Stray animals are also at risk from COVID-19

While many studies have focused on exposure to SARS-CoV-2 among pets and farm animals, the risk to stray animals has been much less thoroughly assessed. However, researchers have shown that stray animals are just as vulnerable to infection.   The COVID-19 pandemic has been widely reported and has sparked considerable scientific interest. While the disease primarily affects humans, it remains a recognized zoonosis. Veterinarians and researchers have therefore examined its potential for infection and transmission within animal populations. Because they are naturally in close contact with humans, pets have been the focus of numerous studies. Living in the same environment, they are highly exposed to human pathogens. It has thus been demonstrated that cats are not only susceptible to SARS-CoV-2 infection and develop an effective immune response, but can also transmit the virus to other cats. Dogs, on the other hand, appear to be less susceptible to infection by the novel coronavirus. They exhibit lower seroprevalence and limited capacity for viral transmission. It is therefore not surprising that SARS-CoV-2-specific RNA or antibodies have been reported in dogs and cats in many countries. However, most studies have focused on pets living in households with at least one confirmed human case. The exposure of animals in uninfected households or stray animals has not yet been fully characterized. Yet these animals may be exposed to a contaminated environment outside their homes. SARS-CoV-2 RNA has already been detected on public surfaces and in the sewer systems of major Brazilian cities, for example. Brazilian researchers therefore set out to study the prevalence of the novel coronavirus among the country’s domestic animals. Brazil, which has been particularly hard-hit by the health crisis, has a large number of stray animals, as well as a significant population of pets, some of which are in vulnerable situations. These animals represent a major concern in terms of public health and animal welfare. During the summer of 2020, 96 animals were tested, including 49 cats (40 from households and 9 strays) and 47 dogs (42 from households and 5 stray dogs). At that time, 100,000 human cases had been confirmed in the city of Rio de Janeiro. Among the animals tested at their owners’ homes, 75.6% (62 out of 82) belonged to households with no confirmed cases of COVID-19. All swabs tested negative for SARS-CoV-2 RNA by RT-PCR, but one stray cat and one stray dog tested positive for neutralizing antibodies against the virus, highlighting the potential vulnerability of animals left to fend for themselves during the COVID-19 pandemic. Although the stray animals tested were not infected at the time, they had been exposed to the virus during the ongoing COVID-19 outbreak in Rio de Janeiro. Despite the small sample size and limited geographic area, the results support the idea that, beyond pets, stray animals are also exposed to SARS-CoV-2. However, the lack of serological testing for feline and canine coronaviruses in the collected samples made it impossible to rule out cross-reactivity, which could have skewed the results. The inclusion of stray animals, however, revealed an important aspect for coronavirus surveillance in urban centers and could be considered an indicator of environmental contamination. For this reason, the researchers believe that investigating SARS-CoV-2 in animal populations through a “One Health” approach is necessary and should be encouraged. In the meantime, it is important to remind people who test positive for COVID-19 to maintain preventive distancing measures around pets.