Deadly Bird Flu Virus Survives Standard Pasteurisation, Study Warns
A new study by the National Institute of Allergy and Infectious Diseases (NIAID) reveals that heat treatment slashes the infectious H5N1 bird flu virus in raw milk—but doesn’t wipe it out completely. Even after the standard pasteurisation of 72℃ (161.6℉) for 15 seconds, tiny traces of the virus lingered when the initial contamination was high. The eye-opening findings are published in the New England Journal of Medicine.
Outbreak Sparks Alarm Across US Dairy Farms
This research arrives amid a growing scare over highly pathogenic avian influenza (HPAI) H5N1 hitting dairy cows. The outbreak began in Texas in late March 2024 and has now spread to 95 cattle herds across 12 states. Three farm workers have caught the virus, showing symptoms like conjunctivitis. Thankfully, there’s no sign yet of human-to-human transmission—but officials remain on high alert.
How Safe Is Your Milk? Inside The Study
The investigation tested milk spiked with H5N1 virus taken from a mountain lion’s lungs. Scientists heated the contaminated samples to 63℃ and 72℃ to see how well pasteurisation kills the virus. At 63℃, infectious virus levels dropped by a whopping 1,010-fold after 2.5 minutes. Standard 30-minute pasteurisation is expected to kill it off for good.
At 72℃, virus levels plunged 10,000-fold within just five seconds. But alarmingly, one out of three samples still held tiny amounts of live virus even after 20 seconds of heating.
“This finding indicates the potential for a relatively small but detectable quantity of H5N1 virus to remain infectious in milk after 15 seconds at 72℃ if the initial virus levels were sufficiently high,” the scientists warned.
What It Means For The Public
The study used artificially spiked milk, so it might not fully mimic real-world conditions in infected cows. Plus, it’s still unclear if drinking contaminated raw milk could cause gut infections in humans. The FDA is quick to reassure shoppers the commercial milk supply is safe. An initial FDA survey of nearly 300 dairy products found no live virus.
The FDA and USDA are conducting further tests on commercial pasteurisation to guarantee safety. Results will be made public as soon as they’re available.
For now, experts urge vigilance as the bird flu outbreak unfolds. This study highlights the urgent need to keep our food supply under strict watch.
