This article is republished from Conversation under Creative Commons License.
Recent bird flu outbreaks – v dairy herds in the USA, poultry farms in Australiaand elsewhere, i individual cases in people—raised the issue of food safety.
So can the virus spread from infected farm animals and contaminate milk, meat or eggs? How likely is this? What should we remember to minimize the risk when shopping or preparing food?
How safe and sound is milk?
Avian influenza (or bird flu) is a bird disease caused by specific types of influenza virus. But the virus can also infect cows. In United Statesto date, more than 80 dairy herds in at least nine states have been infected with the H5N1 variant of the virus.
The research is there during to confirm how it happened. However, we know that infected birds can shed the virus in saliva, nasal secretions and feces. Therefore, bird flu has the potential to contaminate food products of animal origin during processing and production.
Indeed, in: Fragments of bird flu genetic material (RNA) were found. cow’s milk from dairy herds associated with infected American farmers.
However, the spread of bird flu among cattle and possibly to humans is likely due to exposure to the flu contaminated milking equipmentnot just milk.
The test used to detect the virus in milk – using PCR technology similar to laboratory tests for Covid – is also highly sensitive. This means it can detect very low levels of bird flu RNA. However, the test does not distinguish between live and inactivated virus, it is restricted only to the presence of RNA. Therefore, we cannot determine whether the virus in milk is infectious (and can infect humans) based on the test alone.
Does this mean that milk is safe and sound to drink and does not transmit bird flu? Yes and no.
In Australia, where no cases of bird flu have been reported in dairy cattle to date, the answer is yes. You can safely drink milk and dairy products made from Australian milk. In the US, the answer depends on whether it is milk pasteurized. We know that pasteurization is a common and reliable method of destroying microorganisms, including the influenza virus. Like most viruses, the influenza virus (including bird flu virus) is inactivated by heat.
Although there is little direct research on whether pasteurization inactivates H5N1 in milk, we can extrapolate from what we know about heat inactivation of H5N1 in milk. chicken AND eggs. We can therefore be sure that there is no risk of transmitting bird flu through pasteurized milk or dairy products.
However, this is not the case with unpasteurized or “raw” American milk or dairy products. Recent test showed that mice fed raw milk contaminated with bird flu developed symptoms of the disease. Therefore, to be safe and sound, it is recommended to avoid raw milk products.
What about chicken?
Avian influenza causes sporadic epidemics in wild birds and domestic poultry around the world, including wild birds In Australia. It has been in recent weeks three reported outbreaks IN Victorian poultry farms (two with H7N3 bird flu, one with H7N9). There was one an outbreak was reported in Western Australia (H9N2).
Although strains of bird flu identified in outbreaks in Victoria and Western Australia may cause infection in humans are rare and usually result from close contact with infected live birds or polluted environments. Therefore, the risk of transmitting bird flu through chicken meat is negligible.