First detection of an Italian human-to-cat outbreak of SARS-CoV-2 Alpha variant - lineage B.1.1.7

Abstract

The emergence of new SARS-CoV-2 variants and their rapid spread pose a threat to both human and animal health and may conceal unknown risks. This report describes an Italian human-to-cat outbreak of SARS-CoV-2 lineage B.1.1.7 (the Alpha variant) . On March 7th, 2021, approximately ten days after COVID-19 appeared in the family, the onset of respiratory signs in a cat by COVID-19-affected owners led to an in-depth diagnostic investigation, combining clinical and serological data with rt-qPCR-based virus detection and whole genome sequencing. The Alpha variant was confirmed first in the owners and a few days later in the cat that was then monitored weekly: the course was similar with one-week lag time in the cat. In addition, based on comparative analysis of genome sequences from our study and from 200 random Italian cases of Alpha variant, the familial cluster was confirmed. The temporal sequence along with the genomic data support a human-to-animal transmission. Such an event emphasizes the importance of studying the circulation and dynamics of SARS-CoV-2 variants in humans and animals to better understand and prevent potential spillover risks or unwarranted alerts involving our pet populations.

Keywords: Cat; Human-to-animal transmission; Infection cluster; One health approach; Sars-CoV-2 alpha variant lineage B.1.1.7.

Fig. 1

X-rays image on lateral view of cat thoracic region.

Fig. 2

Phylogenetic analysis of SARS-CoV-2 genomes. A total of 204 viral genomes are displayed, including (i) father, daughter and cat genomes, (ii) 200 genomes from GISAID randomly selected among B.1.1.7 lineage of Italian origin; and (iii) the SARS-CoV-2 reference Wuhan Hu-1 genome. The father, daughter and cat genomes cluster together (node highlighted in red). GISAID sequences are labelled with EPI accession numbers. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)