Human, Bird Flu Viruses Can Be Transmitted Through Cattle: Study

A University of Copenhagen study reveals cattle can host human and bird flu viruses, challenging previous beliefs and raising concerns about potential cross-species infections. The findings highlight the importance of pasteurization and ongoing surveillance to ensure dairy safety.

A recent study led by veterinarian Charlotte Kristensen and her team at the University of Copenhagen has made a significant breakthrough in understanding influenza transmission. The study found that cattle can serve as hosts for both human and bird flu viruses, challenging the long-standing belief that cattle are immune to influenza A viruses. This discovery raises concerns about potential cross-species infections and the emergence of new influenza strains.

Study Highlights:

• Influenza A Receptors in Cattle: The research revealed the presence of three types of influenza A receptors in cattle, similar to those found in humans, chickens, and ducks. Notably, the duck variant is abundant in the mammary glands of cattle.
• Transmission Pathways: The study suggests that bird flu could be transmitted to cows through contaminated milking equipment or bloodstream infiltration. This is exemplified by the H5N1 bird flu outbreak in Texas dairy cattle.
• Raw Milk Risks: The presence of these receptors in cattle raises concerns about the safety of raw milk, which hasn’t undergone pasteurization and can carry infectious diseases.

Health Implications:

• Pasteurization Efficacy: Pasteurization, a common heat treatment process, effectively inactivates viruses, including influenza, making pasteurized milk safe for consumption. Health experts emphasize its role in preventing viral transmission through milk.
• Raw Milk Consumption: Despite its popularity among certain consumers for perceived health benefits, raw milk poses significant risks. The US FDA advises against consuming unpasteurized dairy products due to the potential for transmitting infectious diseases.

Expert Insights:

• Minimal Human Infection Risk: Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, notes that there is no evidence of human infection via the ingestion of influenza A virus in milk. Health organizations categorize the risk of bird flu from milk as low.

Despite these reassurances, the study’s findings highlight the potential for genetic reassortment between human and avian influenza strains within cattle, which could lead to novel viruses with pandemic potential. This underscores the importance of ongoing surveillance and research to monitor influenza viruses in livestock populations.

One Health Approach:

The interconnectedness of human and animal health necessitates a One Health approach, as suggested by the Centers for Disease Control and Prevention (CDC). This comprehensive strategy emphasizes the need for collaborative efforts across various sectors to address health risks at the human-animal-environment interface.

The discovery of dual entry portals for influenza in cattle underscores the need for heightened awareness and larger studies to understand the incidence of immune-mediated phenomena post-COVID-19 vaccination. Continued research and surveillance are essential to mitigate the risks associated with influenza viruses in livestock and protect public health.