SARS-CoV-2 Outbreak among Malayan Tigers and Humans, Tennessee, USA, 2020

I n October 2020, the Tennessee Department of Health (Nashville, Tennessee, USA) was notified of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in 3 Malayan tigers (Panthera tigris jacksoni) at a zoo in the state.Felids, including domestic cats and exotic big cats, have greater susceptibility to SARS-CoV-2 infection than other species (1-4).Infected domestic cats can transmit the virus to other cats via respiratory droplets or direct contact (4-6).However, the risk for cat-to-human transmission remains unclear.We investigated the SARS-CoV-2 outbreak in Tennessee to determine its source and provide recommendations to control the spread of infection.The Study Tiger 1, the index case, began showing clinical signs of coronavirus disease (COVID-19), including lethargy, anorexia, and nonproductive cough, on October 12, 2020.Subsequent onset of clinical signs occurred in tiger 2 on October 16 and in tiger 3 on October 17.Oropharyngeal swab specimens were collected under sedation on October 19 and October 27 for SARS-CoV-2 diagnostic testing and submitted to the Runstadler Laboratory, Cummings School of Veterinary Medicine at Tufts University (North Grafton, Massachusetts, USA) for initial testing for open reading frame (ORF) 1b-nsp14 (7).Presumptive positive SARS-CoV-2 diagnoses were made in all 3 animals by real-time reverse transcription PCR (RT-PCR) performed by using Mag-Bind Viral RNA Xpress Kit (Omega BioTek, https://www.omegabiotek.com)and UltraPlex 1-Step ToughMix (Quantabio, https:// www.quantabio.com).Tiger specimens were then sent to the US Department of Agriculture National Veterinary Services Laboratories (Ames, Iowa, USA) for confirmation by RT-PCR and whole-genome sequencing (3).We conducted an environmental assessment at the zoo on October 29, 2020.The tiger exhibit has 3 primary outdoor visitor viewing areas: 2 outdoor viewing areas with fencing between humans and animals creating a separation of ≈6 feet, and 1 outdoor overhead viewpoint where visitors could view animals from a platform >8 feet above the tiger enclosure.The tiger's off-exhibit den areas have concrete walls between each animal enclosure and metal interior caging with open airflow that enables keepers to see the tigers.The den areas are directly adjacent to or across from each other.We observed consistent use of personal protective equipment by zoo employees and veterinary students according to zoo policy.All employees and students in close contact with the tigers before the animals began to show signs of illness wore disposable gloves SARS-CoV-2 Outbreak among Malayan Tigers and Humans, Tennessee, USA, 2020