Coronavirus as Zoonosis
Transferring from wild animals to humans
Coronavirus as Zoonosis
Transferring from wild animals to humans
An outbreak of a new coronavirus, also known as SARS severe acute respiratory syndrome -CoV coronavirus -2, started in December 2019 in the Wuhan region of China. The virus can cause the disease COVID-19.
In the case of SARS and this coronavirus outbreak, bats were most probably the original hosts. They then infected other animals via their poop or saliva, and the unwitting intermediaries transmitted the virus to humans.
“Poorly regulated live-animal markets mixed with illegal wildlife trade offer a unique opportunity for viruses to spill over from wildlife hosts into the human population,” the Wildlife Conservation Society
A study of cultured bat cells shows that their strong immune responses, constantly primed to respond to viruses, can drive viruses to greater virulence. Modeling bat immune systems on a computer, the researchers showed that when bat cells quickly release interferon upon infection, other cells quickly wall themselves off. This drives viruses to faster reproduction. The increased virulence and infectivity wreak havoc when these viruses infect animals with tamer immune systems, like humans.
Bats have a strong developing immune system. This is probably connected to their highly active metabolism.
It is almost impossible that the viruses that bats carry, are directly transferred to humans. It follows from the various studies that it was almost always possible to demonstrate that an intermediate jump was required via a different animal species.
Destroying bats for fear of viruses is questionable. It is better to limit the possible jump between the virus in animals toward humans by ending uncontrolled and illegal trade and markets where live wild animals are sold.
Which animal is the most likely intermediate: There is no conclusive study which proves that one kind of animal could have been the stepping stone in transferring the virus from bats to humans. Depending on studies and kind of similar virusses there are different suspects, such as camels, civet, but also an unexpected suspect the Pangolin. Not only local species (if available), but also probably the poached species of African Pangolin. However, can there be any proof that this animal (either live of dead) coult be the intermediate-species in Wuhan China?
26 FEBRUARY 2020
Mystery deepens over animal source of coronavirus
Pangolins are a prime suspect, but a slew of genetic analyses has yet to find conclusive proof.
Not close enough!
Three similar comparison studies were posted on bioRxiv. One of those papers — by an international research group , posted on 18 February — found that coronaviruses in frozen cell samples from illegally trafficked pangolins shared between 85.5% and 92.4% of their DNA with the virus found in humans. Two other papers published on 20 February, from groups in China, also studied coronaviruses from smuggled pangolins. The viruses were 90.23%3 and 91.02%4 similar, respectively, to the virus that causes COVID-19.
The genetic similarity should be higher than reported in these studies before the host can be identified, says Arinjay Banerjee, who studies coronaviruses at McMaster University in Hamilton, Canada. He notes that the SARS virus shared 99.8% of its genome with a civet coronavirus, which is why civets were considered the source. If pangolins are the origin of the current outbreak, says Banerjee, it is not the pangolins in these studies.
So far, the closest match to the human coronavirus has been found in a bat in China’s Yunnan province. A study published on 3 February found that the bat coronavirus shared 96% of its genetic material with the virus that causes COVID-19. Bats could have passed the virus to humans, but there are key differences between the RBD sites in the two viruses. This suggests that this specific bat coronavirus did not directly infect people, but could have been transmitted it to people through an intermediate host, say researchers.
The papers raise more questions than they answer, says Jiang Zhigang, an ecologist at the Chinese Academy of Sciences Institute of Zoology in Beijing. He asks, if pangolins are the source of the virus, and they came from another country, why haven’t there been reports of people being infected in that location?
Sara Platto, who studies animal behaviour at Jianghan University in Wuhan, worries that all the speculation about pangolins being the source could drive people to kill them. Civets were killed en masse after the SARS outbreak. “The problem is not the animals, it’s that we get in contact with them”
Currently, there is no evidence to suggest that animals infected by humans are playing a role in the spread of COVID-19. Human outbreaks are driven by person to person contact.
However, now that COVID-19 virus infections are widely distributed in the human population there is a possibility for some animals to become infected through close contact with infected humans. Infection of animals with SARS-CoV-2 virus may have implications for animal health and welfare, and for wildlife conservation. Especially in Africa where there are still large numbers of large cat species are playing a role in keeping ecosystems in balance.
Until now there are very limited number of reports of canines or felines where contamination has been detected. And those were cases where the animals were in very close proximity to people who may have had COVID-19 themselves. One of the most remarkable contamination was a tiger at the Bronx Zoo in New York. Furthermore several dogs and cats (domestic cats and a tiger) have tested positive to SARS-CoV-2 virus following close contact with infected humans.
