In experiments, mice get ill from raw milk carrying bird flu virus

Confirming the risks of consuming uncooked cow’s milk when the H5N1 avian flu virus is circulating in U.S. dairy herds, researchers discovered that mice fed the milk shortly obtained ailing.

“Our knowledge point out that HPAI A[H5N1] virus in untreated milk can infect inclined animals that eat it,” concluded a staff led by virologist Yoshihiro Kawaoka, of the College of Wisconsin–Madison. His staff revealed the findings Friday within the New England Journal of Drugs.

In late March, researchers first detected traces of H5N1 chook flu in nasal swabs and milk obtained from U.S. dairy cows. Since then, the outbreak has been detected in lots of dairy herds throughout a number of states.

Thus far, H5N1 doesn’t appear to transmit simply between animals and people: There have been solely two recognized human instances of H5N1 an infection linked to the U.S. dairy cow outbreak. Each have occurred in dairy employees who’ve had prolonged, shut contact with the animals.

Consultants additionally consider the overall milk provide to be protected, for the reason that heating concerned in pasteurization kills the virus.

Nonetheless, consuming unpasteurized “uncooked” milk—a craze amongst a small subset of customers—could, the truth is, run the chance of passing H5N1 to different mammals, together with individuals.

To search out out if that’s true, Kawaoka and his staff gave mice uncooked cow’s milk recognized to be contaminated with the H5N1 virus. The rodents obtained the milk by mouth.

The mice confirmed typical indicators of an infection, akin to “ruffled fur and lethargy” as quickly as at some point after being fed the milk, the researchers reported.

“All of the animals survived till day 4, once they had been euthanized to find out virus titers [levels] in a number of organs,” Kawaoka’s group mentioned.

“We detected excessive virus titers within the respiratory organs [which suggests that infection may have occurred through the pharynx] and reasonable virus titers in a number of different organs, findings in step with the systemic infections sometimes attributable to HPAI H5 viruses in mammals,” the staff reported.

Excessive ranges of virus had been additionally discovered within the feminine mice’s mammary glands, despite the fact that they weren’t lactating, the researchers mentioned.

Based mostly on their findings, the researchers consider that mammalian an infection with the avian flu virus can occur after consuming cow’s milk containing the pathogen if the milk has not been heat-treated, as occurs with pasteurization.

Individuals who drink uncooked milk could consider that refrigeration can kill off the H5N1 virus. The researchers investigated that notion, refrigerating the contaminated milk at a temperature of 39 levels Fahrenheit.

Nonetheless, ranges of virus within the unpasteurized milk declined solely slowly whereas saved at this temperature for 5 weeks, suggesting that the “virus could due to this fact stay infectious for a number of weeks” underneath these circumstances, in line with the researchers.

As for pasteurization, the scientists put uncooked, contaminated milk via heating processes much like these used within the pasteurization course of. They report that ranges of virus had been diminished to undetectable or barely detectable ranges, however in some instances not utterly eradicated.

Kawaoka’s staff harassed that “the circumstances utilized in our laboratory research are usually not similar to the large-scale industrial [pasteurization] remedy of uncooked milk.”

Nonetheless, the analysis appears to substantiate that the true hazard of passing H5N1 onto customers lies within the consumption of uncooked milk.

“Do not drink uncooked milk—that is the message,” Kawaoka advised the New York Occasions.

And there are extra causes than chook flu to keep away from uncooked milk.

In response to one 2022 research from the U.S. Facilities for Illness Management and Prevention, uncooked milk consumption has been linked to 228 hospitalizations, three deaths and sickness in additional than 2,600 individuals between 1998 and 2018.

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