterinary Medical Association Executive Board formed a One Health Initiative Task Force, and the American Medical Association House of Delegates adopted a resolution supporting collaboration between human and veterinary medicine.
Presidents of the two associations at the time – Roger Mahr, DVM, and Ronald M. Davis, MD — worked together to achieve incorporation of the 501 (c) 3 One Health Commission. Davis succumbed to pancreatic cancer in 2008, leaving a gap on the human side that has never truly been filled, noted Cheryl Stroud, DVM, Ph.D., executive director of the North Carolina-based commission.
“It was a huge loss to the one-health effort, because no one else in the human domain was such a strong spokesperson,” she said. “To my knowledge, there has never been a One Health committee within AMA, and you cannot find the words ‘One Health’ anywhere on their website. So while they did financially sponsor the commission from 2009 to 2013, they have not actively continued to help carry the one-health torch.”
In 2009, the clinical textbook “Human-Animal Medicine” was published by Lisa A. Conti, DVM, MPH, and Peter M. Rabinowitz, MD, MPH, dealing with zoonotic diseases, exposure to environmental toxicants and other health risks shared between humans and animals.
Dr. Conti now serves with Kahn on the One Health Initiative autonomous pro bono team; Dr. Rabinowitz is director of the University of Washington’s new Center for One Health Research.
In 2011, the first International One Health Congress was held in Melbourne, Australia.
In 2014, the first International Who’s Who in One Health Webinar was hosted by the One Health Commission, with presentations by researchers from 15 countries.
And in May, the first World Veterinary Association-World Medical Association Global Conference on One Health took place in Madrid.
“Most people don’t understand what ‘One Health’ means,” said Joann M. Lindenmayer, DVM, MPH, board chairman of the One Health Commission. “Simply mentioning ‘One Health’ to a member of the public elicits quizzical looks, but when someone hears about One Health in the context of a disease such as avian influenza, they have a ‘eureka’ moment and they suddenly get it.
“Much of the research that used to fall under the category of zoonotic disease studies is now referred to as ‘One Health’ studies, but strictly speaking, the ‘One Health’ label should refer to complex health problems that involve simultaneously human, animal and environmental health. And because they involve all three ’healths,’ solutions to these problems must take them all into account.”
Dr. Lindenmayer is the AVMA’s representative on the One Health Commission. While it is a separate organization from the One Health Initiative team, the two in January announced they will work together and share resources to capitalize on each other’s strengths.
The catalyst for the human health fraternity to recognize a link to veterinary medicine may have been West Nile virus’s 1999 U.S. invasion, Lindenmayer said.
“The failure to recognize the similarities between massive die-offs of crows and viral encephalitis in people, and communicate those findings, caused precious time to be lost, and more people to sicken and die,” she said.
Princeton physician-researcher Kahn recalled her interest at the time that a veterinarian played a key role in identifying West Nile Virus.
“The vast majority of emerging diseases and bioterrorist agents were zoonotic,” she said. “Veterinarians and medical doctors rarely talked to each other. I thought this was a major problem.
“A lot of animals get the same diseases we do, and there’s not a lot of collaboration and conversation between the two professions, so the disease in a human might not be recognized until years later. Physicians are operating within clinic walls.”
Begun in 2013, the Center for One Health Research at the University of Washington’s School of Public Health in Seattle aims to involve more human, public and environmental health students and professionals in one-health research and training activities, Rabinowitz said.
“As a physician, I am aware that in this country there are not too many one-health programs based in human medical schools or colleges of public health,” he added.
Kahn, a research scholar in the Program on Science and Global Security at Princeton’s Woodrow Wilson School of Public and International Affairs, said human physicians have been slow to expand their perspectives in part because medicine is becoming extremely specialized.
“Unlike the veterinary profession, where the vast majority are generalists, you have specialists in cardiology, gastroenterology …. and all these subspecialists view these issues as being irrelevant to their practice. They’re kind of removed.”
Lindenmayer, senior manager of Disaster Operations and director of the Haiti Program for Humane Society International, said it another way: “Because human physicians study a single species in their education and training, they understand human health but tend to see other species as black boxes. Veterinarians, on the other hand, learn about numerous species of animals and they develop an understanding that every species is just a variation on a theme.”
Kahn said that as a medical student, the word “zoonotic” wasn’t part of the course lexicon. “It just wasn’t discussed,” she said.
The divorce between human medicine and public health is rooted in 1915’s Welch-Rose Report, which became a blueprint for public health schools and turned the public health field into a “Cinderella – unsupported and unfunded,” Kahn said.
“Human medicine became reductionistic in how it treated disease. Now, it is focused on treating, rather than prevention and public health. Physicians are focused on what the patient presents before them. The patient questionnaire doesn’t ask about animal exposure; it’s not even in the mindset. Yet, it’s huge.”
