Naegleria fowleri

Find out about the risk of amoebas in the water: Naegleria Fowleri.


A child dove into fresh warm water. A woman washed out her stuffy sinuses with a Neti pot. A man splashed water vigorously on his face before prayer.

All were seemingly healthy things to do. All carried a very tiny risk.

In rare cases, an ameba (amoeba in British English) travels from the water up the nose to cause a brain infection. This ameba is Naegleria fowleri. It causes primary amebic meningoencephalitis (PAM) - which is an infection and inflammation in the brain and meninges (membrane surrounding brain).

It is also called the "Brain-eating Amoeba".


Exposure to the ameba happens more than infection. Infection occurs when water is pushed generally through someone's nose and the ameba travels into their brains. This is incredibly rare. The infection cannot occur from drinking ameba-containing water. The infection develops in 2-3 days (and up to 1-2 weeks or more). 

In 10 years, 34 people have been infected in the US, mostly swimming, while in 10 years, 34,000 die from drowning in the US. 

Means of Transmission

(a) Recreational Water

Ponds, lakes, geothermal pools can carry the infection. Swimming, diving, wake boarding, water sliding, splashing have led to infection from Florida, Texas, ArizonaLouisiana to farther away in Minnesota, Australia, England, and Pakistan.

Warm water, 80 F/ 27C, favors Naegleria becoming active and infectious. Warm temperatures also make children want to swim.

It is therefore more common in the southern US states and in the summer, more in boys and young men.

Risk is high in geothermal pools; the parasite can survive at high temperatures (113F/45C). The historic baths in Bath, England are closed, in fact, after an infection. It can be found in particular lakes more than others.

Infections have not occurred in well-maintained chlorinated swimming pools. These are considered safe from Naegleria. However a boy died in Arizona after a pool was filled with Naegleria-contaminated, unchlorinated fresh water.

Naegleria has been found in disinfected public drinking water in Louisiana (St Bernard, DeSoto, St John the Baptist Parishes) and in Arizona well water. A child died after using a slip-n-slide with Louisiana Tap-water. 

(b) Neti pots wash out noses and sinuses. Two died in Louisiana in 2011 after using Tap-water containing the ameba.

(c) Religious ablutions and ritual immersions can lead to infection. A man in the US Virgin Islands died from Naegleria after washing and splashing his face and nose before prayers. An infant was likely infected during baptismal immersion in fresh water. Men in Pakistan have been infected during ritual ablutions.


Almost all infections are fatal. 132 US infections are known from 1962-2013; 3 survived.

The disease may start with a headache, fever, maybe nausea and vomitting.

It then develops into meningitis - stiff neck and confusion, possibly with seizures and hallucinations. It can lead to death in less than a week from the start of infection.

The disease may not be diagnosed. 75% of diagnoses are made after death.


For 35 years, no one infected with Naegleria survived in the US. In 1978 one person survived in California and again in Mexico in 2003. Treatment of others following the same treatment failed.

However in 2013, 2 children survived, using a new drug and supportive treatment (that focused on reducing brain swelling). Doctors also cooled one patient with hypothermia. The drug used was Miltefosine, for leishmania infection (and is studied for breast cancer). The CDC is now reporting that miltefosine (trade name, Impavido) may be a possible treatment that the CDC will help make available as needed.

What to do

The risk is very low.


1. Avoid Swimming in water known to be at risk for Naegleria

2. Swimming pools should be properly disinfected.

3. Listen for local reports on public water safety, especially if Naegleria contamination has occurred before or nearby

4. If a water system is thought contaminated with Naegleria, please follow local health department or CDC directions. This advice includes avoiding water entering your nose, especially while bathing. Avoid jumping into water. Do not allow children to play unsupervised with hoses, sprinklers, bathtubs, or kiddie pools. No slip-n-slides. Baths, showers, and hoses should run for 5 minutes to flush pipes. Use only water that is sterile, disinfected, or properly boiled (and cooled) if water will enter your nose.

Advice on Water from the CDC for water for nasal irrigation

Buy "Distilled" or "Sterile" water


Boil water for 1 minute (3 minutes if at higher altitude (6500 feet)). Let it cool.


Filter water with special filters ("NSF 53", "NSF 58", or "absolute pore size of 1 micron or smaller")


Use Chlorine to disinfect water, following: CDC directions

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