A microscopic organism that lives in warm lakes and rivers across the United States can kill in a matter of days, and almost nobody who is infected survives.

Naegleria fowleri, commonly known as the brain-eating amoeba, has once again put freshwater safety in the spotlight after claiming the life of an eight-year-old girl in Louisiana.

What Is Naegleria Fowleri?

Naegleria fowleri is a microscopic amoeba that lives naturally in warm fresh water. It is found in lakes, rivers, ponds and hot springs.

It can also live in soil and in poorly maintained swimming pools. The organism thrives in heat, becoming more active during warmer months.

Infections remain rare in the US, with fewer than ten cases reported each year, according to the Centers for Disease Control and Prevention. Louisiana's health department says only 180 cases have been confirmed nationwide since 1937.

How Does Infection Happen?

The amoeba enters the body when contaminated water goes up the nose. This usually happens while swimming, diving or doing water sports.

From there, it travels to the brain, causing a rare infection called primary amoebic meningoencephalitis, or PAM. PAM is almost always fatal, with a fatality rate above 97 per cent even with treatment.

Crucially, the amoeba cannot cause infection if swallowed. It also does not spread from person to person or cause wider outbreaks.

Symptoms to Watch For

Early symptoms include headache, fever, nausea and vomiting. These usually appear around five days after exposure, though they can surface anywhere between one and 12 days.

As the infection progresses, symptoms can include a stiff neck, confusion, seizures and hallucinations. Coma can follow soon after.

Anyone with a sudden fever, headache or stiff neck after being in warm fresh water should seek emergency care straight away. Early diagnosis is critical to any chance of survival.

Diagnosis usually involves a lumbar puncture, sometimes alongside a brain biopsy. The best outcomes on record combined early drug treatment, including amphotericin B, with cooling the body, helping two children recover fully.

Just How Risky Is Freshwater?

Health officials say it is safest to assume the amoeba could be present any time someone swims in warm fresh water. Precautions should be taken every time, they advise.

Most people infected in the US have been young boys, for reasons that remain unclear. Diving and disturbing lake or river sediment may raise the risk.

Louisiana's case is not isolated. CNN reported a Georgia resident died from the amoeba in 2023, and a Nebraska child died the year before, both after swimming in fresh water.

Infections have also been confirmed since 2010 in Nebraska, Iowa, Minnesota, Indiana, Maryland and northern California. Climate change may be a factor, as rising temperatures warm lakes and ponds.

Specialists advise avoiding still, warm freshwater without nose plugs, and using NSF-rated filters where possible. Tap water for nasal rinsing, such as in a neti pot, should be boiled and cooled first.

A Recent Case in Louisiana

Lillian Smart, from Ruston in northern Louisiana, died in hospital over the weekend after being infected with the amoeba. She had just turned eight.

Health officials confirmed a resident had likely caught the organism at nearby Lake Claiborne. They did not name Lillian, though family and friends identified her to local news.

Her family said in a Facebook post that Lillian had suffered severe brain swelling as a result of the parasite. Louisiana's health department called the infection 'extremely rare, but nearly always fatal.'

'We are heartbroken and honestly do not know what to do next,' her parents said. Lillian was remembered by her community as a joyful child.

Frequently Asked Questions

  • What is Naegleria fowleri?
    Naegleria fowleri is a microscopic amoeba that lives in warm freshwater and can cause a rare and usually fatal brain infection.
  • How does Naegleria fowleri infection occur?
    Infection occurs when contaminated water enters the nose, allowing the amoeba to travel to the brain.
  • What are the symptoms of Naegleria fowleri infection?
    Symptoms include headache, fever, nausea, vomiting, stiff neck, confusion, seizures, and hallucinations.
  • How can I reduce the risk of infection?
    Avoid swimming in warm freshwater, use nose plugs, avoid disturbing sediment, and ensure pools are well-maintained.
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