Bird Flu in Mammals and the Climate Crisis

On April 1, 2024, the U.S. Department of Agriculture confirmed the presence of bird flu (H5N1 virus) in dairy cows in Texas, Kansas, Michigan, and New Mexico. You might be scratching your head over this, but it's no April Fool's joke.

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On the same day, Texas health officials confirmed that an individual who had direct exposure to the infected dairy cows had also contracted bird flu. It is the second reported human case of the H5N1 virus in U.S. history.

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But isn’t bird flu supposed to spread between birds only?

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Bird flu can impact mammals

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Researchers have long believed that avian flu viruses such as H5N1 primarily targeted birds' receptor cells. Humans also possess these cells, but they are deep within our lungs, making it less likely for bird flu to transfer to humans or other mammals.

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But over the last few years, we've found the H5N1 virus in seals, sea lions, dolphins, grizzly bears, foxes, and ferrets.

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In 2022, in a shocking event, a Spanish farm killed 50,000 minks after lab tests showed they had contracted H5N1.

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A 2023 CDC study showed that from 2013–2022, bird flu outbreaks in animals and infections in people didn't just increase in number. They also spread across a larger geographic area and affected more types of animals.

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How did these mammals get the virus? Some might've gotten it from eating infected birds. Other possibilities include increased poultry production and trade, more exposure to wild birds through their repeated migrations, and changes in migration patterns due to farmland expansion or climate change.

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The role of climate change in spreading bird flu

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The climate crisis is changing the weather patterns worldwide, and this is impacting birds’ behavior. As temperatures rise and seasons shift, birds are changing their migration patterns and are mixing with new species. Plus, higher sea levels are changing where birds nest and lay eggs. This could lead to them sharing diseases with species they wouldn't normally interact with.

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Although researchers have been able to make links like this between climate change and the spread of bird flu, figuring out exactly how climate change affects bird flu is still a tough nut to crack.

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