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What is Naegleria fowleri?

Naegleria fowleri is an amoeba that lives in the sediment along the banks of freshwater lakes and rivers. Naegleria fowleri prefer warmer water and more likely to cause infection when water temperatures are above 80°F. However, they can survive for long periods of time in colder water while they are in cyst form and become dormant. For this reason, infection from Naegleria fowleri can be found in tropical as well as cooler climates.

There are many species of Naegleria, but only Naegleria fowleri cause infection in humans. Not all mammals are affected by Naegleria fowleri; dogs can play in the same water that infects humans with no implications themselves. The amoeba may lie dormant for some time, in cyst form when the water temperature is below 80°F and are no threat to humans in this form. However, as water temperatures increase and the amoeba become active, water levels typically decrease, making attack and infection more likely.

What Causes Naegleria fowleri Infection?

Infection from Naegleria fowleri usually comes as a result of water being forced into the nose. The amoeba can then travel through olfactory nerves and eventually enter the brain.

It is most common for the amoeba to enter the nose when people are swimming, diving or doing other recreational activities in freshwater lakes and rivers. However there are some cases where water may be forced into the nose to clean nasal cavities and if unboiled tap water is used for this purpose, infection may occur. In other cases, poorly chlorinated swimming pools may also allow the amoeba to grow and may be a source of infection. There are also rare cases where infants or young children being bathed with tap water may be infected. In general, stagnant water in summer time should be avoided as a source for recreational water activities.

What Are the Risk Factors for Naegleria fowleri Infection?

Naegleria fowleri eating a brainNaegleria fowleri infections are very rare. The Centers for Disease Control and Prevention state that only 126 cases were reported since 1962.

Infection from Naegleria fowleri normally occurs during recreational activities in freshwater lakes and rivers that have abnormally high water temperatures. While swimming diving or playing in the water, the amoeba is ingested through aspiration of water into the nose.

The most common infection from Naegleria fowleri is called primary amoebic encephalitis (or PAM), and most cases in the United States occur in the southern states in summertime.

Most cases occur in young, healthy, active males with a median age of 12 years old. However, infection can equally occur in any age person with good health or those with compromised immune systems.

Symptoms of Naegleria fowleri Infection

Naegleria fowleri infection is called primary amoebic meningoencephalitis and is basically inflammation of brain tissue and also the lining that protects the brain. Naegleria fowleri infections are commonly called brain eating disease, brain eating amoeba or brain eating bacteria.

The amoeba typically enters the body through the nose, travels through the olfactory nerves and reaches the brain.

Symptoms typically occur within 2 to 7 days after the amoeba has reached the brain. Individuals will complain of stiff neck and will appear confused, unstable and will suffer from nausea, headaches, fever before turning semiconscious and finally comatose.

The physician can diagnose Naegleria fowleri infection upon examining spinal fluid under a microscope and finding the amoeba. Early detection is crucial to properly diagnose and treat this rare infection. Anyone known to be, or thought to be in a high risk environment and exhibiting these symptoms should be immediately hospitalized.

Treatment of Naegleria fowleri Infection

Because primary amoebic meningoencephalitis is rare, there are are no known treatments that can stop the infection. However most physicians would opt for intravenous drugs used to treat fungal infections, along with other treatments that may be directly used on the patient’s brain to kill the amoeba.

The intravenous drug of choice is amphotericin B, with other intravenous drugs being used in a supportive manner.

Preventing Naegleria fowleri Infections

The best way to prevent Naegleria fowleri infection is to stop water from entering the nose. Parents opt for nose plugs for their children which are quite effective at keeping water out. Following directions when using chlorine in swimming pools is critical to preventing the amoeba from forming there. Any practice of forcing water into the nose for cleansing or other reasons should use distilled water.

Amoeba are a critical part of the ecosystems of freshwater lakes and rivers. It is not possible to eliminate them as the other wildlife would suffer. Therefore we must be aware of the conditions and the potential threat that freshwater lakes, rivers, swimming pools, and even tap water can pose to our health.

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