The long-feared leap
The H5N1 strain of avian flu has been around since 1996, but until now its been largely confined to animals. But it has now jumped to cattle in America and some think it means we are inching towards eventual human-to-human infection, with potentially serious consequences.
Infected cows have started infecting each other
H5N1 first appeared in geese in wet markets in Guangdong, China. Since then there have been various outbreaks around the world where chickens and wild birds have become infected. But as Covid was ravaging the human world, H5N1 began to spread quickly, killing millions of birds – both reared and wild – and affecting seal and sea lion populations around the globe. The virus has also appeared in a mink farm in Spain and polar bears in the Arctic.
The question we were asking was where would it go next? A few weeks back we got our answer. In March, farmers in Texas and Kansas started reporting that their cows had low appetites and were producing less milk. Tests came back positive for H5N1. And this was not just individual cases brought on by chance contamination: the cows were infecting each other.
BSE taught Europe and the UK to track its cows. America doesn’t.
Since March, H5N1 has been confirmed in dairy cattle in nine US states. Scientists are still trying to establish how the virus is being spread.
“Right now it seems like the milking equipment may be one of the ways,” says Dr Caitlin Rivers, an epidemiologist at the Johns Hopkins School of Public Health
“Scientists are finding very high levels of virus in milk. And so that’s why the milking equipment seems like it might be playing a role.”
She adds that the spread of the virus between states seems to be down to the movement of infected cows across state lines.