This article is republished from The conversation under Creative Commons License.
Recent outbreaks of bird flu—in US dairy herds, poultry farms in Australiaand in other places, and isolated cases Inhuman—have raised the issue of food security.
So can the virus be transferred from infected farm animals and contaminate milk, meat or eggs? How likely is this? And what should we think about to minimize our risk when buying or preparing food?
How safe is milk?
Bird flu (or avian influenza) is a disease of birds caused by specific types of influenza viruses. But the virus can also infect cows. In the USATo date, more than 80 dairy herds in at least nine states have been infected with the H5N1 version of the virus.
The investigations are on going to confirm how this happened. But we do know that infected birds can shed the virus through saliva, nasal secretions, and feces. Therefore, avian flu can potentially contaminate food products of animal origin during processing and manufacturing.
In fact, fragments of genetic material (RNA) from bird flu were found in Cow milk of dairy herds associated with infected American farmers.
However, the spread of avian flu among livestock, and possibly humans, is likely to have been caused by contact with contaminated milking equipmentnot the milk itself.
The test used to detect the virus in milk, which uses PCR technology similar to laboratory Covid tests, is also very sensitive. This means it can detect very low levels of bird flu RNA. But the test does not distinguish between live or inactivated viruses, only that the RNA is present. So with this test alone, we cannot say whether the virus found in milk is infectious (and capable of infecting humans).
Does that mean milk is safe to drink and doesn’t transmit bird flu? Yes and no.
In Australia, where bird flu has not been reported in dairy cattle, the answer is yes. It is safe to drink milk and dairy products made from Australian milk. In the United States, the answer depends on whether the milk is pasteurized. We know that pasteurization is a common and reliable method of destroying microbes, including the influenza virus. Like most viruses, the influenza virus (including the bird flu virus) is inactivated by heat.
Although there is little direct research on whether pasteurization inactivates H5N1 in milk, we can extrapolate what we know about heat inactivation of H5N1 in milk. chicken and eggs. Therefore, we can be sure that there is no risk of transmission of bird flu through pasteurized milk or dairy products.
However, it is another matter for unpasteurized or “raw” American milk or dairy products. A recent study showed that mice fed raw milk contaminated with bird flu developed signs of illness. Therefore, to be safe, it would be advisable to avoid raw dairy products.
How about the chicken?
Avian influenza has caused sporadic outbreaks in wild and domestic birds around the world, including in Australia. In recent weeks there has been three outbreaks reported in Victorian poultry farms (two with H7N3 bird flu, one with H7N9). Has been one outbreak reported in Western Australia (H9N2).
The bird flu strains identified in the Victorian and Western Australian outbreaks can cause human infection, although these They are rare and generally result from close contact with live infected birds or polluted environments. Therefore, the possibility of transmission of bird flu through chicken meat is remote.