More information can be found on the website of the American Veterinary Medical Association.
Studies are underway to better understand the susceptibility of different animal species to the SARS-VoV-2 virus and to assess infection dynamics in susceptible animal species.
Preliminary findings from laboratory studies suggest that, of the animal species investigated so far, cats are the most susceptible species and can be affected with clinical disease. In the laboratory setting cats were able to transmit infection to other cats. Ferrets also appear to be susceptible to infection but less so to disease. In the laboratory setting ferrets were also able to transmit infection to other ferrets. Dogs appear to be susceptible to infection but appear to be less affected than ferrets or cats.
By Veronique Fournier - www.homeoanimal.com/
On the website of HomeoAnimal you can find a very comprehensive article dealing with coronavirus in pets. It is one of the best articles on coronavirus in pets that is available on the web.
We advise veterinarians, but also concerned pet owners to have a look at this page.
You may find here more information, not only about the (new) SARS-CoV-2 virus, but also about other viruses in the corona family which can affect dogs or cats. Including some information about the symptoms on animals infected with one of those viruses.
The following text is lent from the website of the American Veterinary Medical Association.
On April 5, the USDA National Veterinary Services Laboratories announced a positive finding of SARS-CoV-2 in samples from one tiger at the Bronx Zoo in New York City. This appears to be the first instance of a tiger being infected with COVID-19.
On April 3, quantitative PCR testing for SARS-Coronavirus-2 (SARS-CoV-2) on duplicate respiratory tract samples from a four-year-old female Malayan tiger with respiratory signs that was living at the Wildlife Conservation Society’s (WCS) Bronx Zoo was performed at the Animal Health Diagnostic Center and New York State Veterinary Diagnostic Laboratory at Cornell University College of Veterinary Medicine and the University of Illinois College of Veterinary Medicine Veterinary Diagnostic Laboratory. Presumptive positive results of that testing were confirmed by the USDA National Veterinary Services Laboratory on April 4.
The source of infection was presumed to be transmission from a zookeeper, who at the time of exposure had not yet developed symptoms of COVID-19.
Mustelids, including mink, are susceptible to coronavirus infections. That's because these animals have specific receptors on their lung cells that the virus targets.
Felines, hamsters and monkeys are receptive for the same reason. Corona can also be fatal for these animals, but small numbers are involved. Of the twenty infected cats worldwide, only one death has been reported.
May 8, 2020
On April 26, it was announced that mink on two Brabant mink farms had the disease COVID-19. Wageningen Bioveterinary Research (WBVR) tested the animals positively for the coronavirus (SARS-CoV-2). Pneumonia was seen in the mink section 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.
The mink farms had employees working who had symptoms of COVID-19. The virus appears to have been introduced to mink by those workers.
Subsequently, at least one person was most likely infected with the SARS-CoV2 virus through contact with the infected mink.
Current research shows that the SARS-CoV-2 viruses on two of the infected mink farms are very similar.
Martens like the mink are extra sensitive to COVID-19. Dutch researchers have shown that ferrets can infect each other by air. Since minks are closely related to ferrets, they may also be able to transmit the virus to each other.
Like humans, they have a protein on their lungs that the virus likes to attach to; the so-called ACE2 receptor. For example, people also have this "corona coat rack" on their oral mucosa. It appears to be a good predictor of possible COVID-19 contamination.
Virus RNA has been detected in dust particles in the stables, which indicates that people in the stables with infected minks can be exposed to coronavirus.
From mink to cats?
Because antibodies against the virus have been demonstrated in three out of eleven farm cats on one of the infected farms, it is important to further investigate the role of farm cats in potential virus transmission between farms. Further research is still being done on the cats living on the infected mink-farms.
SARS-CoV-2, the corona virusresponsible for the current COVID-19 pandemic, is suspected to be also a threat to our closest livingrelatives, the great apes.
Based on the IUCN Best practice guidelines for health monitoring and disease control in great ape populations National parks in Congo and Rwanda have already shut to tourists and researchers to protect the Gorilla populations.
No great apes have yet been reported to have contracted Covid-19, so the true impact is unknown. But many great apes are already at risk of extinction due to forest destruction and poaching, so the researchers say closing national parks, reserves and zoos must be seriously considered.
Even pathogens producing mild symptoms in humans have been lethal to great apes in the past. The fact that Covid-19 is fatal for some humans leads experts to fear it could potentially prove devastating to great apes.