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

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.
Highlights • Respiratory signs in a household cat ten days after the appearance of COVID-19 in the family led to a thorough investigation. • The Alpha variant (B.1.1.7) was first detected in owners and one week later in the cat which showed a similar course. • A familial cluster was confirmed based on a comparative sequence analysis of the study subjects and 200 Italian random cases. • The temporal sequence together with the genomic data support human-to-animal transmission. • The human epidemic, the easy crossing of species barriers and the abundance of pets suggest monitoring for spillover risks.