Thread by @davidasinclair

One third of homes have a cat. There are 600M globally. A study @NEJM confirms cats spread #coronavirus to each other & may spread it between family members. I’m concerned it could mix with a fatal cat coronavirus... 1/n

Some say “Well, the virus has not been proven to spread from cat to human.” As @StevenAustad has pointed out, this hasn’t been tested or disproven either. It is like saying in December 2019 that a virus in China hasn’t been proven to spread to the US. 2/n

Is no one but me concerned about viral genetic mixing & a new strain emerging from cats? Cats have their own #coronaviruses. They can cause one of the most fatal cat diseases known by destroying white blood cells (HIV-like). 3/n

Feline coronavirus usually only produces mild symptoms but in 5% it causes a condition called feline infectious peritonitis (FIP). The incubation period is long - about 2 weeks, making it easy to transmit. 4/n

Before you say, “stop being an alarmist”:
1. I’m not saying this is likely, I’m saying it could happen.
2. Genetic recombination of #coronaviruses occurs in domestic animals such as camels. 5/n

Humans and domestic camels share MERS #coronaviruses, and a genetic mixing event led to the outbreak of 2015. “Camels therefore serve as an important reservoir for the maintenance and diversification of the MERS-CoVs and are the source of human infections with this virus.” 6/n

So why raise this at all? Because the risk of any virus being here to stay, or a novel one emerging, depends not only on the mutation rate (which for CoV-2 is less then flu), but also the size of the reservoir (now millions) and strain-strain mixing (e.g. human-cat CoVs). 7/n

As for the reservoir, this excellent paper @SciReports looks at flu circulation globally and highlights how important the size of the reservoir is for viral evolution and seasonal recurrence 🌎 ncbi.nlm.nih.gov/pmc/articles/P… 8/n

I don’t hear anyone talking about the importance of the CoV-2 reservoir size or the potential for genetic mixing of viral genomes in cats as risk factors, so I thought I’d raise them for discussion 9/n

Key References:
@NEJM cat-cat: tinyurl.com/ya7z6udc
Feline Coronavirus: tinyurl.com/y8vdrukv
MERS recombination: tinyurl.com/yd3uynrv. 10/n