One Scary, Mysterious Microbe
Scientists Lean Toward Caution in Debate Over Pfiesteria
By Joby Warrick and David Brown
Washington Post Staff Writers
Thursday, September 18, 1997; Page A01
The Washington Post
This much is well documented: When humans have close encounters
with the toxic microbe Pfiesteria piscicida, strange things seem
to happen.
Some people complain of nausea and memory loss. Others develop
sores. One North Carolina biologist, after working with pfiesteria
in a laboratory, lost all feeling in his legs and had to crawl
from the room.
But was it pfiesteria, hysteria or something else? That's the
question being debated by scientists after the microbe has sickened
and killed fish in Chesapeake Bay tributaries. Although scientific
studies have documented the microbe's lethal ways with fish, researchers
are barely beginning to understand how it affects humans.
Opposing opinions have led to sharply different policies in Maryland
and Virginia. Maryland has been cautious, closing waterways and
reporting yesterday that pfiesteria exposure can cause people
to develop chronic memory problems. [Details, Page D1.] Virginia
has gone the opposite way, leaving open the Rappahannock River
after sick fish were found there.
It may be months or even years before scientists can say who is
right. But a consensus is beginning to emerge among scientists
about what should be done in the meantime: When dealing with an
organism as unpredictable as pfiesteria, they say, it's best to
err on the side of caution.
"I think Maryland's being smart," said Don Anderson,
a scientist at Woods Hole Oceanographic Institution in Massachusetts
and the director of the newly formed National Office for Marine
Biotoxins and Harmful Algae.
"You're very likely to get people alarmed when you take
a step like this, and that is a big drawback," he said. "But
you need to bite the bullet and do it if there's some genuine
risk. . . . To do nothing would be irresponsible."
That view, however, is not universal. And even those who advocate
caution don't always agree on what the term means. To some North
Carolina scientists who have been tracking pfiesteria (pronounced
fis-TEER-ee-ya) attacks for years, it means closing waterways
only when fish are dying or sick in large numbers.
"If you have a few fish with lesions, there's probably not
enough pfiesteria around to cause a problem," said B.J. Copeland,
a marine ecologist at North Carolina State University.
He added, "That's what we call a SWAG -- a scientific wild-assed
guess."
His approach is only somewhat more interventionist than that of
Virginia, which has left the Rappahannock open even after samples
in which one-half to three-quarters of fish had pfiesteria-like
lesions.
Others, particularly those personally acquainted with pfiesteria's
toxic effects, believe the line should be drawn much sooner. Howard
Glasgow is one of three N.C. State scientists who became ill in
1992 after working with a large batch of pfiesteria's toxic secretions.
"I personally don't care if it's pfiesteria or some acid
that someone dumped in the water. If you have fish that are literally
dissolving away, you can extrapolate that you don't want be swimming
there," Glasgow said.
Glasgow said his exposure left him virtually disabled for months.
Like many others who were exposed, he suffered a wide range of
physical and neurological symptoms, including dizziness and memory
loss. After the 1992 episode, Glasgow's lab was shut down for
more than a year. It eventually was reopened as a high-security
"biohazard" facility where workers wear respirators
and protective suits.
Glasgow and his boss, aquatic botanist JoAnn Burkholder, pioneered much of the early scientific research on pfiesteria. They documented the microbe's bizarre 24-stage life cycle, which
enables it to change within hours from a
harmless blob of amoeba to a lethal whip-tailed microorganism.
In its killer stage, pfiesteria attacks fish with an arsenal of
powerful toxins that disrupt the nervous system and cause the
skin to slough off.
Later laboratory tests confirmed that pfiesteria's toxins can
cause neurological problems in rats. But while pfiesteria's human
"victims" have reported similar symptoms, finding hard
evidence in the lab has been problematic.
A controversial study this year by East Carolina Unversity found
no conclusive evidence that pfiesteria was causing any of the
illnesses reported by fishermen and others who work in pfiesteria-infested
waters. Some state officials suggested that the symptoms were
caused by other pathogens or that a kind of mass hysteria was
at work. Some of the state's marine scientists have even questioned
whether pfiesteria is responsible for the state's massive fish
kills in recent years.
