Two weeks after Jaysen Carr spent the Fourth of July swimming and riding on a boat on one of South Carolina’s most popular lakes, he was dead from an amoeba that lives in the warm water and entered his brain through his nose.

Most people who come into contact with Naegleria fowleri never get sick. The amoeba can only infect a person when contaminated water goes up the nose, often during swimming or diving. It then travels to the brain, where it destroys brain tissue.