2024-05-05 17:34:49
Since late March, the bird flu virus has spread to many American dairy farms. Could milk, one immediately asked, act as an intermediary to transmit this pathogen to humans?
It is indeed official from March 25: several organizations in the United States have confirmed that the virus, H5N1, is in dairy cows. What is more, according to the experts interviewed by columnist Zeynep Tufekci of New York Times, the first hatches probably started in February. Which raises questions about gaps in oversight.
As of April 30, the data from the Centers for Disease Control and Prevention (CDC) reported that an outbreak affected 36 herds in nine states. In addition, in s status update On May 1, the US Food and Drug Administration (FDA) reported that one in five milk samples contained fragments of the virus.
These were detected using PCR tests and it was not possible to know if the virus was still infectious. Therefore, further tests were carried out by inoculating eggs with milk samples. On May 1, the FDA confirmed that no live virus was found in the samples tested and that pasteurization appeared to be sufficient to inactivate the virus. So the milk on the shelves is safe for human consumption. However, the FDA recommends not to eat raw milk.
The situation in Canada
Prior to that date, the CFIA asked Canadian veterinarians to test cows that had an abnormally low production. That’s how the first infected American cows were identified.
Little risk to people
Still, according to Nitish Boodhoo, many questions remain unanswered. Experts still do not know how the American cows became infected and whether the virus was transmitted directly from person to person. There are several hypotheses on the table, reported by Zeynep Tufekci: for example, the virus could be spread through milking equipment or through food that sometimes consists of leftover chicken litter.
Tufecki criticizes the American authorities for their delay in setting up a screening campaign, given a virus that seems to be able to spread very quickly. The biggest concern is: could a cow act as an intermediary between birds and humans? Since 1997, we have closely monitored this H5N1 flu, cases in humans were very rare: less than 900 between 2003 and 2023. But the mortality rate every time was very high. In the case of this outbreak, as of April 30, the CDC has identified one case of transmission of the virus, after a dairy producer was exposed to an infected cow. He only had a minor infection.
The CDC considers the risk to public health to be low. This is also the conclusion of the WHO after a risk assessment for human health.
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