Burkholder dismisses those questions, citing a sizable body of
laboratory studies documenting pfiesteria's rapid lethality with
dozens of species of fish and shellfish. Throughout the scientific
community, prominent scientists who know Burkholder's work say
she makes a compelling case.
"It's something out of Stephen King novel," said Sandra
Shumway, a shellfish biologist at Long Island University's Southampton
College, who became a believer after witnessing a pfiesteria attack
on shellfish tissue in her lab. "Pfiesteria is an organism
that should be taken very, very seriously."
But in sorting out the truth about pfiesteria's effects on humans,
scientists are hampered by a dearth of data. To date, the clearest
description of what appears to be poisoning by pfiesteria toxin
comes from the report of the three N.C. State people who became
ill while working with samples of the organism in a research laboratory.
The exposure came both from direct skin contact with water in
which pfiesteria was growing and from breathing air that apparently
contained pfiesteria toxin. The water contained pfiesteria in
greatly varying concentrations, and in all three cases, there
was repeated exposure to the organism.
Among the numerous symptoms were numbness and tingling of the
hands and feet, disorientation, problems with memory and thinking,
mood changes, difficulties breathing and skin sores.
In a strict scientific sense, however, those cases cannot be tied
to pfiesteria -- nor can the far less certain ones reported by
a handful of North Carolina and Maryland watermen exposed outdoors.
To do that, scientists will have to isolate the responsible toxin
(or toxins) and identify it in water or air. Although purifying
pfiesteria toxin and developing a lab test for it are the objects
of intensive research, neither has been accomplished to date.
In a study done at Duke University Medical Center, rats injected
with whole pfiesteria cells showed mild impairment in their ability
to learn a new skill. It did not have discernible effects on memory,
although the toxicologist who did the research, Edward D. Levin,
did not rule out the possibility the organism could have such
effects in people.
There are about 1,200 species of dinoflagellates -- the scientific
name for the class of swimming microorganisms that includes pfiesteria
-- but only a few dozen produce toxins. Pfiesteria appears to
be the only one that intentionally releases its toxin as a means
of attacking prey. With other toxic dinoflagellates, poisoning
usually occurs when shellfish or fin fish consume the microorganisms,
concentrating the toxins. Then people can become ill by eating
the fish; it is not known whether people can become ill from eating
fish afflicted by pfiesteria.
Pfiesteria produces two classes of toxins. One is water soluble
and appears to be responsible for the nervous system effects.
The other is soluble in fat and is responsible for causing the
skin ulcerations seen on fish. It is possible that several variants
of each type of toxin exist. Neither class has been isolated in
enough quantity to allow scientists to determine its chemical
structure.
A crucial step in evaluating a poison is determining how little
of it is necessary to cause sickness or, put another way, how
much of it is safe. This will not be known for pfiesteria until
the toxin is isolated. At the moment, scientists also do not know
what concentration of the organism in the water is hazardous.
"It is really critical to understand the `dose-response'
relationship," said John Ramsdell, a toxicologist at the
National Oceanic and Atmospheric Administration's marine toxins
program in Charleston, S.C. "What that will do is allow us
to determine the risk for individuals. Until we have that, most
everything will be anecdotal."
Anderson, the Woods Hole scientist, said the issue of marine toxins
and human health is a huge, but barely recognized, one in the
United States.
Virtually all 33,000 miles of Alaskan coastline have been closed
to shellfish harvesting for decades because there isn't the money
to do widespread monitoring of toxins. "Red tides" caused
by blooms of toxic microorganisms periodically close sections
of the East Coast from Maine to Florida.
"We have been trying for years to get the entire country
to take this toxic algae more seriously. All of a sudden pfiesteria
hits near Washington, and millions of dollars are flowing,"
Anderson said. "I used to joke that to get some attention,
we would have to turn the Reflecting Pool [on the Mall] red, and
this has just about done it."
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