The thermal stability of influenza viruses in milk
Is pasteurization a safe solution for milk infected with the bird flu virus? Does the high rate of infection among dairy herds in the U.S. with the bird flu virus not endanger public health, and is the recommendation to consume pasteurized milk safe?
Not according to a new study published in the journal Viruses by a group of researchers from China. The study indicates that while pasteurization can reduce the viability of influenza viruses, it does not completely inactivate them under certain conditions. Specifically, heat treatment at 72°C for 15 or 20 seconds was found to leave some residual infectious virus in milk, as evidenced by the ability to recover the virus through inoculation into embryonated chicken eggs. In contrast, heat treatment at 63°C for 30 minutes effectively reduced viral viability below the detection limit in MDCK cells, suggesting that longer exposure at lower temperatures may be more effective for inactivation. Additionally, the study found that heat treatment at 80°C for 15 seconds could completely inactivate HPAIV H5N1 in milk. Overall, while pasteurization can significantly reduce the presence of influenza viruses in milk, its effectiveness can vary based on the specific temperature, duration of treatment, and the initial viral load present in the milk.
