A A new study published Friday provides more evidence of the potential risk of drinking uncooked or raw milk containing H5N1 avian flu viruses.
The jobA study published in the New England Journal of Medicine found that mice fed milk from cows infected with H5N1 became severely ill.
The study cannot prove that what happens to mice can happen to people who drink raw milk containing a dangerous virus, but it highlights the danger, experts said. Such studies cannot be done in humans, for ethical reasons.
“Raw milk is highly suspect for overt transmission. [H5N1] For animals, “said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. “It’s not clear yet what the risk is to humans.
Tiges Kuiken agreed. Kuiken, a pathologist in the virology department of the Erasmus Medical Center in Rotterdam, the Netherlands, said that H. including cats. In this outbreak of dairy cattle, there have been several reports of farm cats dying, presumably after drinking contaminated milk.
“Based on the weight of evidence from our knowledge [this lineage of H5N1]What this letter suggests is that people who drink raw milk from infected cows can become infected with systemic disease,” Kuiken told STAT in an email.
Food and Drug Administration as E. It has long been recommended against drinking raw milk, which can contain a number of dangerous pathogens such as coli, salmonella and listeria. The agency is currently investigating H. As of Thursday, 58 herds in nine states have been infected with the virus since the outbreak was first detected in late March, and two human infections have been found in agricultural workers.
Neither Kuiken nor Osterholm were involved in the research, which was conducted by researchers at the University of Wisconsin-Madison. The senior author, Yoshihiro Kawaoka, was a leading influenza virologist who studied H5N1 for decades.
The mice were euthanized on day 4 of the study “because we didn’t want to see mice die before,” Kawaoka told STAT in an email. [tissue] “Sample” studies that involve exposing animals to potentially lethal pathogens do not allow for permanent mortality.
There were several components to the study, which was conducted in early April before the FDA and other academic groups announced research findings showing that an active virus cannot grow from pasteurized milk products.
In addition to the work done on feeding raw milk to mice, the team simulated two different approaches to pasteurization, using heat to inactivate pathogens in milk to see if they could grow active virus from heat-treated samples. One of the approaches they used killed all the virus in the milk, while the other, which involved brief heating, reduced the amount of active virus in the milk to low levels.
The researchers cautioned that the approaches taken to treat the milk are not the same as those used by dairy processors when processing commercial milk.
Another aspect of the study was that raw milk containing the virus was stored in the refrigerator for several weeks and it was found that the amount of the virus decreased over time. They observed only a modest decrease in the amount of active virus in milk, suggesting that “the virus can remain infectious in raw milk at 4°C for several weeks.”
According to one of the authors, Keith Paulson, the finding was not surprising. “The flu likes to be cold and wet,” said Paulson, director of the Wisconsin Veterinary Diagnostic Laboratory and professor of veterinary medicine at the University of Wisconsin-Madison.
Interestingly, the researchers found that the H5N1 virus was found in the mammary glands of the two mice when they studied the location of the virus after the virus was released. The mammary tissues of dairy cattle appear to be most susceptible to the virus, with infected cows shedding extremely high levels of the virus in their milk.
This article has been updated to include comments from the original author.