by Nancy Lapid

London: High levels of lead found in raw milk samples Bird Flu Virusin small quantities Infectious Viruses These symptoms could be detected even after treatment with standard pasteurization methods, researchers reported on Friday.

According to the study authors, these findings reflect experimental conditions in a laboratory and should not be used to draw any conclusions about the safety of the U.S. milk supply. US Government’s National Allergy Institute and Infectious Diseases (NIAID) Rocky Mountain Laboratories,

This research was published in the New England Journal of Medicine.

Compared to the virus-containing raw milk used in the study, raw milk from cows infected with H5N1 influenza may have a different composition or contain the virus inside cells, which could affect the effects of heat, the researchers said.

Bird flu infections were detected in US dairy cows in March. The US Food and Drug Administration surveyed pasteurised retail milk samples and estimated that virus particles were present in about a fifth of the US milk supply. The agency has said pasteurised milk is safe to drink.

The virus used in the experiments was isolated from the lungs of a dead mountain lion, and mixed with samples of raw, unpasteurized cow’s milk, and heated at 63 °C (145.4 °F) and 72 °C (161.6 °F) for varying periods of time.

The study found that after treatment for 20 seconds at 72 degrees Celsius – five seconds longer than the industry standard for pasteurisation at that temperature – one in three samples contained very low amounts of infectious virus.

“This finding suggests that, if initial virus levels were sufficiently high, a relatively small but detectable amount of H5N1 virus may remain infectious in milk even after 15 seconds at 72°C,” the authors write.

Treatment at 63 degrees Celsius led to a significant reduction in levels of infectious H5N1 virus within 2.5 minutes, indicating that 30 minutes of standard industrial pasteurization at that temperature would destroy infectious virus, the researchers said.

The researchers said their experimental conditions are not the same as large-scale industrial pasteurization processes for raw milk and their findings need to be replicated with direct measurements of infected milk in commercial pasteurization equipment.

The researchers said it was still unknown whether consuming active H5N1 viruses in milk could cause illness in people. (Reporting by Nancy Lapid; Editing by Will Dunham)