Primary Amebic Meningoencephalitis (PAM)

What is primary amebic meningoencephalitis (PAM)?

Primary amebic meningoencephalitis (PAM) is a disease caused by infection with Naegleria fowleri, a microscopic amoeba commonly called a "brain-eating amoeba." This infection destroys brain tissue, causing severe brain swelling and death in most cases.

PAM is rare and usually occurs in otherwise healthy children, teens and young adults.

What causes primary amebic meningoencephalitis?

PAM typically occurs when people swim in bodies of warm freshwater (such as lakes and streams/rivers) where Naegleria fowleri is present. Very rarely, infection occurs when contaminated water from other sources enters the nose.

Naegleria fowleri infects people when water containing the amoeba enters the body through the nose. Infection may be more likely when the water enters the nose under pressure, such as when diving into the water. Swallowing contaminated water does not lead to infection.

Naegleria fowleri can NOT be spread from person to person.

To prevent this type of infection, avoid swimming in untreated freshwater, especially during warm weather when the amoeba grows best. Other prevention measures can include wearing nose clips when swimming in these bodies of water, and avoiding diving as much as possible.

What are the symptoms of primary amebic meningoencephalitis?

Initial symptoms of PAM appear ranging from 1 to 9 days after infection, appearing on average 5 days after infection.

The initial symptoms may include:

  • Headache
  • Fever
  • Nausea
  • Vomiting

Later symptoms can include:

  • Stiff neck
  • Confusion
  • Lack of attention to people and surroundings
  • Loss of balance
  • Seizures
  • Hallucinations

What should I do if I suspect my child was exposed to Naegleria fowleri?

First, remember that these infections are extremely rare. The early symptoms of Naegleria fowleri infection are similar to those caused by other more common illnesses, such as bacterial meningitis.

Seek medical care immediately if your child develops a sudden onset of fever, headache, stiff neck, and vomiting. If there has been a recent freshwater exposure, this information should be provided to the treating medical provider. 

For more information:

Reviewed by Kevin P. O'Callaghan, MBBCh

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