Negrito, a four-year-old cat, lived with a family affected by covid-19 with a case of death. When he began to present serious respiratory difficulties in May, he was taken to the Sant Mori Veterinary Hospital in Badalona, where he was diagnosed with a heart disease. Due to a terminal state, it was decided to do euthanasia.
The necropsy, carried out at the High Level of Biosafety facilities of the Animal Health Research Center (CReSA), of the Agrifood Research and Technology Institute (IRTA), confirmed that Negrito suffered from feline hypertrophic cardiomyopathy and that his death was not caused by the new coronavirus. However, the PCR test confirmed that the animal had been infected with SARS-CoV-2, but with a very low and residual viral load.
So far, there have been few cases of SARS-CoV-2 infection of felines worldwide. For this reason, the IRTA-CReSA researchers together with researchers from IrsiCaixa, the Barcelona Supercomputing Center (BSC) and veterinarians from the Sant Mori Veterinary Hospital deepened the study of the case. The results have been published in the journal PNAS.
Negrito developed antibodies
The scientists conducted a blood test on Negrito and another cat who also lived in the same household, Whiskey, who did not have any signs of the disease. The tests, carried out by the IrsiCaixa AIDS Research Institute – a center jointly promoted by the “La Caixa” Foundation and the Health Department of the Generalitat of Catalonia – showed that the two cats had developed antibodies against SARS-CoV-2 .
“In both cases we have detected neutralizing antibodies, that is, they have the ability to bind to the virus and block it”, explains Julià Blanco, IGTP researcher at IrsiCaixa. “This is important as it shows us that the immune system of cats can cope with the virus and, in these specific cases, protect them from developing symptoms,” he adds.
On the other hand, at present, there are experimental studies that show that cats, in addition to being infected with SARS-CoV-2, can transmit it to other nearby cats, even without presenting clinical signs. However, the first suspicions of the researchers were that both Negrito and Whiskey had been infected from their owners because they had not been in contact with other cats.
To verify this, the team analyzed the genetic sequence of the virus that Negrito had and found that it had a 99.9% similarity to the virus of the owner who died. “This suggests that the cat was directly infected from family members”, explains Marc Noguera-Julián, a researcher at IrsiCaixa.
Pets do not transmit the virus
Taking into account the number of infected people around the world and the few reported cases of animals, experts continue to emphasize that “companion animals play an insignificant role in the epidemiology of SARS-CoV-2”, emphasizes Júlia Vergara-Alert , researcher at IRTA-CReSA.
According to the expert, cats infect in a very residual way and there is no evidence of transmission of the virus to people. “This is a case of reverse zoonosis, in which cats are the collateral victims without the virus causing them health problems,” she notes.
So far, there have only been an episode reported in the Netherlands in which a farmer has been infected through mink, which would be the first known potential case of zoonoses from COVID-19.