A distinctive pattern of memory loss was the thread that enabled a medical team to establish for the first time a probable connection between human illnesses and the microorganism that has been killing fish by the thousands.
Doctors who investigated reports of ailments among people who worked on the Pocomoke River said yesterday that they had been skeptical of finding a link between the complaints and Pfiesteria piscicida.
But after subjecting 13 people to hours of physical and psychological testing, doctors were startled to find that most had trouble remembering simple details of everyday life: errands, groceries, phone numbers, tasks just completed.
"What all these people had in common was the Pfiesteria exposure, and all of them had this common problem," said Dr. J. Glenn Morris, a University of Maryland infectious disease specialist who led the team.
"We have for the first time clearly documented there is a pattern of health problems with these people who had heavy exposure (( to water containing this toxin."
Morris said the findings must still be confirmed by additional test results and by studies involving larger numbers of people. Scientists also hope to learn more from people reporting symptoms to a hot line that began taking calls yesterday.
The line, which 20 people called yesterday, is answered between 8 a.m. and midnight. The toll-free number is 1-888-258-8989.
"Medically, we had been skeptical. Now the situation has been reversed," said Maryland Health Secretary Martin P. Wasserman, who assembled the team.
Its findings suggest that the organism is a neurotoxin -- harming pathways in the brain that control memory. Doctors believe that the symptoms are temporary.
So far, the team says, the most telling feature is that subjects had much greater trouble remembering things than would be expected for people of similar age and occupation in the general population.
Tommy East, a waterman who lives in Crisfield, was one of those tested.
"You just forget what you're doing," East said yesterday from Shelltown. "There's been a lot of things I forgot that I have done."
The team's report was released Friday by Gov. Parris N. Glendening, who simultaneously closed a 7-mile stretch of the ,, lower Pocomoke River -- barring watermen, skiers, boaters and everybody else.
Yesterday on the lower Pocomoke, the fish kill continued upstream from Shelltown, although it appeared to be dissipating.
"The bloom is probably over for this spell," said Jack Howard, a waterman hired by the Department of Natural Resources to help monitor the river for Pfiesteria. "It might be gone by tomorrow."
A DNR helicopter searched for fish kills and any boats violating the order closing the river from its mouth to Powell Wharf Road. "Early this morning we told two boats to leave the river," said Sgt. Bernie Clipper of the DNR police.
Watermen who work along that portion have been complaining of various ailments since last autumn, when fish with bloody lesions first began appearing in the area. The complaints ranged from respiratory illnesses that took months to cure to open sores much like those on the fish they were catching. Some also complained of confusion and memory loss.
In some ways, the medical team's conclusions felt like vindication to watermen and families who had felt the state -- and even doctors -- were dismissing their complaints.
"I'm just as happy as a bumblebee in a flower patch," said Howard.
Dr. JoAnn Burkholder, a scientist at North Carolina State University who discovered Pfiesteria, said she wasn't surprised by the findings in Maryland. In 1993, she and colleagues suffered memory loss, respiratory problems and other ills after working with laboratory samples of Pfiesteria.
One man, a 35-year-old associate who had studied organic chemistry, reverted to a 7-year-old's reading level for about three months.
Burkholder has examined North Carolina watermen who have reported ailments that she believes stemmed from their contact with Pfiesteria-polluted waters. But she said North Carolina officials remain in a state of denial, and credits Maryland officials with moving quickly to acknowledge it.
"The Maryland work says now that this is so probable that someone will have to disprove it rather than prove it," Burkholder said. "That is a major milestone."
Morris said he believed just two weeks ago that the investigation would prove as thorny as finding the truth behind gulf war syndrome.
In that matter, scientists have been stymied in their efforts to prove -- or disprove -- a connection between illnesses and veterans' exposure to a variety of substances including oil fires, nerve gas and immunizations. One problem is that complaints are diverse, ranging from chronic fatigue to joint pain, headaches and depression.
But Morris said he was surprised how quickly a pattern emerged in the Pfiesteria investigation, which also involved four state employees who had done water sampling on the Pocomoke.