Symptoms of Naegleria fowleri Infection

Key points

  • Early symptoms of a brain infection caused by Naegleria fowleri can include a headache and fever.
  • Symptoms can develop quickly as the disease progresses.
  • If you or a loved one is experiencing symptoms, get medical help right away.
A young boy seated on a cough with his head in his hands.

Signs and symptoms

Naegleria fowleri can cause a rare but almost always fatal brain infection called primary amebic meningoencephalitis (PAM).

Early symptoms of PAM can include:

  • Headache
  • Fever
  • Nausea
  • Vomiting

The first symptoms of PAM usually start about 5 days after someone is exposed to Naegleria fowleri but can surface anywhere between 1 and 12 days. Early symptoms are similar to those caused by other more common illnesses like bacterial meningitis.

After symptoms begin, PAM progresses quickly. As it does, additional symptoms can include:

  • Stiff neck
  • Confusion
  • Inattention to people and surroundings
  • Seizures
  • Hallucinations
  • Coma

When to seek emergency help

You should seek medical care right away if you suddenly develop fever, headache, vomiting, or stiff neck. This is especially critical if you've been in warm fresh water where Naegleria fowleri thrives.

Death from PAM typically occurs within about 5 days after symptoms first begin but can happen within 1 to 18 days.