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Brain-Eating Amoeba Thrives in Warm, Fresh Water

The brain-eating amoeba that killed three people this summer is an organism that thrives in warm fresh water and can be found in lakes, rivers, hot springs and soil, according to the Centers for Disease Control and Prevention.
/ Source: Discovery Channel

The brain-eating amoeba that killed three people this summer is an organism that thrives in warm fresh water and can be found in lakes, rivers, hot springs and soil, according to the Centers for Disease Control and Prevention.

All three deaths this year occurred in the South: a 16-year-old girl in Florida, a 9-year-old boy in Virginia and a 20-year-old man in Louisiana.

A brutal summer and drought make the conditions perfect for the amoeba. The threat of N. fowleri could potentially be elevated for weeks in some areas. According to the CDC, infections occur mainly in July, August and September.

The microscopic amoeba, Naegleria fowleri, attacks anyone who has the misfortune of inhaling it. It enters first up the nose and then goes to the brain, usually killing its victims within two weeks.

"Once forced up the nose, it can travel to the brain, where it digests brain cells," Jonathan Yoder, an epidemiologist at the Centers for Disease Control and Prevention, told Discovery News. "It's a very tragic disease that thankfully is very rare."

Aside from its rarity, the amoeba "is not looking to prey upon human victims," he said. "They usually go after bacteria in water and soil."

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As single-celled organisms, amoebas do not even have brains. However, Naegleria species, including this disease-causing one, can transform themselves into three different basic "body" types.

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"This one-celled organism hunts and eats bacteria as an amoeba, swims around looking for a better environment as a flagellate, and then hunkers down and waits for good times as a cyst," said Simon Prochnik, a computational scientist at the U.S. Department of Energy’s Joint Genome Institute. "It is a very rare process to go from amoeba to flagellate like this."

Prochnik, who sequenced the genome of a Naegleria species last year, explained that when environmental conditions are not favorable, the "stressed" amoeba can quickly grow two tails, transforming it into the flagellate. It can then swim and move around to a better spot, similar to the way that human sperm travel.

To support these three body or "personality" types, as Prochnik calls them, the organism is packed with genes: 15,727 of them. To put that into perspective, humans have 23,000 protein-coding genes.

Since the creature is so versatile, it can lurk in warm, moist places for extended periods. In the case of the first death from the disease earlier this summer -- a man from Louisiana who used a neti pot -- it's believed the organism was living in his home's water system. The CDC said the investigation into that death is ongoing, but the man may have put the infected tap water into his nose without boiling it first.

Yoder said it is important to follow the directions included with neti pots, which look like teapots and are used to relieve sinus problems. The instructions usually mention that users should put distilled, boiled water in them and not just water right out of the tap.

If users don't follow these instructions, there is a slim chance they too might get the disease caused by Naegleria fowleri, which is called primary amebic meningoencephalitis, or "PAM."

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According to CDC data, 32 cases -- all fatal -- occurred between 2001 and 2010. From 1937 to 2007, there were 121 reported cases. Yoder knew of only one survivor, an individual who became infected in 1978.

"The same treatment course provided then has been tried on others without success," he said.

Diagnosing this disease is difficult. Yoder explained that associated symptoms, such as high fever, headache, and stiff neck, are present with bacterial and viral meningitis, so misdiagnoses are possible.

The Florida Department of Health has issued warnings to prevent further deaths due to the disease.

"During the hottest time of the summer, water in ponds, lakes, and rivers become very warm and there can be increases in the amounts of amoeba present," said Florida DOH spokesperson Christie Goss. "We advise everyone to be aware of the danger of swimming in such water, but especially of stirring up the sediment in shallow water or diving and swimming under water which can enable the amoeba to enter the nose and possibly infect the brain."

Both the DOH and the CDC add that it may help to "hold your nose, or use nose plugs when jumping or diving into water."


Much about N. fowleri remains a mystery.  Anne Oplinger, a spokesperson for the National Institute of Allergy and Infectious Diseases, told Discovery News that she wasn't aware of any federally funded studies investigating the disease at present.

Health officials at the CDC and elsewhere, however, are closely monitoring the cases, to detect any possible patterns or if the caseload might rise in future due to climate change or other possible contributing factors. So far, the number of PAM deaths this year falls within the annual national average.