Naegleria fowleri — Primary Amebic Meningoencephalitis (PAM) — Amebic Encephalitis

What is brain-eating amoeba (Naegleria fowleri)?

Naegleria fowleri

An amoeba called Naegleria fowleri can be found in warm, shallow freshwater bodies of water all around the world, including lakes, rivers, and hot springs. In soil, it also thrives. It is regarded as a free-living creature because it can survive without a host.

Primary amoebic meningoencephalitis (PAM) is a disorder that affects those who are infected with this amoeba. PAM is an extremely dangerous, virtually invariably fatal infection of the central nervous system.

Note: The words “ameba” and “amebic” may also appear in place of “amoeba” and “amoebic,” respectively. Though the word amoeba is more prevalent than ameba, both terms describe a creature with a single cell.

How do you get infected by brain-eating amoeba (Naegleria fowleri)?

When contaminated water enters your nose, you are most likely to become infected by this species of amoeba. The amoeba then travels to your brain. This typically occurs while swimming, diving, or engaging in an activity like water skiing in contaminated water. In exceedingly rare circumstances, contaminated water may be hot tap water or inadequately chlorinated pool water.

You are unable to acquire an infection by consuming contaminated water.

How common is an infection due to brain-eating amoeba (Naegleria fowleri)?

Fortunately, there are only a few occurrences per year in the United States (between zero and eight are estimated). The majority of the incidents involve young boys and take place in southern states like Florida and Texas.

However, in more recent years, a few cases have occurred in colder states during extremely hot spells. Climate change may be to blame for this shift in the location of illnesses.

Studies are being conducted that cast doubt on how uncommon Naegleria fowleri infection really is. Some persons contain amoeba-specific antibodies, showing that they have contracted the infection and survived. Some meningitis-related deaths have been categorized as brain-eating amoeba (Naegleria fowleri) deaths.


What are the symptoms of infection with brain-eating amoeba (Naegleria fowleri)?

Primary amoebic meningoencephalitis (PAM) begins abruptly and with severe first signs and symptoms, such as:

  • very high.
  • a terrible headache.
  • vomiting and nauseous.
  • Meningitis-like symptoms, such as a stiff neck and an excessive sensitivity to light (photophobia).
  • bewilderment in the mind.

Even with treatment, the death rate is more than 97%.

What causes infection with brain-eating amoeba (Naegleria fowleri)?

The Naegleria fowleri amoeba infects you when it enters your nasal passage and travels to your brain. If you breathe in any contaminated water, it can get inside of you. The amoeba typically inhabits warm freshwater bodies of water, such as hot springs (geothermal water).

Infected dust can also be inhaled, resulting in infection.

Using tap water instead of distilled or sterilized water to rinse out their noses with tools like neti pots has resulted in other cases of reported infection by the brain-eating amoeba (Naegleria fowleri).


How is infection with brain-eating amoeba diagnosed?

A spinal tap, sometimes referred to as a lumbar puncture, is advised if a medical professional suspects you may have contracted the brain-eating amoeba (Naegleria fowleri), in order to determine whether the organism is present in your cerebrospinal fluid (CSF).

A brain biopsy may also be suggested by your doctor. To check for the amoeba during this process, a tissue sample will be taken and examined under a microscope.


How is infection with brain-eating amoeba (Naegleria fowleri) treated?

The antifungal amphotericin B is the drug of choice for treating primary amoebic meningoencephalitis (PAM), also known as an infection with the brain-eating amoeba (Naegleria fowleri). Some survivors in North America received treatment with a cocktail of medications that comprised miltefosine, amphotericin B, rifampin, and fluconazole. Leishmaniasis is a parasite disease that is carried by sandflies, and miltefosine is a medication licensed for treating it.

The best outcomes (in two children who fully recovered) resulted from early diagnosis, drug therapy using the suggested medications, and body cooling to address brain swelling.


How can I prevent myself from being infected with brain-eating amoeba (Naegleria fowleri)?

Despite the fact that this ailment is extremely rare, prevention can still be crucial given its grim prognosis. The following are essential reminders:

  • In warm freshwater areas, especially still waters, never swim, wade, or engage in water sports without nose plugs. If Naegleria fowleri is known to be there or is suspected to be present, avoid entering the water entirely.
  • Never use tap water to rinse your nasal passages with a neti pot or any other device. Use only sterilized or distilled water. If you must use tap water, boil it for one minute before allowing it to cool. Boil the water for three minutes, then let it cool if you reside somewhere that is 6,500 feet above sea level.
  • Filters can be used to clean water of microorganisms. Filters with the designations “NSF 53,” “NSF 58,” or “absolute pore size of 1 micron or smaller” should be used.
  • To disinfect water for cleansing your nose and sinuses, you can also use chlorine bleach tablets or liquid. A different amount of bleach is needed to sterilize water for drinking versus water for nasal usage.
  • Inform your healthcare physician of your recent activities if you do have fever or headache symptoms after bathing in warm freshwater



  • Amebic Meningoencephalitis, Primary. In: Papadakis MA, McPhee SJ, Bernstein J, eds. Quick Medical Diagnosis & Treatment 2021. McGraw Hill.
  • Andrade RM, Reed SL. Amebiasis and Infection with Free-Living Amebae. In: Jameson J, Fauci AS, Kasper DL, Hauser SL, Longo DL, Loscalzo J, eds. Harrison’s Principles of Internal Medicine, 20e. McGraw Hill.
  • Centers for Disease Control and Prevention. Parasites – Naegleria Fowleri – Primary Amebic Encephalitis (PAM) – Amebic Encephalitis. ( Accessed 11/29/2022.
  • Jahangeer M, Mahmood Z, Munir N, et al. Naegleria Fowleri: Sources of infection, pathophysiology, diagnosis, and management; a review. ( Clin Exp Phacol Physiol. 2020;47(2):199-212. Accessed 11/29/2022.
  • Wade TJ. Water Pollution. In: Boulton ML, Wallace RB, eds. Maxcy-Rosenau-Last Public Health & Preventive Medicine, 16e. McGraw Hill.
  • Yuma County, Arizona. Naegleria Fowleri – What You Need to Know. ( Accessed 11/29/2022.


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