key: cord-1025375-9ko5h0ki authors: Grome, Heather N.; Meyer, Becky; Read, Erin; Buchanan, Martha; Cushing, Andrew; Sawatzki, Kaitlin; Levinson, Kara J.; Thomas, Linda S.; Perry, Zachary; Uehara, Anna; Tao, Ying; Queen, Krista; Tong, Suxiang; Ghai, Ria; Fill, Mary-Margaret; Jones, Timothy F.; Schaffner, William; Dunn, John title: SARS-CoV-2 Outbreak among Malayan Tigers and Humans, Tennessee, USA, 2020 date: 2022-04-03 journal: Emerg Infect Dis DOI: 10.3201/eid2804.212219 sha: 2b069bbf6f47f785c15d2fa85b36685dcdbf2fb5 doc_id: 1025375 cord_uid: 9ko5h0ki We report an outbreak of severe acute respiratory syndrome coronavirus 2 involving 3 Malayan tigers (Panthera tigris jacksoni) at a zoo in Tennessee, USA. Investigation identified naturally occurring tiger-to-tiger transmission; genetic sequence change occurred with viral passage. We provide epidemiologic, environmental, and genomic sequencing data for animal and human infections. We report an outbreak of severe acute respiratory syndrome coronavirus 2 involving 3 Malayan tigers (Panthera tigris jacksoni) at a zoo in Tennessee, USA. Investigation identified naturally occurring tiger-to-tiger transmission; genetic sequence change occurred with viral passage. We provide epidemiologic, environmental, and genomic sequencing data for animal and human infections. and cloth facemasks. After the onset of clinical signs of illness and SARS-CoV-2 testing in tigers, persons in the tiger den area wore protective coveralls, disposable gloves, and plastic face shields. At the time of this outbreak in October 2020, fewer data existed for relative mask efficacy, and mask types were not further specified by zoo policy. Before and after onset of animal illness, cleaning practices in the off-exhibit cages included use of high-pressure water hoses to clean the floors. Staff used disinfectants daily in the den area, and we confirmed disinfectants were on the US Environmental Protection Agency's List N: Disinfectants for Coronavirus (COVID-19) (https://www.epa.gov/ coronavirus/about-list-n-disinfectants-coronaviruscovid-19-0). All zoo employees and veterinary students used a self-reported evaluation tool via mobile phone that screened for COVID-19 symptoms before their shifts. Zoo visitors were encouraged to wear masks; masks were not required in outdoor spaces at the time of this outbreak. We also conducted an epidemiologic investigation on October 29, 2020. Our investigation focused on the timeframe beginning 2 weeks before onset of index tiger clinical signs (starting September 28) until date of investigation (October 29). We identified 18 zoo employees and veterinary students who prepared food for or were in close contact with the tigers during this timeframe. For this investigation, we defined close contact to tigers as being within 6 feet of any tiger at the zoo for any length of time during the observation period (September 28-October 29). We selected these proximity criteria based on the US Centers for Disease Control and Prevention (CDC) definition of close contact defined (8) ; however, SARS-CoV-2 transmission can occur from inhalation of virus in the air >6 feet from an infectious source (9, 10) . During the week after the index tiger showed signs of illness, community transmission of SARS-CoV-2 was at a 7-day average of 101 new cases/day in the county where this zoo is located, and the 7-day test positivity rate was 10.2%. We identified 2 employees with COVID-19 during the September 28-October 29 timeframe: a tiger keeper and veterinary clinic assistant. Contact tracing identified an additional household contact to the SARS-CoV-2-positive tiger keeper, but no other SARS-CoV-2-positive contacts were identified. We created a timeline comparing signs of animal illness onset and RT-PCR cycle threshold values with dates of zoo employee symptom onset and testing ( Figure 1 ). We sent specimens from all zoo employees and veterinary students who tested positive for SARS-CoV-2 to CDC for sequencing and genomic analyses. CDC staff performed whole-genome sequencing as previously described (12) . We phylogenetically compared tiger sequences with 30 sequences from geographically-associated human SARS-CoV-2 cases collected from the county surrounding the zoo during October 29-November 12, 2020. We also compared tiger sequences with 233 statewide background sequences