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Primary Amebic Meningoencephalitis (PAM)

Primary Amebic Meningoencephalitis (PAM) is a rare, but serious disease of the central nervous system (brain and spinal cord). It is caused by Naegleria fowleri, also called the brain-eating ameba.

The brain-eating ameba loves warm water.

It can be found around the world in the natural environment, usually in warm or hot freshwater lakes, rivers, and hot springs. It is not active in cold temperatures, but it can survive in the soil of bodies of water.

When water with the brain-eating ameba enters the nose, it can travel up the nose and into the brain.

It is important to take steps to prevent water from going up the nose while swimming, and to only use safe water when rinsing the sinuses.

Boy splashing in lake

PAM 101

People can get PAM when water with the brain-eating ameba goes up the nose and into the brain.
  • The brain-eating ameba can be found in warm freshwater, such as lakes and rivers.
    • PAM is usually seen in young, healthy people who have been swimming or diving in warm freshwater.
  • The brain-eating ameba can also be found in tap water or swimming pool water, though this is rare.
    • It is possible to get PAM by using tap water with Naegleria fowleri in it to rinse the sinuses.
    • People can get PAM by swimming in pools that have not been properly cleaned with the appropriate amount of chlorine.

You cannot get PAM by drinking water with the ameba in it.

Symptoms usually appear one to nine days after water with the brain-eating ameba gets into the nose.

Symptoms of PAM can be mild at first, but they quickly get worse. Symptoms usually start about five days after the ameba gets into the nose. The ameba kills brain tissue and causes brain swelling and death. This usually happens within five days after symptoms start.

Stage 1 mild signs and symptoms:

  • Severe frontal headache
  • Fever
  • Nausea
  • Vomiting

Stage 2 severe signs and symptoms:

  • Stiff neck
  • Seizures
  • Confusion
  • Hallucinations
  • Coma
  • Death

PAM is a life-threatening emergency. Go to the emergency department as soon as possible if you think you may have PAM. Starting treatment right away may increase the chances that you will live.

While swimming:

The only sure way to prevent PAM is to not swim in warm freshwater. However, there are a few steps you can take to lower your risk of the ameba going up your nose while swimming:

  • Hold your nose shut with your hands or nose clips.
  • Keep your head above water.
  • Do not spend time in warm freshwater when the water temperature is high and water levels are low.
  • Do not dig in or stir up the dirt while swimming in shallow, warm freshwater areas.
  • Keep swimming pools clean using chlorine.
While using tap water:

PAM is rarely caused by using tap water. However, cases can occur when people rinse their sinuses through the nose or cleanse their noses during religious practices. There are steps you can take to make sure your water is safe. Take at least one of these actions to lower your risk of getting PAM:

  • Boil tap water for 1 minute and let it cool.
  • Buy distilled or sterile water.
  • Use a filter designed to remove small germs.

Provider Information

This is a Wisconsin disease surveillance category I disease:

Wisconsin case reporting and public health follow-up guidelines:

Primary Amebic Meningoencephalitis (PAM) EpiNet, P-02191 (PDF): PAM case reporting and investigation protocol for health professionals.

Questions about PAM? Contact us!
Phone: 608-267-9003 | Fax: 608-267-9009

Last revised June 15, 2022