Avian Flu Virus Survives Pasteurization Process

Shock: Avian Flu Virus Survives Pasteurization Process, Causes Concern

United States: In raw milk samples deliberately infused with elevated levels of the avian influenza virus, trace amounts of the infectious agent persisted post-treatment using conventional pasteurization techniques, researchers disclosed on Friday.

These observations, derived from controlled laboratory settings, should not be extrapolated to infer the safety of the United States milk supply, as emphasized by the study’s authors from the National Institute of Allergy and Infectious Diseases (NIAID) Rocky Mountain Laboratories. The investigation’s results were disseminated in the New England Journal of Medicine, according to the reports by Reuters.

In the study, the raw milk was intentionally contaminated with the virus, floating freely. However, raw milk sourced from bovines afflicted with H5N1 influenza might differ in composition or contain the virus intracellularly, potentially influencing thermal treatment efficacy, the researchers elaborated.

In March, avian influenza was detected in US dairy cattle. The Food and Drug Administration’s survey of pasteurized milk samples from retail sources estimated that one-fifth of the nation’s milk supply harbored viral strands. Nevertheless, the agency has affirmed that pasteurized milk remains safe for consumption.

The virus utilized in these experiments was extracted from the pulmonary tissues of a deceased mountain lion, amalgamated with raw, unpasteurized bovine milk, and subjected to thermal treatment at 63 degrees Celsius (145.4 degrees Fahrenheit) and 72 degrees Celsius (161.6 degrees Fahrenheit) for varied durations, the reports by Reuters mentioned.

Post-treatment at 72 degrees Celsius for 20 seconds—surpassing the industry standard by five seconds—minimal quantities of infectious virus were detectable in one out of three samples, the study reported. This suggests a potential for a diminutive yet detectable amount of H5N1 virus to retain infectivity in milk treated for 15 seconds at 72 degrees Celsius, given sufficiently high initial viral loads, the authors noted, the reports by Reuters concluded.

Thermal treatment at 63 degrees Celsius for 2.5 minutes precipitated a significant reduction in infectious H5N1 virus levels, indicating that standard industrial pasteurization protocols of 30 minutes at this temperature would obliterate infectious viral presence, the researchers asserted.

It is crucial to note that the experimental conditions employed do not mirror the large-scale industrial pasteurization processes for raw milk. Thus, these findings necessitate corroboration through direct measurement of infected milk in commercial pasteurization equipment, the researchers advised.

The researchers also highlighted the current uncertainty regarding whether ingestion of active H5N1 virus through milk could lead to illness in humans.

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