After the discovery of high concentrations of H5N1 virus in the milk of cows contaminated by avian flu in the United States, the WHO recommended Friday to apply common-sense food safety measures such as the use of pasteurized milk.
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For now, studies are underway to try to determine how long the virus can survive in milk and the World Health Organization has called for vigilance.
“While studies are ongoing, it is important for people to practice safe dietary practices including consuming only pasteurized milk,” said Dr. Wenqing Zhang, who leads the WHO’s global influenza program. , during the regular UN briefing in Geneva.
“We are now seeing that several herds of cows are affected in a growing number of American states, which shows a new stage in the spread of the virus to mammals,” underlined the WHO official.
Health authorities in Texas (southern United States), where the first case of cow-to-human transmission was discovered, stressed that there was no risk for the commercial dairy circuit, due to the obligation to destroy milk from sick cows.
Pasteurization, which involves heating the milk, also kills the virus.
Human infections with the A(H5N1) virus remain rare and are linked to exposure to infected animals and environments.
There is no evidence of human-to-human transmission at this time, but health officials fear that high circulation could facilitate a mutation of the virus that would allow it to pass from one human to another.
Dr. Zhang clarified, however, that the virus in Texas does not show signs of increased adaptation to mammals.
Between the start of 2023 and April 1, 2024, the WHO said it recorded a total of 889 human cases of avian flu in 23 countries, including 463 deaths, bringing the case fatality rate to 52%.
More species
Avian influenza A (H5N1) first appeared in 1996, but since 2020 the number of outbreaks in birds has exploded and an increasing number of mammal species have been affected.
Last month cows and goats joined the list – a surprising development for experts because they are not considered susceptible to this type of flu.
U.S. authorities said earlier this month that a person working on a dairy farm in Texas was recovering from bird flu after exposure to livestock.
“The case in Texas is the first human case infected with avian flu from a cow,” recalled Dr. Zhang.
“Bird-to-cow, cow-to-cow and cow-to-bird transmission have also been recorded during the current outbreaks, suggesting that the virus may have found other transmission routes than we previously imagined “, she said.
This was only the second human case to test positive for bird flu in the United States.
As for potential vaccines, Dr. Zhang said there are nearly 20 flu vaccines authorized for use in a pandemic and they could be tailored to the specific virus strain circulating.
