ARCADIA, Oklahoma - The Oklahoma State Department of Health is warning swimmers about a rare, albeit exceedingly fatal disease lurking in Oklahoma bodies of water.

The disease is called primary amoeba meningoencephalitis or PAM. It’s brought on by an amoeba which is naturally occurring in fresh water ecosystems like lakes, rivers or ponds, according to the Centers for Disease Control and Prevention.

“Especially in the shallow areas, in the sediment or the soil. If you're playing or swimming in that area, then there could be a risk,” state epidemiologist Laurence Burnsed said.

Burnsed follows the rise of diseases like PAM and said swimmers are often unaware the disease is present in the water until it's too late.

“If [swimmers] accidentally snort or inhale water when they're diving in or going underwater, then the amoeba can get up into your nose and then up into your brain which is when it can cause problems,” he said.

Once inside the brain, the amoeba multiplies causing fever, nausea, stiff neck and even brain swelling, according to the health department’s website. Symptoms similar to meningitis or encephalitis.

In Oklahoma, there have been seven reported cases since 1998, all fatal. Nationwide, the disease kills 97 percent of those infected.

PAM was ruled the cause of death of an Oklahoma swimmer last year who was visiting Lake Murray. Authorities did not release details of the case, but issued a similar warning about PAM after the incident.

But the good news is that the disease is rare, just 138 cases in the last 50 years.

The health department website suggests swimmers use nose plugs and goggles when swimming. Burnsed also suggests swimmers heed warning signs and avoiding stagnant water to lower the risk of infection. 

The Oklahoma Department of Tourism also has a website for families to check for alerts or warning for the body of water they plan to visit.