Avian flu has killed 1.5 million chickens and turkeys in California and 100 million birds nationwide since the outbreak began in 2022. And earlier this year, scientists discovered that the virus had jumped to mammals, specifically cattle, raising questions about the virus’ mutation. In California, the largest dairy producing state in the country, 475 dairies have reported incidences of avian flu in their herds, and the state recently recalled raw milk from shelves after the virus was detected in milk samples. The virus has also been detected in the wastewater of several Bay Area cities, and 29 dairy workers, and a child in Alameda County with no known contact with animals, have been diagnosed with the flu. We’ll talk to experts about whether avian flu has the makings of a new pandemic and what is being done to contain its spread.
Is Avian Flu the Next Pandemic?
Guests:
Susanne Rust, investigative reporter specializing in environmental issues, Los Angeles Times
Dr. Peter Chin-Hong M.D., infectious disease specialist, UCSF Medical Center
Dr. Michael Payne DVM, large animal vet researcher, Western Institute of Food Safety and Security, University of California, Davis School of Veterinary Medicine
Show Highlights
Understanding Avian Flu
Avian flu, or bird flu, refers to the influenza virus that can infect both wild birds and poultry.The current strain, H5N1, is highly pathogenic and contagious, capable of wiping out entire commercial poultry flocks within days. As Dr. Michael Payne explains, “If a commercial flock – layers, broilers, turkeys – can get it, it can kill on the order of a hundred thousand or half a million birds in just a matter of a few days.” He has called it the “Ebola” of bird illnesses. This particular H5N1 strain has exhibited an unprecedented ability to jump across species, infecting over 50 types of mammals. In late 2023 or early 2024, it acquired mutations allowing it to infect dairy cattle, marking the first time the virus appeared in cattle. According to Dr. Payne, researchers traced that first cattle infection to a herd in the Texas panhandle, and from there, the virus came west.
Outbreak Among Dairy Cattle in California
The virus’s jump to dairy cattle raises economic and public health concerns. As Dr. Payne explains, “You’ve got a general concern about the spread of…avian influenza into a different mammal species raising understandable concerns. Does this mean that we’re moving closer to an easily transmittable version of avian influenza inside people?”
In California, the nation’s largest dairy producer, 475 dairies have reported cases in their herds. Infected cows exhibit flu-like symptoms, including fever, loss of appetite, and plummeting milk production. Los Angeles Times journalist Suzanne Rust reports that as of the time of the broadcast, “Twenty-nine dairy workers have been diagnosed with the flu.” However, most cases among dairy workers have been mild, primarily causing conjunctivitis or mild respiratory symptoms.
Potential for Human Transmission
While human-to-human transmission has not been firmly established, the virus’s ability to infect multiple species raises concerns. As UCSF infectious disease specialist Dr. Peter Chin Hong states, “The worry is that a person could get a human flu and then be exposed to something like infected dairy with H5N1 virus, and the two flu viruses can reassort and create a new super virus, one that could be easily transmitted to people and cause severe disease.”
Experts are closely monitoring for mutations that could enable efficient human-to-human transmission, which Dr. Chin Hong identifies as “the tipping point at which you’re gonna see a lot of movement around protecting the community.” However, he also notes that existing immunity from previous flu exposures may be providing some protection.
Food Safety and Prevention Efforts
Regarding food safety, pasteurization effectively kills the H5N1 virus in milk products. As Dr. Payne explains, “High temperature, short time pasteurization will inactivate the virus.” Raw milk, however, remains a concern. Dr. Payne states, “Raw milk is fundamentally unsafe, and if you’re feeding it to your family, it’s playing Russian roulette with their health.” He notes that raw milk has been responsible for other illnesses in people including salmonella and E.coli.
Prevention efforts include providing personal protective equipment (PPE) to dairy workers, though usage appears inconsistent due to challenging working conditions. Vaccinations for dairy workers and a national vaccine stockpile are also part of the response. However, coordination across multiple agencies at local, state, and federal levels remains a challenge.
Lessons from COVID-19 Pandemic
The COVID-19 pandemic has provided both positive and negative lessons for handling potential outbreaks like avian flu. Dr. Chin Hong cites advancements in technology and molecular methods for tracking pathogens, but also notes concerns about loss of public trust in public health.
He emphasizes the need for better national strategies and alignment in public health responses, drawing comparisons to successful approaches in places like the Bay Area, New York, and other regions during the COVID-19 and monkeypox outbreaks. The development of mRNA vaccines could also provide a faster response to emerging mutations.
What Events In This Outbreak Would Cause More Concern
When asked what changes or events would cause concern that the outbreak was shifting to a more serious footing, Dr. Chin Hong notes that two events would give him pause: First, an increase in the number of severe cases, the type that sends people to the ICU and a higher mortality rate, similar to previous outbreaks of H5N1. Second, and even more concerning, would be the jump to human to human transmission. “That is going to be the tipping point at which you’re gonna see a lot of movement around protecting the community.”
Overall, while the current risk to humans remains low, experts stress the importance of closely monitoring the evolving situation with avian flu. They highlight the virus’s unpredictable nature and the need for continued preparation and coordination across agencies to mitigate potential severe outcomes. They also recommend getting the current flu vaccine. Although this season’s flu vaccine does not specifically provide protection from H5N1, the vaccine will help contain flu outbreak numbers thus lessening the chance for the H5N1 virus to mutate.
***This content was edited by the Forum production team but was generated with the help of AI.***