ST. PAUL, Minn. (AP) — Experts are trying to gauge the threat to Minnesota from a deadly water parasite that's more common in warmer southern states.

The Centers for Disease Control and Minnesota Department of Health are trying to confirm whether a teenager with a life-threatening brain infection got it from an amoeba.

Fourteen-year-old Hunter Boutain, of Alexandria, became ill after swimming in Lake Minnewaska. If confirmed, it would be Minnesota's third verified case of the amoeba.

Minnesota Public Radio reports the case has officials puzzled because it happened in a bigger lake than the two previous cases amid a cool summer.

The parasite was confirmed in the deaths of two children who became infected in Lily Lake in Stillwater, in 2010 and 2012. The infection had never been found so far north before.