A North Carolina teenager is critically ill from a rare brain-eating amoeba called Naegleria fowleri, according to state health officials. 

The amoeba is found in warm freshwater including ponds, lakes and rivers, and officials are still investigating where the teenager contracted the amoeba, ABC News reported. 

Neither the teenager's identity nor condition have been released, but the person is receiving care, the North Carolina Department of Health and Human Services said on Thursday.

According to the agency, "once symptoms start, the disease progresses rapidly and usually causes death within about five days."

The agency said that the amoeba doesn't cause illness if swallowed, but it can be fatal if water containing the organism is forced up the nose into the brain, which can occur by jumping into water, diving, water-skiing or other water activities.

There are, on average, fewer than 10 cases in the U.S. annually. An 8-year-old girl, Lillian Smart, in Louisiana died last weekend from the same amoeba.