Absence of SARS-CoV-2 RNA and anti-SARS-CoV-2 antibodies in stray cats

SARS-CoV-2 positive or seropositive owned cats have been reported worldwide. The detection of seropositive stray cats in the proximity of farms of infected minks, coupled with the demonstration of cat-to-cat transmission in experimental settings, raise the question whether stray cats may have an epidemiological role in the COVID-19 pandemic and may act as sentinel for the circulation of SARS-CoV-2. The aim of this study was to evaluate the presence of SARS-CoV-2 RNA and anti-SARS-CoV-2 antibodies in free roaming cats belonging to colonies located in an area highly affected by the COVID-19 pandemic and to correlate the results with the positivity rate in people sharing the same area. Interdigital, cutaneous, oropharyngeal, nasal and rectal swabs, as well as blood samples, were collected from 99 cats living in colonies and admitted to our hospital for neutering. This caseload corresponds to the 24.2% of the feline population living in the 25 sampled colonies and to the 5.6% of all the free-roaming registered cats. The presence of SARS-CoV-2 RNA in swabs was assessed using real time RT-PCR. Anti-SARS-CoV-2 serum antibodies were assessed using commercially available ELISA kits and confirmed by serum virus neutralization. In people, the SARS-CoV-2 positivity rate ranged from 3.0% to 5.1% (mean rate: 4.1%) and the seropositive rate from 12.1% to 16.3% (mean rate: 14.2%). Most of the colonies were in urban areas and resident cats had frequent contacts with external cats or people. A COVID-19 positive caretaker was found, whereas all the cats were negative for SARS-CoV-2 RNA and seronegative. Although the negative results cannot exclude previous infections followed by decrease of antibodies, this study suggests that colony cats do not have an important epidemiological role in SARS-CoV-2 transmission dynamics. Further studies on larger caseloads are warranted, also in the light of the emerging new viral variants, on a One Health perspective.