Researchers recently found that even after undergoing standard pasteurization, small amounts of the bird flu virus still persisted in raw milk samples containing high levels of the virus.
According to the authors of the study, who are researchers from the National Institutes of Health, the findings are based on experimental conditions in a laboratory and should not be used to make any conclusions about the safety of the U.S. milk supply.
The findings were reported in the New England Journal of Medicine. With increasing knowledge about the virus, countries worldwide are ramping up their vaccination campaigns to avert a potential pandemic situation.
Researchers conducted experiments to investigate the effect of different time intervals of heat treatment on bird flu susceptibility in raw milk, using temperatures commonly used in commercial dairy pasteurization processes, specifically 63 degrees Celsius and 72 degrees Celsius. Due to the limited available data on this topic, the study aimed to fill the gap in understanding how pasteurization affects bird flu in milk.
While pasteurization quickly reduced the bird flu virus levels in the samples, a small amount was still detected in one-third of the samples after up to 20 seconds of heat treatment at 72 °C.
The study's authors noted that this finding suggests a small but detectable amount of the H5N1 virus could remain infectious in milk after being heated to 72 °C for 15 seconds, provided the initial virus levels were sufficiently high.
Despite the potentially concerning findings, the researchers emphasized limitations in their study. Raw milk from cows infected with the virus might behave differently during pasteurization compared to the experimental samples, which were contaminated with H5N1 and isolated from the lungs of a deceased mountain lion in Montana.
As of now, the U.S. Food and Drug Administration has affirmed the safety of the commercial milk supply for human consumption. Additionally, the department has tested retail dairy products for bird flu, and all results have been negative.
In recent years, the H5N1 strain of bird flu has led to the death or culling of hundreds of millions of poultry globally, with an increasing number of cases affecting mammals and, in some instances, humans.
Reuters reported that Finland will start providing bird flu vaccinations to workers who have been exposed to the virus starting next week, making it the first country globally to do so. Despite no reported cases of humans contracting the virus in the Nordic country, Finland is prepared to distribute the vaccine due to the transmission risks associated with its fur farms.
In the United States, cases of bird flu among dairy cows have significantly increased in Idaho, Iowa, and Colorado.