Naegleria fowleri Infection
(Brain-Eating Amoeba Infection)

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Naegleria fowleri (brain-eating amoeba) infection facts

  • Naegleria fowleri is an amoeba that lives predominately in warm freshwater.
  • Naegleria fowleri is acquired by people when infected water is forcibly aspirated into the nose. This can occur through recreational swimming, diving, or during sports like water skiing.
  • Once acquired, the amoeba travels into the brain, causing primary amoebic meningoencephalitis (PAM). In the popular press, Naegleria fowleri is sometimes called the
    "brain-eating amoeba," and meningoencephalitis is sometimes referred to as Naegleriasis.
  • PAM is very rare, and there are only a few cases reported each year in the United States.
  • People with PAM have a rapidly progressive illness with fever, headache, and stiff neck, and finally coma and death.
  • Infection is diagnosed by examining spinal fluid under the microscope to identify the amoeba. Naegleria fowleri may also be grown in the laboratory, although this takes several days. Newer tests based on PCR technology have been developed but are not widely available.
  • The treatment of choice is an intravenous drug called amphotericin B. Amphotericin B may also be instilled directly into the brain. Because treatment with amphotericin B alone usually fails, other drugs are often added. Miltefosine is a drug that has shown promise, and it is available through the Centers for Disease Control and Prevention. Treatment should be initiated as rapidly as possible, and immediate consultation with an infectious-diseases expert is highly recommended.
  • More than 99% of cases of PAM are fatal despite treatment.
Medically Reviewed by a Doctor on 12/9/2013

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Naegleria fowleri:
Brain-Eating Amoeba

Risk of Infection and Symptoms

Brain-Eating Amoeba signs and symptoms may start about 1 day to 1 week after exposure; initially symptoms may include:

  • changes in smell and taste,
  • headache,
  • fever,
  • stiff neck,
  • nausea, and vomiting.

The patient may have confusion, ataxia (wobbliness), and seizures; and rapidly worsen over about 3 to 7 days with death occurring about 7 to 14 days after exposure.