“I think there is more interest in One Health by human physicians from a research standpoint, because describing a research project in one-health terms makes it more eligible for funding,” Lindenmayer said. “But in my opinion, the solutions to one-health problems–which usually involve public policy decisions—still don’t command, and certainly don’t seek, a one-health approach.
“The reasons for this are numerous,” she continued. “Human and animal health professionals are not often members of the same professional networks, and the language each uses is not necessarily the same. For that reason, animal and environmental health professionals are not often at the table when policy and funding decisions are being made. “
Moreover, Lindenmayer said, in some countries veterinarians are not trained to the level that they are in the United States and they function more as “food hygienists” than doctors, so that physicians and veterinarians may not be mutually respectful.
At the University of Washington’s new Center for One Health Research (COHR), activities focus on occupational health risks to veterinary workers and animal agriculture workers, including injuries and zoonotic diseases, said Rabinowitz, associate professor of environmental and occupational health sciences and global health.
The program also is looking at microbiome “sharing” between humans and animals, and animals as sentinels of environmental health hazards, “like the canary in the coal mine,” he said.
“In the fall of 2014, we worked with the Seattle Woodland Park Zoo and the Washington State College of Veterinary Medicine on a ‘Zoobiquity’ course that brought together veterinarians and human health professionals to discuss cases of humans and animals experiencing health issues related to the environment,” Rabinowitz said.
“Cases included cats, calves and children with asthma from air pollution, pets and people experiencing domestic violence and abuse, and shared obesity between pets and their owners.”
One Health is as local as it is global, according to COHR Ph.D. candidate Heather Fowler, VMD, MPH, who is studying veterinary occupational injuries, specifically animal bites or scratches and needle-stick or sharps injuries. Past research has dealt with frequency and percentages of accidents, she said, but Fowler‘s work is centered on causes.
“In veterinary school, animal-related injuries and blood-borne pathogens are talked about very briefly. Is the mindset that ‘It’s somewhat inevitable because I can’t interpret an animal’s behavior’?” she said. “If part of it is inevitable, it is likely only a small part. The risk will never be zero, but if we can raise awareness and train personnel properly we can potentially reduce injury a large majority of the time.”
Dr. Fowler said occupational health fits the one-health paradigm.
“The environment I’m focused on is the workplace, with animals being in that environment and having the potential to impact human health,” she said.
“A stressful workplace environment can lead to increased animal stress, which in turn may lead to injuries to the workers in charge of caring for them. Thus, a one-health approach is clearly necessary to address occupational injuries among veterinary personnel.”
Consequences show human-centricity to health issues can be short-sighted
Honey bees, vultures, ticks and bacteria are four examples of countless organisms that humans and animals can throw out of balance, causing waves of environmental repercussion, according to Lindenmayer.
“In the past, we have taken a very human-centric approach to health and we continue to do so even now,” she said. “But we are increasingly recognizing that many of the one-health problems the world faces are caused by human behavior.” Antibiotics delivered to humans or animals, or formerly sprayed onto fruit trees to fight bacterial infections, get into soil and water and become widespread into the environment, said Lindenmayer, senior manager of Disaster Operations and director of the Haiti Program for Humane Society International.
“Antimicrobial-resistant bacteria are now recognized by the CDC as a problem that kills tens of thousands of people a year,” she said, referring to the U.S. Centers for Disease Control and Prevention. “To make matters worse, there are few drugs in the pipeline that could even replace antibiotics that were once effective for treating bacterial infections.”
When cattle in India in the 1990s were treated with the non-steroidal anti-inflammatory drug diclofenac, who would have predicted it would lead to increased human rabies cases?
Yet that’s exactly what happened.
Lindenmayer said ticks that fed on diclofenac-treated cattle were picked off and eaten by vultures, which became poisoned and died. The resulting vulture shortage led to a surplus of rotting animal corpses and, with few vultures to act as a natural clean-up crew, the dog-pack population exploded, leading to a large increase in the number of human rabies cases from bites of infected dogs, she said.
In another example, “The indifference that once greeted honey bee colony collapse disorder is now understood as potentially a consequence of pesticide application, and the effect of losing these pollinators on agricultural crop production is now widely appreciated and feared,” Lindenmayer said.
“Human activity expanded pig farms into forested areas in Malaysia in 1999, leading to an increase in interactions between farm workers and bats that carried the deadly Nipah virus, and there is some evidence that those bats relocated to West Malaysia after massive areas of tropical rainforest in Borneo were slashed and burned for industrial plantation and pulpwood,” she said.
One Health goes far beyond bacterial and viral disease infections, Lindenmayer added.
“Hurricane Katrina showed us that people in the U.S. will put their lives in danger to avoid leaving family pet members, and human and animal health responders should work together as one when disasters involve people and livestock. Many small farming communities rely on livestock for their livelihoods.”