The big cat is the first non-domesticated animal to test positive for coronavirus in the United States and is one of seven big cats at the Bronx Zoo with coronavirus symptoms
Nadia, a Malayan tiger at the Bronx Zoo in New York City that tested positive for coronavirus, is … [+]
Wildlife Conservation Society
A female tiger at the Bronx Zoo has tested positive for the novel coronavirus, according to a statement released today by the Wildlife Conservation Society, a nonprofit organization that oversees the Bronx Zoo. The positive test was confirmed by the National Veterinary Services Laboratory in Ames, Iowa.
“Public health officials believe these large cats became sick after being exposed to a zoo employee who was actively shedding [the] virus”, according to a statement from the USDA. Coronavirus infections result from person-to-person transmission, experts say.
“Our cats were infected by a person caring for them who was asymptomatically infected with the virus or before that person developed symptoms”, according to zoo officials.
Nadia, a four-year-old Malayan tiger, was tested for coronavirus on 2 April after developing a dry cough and a decreased appetite on 27 March. Nadia’s sister, Azul, two Amur tigers and three African lions also developed a dry cough and loss of appetite but have not been tested for coronavirus.
“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”, The WCS statement said.
The seven big cats are expected to fully recover.
“We tested the cat [Nadia] 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 zoo said in a statement on Sunday.
Nadia was anaesthetized to undergo X-rays, an ultrasound and blood tests to diagnose what was ailing her. Considering the large surge in human cases in New York City, it was decided to also test Nadia for Covid-19, since she was already sedated. Samples were sent to the New York State Diagnostic Laboratory at Cornell University and to the USDA-APHIS veterinary lab in Ames, Iowa. The coronavirus test is not the same test designed for people, so there was no competition for a test with a potentially sick person.
Nadia is the first animal to test positive for coronavirus in the USA, but there are reports that several pets have tested positive for SARS-CoV-2, the virus that causes COVID-19, including a Pomeranian and a German shepherd in Hong Kong, and a domestic cat in Belgium.
“Anyone sick with COVID-19 should restrict contact with animals, out of an abundance of caution, including pets, during their illness, just as they would with other people”, the USDA said in a statement.
A preliminary study published at the end of last week found that cats can catch coronavirus and may infect each other (ref), just as people do. However, that study found no evidence to suggest that felines could pass SARS-CoV-2 back to humans.
“Although there have not been reports of pets becoming sick with COVID-19 in the United States, it is still recommended that people sick with COVID-19 limit contact with animals until more information is known about the virus”, the USDA added.
Another report suggests that this novel coronavirus may have come from a very closely related coronavirus found in bats (ref).
“It is not known how this disease will develop in big cats since different species can react differently to novel infections, but we will continue to monitor them closely and anticipate full recoveries”, the zoo said in a statement.
The four symptomatic tigers live in the zoo’s Tiger Mountain exhibit. However, several other tigers in this exhibit are asymptomatic, including a male Amur tiger who lives in the same enclosure. A Malayan tiger and two Amur tigers housed in the zoo’s Wild Asia exhibit also remain symptom-free.
None of the zoo’s other big cats, including snow leopards, cheetahs, a serval, a clouded leopard, an Amur leopard, and a puma are showing signs of illness. This raises important questions, such as whether tigers and lions are particularly susceptible to coronavirus, which causes respiratory symptoms.
Other animals may also be especially susceptible to SARS-CoV-2. For example, zookeepers throughout the country have been taking special precautions to protect great apes in their care because these animals can easily catch respiratory illnesses from humans, and may be particularly susceptible to coronavirus.
Nadia may be the first captive tiger diagnosed with coronavirus, but it’s likely she won’t be the last. This also raises concerns for wild tigers.
The Malayan tiger, Panthera tigris tigris, inhabits the southern and central parts of the Malay Peninsula, and was formally classified as Critically Endangered by the IUCN Red List in 2015. The wild population of Malayan tigers was estimated to be between 250-340 adult individuals in 2013, comprising less than 200 breeding individuals. These tigers’ wild population continues to decline.
Amur tigers (also known as Siberian tigers) are in even worse shape: although there are about 500 Amur tigers alive in the wild (and nearly as many in captivity around the world), the total genetic diversity of the entire population is very limited and is estimated to comprise just 35 individuals. These, the largest of all the tigers, are thinly distributed throughout the Russian Far East and Northeast China.
The Bronx Zoo has been temporarily closed to the public since 16 March. However, its empty parking lots were converted into coronavirus testing centers, complete with white tents, for the employees of the nearby Montefiore Medical Center.
Peng Zhou, Xing-Lou Yang, Xian-Guang Wang, Ben Hu, Lei Zhang, Wei Zhang, Hao-Rui Si, Yan Zhu, Bei Li, Chao-Lin Huang, Hui-Dong Chen, Jing Chen, Yun Luo, Hua Guo, Ren-Di Jiang, Mei-Qin Liu, Ying Chen, Xu-Rui Shen, Xi Wang, Xiao-Shuang Zheng, Kai Zhao, Quan-Jiao Chen, Fei Deng, Lin-Lin Liu, Bing Yan, Fa-Xian Zhan, Yan-Yi Wang, Geng-Fu Xiao and Zheng-Li Shi (2020). A pneumonia outbreak associated with a new coronavirus of probable bat origin, Nature 579:270–273 | doi:10.1038/s41586-020-2012-7
Hualan Chen (2020). Susceptibility of ferrets, cats, dogs, and different domestic animals to SARS-coronavirus-2, bioRxiv | doi:10.1101/2020.03.30.015347