A rare but deadly germ has claimed three lives in the United States so far this summer. This microscopic killer's terrifying name — the "brain-eating amoeba" — accurately describes the way it extinguishes its hosts. Though public health experts are reminding people that the odds of encountering the germ are very low, many parents are worried: The average age of the amoeba’s victims is just 12. Here’s what you should know:

What is this amoeba?
It’s known as Naegleria fowleri, and it’s found in warm fresh water, especially in the southern United States during the summer months. Though infections from Naegleria fowleri are rare, they’re almost always fatal. "Of 118 people known to have had the infection since 1962, only one survived," says David W. Freeman of CBSNews.com.

Does it really eat brains?
Essentially. "Like something out of a horror movie, the microbe enters the human body through the nose, usually after a person has swum or dived into a warm body of fresh water" like a lake or river, says Sora Song in TIME. Once the microorganism gets in the sinuses, it starts looking for food; if it ends up in the victim’s brain, it begins to feed on his brain cells. With no known cure, the infection typically results in death within a few days.

Who were this summer’s victims?
A nine-year-old Virginia boy and a 16-year-old Florida girl were the first two victims — both had been swimming in freshwater ponds days before their deaths. The third victim was a Louisiana man in his early 20s who was exposed "while rinsing his sinuses with tap water using a neti pot," says Philip Caulfield of the New York Daily News.

Is it safe to go swimming?
Statistically, yes. Infections with Naegleria fowleri occur only two or three times each summer in the United States, and besides, there are bigger safety issues to mind. "A more immediate concern for most swimmers in the hottest months of the summer is getting diarrhea, a rash, or other problems" from the microbes that lurk in swimming pools, lakes, and on beaches, says Eryn Brown of the Los Angeles Times.

Sources: CBS News, LA Times, MSNBC.com, NY Daily News, TIME