A deadly brain-infecting amoeba which has already killed two children this year was detected for the first time in a U.S. drinking water supply near New Orleans. The parasite is ordinarily harmless, but becomes life threatening when in contact with the nose.

The parasite, Naegleria fowleri, ordinarily lives in hot springs and warm freshwater ponds, but officials have detected it in the water supply of St. Bernard Parish, near New Orleans, NBC News reports. A 4-year-old Mississippi boy died earlier this month from the parasite, which he is thought to have contracted while playing on a Slip-n-Slide. A 12-year-old Miami boy died from the amoeba in August, and a 12-year old Arkansas girl who was infected earlier in the summer is making a slow recovery.

Officials at the Center for Disease Control say that they’ve never seen this parasite in a treated water supply before. “From a U.S. perspective this is a unique situation,” said Dr. Michael Beach, head of water safety for the CDC.

N. fowleri infects victims through the nose by attaching to one of the nerves that sends smell signals to the brain. It then infects the brain, causing a swelling that is nearly always deadly.

Officials say that the water is safe to drink and bathe in, but that residents should avoid situations where water can easily get up the nose, such as water toys and kiddy pools.

[NBC News]