Recent reports of bird flu, specifically the H5N1 strain, being detected in dairy cows have raised questions about the safety of our milk supply. This development has understandably led to public concern regarding the potential for the virus to be present in milk and whether it poses a risk to human health. Understanding the nature of this virus and the measures in place to ensure milk safety can help address these concerns.
Understanding Bird Flu and Its Presence in Milk
Bird flu, or avian influenza, is caused by influenza A viruses that primarily infect wild birds and poultry. The H5N1 strain, which has been circulating globally, has recently been detected in dairy cattle across multiple states in the US, marking its first detection in cows. This spillover from birds to mammals, including dairy cows, is notable.
Infected dairy cows may exhibit symptoms such as a sudden decrease in milk production, often accompanied by the milk appearing thicker or colostrum-like. While the virus primarily affects the mammary glands, it has been detected in the milk of infected cows at high concentrations.
Ensuring Milk Safety for Consumers
The commercial milk supply undergoes a process called pasteurization, which is a heat treatment designed to eliminate harmful bacteria and viruses. This process involves heating milk to specific temperatures for set durations, such as 72°C (161°F) for 15 seconds or 63°C (145°F) for 30 minutes. Studies have shown that standard pasteurization methods are effective in inactivating all tested subtypes of influenza viruses, including H5N1, in raw milk.
The U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) have stated that commercially pasteurized milk remains safe for consumption. Even when viral fragments of H5N1 have been detected in retail milk samples, these fragments are remnants of inactivated viruses and are not infectious. Regulatory oversight and rigorous safety standards, including the requirement for clinically ill cows producing abnormal milk to be segregated, further ensure the safety of the commercial milk supply.
What to Know About Raw Milk
Raw milk has not undergone pasteurization, meaning it has not been heated to kill potential pathogens. While some believe raw milk offers certain health benefits or a different taste, it carries a higher risk of containing harmful bacteria and viruses, including H5N1. The absence of heat treatment means that any H5N1 virus present in raw milk from an infected cow would remain viable.
The Centers for Disease Control and Prevention (CDC) and other health organizations advise against consuming raw milk and products made from it. This is due to raw milk’s potential to harbor various disease-causing germs, such as Salmonella, E. coli, Campylobacter, and potentially H5N1. Consuming raw milk could lead to serious illness, hospitalization, or even death, particularly for vulnerable populations like young children, the elderly, pregnant women, and individuals with weakened immune systems.