Brain Eating Amoeba

Brain Eating Amoeba morphology

What is Brain Eating Amoeba?

Brain Eating Amoeba is a single-celled organism from the specie of Naegleria. There are many species of Naegleria but only the Naegleria fowleri is known to cause human disease. They belong to a group of Heterolobosea. It was first identified in Australia in 1965 and is believed to have evolved in the United States. The amoeba-flagellates human disease was first identified by 2 physicians M. Fowler and R. F. Carter whose work provided an example of how protozoan can freely live in the environment and human host. Fowleri termed the infection from Naegleria fowleri as primary amoebic meningoencephalitis distinguishing its invasion of the central nervous system.

Brain Eating Amoeba morphology

Picture 2 : Brain Eating Amoeba

These amoebas can be found in warm bodies of fresh water where they can survive in water as hot as 113 degrees Fahrenheit. They are most in warm part of the globe and can be located in fresh water such as lakes, ponds, shallow slow-flowing rivers, untreated swimming pools, geothermal plants, polluted waters such as industrial plants run off. They can also thrive in soil near warm water discharges of industrial plants where waste water is disposed.

Brain Eating Amoeba Life Cycle

The life cycle of N. fowleri begins in cyst form when induced by food deprivation, cold temperatures, and accumulation of waste products and crowding. They reproduced by cell division like any other amoebas. The cyst stage of naegleria can be found at the bottom of the water. The cyst turns into trophozites or the feeding form of the amoeba when the condition becomes favorable. The trophozite form grows a tail which can allow them to swim freely. The tailed form of amoeba unable them to eat that they revert to trophozites. The tailed form or flagellate form rapidly and may occur within a few minutes.

naegleria fowleri life cycle

Picture 2 : Brain Eating Amoeba Life cycle


Invasion of the central nervous system by N. fowleri starts when it enters the nose of the human host especially entering through the olfactory mucosa and cribriform palate of the nasal tissue. Hemorrhaging and necrosis of the olfactory bulbs occur during the initial penetration of the amoeba.

It is said that N. fowleri gets attracted on the chemicals of the nerve cells that are use for communication. The amoeba feeds on the brain tissues and slowly destroys it. The amoeba takes on a protective coat for protection against the immune system of the body. The organism eats the brain cells slowly through the unique sucking structure from their cell surface.

The incidence of the organism to enter the central nervous system is potential to people who dive, water ski and other water sports that may force the water into the nose of an individual. Dipping the head under warm water bodies may also put the individual at risk for harboring the organism. Once the amoeba gets into the nose it will travel from the olfactory nerve to the central nervous system and the spinal cord.


Invasion of Naegleria fowleri in the central nervous system is termed as primary amoebic meningoencephalitis or PAM. The onset of symptoms manifest usually two to fifteen days after invasion. The symptom is similar to that of viral meningitis. Infection from N. fowleriI is fatal and death occurs within 3 to 7 days after onset of symptoms.

The initial symptoms of primary amoebic meningoencephalitis include:

  1. Distortion in taste
  2. Change in sense of smell
  3. Headache
  4. Fever
  5. Nausea and vomiting
  6. Stiff neck

Secondary symptoms of primary amoebic meningoencephalitis include:

  1. Ataxia or loss of muscle movement coordination
  2. Confusion
  3. Hallucination
  4. Seizure

Primary amoebic meningoencephalitis is a rare illness although mortality rate of people infected is extremely high. The invasion of N. fowleri is common during warm summer months.

Diagnosis (Detection)

Detection of N. fowleri can be achieved through collection of spinal fluid by doing spinal tap. The diagnosis is imperative as the infection is rapid. The organism is cultured on non-nutrient agar plates coated with bacteria and incubated at 37 degrees Celsius temperature and is daily assessed for clearing which is indicative of the trophozites feeding on bacteria and its presence.

Flagellation test can be done to confirm the presence of Naegleria fowleri by subjecting the organism to distilled water. Final confirmation is done through subjecting the organism in high temperature of about 42 degrees Celsius where it can cultivate.


The prognosis for harboring primary amoebic meningoencephalitis although rare in incidence is very austere. Survival rate is at 1% making the mortality rate of 99%.

An effective agent against N. fowleri is Amphotericin B which is an antifungal drug administered intravenously. Drugs such as miltefosine, rifampin and voriconazole used in combination with Amphotericin B have actions against N. fowleri although the therapy is best administered on the early stage of infection.


Presence of Brain Eating Amoeba cannot be eliminated from fresh water bodies. The only way one can prevent from harboring the fatal amoeba is by avoiding aspiration of fresh water in the nose. It can possibly be done by avoiding water sports activities or other activities involving use of water. Using a swimming pool requires extra precaution in assuring that it is properly treated. Water in the pool must be properly chlorinated to eradicate amoeba. Activities near thermally polluted water must be avoided and untreated water must not be used in irrigating nor forced into the nose.


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