Alert as bird flu is found in ‘raw’ cow’s milk – and it may survive heat treatment and refrigeration, scientists say
Deadly bird flu has been found in raw cow’s milk and may survive standard pasteurization, a study suggests.
Scientists tested milk samples from herds infected with H5N1 in New Mexico and found high levels of the virus even after it was chilled at 4c (39F).
It means that animals that drink the milk, including humans, are at risk of contracting the milk.
When mice were fed untreated milk, they showed signs of illness from day one and the virus was detected in their respiratory tract and other organs of their body.
The researchers subjected the milk to a heat treatment at 72 degrees Celsius, similar to how supermarket milk is pasteurized, for different periods of time.
Raw milk is available at some health food stores and trendy coffee shops
Bird flu has been found in British chickens, but no cases have been reported in cows
In Great Britain, milk must be heated for a minimum of 15 seconds and no longer than 25 seconds.
The researchers found that the virus was reduced, but not eliminated, even after 20 seconds of heating. Only after 25 seconds was it destroyed.
They wrote in the New England Journal of Medicine: ‘Our data indicate that the H5N1 virus in untreated milk can infect susceptible animals that consume it.
‘A heat treatment for 15 or 20 seconds reduced the virus titers by more than 4.5 log units, but did not completely inactivate the virus.
‘H5N1-positive milk poses a risk if consumed untreated.’
However, the researchers admitted that it was impossible for them to accurately replicate industrial pasteurization methods in their laboratory.
Raw milk is available in certain health food stores, trendy coffee shops and directly from artisan dairies.
The virus was confirmed in commercial poultry in England in February, but no cases of the virus in British cows have been reported.
Meanwhile, World Health Organization disease expert Maria van Kerkhove said bird flu could be the cause of a future pandemic.
She said: ‘It has infected many different species. That’s why we have a whole system in place to be prepared for this.
“I’m not saying this to scare people, but for us it’s something we have to be prepared for.
‘We have to think out-of-the-box. We really prepare for the known threats, but we also think about something else, maybe from water or whatever.
“So for me, pandemics are unfortunately part of what we’re going to have to deal with in our lifetimes. “I don’t believe (Covid) will be the last pandemic we will face in our lifetimes.”