U.S. Bird Flu Outbreak Spreads to Dairy Cows, Raising Egg Safety Concerns

The ongoing bird flu outbreak in the United States has now been found to be spreading from birds to dairy cows, with some cows being asymptomatic, according to recent reports. While the risk to humans remains low, the U.S. Department of Agriculture (USDA) and Centers for Disease Control and Prevention (CDC) are being called upon to further investigate the reach and transmission of the virus.

The H5N1 avian flu virus strain has been detected in high concentrations in raw milk from infected animals, prompting the World Health Organization (WHO) to advise people to consume only pasteurized milk and milk products. The virus has been detected in dairy herds, poultry flocks, and wild birds across multiple states. The USDA's Animal and Plant Health Inspection Service (APHIS) has shared 239 recent genetic sequences of the virus to aid scientific research and understanding of its spread.

However, there are still unanswered questions about how the virus is able to infect cows and how it is spreading in dairy herds. Veterinary experts are working to find answers to protect both animal and human health as the virus continues to spread across multiple regions. The CDC is also taking actions, including lab studies to assess the impact of antiviral drugs and candidate vaccine viruses.

Why this matters: The bird flu outbreak in U.S. dairy cows raises concerns about the potential for the virus to spread to humans and the safety of the nation's egg and milk supply. As the virus continues to evolve and infect more mammals, it is critical for government agencies and scientists to closely monitor the situation and take proactive measures to prevent a potential pandemic.

The outbreak has also affected egg-laying hen farms, raising concerns about egg safety and consumption risks. In early April 2024, the nation's largest egg producer, Cal-Maine Foods, had to destroy over 1 million laying hens and 337,000 pullets after the virus was detected at its facility in Texas. Despite this outbreak, economist Jada Thompson believes the impact on prices may not be as severe as in 2023, as the industry has taken actions to prevent a repeat of the previous year's price fluctuations.

The federal government has stated that if the virus were to start spreading widely among humans, they could distribute enough vaccines within four months to inoculate a fifth of the U.S. population. However, the effectiveness of the vaccine and its ability to blunt the impact of a human pandemic is unclear, as clinical trials have yet to produce data. WHO's top scientist, Dr. Jeremy Farrar, expressed "great concern" about the recent bird flu outbreak and stated that vaccine development to halt the virus is "not where we need to be."

As of April 23, 2024, the bird flu outbreak has infected 29 dairy herds in 8 states, with no detections in commercial beef herds so far. The virus has been passed from cow to cow, and there is evidence it has also spread from dairy cattle to nearby poultry facilities. While bird flu poses a low risk to human health, a Texas dairy worker was treated for mild symptoms.

Key Takeaways

• Bird flu spreading from birds to dairy cows, some asymptomatic
• H5N1 virus detected in raw milk, WHO advises consuming only pasteurized
• Virus infecting dairy herds, poultry, and wild birds across multiple states
• Outbreak affects egg supply, but may not impact prices as severely as 2023
• Concerns about potential for human pandemic, vaccine development not ready