The CDC has confirmed a total of 66 human cases of bird flu across the United States as of Friday, although the number is believed to be higher.

Here’s what to know about the United States’ first confirmed severe case of H5N1 avian influenza—and how to protect yourself.

After someone in southwest Louisiana was hospitalized with a severe case of bird flu, the first such illness reported in the United States, health workers swabbed the person’s nose and throat, looking for genetic clues about the virus.