Seroprevalence of SARS-CoV-2 in pet--owned cats from Portugal

Dissertação de Mestrado em Enfermagem Veterinária de Animais de Companhia apresentada na Escola Superior Agrária de Ponte de Lima

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the agent responsible for the infectious disease named COVID-19, the most recent pandemic disease. This dissertation aims to focus on the epidemiology of the virus, including the impact under the concept of "One Health" and description of preventive measures to be taken, namely in animal health promotion, as well as investigate anti-SARS-CoV-2 IgG seroprevalence in client-owned cats from Portugal and evaluate the infection risk of cats that maintain contact with human COVID-19 cases. The first human case was reported in Wuhan, China, in late 2019, and bats were the first hosts considered the vehicle of transmission of this virus, however, the possible animal origin of the new Coronavirus has not been yet confirmed. The close contact between humans and domestic cats raises concerns about the potential risks of SARS-CoV-2 transmission. The first case described in animals was a cat that tested positive for SARS-CoV-2 in March 2020, in China. After that, several cases in different animal species have already been identified around the world, in Europe and even in Portugal. In order to understand the potential infection for SARS-CoV-2 in animals, a total of 176 cats were sampled. Cat owners answered an online questionnaire and cats were screened for antibodies against SARSCoV-2, using a commercial ELISA. Twenty (21.3%) households reported at least one confirmed human COVID-19 case. Forty cats (22.7%) belonged to a COVID-19 positive and 136 (77.3%) to a COVID-19 negative household. The seroprevalences of cats from COVID-19 positive and negative households were 5.0% (2/40) and 0.7% (1/136). The two SARS-CoV-2-seropositive cats from COVID-19-positive households had an indoor lifestyle, and their owners maintained a close and frequent contact with them, even after being diagnosed with COVID-19, pointing towards human-to-cat transmission. The SARS-CoV-2-seropositive cat from the COVID-19 negative household had a mixed indoor/outdoor lifestyle and chronic diseases. Owners of the three SARS-CoV2-seropositive cats did not notice clinical signs or behavior changes. This results highlights the low risk of SARS-CoV-2 transmission from COVID-19 positive human household members to domestic cats, even in a context of close and frequent human–animal contact.