Pfiesteria: A Mangy, Mysterious Microbe
By John P. Martin
The Cell from Hell?
Washingtonpost.com Staff Writer
Thursday, March 5, 1998
For an organism as small as a pinpoint and unnoticed for years, Pfiesteria is, quite simply, awesome.
In less than a decade, this single-cell life form has killed millions of fish, debilitated scores of humans, earned the nicknames "Cell from Hell" and "Toxic Ambush Predator," and spawned fierce debates pitting chicken farmers against environmentalists and scientists against politicians.
But for as much attention as Pfiesteria (pronouced fis-TEER-ee-a) has received since it was blamed for fishkills in North Carolina and Chesapeake Bay tributaries, scientists are still scraping for answers about the mangy microbe. Here's what they know, what they suspect and why the Pfiesteria focus is likely to continue:
What is Pfiesteria?
A dinoflagellate, or single-cell organism, that some say has at least 24 different life stages. Neither animal nor plant, Pfiesteria has shown the characteristics of both, which makes it hard to detect and led some to refer to it as a phantom cell.
When was it discovered?
Drs. JoAnn Burkholder and Ed Noga, researchers at North Carolina State University, are credited with first identifying the life form in 1991, after it was found in waters where massive fishkills occurred. They named the new genus Pfiesteria, after the late Dr. Lois Pfiester, a pioneer in the research of dinoflagellates. Pfisteria piscicida is the species name assigned to the specimen found in the North Carolina and Virginia rivers.
Where does it come from?
No one is sure of the history, but experts suspect Pfiesteria has been around for at least a decade. Only since its recent link to fishkills in mid-Atlantic and Gulf Coast states has it commanded such attention from scientists and the public.
Can it be detected by the human eye?
Rarely. The largest dinoflagellate spans only four-tenths of millimeter wide. Andrew Kane, associate director of University of Maryland's Aqautic Pathobiology Center, likened it to "a small dot drawn with the finest Pilot pen."
Under a microscope, a Pfiesteria cell might look like other dinoflagellates, resembling a slightly deflated beach ball wearing a belt and a tail. Or it could look like an amoeba, the seemingly undefined single-cell blob. At times, it assumes a cyst-like shape.
Is it dangerous?
Sometimes, Pfiesteria turns offensive, releasing toxins the same way a skunk might fire its foul-smelling spray when attacked or frightened. This tends to happen in the warmer seasons.
"It's not always toxic," says Dr. Diane Matuszak, the associate director of Maryland's Community and Public Health Administration. "Most of the time it [Pfiesteria] is there and just minding its own business."
What prompts the outbreak?
Researchers aren't sure -- hence, the stormy debate about how the government should react. Among the popular explanations is that Pfiesteria is stimulated toward toxicity when large amounts of nutrient-rich animal waste enter the water, the same waste that flows in runoff from farms where it is used as fertilizer. This view has led some to call for tougher regulations on farmers.
Others believe a large presence of fish might be enough to turn Pfiesteria toxic.
How does Pfiesteria harm the fish?
The most visible symptoms are lesions, or sores, and a "sloughing" of the fish's skin. Other effects include ulcers, listlessness, and disorientation. Though Pfiesteria has been blamed for killing millions of fish in North Carolina and Maryland, scientists haven't determined exactly why they die.
"We don't yet know what's killing them," Kane said.
Does it kill people?
It hasn't. Dozens of people -- usually fishermen, scientists or environmental officials who spend a lot of time around the water -- have been treated for illnesses after contact with toxic Pfiesteria-populated waters or fish. They've reported lesions, fatigue, dizziness, and disorientation. Duke University researchers reported Pfiesteria caused memory and learning impairment in rats.
Maryland medical officials who examined suspected victims of Pfiesteria-related illnesses last fall were struck by the victims' struggle to grasp and retain information. One compared it to a child who needs four or five spelling lessons to learn a word that his peers absorb in one.
Are the effects lasting?
It's too early to tell. Matuszak, the Maryland public health official, reported that follow-up tests of 13 suspected victims showed that in all but two, the symptoms seemed to have subsided. But officials aren't sure when the illnesses took hold, so it's hard to speculate on their duration.
Has it affected seafood?
Experts stress that there is no evidence thus far of a person suffering Pfiesteria-related illnesses after ingesting seafood.
Will the outbreaks continue?
Most think so. Maryland Gov. Parris N. Glendening, in his January State of the State address, warned that the state has to act or expect a yearly crisis on the waters. "In all likelihood," he said, "toxic Pfiesteria will return this summer."
What is being done to counter it?
Besides the pending legislative battles over regulation of livestock farmers, researchers are constantly studying Pfiesteria to determine ways to combat or stifle its toxicity. Scientists hope to soon develop a field probe that will enable them to monitor Pfiesteria at waterside. They also are enrolling people likely to come in contact with such waters as subjects for a long-term impact study
and encouraging those who spend a lot of time on Chesapeake tributaries to wear protective gear, such as gloves and a mask.
Environmental officials have increased monitoring on suspect waterways and established 24-hour Pfiesteria hotlines to field questions and reports of possible detections and to inform the public. Maryland's hotline is 888-584-3110. In Virginia, the number is 888-238-6154.
Will it get worse before it gets better?
No one is sure or will be sure until a scientific body of evidence is developed. Said Liz Kalinowski, spokeswoman for Maryland's Department of Natural Resources, "We're writing history right now."
© Copyright 1998 The Washington Post Company
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