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This article is taken from our Animal Pharm platform dated
22/04/20.
The World Small Animal Veterinary Association (WSAVA) has
confirmed there is no evidence pets are a transmission risk during
the ongoing COVID-19 pandemic and highlighted the importance of
ongoing data gathering.
A WSAVA webinar in partnership with Zoetis and the Purina
Institute outlined the current events surrounding the outbreak,
information that has come to light regarding virus interaction with
animals and how vets should approach the crisis.
The organization said the amount of information concerning
infection of dogs and cats with SARS-CoV-2 is minimal at this point
in time, although the situation is rapidly evolving. It encouraged
people to frequently monitor official industry body websites for
new information in the coming days and weeks.
Dr Lizzie Parker, global head of the Purina Institute, explained
owners are increasingly turning to their vets for facts and
reassurance their pets will be OK during the pandemic. She said,
aside from SARS-CoV-2 being a new virus and industry having to keep
up with the evolving situation, a big challenge is tackling the
misrepresentation of information by the media.
She commented: "This is causing a lot of concern and distress
among pet owners, but it also poses a very real and significant
threat to pet welfare."
Michael Lappin, chair of the WSAVA One Health Committee, is
currently working on a 'reverse zoonoses' statement for scientific
publication, to provide comment on the issues surrounding pets
during the crisis - particularly cats, after indications the
species is susceptible to SARS-CoV-2. He stressed he will be making
the conclusion there is still no evidence of cats-to-people
transmission.
At the WSAVA-level, Dr Lappin revealed the organization's One
Health Committee has also partnered with the Scientific Advisory
Committee to set-up a resource site.
World caught off-guard by new virus
Dr Lappin explained coronaviruses are not necessarily a new
threat. Other coronaviruses are already a problem in pets, such as
feline infectious peritonitis (part of the alpha group) and canine
respiratory coronavirus (the one coronavirus in small animals
belonging to the beta group).
He also highlighted historical cases of Middle East respiratory
syndrome (MERS) identified in 2012 and SARS-CoV-1 in 2002/2003 in
humans - both belonging to the beta group like the new SARS-CoV-2
strain.
Dr Lappin said: "We're used to these viruses but we weren't
ready for SARS-CoV-2. Back in 2002/2003, that first infection in
this class of betas that infects people and can cause fairly
significant disease was our predecessor. Shortly after, we saw MERS
and now the mutant SARS-CoV-2.
"To be clear with our definitions, the virus is SARS-CoV-2 that
we're dealing with now - the disease syndrome in people is
COVID-19. Sometimes the definitions are lost with people that
aren't in the sciences and sometimes this leads to some
confusion."
He noted other examples of confusion during reporting on the
pandemic, such as that witnessed "with some of the early cruise
ship data, where it was stated this virus was on railings on the
ships for as long as 17 days". Dr Lappin suggested this statement
made people think SARS-CoV-2 would actually 'live' for 17 days.
Turning to current testing methods for SARS-CoV-2 detection, he
remarked: "That work was actually based on PCR testing, which is a
fantastic tool to prove nucleic acids of viruses, bacteria, etc. In
this case, we've been doing quantitative reverse transcription PCR
(RT-PCR) but that doesn't actually prove the virus is live.
"What we have to do when we're using PCR is discriminate whether
or not a virus is just from a contaminated environment. So, whether
it's not actually a living virus, versus if the virus is still
there and potentially active. That's where virus isolation and
culture can really help us because that proves whether the virus
collected from a surface, a nasal swab, a rectal swab, is still
viable."
Dr Lappin stated serology can be beneficial in "sorting out
what's going on epidemiologically, as well as what's happening with
one animal". He pointed out the body is "probably not going to make
antibodies unless that virus, bacteria, protozoan is truly
infecting you".
"Right now with SARS-CoV-2, we believe virus isolation proves
live virus in a particular sample," he continued. "The higher level
PCRs are being persistently PCR-positive and while not always
proving live virus, probably prove current infection. Then
seropositivity - that might develop a little bit later - also
probably suggests the body cared enough to react and an infection
probably existed at some point."
Vanessa Barrs, professor of companion animal health at the City
University of Hong Kong, said the SARS-CoV-1 epidemic in 2003 gives
some insight into why Hong Kong has been proactive in testing
companion animals in the current COVID-19 pandemic.
She commented: "During that SARS-CoV-1 outbreak in 2003, there
was a large cluster of infections in a housing estate in Hong Kong.
Most of those cases were from people living in one block of flats,
above or below each other with no direct contact. So, there was an
investigation to determine whether pests might be involved in
direct spread - pests like rats and cockroaches. They were quickly
ruled out.
"Later, it was actually aerosol spread from sewage drains that
was identified as a cause of transmission. But before finding that
out, investigators also collected samples from cats and dogs living
in that same housing estate where there was that large cluster of
infections.
"What they found for the first time is most cats and dogs tested
positive on multiple swabs by PCR on consecutive days. They did
culture virus from the cats and five of the cats were also
seropositive, confirming that they were infected. But importantly,
none of those animals were sick and there was no evidence during
the SARS-CoV-1 outbreak of 2003 of any animal-to-human
transmission.
"As a follow-up to the natural infection of cats and dogs in the
SARS-CoV-1 outbreak, investigators then looked at experimental
infection to look at whether cats and ferrets were susceptible, and
they also performed transmission studies."
During this research, cats and ferrets were infected
intratracheally by virus taken from a human patient. Investigators
took daily swabs and performed transmission studies.
They found both species could be experimentally infected. None
of the cats became ill but they all spread virus from their
respiratory tract and virus was transmitted to other previously
uninfected cats, which also did not become sick. Similar results
were shown with ferrets, except some did become ill and one
died.
Dr Lappin remarked: "Things [subsequently] kind of quietened
down. We would by definition say that SARS-CoV-1 was a reverse
zoonosis because cats did become infected from people. But, to
restate, there was never evidence it then went from a naturally
infected cat into a human."
