Cats emerging as potential vectors
Time spent with cats is never time wasted, as Sigmund Freud is said to have said but didn’t. And a good job too because it might turn out to be poor advice in a Covid-19 world.
Evidence is rapidly accumulating to suggest that cats should probably be kept at a distance or strictly kept within your household bubble. Good hygiene around cats is important.
Bluntly, you don’t know where your cat has been and cats are emerging as potential vectors of the Covid-19 virus. They can be infected, get ill, exchange it with other cats and (given the origins of the disease) it is likely they could pass it on to humans.
Animal lovers should wash their hands before and after touching pets, including cats. Keep pets clean, as well as their food and water bowls. Surfaces they touch and pets’ beds should also be cleaned regularly.
New diseases don’t emerge spontaneously but result from the evolution of existing diseasecausing microbes. Zoonotic transfer to humans involves the normal background process of microbes moving among potential hosts in nature. Humans are not specifically targeted but our activities can increase our exposure to potential microbial parasites.
In particular, the burgeoning human population on Earth causes increased contact between species as we compete for resources. Situations where wild animals, farm animals and people interact are ideal for transfer.
Covid-19 is closely related to Sars 2003 (Severe Acute Respirator Syndrome) and they are now formally known as SARS-CoV-1 and SARS-CoV-2 (Covid-19). They are descended from viruses transmitted among bats, but probably reached humans via another wild mammal.
Genetic samples from animals traded in Chinese markets show lots of SARS-CoV in palm civets and other carnivores. These Sars viruses invade human cells by recognising a particular protein, that is almost identical in humans, cats and other species. This means that Covid-19 can break into cat cells as well as human cells and has reached cats, dogs, tigers, ferrets and other animals.
Although transmission via dogs may have occurred in the Italian outbreak, domestic cats show greater potential to spread SARS-CoV-2 because they are more easily infected and roam widely.
In lockdown, we focused on people socially distancing and maintaining their small household bubbles. Meanwhile most of New Zealand’s 1 million domestic cats (and 2.5 million feral cats) continue to roam across an average of 16 neighbouring bubbles.
As yet, cats have not been tested in New Zealand but pet cats in New York and Belgium have tested positive. In Wuhan, China, 15 per cent of cats tested had antibodies for SARS-CoV-2, showing they had had the disease.
We know that human-animal transmission of viral diseases is common. The related camel flu (MERS-CoV) for instance has a shared human-camel host community.
Viral success is measured only in its survival. Viral survival requires a large and accessible pool of hosts, so there is an evolutionary advantage to being able to invade different species. This means that viral (and bacterial) pathogens will continue to cross species boundaries.
Pandemics in the most abundant, widespread and mobile mammal species on Earth is inevitable and potentially devastating.