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Medical Author:

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP

Mary D. Nettleman, MD, MS, MACP is the Chair of the Department of Medicine at Michigan State University. She is a graduate of Vanderbilt Medical School, and completed her residency in Internal Medicine and a fellowship in Infectious Diseases at Indiana University.

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Medical Editor:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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In this Article

• Naegleria fowleri infection facts
• What is Naegleria fowleri?
• What causes a Naegleria fowleri infection?
• What are risk factors for Naegleria fowleri infection?
• What are symptoms and signs of a Naegleria fowleri infection?
• How is a Naegleria fowleri infection diagnosed?
• What is the treatment for a Naegleria fowleri infection?
• Can Naegleria fowleri infections be prevented?
• What is the prognosis of a Naegleria fowleri infection?
• Where can people find additional information about Naegleria fowleri infections?
• Naegleria Infection Index

After entering the nose, the amoeba travels into the brain along the olfactory nerve and through membranes to enter the brain. Once there, it causes primary amoebic meningoencephalitis (meaning inflammation of the brain and the lining around the brain). In the popular press, Naegleria fowleri is sometimes called the brain-eating amoeba, and meningoencephalitis is sometimes referred to as Naegleriasis.

Symptoms usually appear within five days after exposure but can be delayed up to two weeks. Patients may initially notice changes in smell or taste. Fever, headache, loss of appetite, and nausea follow quickly. The patient becomes confused or semiconscious and finally comatose. Physical examination shows fever and a stiff neck (meningismus).

A spinal tap will be done to examine the spinal fluid. Infection is diagnosed by seeing the amoeba under the microscope. Traditional Gram staining is not used to detect Naegleria because the heat used in the fixation process destroys the organism. Although not specific to Naegleria, the spinal fluid often has a mild elevation in the levels of proteins and a mild decrease in glucose, along with a high white cell count, and is often bloody in the later stages of disease.

Because rapid diagnosis is critical, examination of the spinal fluid is imperative. The organism can also be cultured in the laboratory using on a plate that is coated with bacteria for the amoeba to eat. The culture takes a few days. Newer tests are becoming available that use polymerase chain reaction (PCR) technology to detect amoebic DNA in spinal fluid.