#15,382
Six months into the SARS-CoV-2 (COVID-19) pandemic and there remain major gaps in our understanding of how this virus spreads, which species (beyond humans) are susceptible, and how that might affect this (and future) pandemics.
SARS-CoV-2, much like MERS-CoV, appears to have originated from bats, and then jumped - either directly, or more likely via an intermediate host - to humans.
While the initial damage has all ready been done, should SARS-CoV-2 find other suitable animal reservoirs, it could make it much harder to eradicate, and could conceivably provide the virus with additional evolutionary options.
An already `humanized' coronavirus circulating, and evolving, in a non-human animal reservoir would significantly increase the risk of seeing a new and improved `SARS-CoV-3' pandemic emerge down the road.
Luckily, early research has shown that the virus does not replicate well in pigs and chickens (see Susceptibility of Ferrets, Cats, Dogs & Other Domestic Animals to SARS-CoV-2) by Dr. Hualan Chen et al.
We found that SARS-CoV-2 replicates poorly in dogs, pigs, chickens, and ducks, but efficiently in ferrets and cats. We found that the virus transmits in cats via respiratory droplets. Our study provides important insights into the animal reservoirs of SARS-CoV-2 and animal management for COVID-19 control.
While encouraging news, SARS-CoV-2 continues to evolve, and what we can say about its transmissibility and replication today many not hold tomorrow. And we've seen at least one farmed animal - mink - are highly susceptible to infection and may even have infected humans in the Netherlands (see COVID-19: Back To The Mink Farm).
Since then nearly a million mink have been culled in the Netherlands, and recently Spain ordered the culling of close to 100,000 after an outbreak at a mink farm in Teruel (see CNN Spain orders cull of nearly 100,000 farmed mink after animals test positive for Covid-19).
COVID-19 detected on multiple Dutch mink farms
(Excerpt)
Risk analysis 20 July
In a letter to parliament dated 20 July, the OMT-Z recommends expanding existing measures for persons who are in contact with mink. If new infections are still being detected on Dutch mink farms after mid-August, it is advised to cull all mink farms to prevent them from becoming a reservoir for the coronavirus.
Spread of the virus between mink
Previous research has shown that ferrets are susceptible to SARS-CoV2. Therefore it was already assumed that mink might be susceptible too. Pneumonia was seen in sections on mink and SARS-CoV-2 was detected in organs and throat swabs. Based on the variations in the genetic codes of the virus, it could be concluded that mink farms have transmitted the virus to each other.
Possible spread from mink to employee
Minister Schouten of Agriculture, Nature and Food Quality (LNV) reports in a letter to parliament dated 19 May that it is plausible that one of the employees was infected with the coronavirus by mink. In a second letter dated 25 May, she announced that it is plausible another infection of an employee via mink took place.
Admittedly, farmed mink being susceptible to SARS-CoV-2 poses far less of a concern than if the virus had an affinity for pigs or poultry - but it is important to monitor other potential hosts for the virus - as they could provide additional opportunities for the virus to adapt and evolve outside of our view.
As far as felines are concerned, over the past couple of months we've looked at a small number of field reports, and some limited research, on the susceptibility of cats to the COVID-19 pandemic and their potential for transmitting the SARS-CoV-2 virus to others.
CDC: Pets & Other Animals and COVID-19
NEJM: Transmission of SARS-CoV-2 in Domestic Cats
APHIS: Confirmation of COVID-19 in Two Pet Cats in New YorkThe evidence thus far suggests your cat is far more likely to contract the SARS-CoV-2 virus from you, or another human, than to spread it to humans What is known as Reverse Zoonosis.
Today, however, we have a new (pre-print) study from Italy which suggests both dogs and cats may be more susceptible to SARS-CoV-2 than previously believed, although they rarely show symptoms or test positive by RT-PRC.
