Coronavirus: No proof yet that pets can get COVID-19 from owners, but human to animal spread has happened before
While there is no evidence yet that pets such as dogs and cats can get COVID-19 from their owners, human to animal transmission has happened before, says science.
Known as “reverse zoonoses,” the most contemporary example is the H1N1 virus.
What are some examples of human to animal transmission?
Reverse zoonoses occur when a person spreads a disease to an animal. For example, methicillin-resistant Staphylococcus aureus (MRSA) can be spread to people from animals, but it can also be spread to animals from people (reverse zoonotic disease) and then possibly back to people from the infected animal.
“Reverse zoonoses can occur in which disease is transmitted from the human reservoir to the dog or cat. The most contemporary examples are methicillin-resistant Staphylococcus aureus and influenza A (H1N1)pdm09 virus infections,” says the US Centers for Disease Control and Prevention (CDC),
During the 2009 H1N1 influenza pandemic, there were several confirmed cases of people infecting their pets (ferrets, cats and dogs) with the influenza virus. “In the midst of the H1N1 influenza pandemic of 2009, humans passed the deadly swine flu virus to household pets, including at least three dogs, five cats and a handful of ferrets, said Christiane V. Löhr, a veterinary pathologist at Oregon State University,” reports the Los Angeles Times.
Outbreaks of fatal respiratory disease in wild chimpanzees have been reported previously, and “human metapneumovirus” has been one of several human viruses isolated from these primates. “An example of a reverse zoonosis occurred at Lincoln Park Zoo in Chicago, where a 9-year-old chimpanzee died of respiratory disease caused by human metapneumovirus,” says a report. It says that the virus was likely transmitted to the chimps by humans, but precisely how and when is not known.
Human influenza viruses are also frequently isolated from pigs. “Since its emergence in 1968, the H3N2 subtype has infected pigs many times throughout the world, and has often caused serious outbreaks. More recently the influenza H1N1 subtype has been shown to infect pigs,” adds the report.
In a 2014 study, published in PLOS One, experts had said that an increasing number of reports indicate that humans are transmitting pathogens to animals. “Recent examples include methicillin-resistant Staphylococcus aureus, influenza A virus, Cryptosporidium parvum, and Ascaris lumbricoides,” says the report.
After screening, 56 articles from 56 countries over three decades with documented human-to-animal disease transmission were included in the report.
“In these publications, 21 (38%) pathogens studied were bacterial, 16 (29%) were viral, 12 (21%) were parasitic, and 7 (13%) were fungal, other, or involved multiple pathogens. Effected animals included wildlife (28, 50%), livestock (24, 43%), companion animals (13, 23%), and various other animals or animals not explicitly mentioned (2, 4%). Published reports of reverse zoonoses transmission occurred in every continent except Antarctica therefore indicating a worldwide disease threat,” says the research team.
Animal source of COVID-19
Scientists are still trying to figure out how the Wuhan coronavirus jumped from animals to humans, and from which animal. According to a report by the WHO-China Joint Mission on COVID-19, the bat is likely the host, and the pangolin is possibly one of the intermediary hosts.
The US Centers for Disease Control and Prevention (CDC) says that six out of every 10 infectious diseases in people spread from animals. They are referred to as zoonotic diseases -- illnesses that can spread between animals and people. Approximately 60% of infectious diseases in humans are zoonotic, and about 70% of emerging infections in humans are zoonotic.
Has any pet been infected by COVID-19?
A spokesman for the Agriculture, Fisheries and Conservation Department (AFCD) said on February 28 that a pet dog (pomeranian) had “tested weak positive” to COVID-19 virus. However, whether that means the dog actually contracted the virus, is yet to be determined.
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The dog does not have any relevant symptoms but has been quarantined at the animal keeping facility at the Hong Kong Port of Hong Kong-Zhuhai-Macao Bridge.
“Oral, nasal and rectal samples were collected for testing of COVID-19 virus. The nasal and oral cavity samples were tested weak positive to COVID-19 virus,” says the statement. It says, "At present, the AFCD does not have evidence that pet animals can be infected with COVID-19 virus or can be a source of infection to people. The Department will conduct close monitoring of the above dog and collect further samples for testing to confirm if the dog has really been infected with the virus or this is a result of environmental contamination of the dog's mouth and nose. Repeated tests will be conducted for the dog and it will only be returned when the test result is negative.”
Can pets at home get or spread the new coronavirus?
No, they cannot. According to the World Health Organization (WHO), there is no evidence that companion animals or pets such as cats and dogs have been infected or could spread the virus that causes COVID-19. Professor Jonathan Ball, Professor of Molecular Virology, University of Nottingham, says there is no evidence that the human novel coronavirus can infect dogs and it would be ‘incredible’ for a virus to make so many species jumps in such a short space of time.
“We have to differentiate between real infection and just detecting the presence of a virus – these are very different – and the fact that the test result was weakly positive would suggest that this is environmental contamination or simply the presence of coronavirus shed from the human contact that has ended up in the dog’s samples,” says Dr. Ball.
Dr. Niels Pedersen, a distinguished emeritus professor at the UC Davis School of Veterinary Medicine and a renowned expert on infectious and immunologic diseases in dogs and cats, also emphasizes that humans will not transmit the virus to their pets.
“Can pets contract coronavirus from humans or vice versa? The simple answer is as follows: No, you won’t get or give the coronavirus to your family pet. Coronaviruses occur in virtually every species of animal, including humans, and are commonly associated with unapparent or transient intestinal and respiratory infections. They tend to be very species-specific and cross-species transmission is uncommon,” he says.
But can you take any precautions?
The WHO says that it is always a good idea to wash your hands with soap and water after contact with pets. “This protects you against various common bacteria such as E.coli and Salmonella that can pass between pets and humans,” says the WHO.
Besides advising people infected with the virus to stay in a specific room and away from other people in their home, the CDC says such patients should also restrict contact with pets and other animals.
“When possible, have another member of your household care for your animals while you are sick. If you are sick with COVID-19, avoid contact with your pet, including petting, snuggling, being kissed or licked, and sharing food. If you must care for your pet or be around animals while you are sick, wash your hands before and after you interact with pets and wear a facemask,” recommends the CDC.