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Waterborne Illness: Primary Amebic Meningoencephalitis (PAM)

Primary Amebic Meningoencephalitis (PAM) is a rare but serious disease. It affects the central nervous system, which includes the brain and spinal cord. No cases of PAM have ever been seen in Wisconsin. However, PAM illnesses have been seen in some other mid-western states.

How people get PAM

PAM is caused by a very tiny germ called Naegleria fowleri sometimes called the "brain-eating ameba." People can get PAM when water with this ameba in it goes up the nose and into the brain.

This type of ameba can be found in very warm freshwater, such as lakes and rivers. It can also be in tap water or swimming pool water that's not properly disinfected, but this is rare.

PAM most often happens in young, healthy people who have been swimming, jumping, or diving in warm freshwater. It is possible to get PAM by using tap water with the ameba in it to rinse the sinuses.

You can't get PAM by drinking water with the ameba in it.

PAM symptoms

Symptoms of PAM often show up one to nine days after water with the ameba in it gets into the nose. Symptoms are mild at first but then quickly get worse. The ameba kills brain tissue and causes brain swelling, which can lead to death within five days after symptoms start.

Stage 1 mild signs and symptoms include:

  • Severe headache near the front of the head
  • Fever
  • Nausea
  • Vomiting

Stage 2 severe signs and symptoms include:

  • Stiff neck
  • Confusion and/or hallucinations
  • Seizures
  • Coma or death

Treatment for PAM

PAM is an emergency and can put your life in danger. Go to the emergency department as soon as possible if you think you or a family member might have PAM. Starting treatment right away may improve chances of survival.

How to prevent PAM

The only way to fully prevent PAM is to avoid swimming in warm freshwater. There are other safety tips though that can help lower your risk of PAM:

  • Hold your nose, shut your fingers, or use nose clips when swimming.
  • Keep your head above water
  • Don't spend time in freshwater if the water temperature is warm and water levels are low
  • Don't dig in or stir up the dirt while swimming in shallow, warm freshwater.

Keep swimming pools clean using chlorine. Although tap water rarely causes PAM, some cases can happen when people rinse their sinuses or clean their noses. If you use tap water to clean your nose, follow at least one of these safety tips. They can lower your risk of getting PAM from tap water:

  • Boil tap water for one minute. Then let it cool.
  • Buy distilled or sterile water
  • Use a water filter designed to remove small germs (absolute pore size of 1 micron or smaller).

Related topics

Provider information

If you are a provider, expand each section to learn more

PAM is a Wisconsin disease surveillance category 1 disease. Category 1 means that health care providers should:

Learn more about Disease Reporting

Learn more about Communicable Disease Case Reporting and Investigation Protocol: PAM, P-02191. (PDF)

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

Last revised April 6, 2023