Discover more from Your Local Epidemiologist
Why are there no eggs? Avian flu and keeping human risk low
Thanks to all 38,000 (!!) of you who completed the “Who are you?” survey. If you are one of those people who was told they were a robot, traffic has now slowed down now. If you have the patience to try one more time, click the link here. Thank you!!
Why? A constellation of reasons, but there is one we can’t ignore: the avian flu is hammering poultry farmers. For the general public, there’s no immediate concern, except that it’s a pain at the grocery store. However, avian flu is mutating, which may have implications for our future health. Here’s the lowdown.
What’s going on?
In early January 2022, U.S. infectious disease surveillance systems detected a highly pathogenic avian influenza virus (HPAI) called A(H5N1), more commonly known as the bird flu or avian influenza.
Since then, more than 54 million wild and domestic birds have been infected across 47 U.S. states leading to an unprecedented outbreak. This includes 44 million egg-laying hens, hence egg prices. We haven’t detected the avian flu in the U.S. since 2016, so this new outbreak this is noteworthy.
Why does this matter?
The risk of avian flu to human health is currently very low. To demonstrate, CDC has tracked the health of more than 5,190 people exposed to birds with the virus in 2022, with one human case reported. If someone does get infected, there is no sustained human-to-human transmission. In other words, a human can typically only get it from an infected bird.
But, as Dr. Michael Osterholm said to STAT, “Any time you’re dealing with H5N1, you sleep with one eye open.” This is for three reasons:
Economic damage. On a small scale, outbreaks can wreak havoc on backyard chicken coops, which is stressful for families who are reliant on their egg and meat production. On a larger scale, outbreaks in commercial poultry farms have devastate local food supplies, affect farmers’ and employees’ livelihoods, and raise poultry prices due to a limited and strained supply. For example, an egg factory in Iowa killed 5.3 million chickens over a single case of avian influenza in the flock. This was the largest culling of commercial birds in the U.S.
High mortality rate. If someone does get infected, symptoms can range from asymptomatic to severe illness, hospitalization, and death. From 2003-2021 there have been very few human cases worldwide: 864. But, among these cases, 456 died—a 53% mortality rate.
Mutations. H5N1 has the potential to mutate into being better adaptable to humans. This can happen over time with single mutations or at one time with one big change in which large sections of the virus recombine (like with the human flu) to create a very different virus. Concern recently heightened when a European report confirmed sustained mammal-to-mammal transmission of H5N1 in Spain in October 2022 at a mink farm. The weekly mortality rate reached 4.3% per week. Scientists mapped the genome of the virus at the mink farm and found that it carried rare and previously unreported mutations. This means the virus could be mutating in a concerning direction. Many epidemiologists continue to put money on the flu causing the next pandemic. (Keep in mind that the 1918 flu was linked to the avian flu.) I cannot think of a bigger disaster than having another respiratory pandemic on the heels of COVID-19, given fatigue, polarization, loss of trust, and limited time to improve.
What to do?
Infected birds shed the virus through their mucous, salvia, and feces. Humans can get sick from breathing in the droplets or aerosols containing viral particles.
You cannot get avian flu from eating poultry or eggs. The FDA conducted a risk assessment and found risk was very low for three reasons:
Rapid onset of bird symptoms = low likelihood of entering the food chain;
Safeguards in place, like testing flocks and federal inspections;
Proper storage and food preparation at home is enough to inactivate the virus.
Right now you don’t need to do anything, unless you’re in close contact with birds. A person’s level of risk is dependent on duration and intensity of exposure. In other words, a person with one chicken in their backyard is at much lower risk than someone at a poultry farm.
Those around wild birds, such as at parks, lakes, rivers, or other waterways, need to exercise caution, including wearing PPE, washing hands, and changing clothes. If you have backyard poultry, wear a mask and wash your hands. Also, monitor the health of your flock, especially if they come in contact with other wild birds.
Commercial facilities have stepped up control measures to monitor cases and safety measures to protect their flocks, which is also contributing to increasing egg prices.
All of these practices will help you, as an individual, avoid sickness. But it will also help lower the population risk by reducing the number of times the virus mutates (and reducing the possibility of a human outbreak).
How long will this outbreak last?
We don’t know. Just like with COVID-19, it’s difficult to predict a virus’s future. The last large avian flu pandemic lasted 6 months, so the current outbreak has already been twice as long.
We are experiencing a record outbreak of avian flu—the largest and longest in U.S. history. It has been devastating to farmers and birds but likely only affects you at the grocery store. Epidemiologists continue to pay close attention and are crossing our fingers that we don’t see sustained human-to-human transmission.
Special thanks to Lauren Leining—a rock star PhD candidate in epidemiology—who helped gather research for this article.
“Your Local Epidemiologist (YLE)” is written by Dr. Katelyn Jetelina, MPH PhD—an epidemiologist, data scientist, wife, and mom of two little girls. During the day she works at a nonpartisan health policy think tank and is a senior scientific consultant to a number of organizations, including the CDC. At night she writes this newsletter. Her main goal is to “translate” the ever-evolving public health science so that people will be well equipped to make evidence-based decisions. This newsletter is free thanks to the generous support of fellow YLE community members. To support this effort, subscribe below: