It’s not enough to rate a warning of “don’t go near the water,” but people who splash around in freshwater lakes and streams may want to take some extra precautions this summer.

A microscopic amoeba lives in these waters in a crescent of about fifteen Southern states stretching from Florida to Arizona. The amoeba, officially called Naegleria fowleri [nigh-GLEER-e-uh foul-AIR-e], can cause a rare but deadly brain infection if water where it is present is inhaled up the nose.

These infections are extremely rare. The Centers for Disease Control and Prevention reports there were an average of about two cases per year over the last seventy years. By comparison, a person is a thousand times more likely to die from drowning.

But there are reasons to take heed. Most infections occur in July, August and September, when water and air temperatures are above eighty degrees Fahrenheit. They are also more likely during prolonged periods of heat and drought, which many Southern states are experiencing.

Wearing nose clips is one precaution swimmers can take, especially those who are waterskiing and wakeboarding, which can force water up the nose. Because the amoeba thrives in the muddy bottoms of lakes and ponds, and even in poorly maintained swimming pools, these areas should be avoided.

Avoiding fresh water recreation altogether during the higher-risk months is the best way to stay safe, but that might not be practical for most people. Just use common sense, and the odds favor a wonderfully wet summer.