Naegleria Fowleri

What is Naegleria fowleri?

Naegleria fowleri (N. fowleri) is an environmental protozoan parasite with worldwide distribution. They are not well adapted to parasitism and do not require a vector for transmission to humans or animals. N. fowleri is commonly referred to as the “brain-eating ameba”. It can cause a rare and devastating infection of the brain called primary amebic meningoencephalitis (PAM).

Who gets N. fowleri infections?

N. fowleri infections are uncommon. Infection primarily occurs in healthy children and young adults who come into contact with water contaminated by the parasite.

How is N. fowleri infection spread?

N. fowleri can cause an infection in people when contaminated water enters the body through the nose while the person is swimming or diving in warm, stagnant fresh water. Ameba can attach to the olfactory nerve inside the nose, where it may travel to the brain and cause a PAM infection. In uncommon instances, N. fowleri infections may also occur when contaminated water from other sources, such as inadequately chlorinated swimming pool water or warm, contaminated tap water, enters the nose. A few cases have been associated with the use of nettie-pots, after using household tap water to irrigate the sinuses.

What are the symptoms of N. fowleri infection?

Symptoms for stage 1 of the disease include severe frontal headache, fever, nausea and vomiting. Symptoms for stage 2 of the disease include stiff neck, seizures, altered mental status, hallucinations and coma.

How soon after exposure do symptoms appear?

In the case of N. Fowleri, symptoms typically appear within 1-14 days after infection. The disease progresses rapidly and infection usually results in death within 3-7 days after the onset of symptoms.

How is N. fowleri infection diagnosed?

Laboratory-confirmed N. fowleri infection is defined as the detection of N. fowleri via:

  • Organisms in cerebrospinal fluid (CSF), biopsy, or tissue specimens, or
  • Nucleic acid in CSF, biopsy, or tissue specimens, or
  • Antigen in CSF, biopsy, or tissue specimens.

What is the treatment for N. fowleri infection?

Disease caused by N. fowleri is generally fatal. There are five known survivors of N. fowleri PAM infections in North America. The medication miltefosine has shown ameba-killing activity against free-living amebae, including N. fowleri, in the laboratory.

How can N. fowleri infection be prevented?

N. fowleri are naturally occurring organisms in lakes and rivers. Because of this, swimmers and other recreational water users should assume that there is a low-level risk of exposure whenever they enter warm freshwater lakes, rivers, and hot springs. Activities such as swimming, diving, or waterskiing, or participating in activities where water might be forced up the nose, may increase the risk of exposure. Wearing nose plugs when participating in these activities may help reduce the risk of exposure.

How can I get more information about N. fowleri?

  • If you have concerns about free-living ameba exposure, contact your health care provider.
  • Call your local health department. A directory of local health departments is located at the VDH Local Health Districts page.
  • For information on N. fowleri and PAM infections, visit the Centers for Disease Control and Prevention (CDC) website at the CDC page on N. fowleri.

November 2018

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