Australian dairy farmers and consumers recently received a wake-up call with the outbreaks of H5N1 in American dairy cows. This concerning development prompted researchers to delve into the realm of pasteurisation temperatures and their effectiveness in inactivating H5N1 influenza viruses present in cows’ milk to ensure its safety for consumption.
The research, which is available as a pre-print on medRxiv, addresses the critical need to understand how pasteurisation can combat the spread of infectious influenza viruses in milk. The study not only highlights the effectiveness of pasteurisation in killing influenza viruses but also underscores the potential dangers of consuming ‘raw’ or unpasteurised milk that may carry infectious influenza viruses, including the H5N1 strain.
### Collaborative Efforts in Research
The study represents a collaborative effort between prominent institutions such as the MRC-University of Glasgow Centre for Virus Research, the University of Edinburgh’s Roslin Institute, The Pirbright Institute, and the UK Animal & Plant Health Agency. Leading the charge in this research consortium is Professor Ian Brown from The Pirbright Institute, an expert in avian virology.
Professor Brown stresses the importance of global cooperation in understanding and combating diseases like high pathogenicity avian influenza virus in dairy cattle. While the infection with this virus is currently limited to the US, it’s crucial to be prepared for any potential risks that may arise in the future.
### Understanding Influenza Viruses in Milk
The researchers conducted experiments where a panel of influenza viruses was mixed with milk, both unpasteurised ‘raw’ milk and commercially available whole milk. The mixtures were heated to pasteurising temperatures of 63°C or 72°C to assess the viruses’ response to heat treatment. The panel of viruses tested included human and avian influenza A viruses, which include the H5N1 strain, as well as an influenza D virus naturally infecting cattle.
Ed Hutchinson, a senior lecturer at the MRC-University of Glasgow Centre for Virus Research and corresponding author of the study, emphasised the urgency of determining the safety of milk through pasteurisation. The results indicated that pasteurisation at appropriate temperatures effectively inactivates all influenza viruses present in the milk, reducing the risk of transmission through consumption.
However, the study also highlighted the potential dangers of consuming unpasteurised milk, which can harbour infectious influenza viruses. Given the severe consequences of human infections with H5N1 influenza viruses, it’s essential to avoid consuming raw milk in areas where cattle may be infected with such viruses.
### The Risks of Raw Milk Consumption
Raw milk is known to carry various pathogens, posing significant health risks to consumers. In areas where there are concerns about infections like H5N1 influenza, pasteurisation of milk serves as a crucial preventive measure to minimise the transmission of infectious viruses. By heating milk to appropriate temperatures, the viruses are rapidly inactivated, reducing the likelihood of human infections and potential adaptations of the virus to enable transmission among humans.
In conclusion, the research on pasteurisation temperatures and their effectiveness in inactivating H5N1 influenza viruses in cows’ milk sheds light on the importance of food safety measures, particularly in the dairy industry. By adhering to proper pasteurisation protocols, dairy farmers and consumers can mitigate the risks associated with infectious influenza viruses in milk, safeguarding public health and well-being.
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