http://www.webmd.com/news/20080529/brain-eating-amoeba-strikes-in-summer

Brain-Eating Amoeba Strikes in Summer
Six Deaths in 2007 From Amoeba in Warm Fresh Water
By Daniel J. DeNoon
WebMD Health News
Reviewed by Louise Chang, MD

May 29, 2008 -- Six young men died last year
after swimming in lakes or pools infested with
a brain-eating amoeba, the CDC reports.

The bad blobs -- known as Naegleria fowleri
or N. fowleri -- thrive in warm, fresh water all
over the world. But the key word here is warm.
The amoeba loves heat. In the U.S., it inhabits
the relatively hot waters of lakes, hot springs,
and poorly maintained pools in Southern or
Southwestern states.

All six of the 2007 cases were in Florida,
Texas, and Arizona (the victims' names and
swimming sites come from local media reports):

* May/June 2007: Angel A. Vasquez, age 14,
  of Orlando, FL, was swimming in an
  apartment swimming pool.
* July 2007: Will Sellars, age 11, of Orlando, FL,
  was swimming/wakeboarding in Lake Conway.
* August 2007: Richard Almeida, age 10, of
  Kissimmee, FL, was swimming/wakeboarding
  at Orlando Watersports Complex.
* August 2007: John "Jack" Herrera, age 12,
  participated in water activities during summer
  camp at Lake LBJ in Texas.
* August 2007: Colby Sawyer, age 22, ruptured
  his eardrum while wakeboarding at Lake LBJ
  in Texas.
* September 2007: Aaron Evans, age 14, was
  swimming at Lake Havasu in northeastern AZ.

Why the deadly amoeba struck these six and
not the thousands of other people exposed in
the same places at the same times is a mystery,
says CDC epidemiologist Jonathan Yoder.

"Humans are the accidental host -- we are not
part of this amoeba's life cycle," Yoder tells
WebMD. "But when it finds a nice warm environ-
ment like your nose, it looks for a food source."

How Brain-Eating Amoebas Attack

That food source is the human brain. The CDC
doesn't like to call N. fowleri "the brain-eating
amoeba," but that's what it does.

"It actually is using the brain for food," Yoder
says. "So it is a very tragic situation for the
person unfortunate enough to have that happen."

After the amoeba enters the nose, it finds its
way to the olfactory nerve. N. fowleri appears
to be attracted to nerve cells, so it follows the
nerve into the brain. That's when bad things
happen.

The amoeba has mouth-shaped structures
on its surface called food cups. It's perfectly
capable of chewing up brain and blood cells
with these food cups, but the blob finds it
more efficient to secrete enzymes & proteins
that dissolve brain cells so it can suck up the
debris with its food cup.

Obviously, this causes a lot of damage.
And it happens fast: Victims usually die
seven to 10 days after infection, although
symptoms may not appear for up to 14 days.

Initial symptoms include headache, fever,
nausea, vomiting, and stiff neck. Later
symptoms include confusion, inability to
pay attention to people and surroundings,
loss of balance, seizures, and hallucinations.
Death follows the first symptoms by three
to seven days.

The disease is technically called primary
amoebic meningoencephalitis, or PAM.

"We want to make sure people understand
this is a tragic event," Yoder says. "When
it happens to a person, particularly if it is a
child, we don't want to minimize the tragedy."

At least eight people have survived PAM.
All were treated with powerful drugs soon
after infection. Unfortunately, most victims
aren't treated in time. There are rapid tests
for N. fowleri infection, but because the
infection is so rare, doctors usually don't
suspect a brain-eating amoeba until it's too late.

Brain-Eating Amoeba Not on the Rise

Last summer's 6 cases were a lot compared
to most years. But the CDC says there's no
evidence that the brain-eating amoeba is on
the rise. There were eight cases in 1980,
seven cases in 2002, and six cases in 1978,
1986, and in 1995. Since 1937, there have
been only 121 known cases.

So far, there haven't been any cases in 2008.
But the CDC warns people either to avoid
swimming in warm, fresh water or to wear
nose plugs if they do. N. fowleri does not live
in salt water or in properly maintained swim-
ming pools, although it has been found in
domestic water supplies.

"People should assume there is a risk of
swimming in warm, fresh water," Yoder says.
"And we think that things people do to minimize
entry of water into the nose might provide
some reduction of risk, such as using a nose
clip. We can't say there is scientific evidence
this works, but that's a commonsense approach."

The CDC also suggests that people avoid
digging or stirring up sediment while playing
or working in warm waters. The CDC further
suggests that people avoid thermally polluted
water, such as the water near power plants,
although Yoder says the CDC has not yet
looked at how much thermal pollution affects
amoeba populations in public waters.

States where N. fowleri has caused disease
include Arkansas, Arizona, California, Florida,
Georgia, Louisiana, Missouri, Mississippi,
North Carolina, New Mexico, Nevada, Okla-
homa, South Carolina, Texas, and Virginia.

Infections have been seen around the world,
including 16 cases traced to the same swim-
ming pool in the Czech Republic.

There's no question of eradicating the blob.
N. fowleri turns into its cyst form when
conditions aren't right -- and can survive
for years in the soil.

The CDC reports details of the six 2007
cases, and analyzes PAM trends, in the
May 30 issue of Morbidity and Mortality
Weekly Report.
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