Des Moines, Iowa (AP) — As the U.S. dairy industry confronts a bird flu outbreak, with cases reported at dozens of farms and the disease spreading to people, the egg industry could serve as an example of how to slow the disease but also shows how difficult it can be to eradicate the virus.

There have been earlier bird flu outbreaks in the U.S., but the current one started in February 2022 and has forced the slaughter of nearly 100 million chickens and turkeys. Hot spots still occur, but their frequency has dropped in part because of biosecurity efforts at farms and a coordinated approach between companies and agricultural officials, experts say.

Dairy farmers could try to implement similar safeguards, but the vast differences between the animals and the industries limit what lessons can be learned and applied.

How can a 1,500-pound cow and a 5pound chicken have the same illness?

It’s commonly called bird flu because the disease is largely spread by wild birds that can survive infections. Many mammals have caught the illness too, including sea lions and skunks.

Animals can be infected by eating an infected bird or by being exposed to environments where the virus is present. That said, there are big differences in how cows and chickens have fared after getting infected.

Bird flu is typically fatal to chickens and turkeys within days of an infection, leading to immediate mass killings of birds. That’s not true for cows.

Dairies in several states have reported having to kill infected animals because symptoms continued to linger and their milk production didn’t recover, but that’s not the norm, said Russ Daly, an extension veterinarian at South Dakota State University.