Tiger with SARS-CoV-2 infection demostrates reverse zoonosis
Some viruses come from animals and jump to humans to cause disease. In the case of the novel coronavirus, now known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), it is thought to have come from bats, jumped to an intermediate animal host, and then onto humans. But can the virus leap from humans to other animals?
Two dogs were recently infected with the novel coronavirus in Hong Kong, a Pomeranian, and a German Shepherd. Now, the Wildlife Conservation Society has confirmed that a tiger in Bronx Zoo in New York City has tested positive for COVID-19 after apparent exposure to an infected worker.
“Our cats were infected by a person caring for them who was asymptomatically infected with the virus or before that person developed symptoms. Appropriate preventive measures are now in place for all staff who are caring for them, and the other cats in our four WCS zoos, to prevent further exposure of any other of our zoo cats,” the WCS said.
The four-year-old female Malayan Tiger, known as Nadia, was tested after it developed a dry cough and loss of appetite. The tiger’s sister, Azul, two Amur tigers, and three African lions are now manifesting coronavirus symptoms. All cats are expected to recover.
The zoo imposed appropriate preventive measures for all staff who are caring for the animals to prevent further exposure to other zoo cats.
The testing was carried out by the USDA’s National Veterinary Services Laboratory in Ames, Iowa.
“We tested the cat out of an abundance of caution and will ensure any knowledge we gain about COVID-19 will contribute to the world’s continuing understanding of this novel coronavirus,” the WCS said in a statement.
“Though they have experienced some decrease in appetite, the cats at the Bronx Zoo are otherwise doing well under veterinary care and are bright, alert, and interactive with their keepers. It is not known how this disease will develop in big cats since different species can react differently to novel infections. Still, we will continue to monitor them closely and anticipate full recoveries,” it added.
What is Reverse Zoonotic Disease Transmission?
Animals can transmit pathogens, such as viruses, to humans. But can humans transmit the virus back to animals? Reverse zoonotic disease transmission also called reverse zoonosis or zooanthroponosis, occurs when humans transmit pathogens to animals.
Previous reports have shown that methicillin-resistant Staphylococcus aureus, Ascaris lumbricoides, Cryptosporidium parvum, and the influenza A virus can pass from humans to animals. During the 2009 H1N1 influenza pandemic, there were several confirmed cases of people infecting their pets (ferrets, cats and dogs) with the influenza virus.
One outbreak of influenza lead to the death of 6 bonobos (a species of chimpanzee) in a Congo wildlife sanctuary. It was thought that the source was one or more visitors during the February epidemic of influenza in Kinshasha.
Recently, amid the coronavirus disease (COVID-19) outbreak, reports have shown that the virus can go from humans to animals.
COVID-19 is a disease caused by the SARS-CoV-2, which is similar to the SARS outbreak in 2002, and the MERS outbreak in Saudi Arabia in 2012. It is believed that the virus was first transmitted to people at a wet market that trades wildlife in Wuhan City, Hubei Province, China.
Human and animal relationships are likely to continue to intensify worldwide over the next several decades due in part to animal husbandry practices, the growth of the companion animal market, climate change and ecosystem disruption, anthropogenic development of habitats, and global travel and commerce. As the human-animal connection escalates, so does the threat for pathogen spread. The viruses humans pass back to animals may come back to haunt us another day.
COVID-19 global numbers
The novel coronavirus has now spread to 184 countries and territories, with the United States reporting the highest number of infections. The U.S. has more than 368,000 infections, followed by Spain, with more than 136,000 confirmed cases, Italy, with more than 132,000 confirmed cases, and Germany, with more than 103,000 cases, among others.
The total number of infections across the globe has topped 1.34 million, and the number of deaths has reached over 74,000.
The coronavirus disease is life-threatening for those who are at high risk, such as those above 60 years old, those who are immunocompromised, and those with underlying medical conditions.
The disease usually starts with fatigue, fever, and sore throat. As the disease progresses, it leads to dry cough, high fever, and shortness of breath. Some people have reported having a loss of smell and taste. These symptoms are similar to other respiratory ailments.
The U.S. Centers for Disease Control and Prevention (CDC) recommends that people should practice proper handwashing as well as maintaining social distancing when around other people. There is still no vaccine or treatment developed for the disease, making it harder to contain.
- Wildlife Conservation Society. (2020). A Tiger at Bronx Zoo Tests Positive for COVID-19; The Tiger and the Zoo’s Other Cats Are Doing Well at This Time. https://newsroom.wcs.org/News-Releases/articleType/ArticleView/articleId/14010/A-Tiger-at-Bronx-Zoo-Tests-Positive-for-COVID-19-The-Tiger-and-the-Zoos-Other-Cats-Are-Doing-Well-at-This-Time.aspx
- Messenger, A., Barnes, A., and Gray, G. (2014).Reverse Zoonotic Disease Transmission (Zooanthroponosis): A Systematic Review of Seldom-Documented Human Biological Threats to Animals. PLOS ONE. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3938448/
- Coronavirus COVID-19 Global Cases by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - https://gisanddata.maps.arcgis.com/apps/opsdashboard/index.html#/bda7594740fd40299423467b48e9ecf6
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