Climate Change and Bird Flu: A New Pandemic?

What Is H5N1? 

Avian influenza, also known as bird flu or H5N1, is a viral disease that has recently been on the rise, disrupting global food chains. Although H5N1 is most commonly found in wild birds, it has been known to infect livestock, mammals, marine mammals, and even humans, with the first reported human case of H5N1 happening in 1997. More recently, an outbreak in the US has been affecting poultry and livestock, having killed over 20 million egg-laying chickens. In order to prevent the spread of this disease, farmers are required to kill all the birds in an infected flock. While this method has been very effective, it has created a massive shortage of egg-laying birds, driving egg prices to record-high levels.

What Does Climate Change Have to Do With It?

Like many diseases such as HIV and COVID-19, H5N1 has experienced “zoonotic spillover”–meaning it was originally found only in wild animals, then became transferable to humans through mutations and adaptations. Although H5N1 has not been historically known to transmit to humans frequently, the recent US outbreak has presented at least 67 confirmed cases so far, making it the largest ever outbreak of H5N1 in humans.  Moreover, even though there are relatively few human cases, flu viruses like H5N1 are known to adapt quickly. If the virus continues to mutate and spread among humans, it could pose a significant risk for a new pandemic. A key reason for this increased zoonotic spillover is actually climate change. Heat waves caused by climate change can often prevent personal protective equipment (or PPE), including masks and gloves, from working properly, meaning that farmers and healthcare professionals handling infected animals and poultry are far more likely to be infected, while high temperatures often lead farmers to forego wearing PPE altogether, increasing their vulnerability to the virus. This PPE malfunction has already caused the first-ever cluster of human H5N1 cases in Colorado. Additionally, climate change and the resulting elevated temperatures changes migratory patterns of birds, which has caused increased crossover between H5N1-infected wild birds and animals on farms. Luckily, although direct viral infection from H5N1 can pose a threat, we know that H5N1 does not pose a risk of infection through properly prepared food, so there is no need to cut eggs or poultry from our diet at the moment. 

What Are We Doing About It? 

Due to the low public health risk in humans, the CDC is currently monitoring bird flu outbreaks in humans through surveillance as opposed to aggressive prevention measures. However, the situation in the agricultural sector poses a concerning indirect risk to humans because of food prices, which is being more actively controlled. As of February 26th, the US Department of Agriculture (USDA) has announced a five-pronged approach to mitigating the outbreak, including $1 billion of funding. This approach involves investing in biosecurity measures for the poultry industry, researching vaccines and therapeutics to reduce chicken depopulation, sending aid and relief to farmers who were affected, working with the FDA to remove “unnecessary” regulations on the egg and poultry industries for faster production, and a consideration of shifting some egg production to imported sources to reduce egg prices. Brooke Rollins, the secretary of the USDA and the creator of this plan, recently recommended that people frustrated by egg prices should raise their own chickens. This suggestion, however, is an inaccessible option for most Americans, due to livestock regulations and factors such as living in apartments. Additionally, it would only become more cost-effective to produce if egg prices had risen to $10—more than double their current price. 

References 

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CDC. (2024a, June 4). 2020-2024 Highlights in the History of Avian Influenza (Bird Flu) Timeline. Avian Influenza (Bird Flu). https://www.cdc.gov/bird-flu/avian-timeline/2020s.html 

CDC. (2024b, June 21). H5N1 Bird Flu: Current Situation. Avian Influenza (Bird Flu). https://www.cdc.gov/bird-flu/situation-summary/index.html 

CDC. (2025, January 6). First H5 Bird Flu Death Reported in United States. CDC Newsroom. https://www.cdc.gov/media/releases/2025/m0106-h5-birdflu-death.html 

CDC. (n.d.-b). Past reported global human cases with highly pathogenic avian influenza A(H5N1) (HPAI H5N1) by country, 1997-2025. Centers for Disease Control and Prevention. https://www.cdc.gov/bird-flu/php/avian-flu-summary/chart-epi-curve-ah5n1.html#:~:text=Background,in%20southern%20China%20in%201996 

Ellwanger, J. H., & Chies, J. A. B. (2021). Zoonotic spillover: Understanding Basic Aspects for Better Prevention. Genetics and Molecular Biology, 44(1). https://doi.org/10.1590/1678-4685-GMB-2020-0355 

FUNK, J. (2025, February 12). US egg prices hit a record high and are likely to keep climbing. AP News. https://apnews.com/article/egg-prices-record-bird-flu-a2394bdefc7bd0514d4f003cc5e8a908 

H5N1 bird flu: Questions patients may have and how to answer. (2024, June 6). American Medical Association. https://www.ama-assn.org/delivering-care/public-health/h5n1-bird-flu-questions-patients-may-have-and-how-answer 

Kozlov, M. (2025). Will bird flu spark a human pandemic? Scientists say the risk is rising. Nature.com. https://doi.org/10.1038/d41586-025-00245-6 

Mazza, E. (2025, March 4). Trump Ag Secretary’s Clucked-Up Advice On Eggs Has Critics Squawking. HuffPost. https://www.huffpost.com/entry/brooke-rollins-eggs-backyard-chickens_n_67c676c9e4b044c440ed7fa7 

Schreiber, M. (2024, July 19). Extreme heat may be crucial factor in human spread of bird flu. The Guardian; The Guardian. https://www.theguardian.com/world/article/2024/jul/19/extreme-heat-human-bird-flu 

U.S. egg industry sees record chicken deaths from bird flu outbreak. (2025, January 14). The Transmission. https://www.unmc.edu/healthsecurity/transmission/2025/01/14/u-s-egg-industry-sees-record-chicken-deaths-from-bird-flu-outbreak/ 

USDA. (2025, February 26). USDA Invests Up To $1 Billion to Combat Avian Flu and Reduce Egg Prices. Usda.gov. https://www.usda.gov/about-usda/news/press-releases/2025/02/26/usda-invests-1-billion-combat-avian-flu-and-reduce-egg-prices 

Virology Research Services. (2019). Why bird flu doesn’t do well in humans | VIROLOGY RESEARCH SERVICES. Virologyresearchservices.com. https://virologyresearchservices.com/2019/12/19/what-halt-bird-flu-in-human-cells-another-piece-of-the-puzzle/