“When Beth Emhoff (Gwyneth Paltrow) returns to Minnesota from a Hong Kong business trip, she attributes the malaise she feels to jet lag. However, two days later, Beth is dead, and doctors tell her shocked husband (Matt Damon) that they have no idea what killed her. Soon, many others start to exhibit the same symptoms, and a global pandemic explodes.”
So begins the Google description for Contagion, a 2011 fictional movie that tracked the day-by-day progression of the rapid spread of an infectious disease.
Eight years later, in December 2019, a new, unknown virus producing pneumonia-like symptoms in humans emerged in Wuhan, China, before rapidly erupting into a global pandemic. But, this time, it was not the stuff of Hollywood make-believe and movie stars.
Known as a novel (new) coronavirus (type of virus that typically leads to upper respiratory infections), formally dubbed HCoV-19 or COVID-19 (short for coronavirus disease 2019), the virus has disrupted virtually every aspect of daily lives and conducting business. The virus is believed to have originated from bats but may have had intermediate carriers (that is, before transferring humans) such as civet cats or pangolins.
The world has received a crash course on pandemics, but they are not new to this century. In 2003, a mysterious disease with flu-like symptoms that came to be known as Severe Acute Respiratory Syndrome (SARS), ultimately spread to 26 countries, infecting more than 8,000 people and killing close to 800. While the source of what is considered to be an animal virus remains somewhat uncertain, it is believed SARS started in bats and then spread to other animals. SARS was found to be carried and spread by civet cats and raccoon dogs, as well as domestic cats and ferrets.1
The Middle East Respiratory Syndrome (MERS), which first appeared in 2012, has since spread to 27 countries; it has been traced to originating in camels.
But none of those numbers compare to the Spanish flu which, from around 1917 to 1918, infected an estimated 500 million people worldwide and killed an estimated 50 million people. One theory for the source of the Spanish flu is a bird flu that migrated to pigs and then jumped to humans.
What do these viruses have in common and why should you, an animal care provider, care?
They are all zoonotic and airborne.
Zoonotic Diseases
A zoonotic disease can be transmitted from animals to humans or from humans to animals. The SARS virus, as noted previously, is believed to have ultimately spread to and been carried by domestic cats and ferrets, and COVID-19 is believed to have been carried by bats and, possibly, civet cats or pangolins, but could humans give the virus to animals?
In a widely publicized news report, on February 28, 2020, a pet dog of a COVID-19 patient in Hong Kong tested “weak positive” for the disease but did not display any “relevant symptoms.” The widely held presumption was the “weak positive” test may have been the result of environmental contamination of the dog’s mouth and nose. That is, a dog being a dog, the pet may have picked up ( licked up) traces of the virus. Upon additional testing which resulted in “weak positive” results, some experts concluded that the dog had a “low level” infection caused by human-to-animal transmission2 but, as of mid-March, the Centers for Disease Prevention and Control (CDC) has maintained:
“To date, CDC has not received any reports of pets or other animals becoming sick with COVID-19. At this time, there is no evidence that companion animals including pets can spread COVID-19. However, since animals can spread other diseases to people, it’s always a good idea to wash your hands after being around animals.”
For the latest, particularly as it pertains to animals, be sure to check the CDC’s Coronavirus Disease 2019 (COVID-19): Frequently Asked Questions: COVID-19 and Animals.3
Airborne Infection
In addition to being zoonotic, COVID-19, Spanish flu, SARS and MERS are also viruses that may be spread by the airborne route.
In its published information for health care professionals on the subject of COVID-19, the American Society of Anesthesiologists (ASA) addresses the airborne route as follows:
“Droplets are larger liquid particles that settle from the air rapidly and typically do not travel more than 3-6 feet from the source. Droplets may be transmitted directly by settling on a potential host’s mucous membranes or indirectly by settling on surrounding environmental surfaces and then spread by hand contact to vulnerable hosts. Hand hygiene and other contact precautions are important ways to prevent spread of droplet infections.”
But (and this is key), as the ASA continues, those droplets “may be ‘aerosolized’ into smaller particles by coughing or sneezing…The smaller particles may become suspended in air currents in which they may travel longer distances.”
In other words, droplets are larger, heavier particles that are expelled. Droplet nuclei are the dried residual of droplets typically generated from the respiratory system. These infective particles are small enough to evaporate quickly and therefore become aerosolized traveling on dust particles and remain infective for hours, days or weeks, depending on the particular pathogen.
