Dr. Terry Simpson's Substack

Dr. Terry Simpson's Substack

Bird Flu is Coming Back

See those migrating birds? Guess what is coming with them and what you can do

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Dr. Terry Simpson
Oct 11, 2025
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a flock of birds flying across a cloudy sky
Photo by Justin Wilkens on Unsplash

It was a quiet summer for bird flu.
Egg prices dipped, fewer flocks were culled, and agricultural officials could breathe.

“It was lovely,” said Shauna Voss, assistant director of the Minnesota Board of Animal Health.

But that calm didn’t last.

As wild geese, ducks, and cranes begin their fall migrations, avian influenza (H5N1) is back — spreading through lakes and wetlands where migrating birds mingle and share viruses like frequent-flier miles.

This marks the fourth straight autumn of bird flu spikes — and this year, it’s arriving earlier than expected.
Over four million poultry birds have been culled in Minnesota and Iowa in the past month.

“Last week, we had our first confirmed positive,” said Iowa Agriculture Secretary Mike Naig. “The question for us now is how extensive will it be — and what kind of fall will we have?”

That’s the question every veterinarian, virologist, and egg producer is asking right now.

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🐔 A Virus That’s Not Going Away

This strain of H5N1 has become deeply entrenched in wild bird populations — effectively endemic.

“It’s not going away. It seems pretty embedded,” Voss said.

Since it first appeared in U.S. flocks in 2022, the virus has forced the culling of more than 175 million birds, disrupted egg supplies, and even turned up in dairy cows and raw milk.

And the more it circulates, the more chances it has to adapt — or combine — in ways that could eventually reach humans.
So far, 70 people — mostly farmworkers — have been infected, and one has died.
There’s no evidence of sustained person-to-person spread yet, but this virus has proven it can surprise us.

“Everyone is waiting with bated breath,” said virologist Declan Schroeder of the University of Minnesota.


🧬 Want to know why your flu shot might actually help slow bird flu — and what scientists fear could happen if the two viruses combine?

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