Evidence of exposure to SARS-CoV-2 in cats and dogs from households in Italy
Edward Ian Patterson, Gabriella Elia, Andrea Grassi, Alessia Giordano, Costantina Desario, Marta Medardo, Shirley L. Smith, Enyia R Anderson, Tessa Prince, Grace T. Patterson, Eleonora Lorusso, Maria Stella Lucente, Gianvito Lanave, Stefania Lauzi, Ugo Bonfanti, Angelica Stranieri, Vito Martella, Fabrizio Solari Basano, Vanessa R Barrs, Alan D Radford, Umberto Agrimi,Grant L Hughes, Saverio Paltrinieri, Nicola Decaro
doi: https://doi.org/10.1101/2020.07.21.214346
This article is a preprint and has not been certified by peer review [what does this mean?].
Abstract
SARS-CoV-2 originated in animals and is now easily transmitted between people. Sporadic detection of natural cases in animals alongside successful experimental infections of pets, such as cats, ferrets and dogs, raises questions about the susceptibility of animals under natural conditions of pet ownership.Here we report a large-scale study to assess SARS-CoV-2 infection in 817 companion animals living in northern Italy, sampled at a time of frequent human infection. No animals tested PCR positive.However, 3.4% of dogs and 3.9% of cats had measurable SARS-CoV-2 neutralizing antibody titers, with dogs from COVID-19 positive households being significantly more likely to test positive than those from COVID-19 negative households. Understanding risk factors associated with this and their potential to infect other species requires urgent investigation.
The surprise here isn't that nearly 4% of cats tested showed antibodies to SARS-CoV-2, but rather that dogs lagged behind by only .5%. Earlier studies had suggested that dogs are far less susceptible to infection than cats.
In the study's conclusion, the authors wrote:
In this extensive epidemiological survey of SARS-CoV-2, we found that companion animals living in areas of high human infection can become infected. Our results suggest that dogs warrant further investigation regarding SARS-CoV-2 susceptibility in contrast to experimental studies which suggested cats were most susceptible (9).
We also observed seropositivity rates in animals comparable to those of humans via community sampling at a similar time in European countries (19-21). This suggests that infection in companion animals is not unusual. Based on current knowledge, it is unlikely that infected pets play an active role in SARS-CoV-2 transmission to humans.
However, animal-to-human transmission may be more likely under certain environmental conditions, such as the high animal population densities encountered on infected mink farms (22). As and when human transmission becomes rarer and contact tracing becomes more accessible, serological surveillance of pets may be advocated to develop a wholistic picture of community disease dynamics and ensure that all transmission opportunities are terminated.
While there is limited evidence of animal-to-human transmission of SARS-CoV-2 from companion animals, the CDC does maintain a web page with advice for pet owners.
Updated June 28, 2020What you need to know
- A small number of pets worldwide, including cats and dogs, have been reported to be infected with the virus that causes COVID-19, mostly after close contact with people with COVID-19.
- Based on the limited information available to date, the risk of animals spreading COVID-19 to people is considered to be low.
- It appears that the virus that causes COVID-19 can spread from people to animals in some situations.
- Treat pets as you would other human family members – do not let pets interact with people outside the household.
- If a person inside the household becomes sick, isolate that person from everyone else, including pets.
- This is a rapidly evolving situation and information will be updated as it becomes available.
(SNIP)What to do if you own petsUntil we learn more about how this virus affects animals, treat pets as you would other human family members to protect them from a possible infection.Because there is a small risk that people with COVID-19 could spread the virus to animals, CDC recommends that pet owners limit their pet’s interaction with people outside their household.
- Keep cats indoors when possible and do not let them roam freely outside.
- Walk dogs on a leash at least 6 feet (2 meters) away from others.
- Avoid public places where a large number of people gather.
- Do not put face coverings on pets. Covering a pet’s face could harm them.
There is no evidence that the virus can spread to people from the skin, fur, or hair of pets. Do not wipe or bathe your pet with chemical disinfectants, alcohol, hydrogen peroxide, or any other products not approved for animal use.Talk to your veterinarian if your pet gets sick or if you have any concerns about your pet’s health.
