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

Abstract

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.

Keywords: COVID-19; Malayan tigers; SARS; SARS-CoV-2; Tennessee; United States; coronavirus; coronavirus disease; outbreak investigation; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.

Figure 1

Timeline of events identified during the epidemiologic investigation of an outbreak of SARS-CoV-2 infection among Malayan tigers and humans at a zoo, Tennessee, USA, October 12–30, 2020. Dates related to tiger events are shown above the timeline; dates related to human events are shown below the timeline. C_t values for the first positive open reading frame 1b reverse transcription PCR test per animal are shown; methods for extraction and C_t value calculation were described previously by Sawatzki et al. (11). C_t, cycle threshold; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.

Figure 2

Whole-genome phylogenetic analysis from of an outbreak of SARS-CoV-2 infection among Malayan tigers and humans at a zoo, Tennessee, USA, October 2020. The tree shows a close-up view of clade 20G divergence estimates from the SARS-CoV-2 Wuhan-Hu-1 reference genome and sequences from humans living in Tennessee and Malayan tigers sampled during the outbreak investigation. Sequence analysis showed 3–6 SNP differences between 1 human tiger keeper and all 3 tiger sequences (GISAID accession nos. EPI_ISL_292844–6). Differences are indicated by 1-step edges (lines) between colored dots (individual SARS-CoV-2 sequenced infections). Numbers indicate unique sequences. Phylogenetic relationships were inferred through approximate maximum-likelihood analyses implemented in TreeTime (13) by using the NextStrain pipeline (14). All high-quality genome sequences from Tennessee were downloaded from the GISAID (https://www.gisaid.org) database on March 16, 2021. Pangolin lineages for investigation sequences were assigned on March 16, 2021. Not all analyzed sequences are shown in this figure because some were outside clade 20G. CDC, Centers for Disease Control and Prevention; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; SNP, single-nucleotide polymorphism.