The distinct possibility of aerosolization received further support on March 11, 2020, when scientists at Princeton University, the University of California-Los Angeles and the National Institutes of Health (NIH) posted the results of federally funded tests that stated the viable virus “could be detected in aerosols up to 3 hours post aerosolization.” The study also found the virus viable up to 4 hours on copper, up to 24 hours on cardboard, and up to 2-3 days on plastic and stainless steel.4
In one high-rise apartment building in China, the virus reportedly spread to different floors—the two people initially infected lived directly above each other but 10 floors apart. At least one working theory pointed to transmission of the virus via the building’s pipes. As described in an article by Live Science, Dr. Amesh Adalja, an infectious disease specialist and a senior scholar at the Johns Hopkins Center for Health Security in Baltimore, Maryland, explained that a faulty piping system could allow the virus to become “aerosolized” out of a pipe and get into the surrounding air.5
Whether spread from animal to human, human to human, or animal to animal, the airborne route of transmission is a serious one. Surface cleaning is not enough to prevent transmission. And, when it comes to new and emerging diseases, there are no ready-to-go vaccines. Beyond those airborne diseases that impact humans, what about those that impact the animals in your care? For example, canine cough, dog flu and feline calicivirus may all be spread via the airborne route.
One Health
According to the CDC, six out of every 10 infectious diseases in people are zoonotic. In short, these diseases are an integral part of the human-animal bond. So, in protecting animal health and welfare, animal care providers contribute toward improving human health. The interdependence of human health and animal health has led to an initiative known as “One Health,” which takes an integrative approach to attain optimal health for people and animals, as well as the environment.
As the human-animal bond continues to grow, and as the human population continues to expand geographically, as noted by the American Veterinary Medical Association, “The contact between human and wild animal habitats increases, introducing the risk of exposure to new viruses, bacteria and other disease-causing pathogens.”
Simply put, optimal health for both humans and animals requires an approach beyond considering human-to-human or, separately, animal-to-animal transmission. Rather, in sickness and in health, there is a human-animal bond.
In October 2019, the American Association of Feline Practitioners (AAFP) released their updated Feline Zoonoses Guidelines. In publishing the guidelines, the AAFP aims to provide accurate information about feline zoonotic diseases to owners, physicians and veterinarians to allow logical decisions to be made concerning cat ownership. Further, as announced by the AAFP, the guidelines provide “a document that can be used to support the International One Health movement, which is a globally recognized practice of studying the similarities in disease processes between humans and animals.”
Infection Control for the Known and the Unknown
According to the World Organization for Animal Health, five new human diseases appear every year, three of which are of animal origin. Some of these new diseases will make big headlines, like COVID-19, but most will stay under the radar, known only to those humans impacted, their medical care providers and a few dedicated researchers. The infection control protocols you have in place are protecting you, your staff and the animals in your care not only from known pathogens, but unknown ones as well.
In 2004, an unknown respiratory illness in dogs was reported that was determined to be caused by equine influenza A(H3N8) viruses. As a newly detected illness, there was no vaccine. In September 2005, it was considered by experts as a “newly emerging pathogen in the dog population” and, today, has been detected in dogs across the U.S. Also, today, there is a vaccine for what is now commonly known as dog flu but there wasn’t one in 2004.
In 2006, a second form of canine influenza was identified in South Korea and southern China—H3N2. In April 2015, the Chicago area became a hot spot for this variant of avian flu and outbreaks in dogs in other parts of the U.S. were reported throughout 2015. Approximately eight months after the CDC reported the H3N2 outbreak in Chicago, a vaccine for H3N2 received conditional approval from the U.S. Department of Agriculture.
What’s the next unknown respiratory illness? What’s the next “dog flu” that’s spread by the airborne route but has no vaccine, possibly for months on end while one is being developed and tested and submitted for approval?
As animal care providers, you are on the front line of both animal health and human health, which is why your infection control must be multi-pronged to go beyond surface cleaning and vaccine protocols to include cleaning the air as well. You’re not only protecting against the spread of known pathogens, but unknown ones as well. As described by the ASA above, aerosolized pathogens may become suspended in air currents and travel longer distances.
Whether human or animal, whether COVID-19 or H3N8, aerosolization is a studied, researched and supported fact of the airborne transmission route, which makes eliminating those aerosolized pathogens while they’re in the air imperative. Air can be sanitized and achieve up to a 99.9% kill rate of pathogens with ultraviolet germicidal irradiation (UVGI) if it’s done properly. This type of UV has been used in human healthcare for close to a century to disinfect, sanitize and control infection in hospitals and other highly sensitive environments where maintaining sanitary air circulation is critical.
Animal care should be no different, particularly where there are fewer barriers to transmission (animals typically don’t wear surgical or respirator masks). For effective air sanitizing, it’s also imperative to work with experts who understand the human-animal bond, and understand animal pathogens and human pathogens—both existing and emerging.⊂
References
1. Why Tracing The Animal Source Of Coronavirus Matters, www.cbc.ca/news/health/coronavirus-zoonosis-1.5440146
2. Low-level of infection with COVID-19 in Pet Dog, https://www.info.gov.hk/gia/general/202003/04/P2020030400658.htm
3. Frequently Asked Questions: COVID-19 and Animals, https://www.cdc.gov/coronavirus/2019-ncov/faq.html#animals
4. Aerosol and surface stability of HCoV-19 (SARS-CoV-2) compared to SARS-CoV-1, https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v1.full.pdf
5. Can The New Coronavirus Spread Through Building Pipes, www.livescience.com/coronavirus-spread-building-pipes.html
