Naegleria fowleri (Brain-Eating Ameoba) Infection

Brain-Eating Amoeba
Millions of people get exposed to Naegleria fowleri (N. fowleri) every year, but only a small percentage get ill from this brain-eating amoeba.

Naegleria fowleri (N. fowleri), a brain-eating amoeba, is a free-living, single-celled organism found in warm freshwater and soil. The organism causes primary amoebic meningoencephalitis (PAM), a rare but deadly infection of the brain (PAM).

  • PAM develops when water containing N. fowleri goes up the nose, usually while swimming, diving, or falling into warm fresh water.
  • Once inside the nose, the amoeba proceeds to the brain, where it infects and kills brain tissue.

Disease development is rapid, and recovery from the infection is extremely rare.

What Are the Signs and Symptoms of Naegleria fowleri Infection or Primary Amoebic Meningoencephalitis?

Every year, millions of people get exposed to Naegleria fowleri (N. fowleri), which causes naegleria infection, yet only a small percentage of them get ill. Symptoms could be mild at first, but they soon worsen. According to the Centers for Disease Control and Prevention (CDC), symptoms may begin as flu-like and may mimic viral or bacterial meningitis.

Signs and symptoms of primary amoebic meningoencephalitis include:

  • Fever
  • Sudden, severe headache (frontal headache)
  • Nausea and vomiting
  • Lack of attention to people and surroundings
  • Loss of balance
  • Fatigue
  • Sensitivity to light
  • A change in the sense of smell or taste
  • Stiff neck
  • Sleepiness or drowsiness
  • Confusion
  • Altered mental status
  • Hallucinations
  • Seizures
  • Coma

These symptoms generally appear five to nine days after exposure to N. fowleri. According to the CDC, death generally occurs within five days. Many other diseases, including viral and bacterial meningitis, can cause similar symptoms. These diseases are less severe and more common than amoebic meningitis.

What Are the Causes and Risks of Developing Primary Amoebic Meningoencephalitis?

Amoebic meningitis develops only when water containing active amoebae enters the nose. The amoebae move up the nerves and into the brain, causing inflammation and tissue destruction.

  • Children and young adults are the most vulnerable to the infection though it can affect anyone.
  • Amoebae are most active in water temperatures ranging from 82.4° to 104° F. Any warm, fresh water could potentially contain Naegleria fowleri amoeba.
  • Unchlorinated or incorrectly chlorinated fresh water, such as tap water or bore water.
  • Warm inland waters, such as dams, lakes, geothermal water (hot springs), or waterholes, even if the water appears clear and clean.
  • Improperly maintained swimming pools, water parks, and spas.
  • Infected water pipes.
  • Warm or stagnant water in garden hoses and sprinklers.
  • Nasal irrigation using contaminated water.
  • While Naegleria fowleri infections are rare, they do often occur during the summer months: July, August, and September.
  • Infections typically arise when temperatures rise for an extended time, resulting in higher water temperatures and lower water levels.

You cannot get amoebic meningitis from another person or by drinking water. The amoebae will not grow in salty water (more than two percent salt), such as seawater and river creeks.

How to Diagnose Naegleria fowleri Infection

The diagnosis is based on the medical history, clinical examination, and signs and symptoms. Microscopy and further referral testing may need cerebrospinal fluid (CSF) samples. Because of the infection's rarity and difficult early identification, about 75 percent of case diagnoses are made after the person’s death.

In the laboratory, Naegleria fowleri infection is diagnosed by identifying the following in the CSF, biopsy, or tissue specimens:

  • Naegleria fowleri amoeba
  • Naegleria fowleri nucleic acid
  • Naegleria fowleri antigen

Imaging studies

MRI of the brain often shows abnormalities in various regions of the brain, including the midbrain and subarachnoid space

Water samples can be collected, condensed, and grown in culture to find Naegleria fowleri. Samples can be examined utilizing the mentioned culture or molecular approaches.

What Are the Treatment Options for Naegleria fowleri Infection?

In the laboratory, several medicines are effective against Naegleria fowleri. However, their efficacy is debatable because virtually all infections have been deadly, even when people were treated with similar medication combinations.

Report suspected infections to the health authorities at once so that they can take remedial action. A prompt diagnosis and extensive supportive treatment may increase the chances of survival.

Medications that may help treat Naegleria fowleri infection

The use of amphotericin B, rifampicin, and fluconazole in conjunction with steroids could be effective. Azithromycin can be used in conjunction with amphotericin B. Miltefosine has recently been demonstrated to be effective against Naegleria fowleri.

Headache is a symptom of primary amebic meningoencephalitis, or Naegleria fowleri infection.

Symptom of Brain-Eating Amoeba (Naegleria fowleri) Infection


Headache is caused by irritation or injury to pain-sensing structures of the head. The structures that can sense pain include the scalp, forehead, top of head, the muscles of the neck and head, major arteries and veins in the head, the sinuses, and the tissues that surround the brain. The brain has no sensory nerve endings so the brain itself cannot "hurt."

Headache may occur when these structures suffer compression, spasm, tension, inflammation, or irritation.

Image Source: iStock image

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