from specimens collected in Tennessee during March 1-November 12, 2020. Most viral sequences clustered into NextStrain Clade 20G and Pangolin lineage B.1.2, which correspond to the predominant clades observed for human specimens from Tennessee during the time of the outbreak at the zoo. Nucleotide sequence analysis of viral sequences from the tigers (GISAID accession nos. EPI_ISL_2928444-6; https://www.gisaid.org) and the tiger keeper (GenBank accession no. OK170070) also clustered in SARS-CoV-2 clade 20G by Nextstrain tree (Figure 2 ). The multiple alignment of 4 SARS-CoV-2 genome sequences (tigers 1, 2, and 3 and the tiger keeper) showed a total of 6 single-nucleotide polymorphisms (SNPs) across 4 genomes. Sequences from tigers 1 and 2 were identical and had no substitutions compared with the reference sequence at those 6 SNP positions. Tiger 3's SARS-CoV-2 sequence contained 3 substitutions that were nonsynonymous G12565T (ORF1a: Q4100H), C17822T (ORF1b: P1452L), and G19889A (ORF1b: R2141K), and the tiger keeper's SARS-CoV-2 genome sequence had 3 synonymous substitutions (C1498T, C24904T, T26048C) compared with tigers 1 and 2. SARS-CoV-2 genome sequences from the tiger keeper and tiger 3 had 6 SNP differences. Genomic and epidemiologic data suggest that tiger-to-tiger transmission occurred under natural conditions, and genetic change occurred in vivo for tiger 3's sequence. We describe SARS-CoV-2 infection in captive tigers with respiratory clinical signs and provide additional evidence for nonhuman species as hosts for SARS-CoV-2. Findings of this study support tigers' susceptibility to the virus and potential for sustained transmission among large cats and a risk for zoonotic transmission to humans. The SARS-CoV-2 sequence from the tiger keeper was 3 SNPs different from tigers 1 and 2 and 6 SNPs different from tiger 3. The close genetic relationship between viruses of the tigers and tiger keeper is consistent with the timing of clinical signs of illness and job duties of the tiger keeper, although transmission source or zoonotic transmission cannot be proven from these data alone. These findings have implications for both the public health and zoologic communities. Zoos should be aware of the possibility of animal infection through incidental exposure by the public or asymptomatic staff members. Humans with known or suspected infection should avoid direct or indirect exposure to susceptible species unless completely unavoidable to avoid potential transmission. Results of this investigation should also prompt zoo and wildlife organizations to reevaluate biosecurity and administrative protocols to minimize risk to and from employees, students, volunteers, and the visiting public interacting with susceptible species. Experimental infection of domestic dogs and cats with SARS-CoV-2: pathogenesis, transmission, and response to reexposure in cats Susceptibility and attenuated transmissibility of SARS-CoV-2 in domestic cats From people to Panthera: natural SARS-CoV-2 infection in tigers and lions at the Bronx Zoo Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS-coronavirus 2 Transmission of SARS-CoV-2 in domestic cats SARS-CoV-2 in quarantined domestic cats from COVID-19 households or close contacts Duration of antigen shedding and development of antibody titers in Malayan tigers (Panthera tigris jacksoni) naturally infected with SARS-CoV-2 Case investigation & contact tracing guidance Indirect virus transmission in cluster of COVID-19 cases Cluster of coronavirus disease associated with fitness dance classes Host barriers to SARS-CoV-2 demonstrated by ferrets in a high-exposure domestic setting Rapid, sensitive, full-genome sequencing of severe acute respiratory syndrome coronavirus 2 TreeTime: maximumlikelihood phylodynamic analysis Nextstrain: real-time tracking of pathogen evolution This work was support by the National Institutes of Health (grant no. HHSN272201400008C/AI/NIAID to K.S.) Dr. Grome is an infectious diseases physician and Epidemic Intelligence Service officer in the Center For Surveillance, Epidemiology, and Laboratory Services of the Centers for Disease Control and Prevention, Atlanta, Georgia. She is currently assigned to the Tennessee Department of Health in Nashville, Tennessee. Her research interests include communicable disease prevention for vulnerable populations.