For David Oldach, crossing the Bay Bridge was usually a homecoming — but not today. He grew up in the Eastern Shore town of Salisbury, but today he was driving down to West Ocean City and Chincoteague, oceanside fishing ports where he used to work on scallop boats and ocean clam boats. Slim, articulate, and confident, Oldach was an infectious disease doctor who had talked his way onto the Pfiesteria medical team, and today he had Lynn Grattan riding shotgun in his Jeep Cherokee hauling her briefcase of tests. Oldach knew there were holes in the medical team's findings and he was hoping they could patch one of them.

Thirteen people showing memory problems on three tests taken on one day. Could these medical findings be a fluke? Was this enough evidence to close down a river, kick off a media blitz, and perhaps cause a panic? Could the science case hold up?

Here was one hole in their science: The findings about Pocomoke watermen had no control group study to back it. Perhaps the memory problems among watermen were not caused by a biotoxin. Perhaps commercial fishermen everywhere — not just watermen on the Pocomoke — were more likely to score poorly on tests for memory and mental agility. Perhaps they were affected by antifouling paints or diesel fumes or long days on the water. Perhaps they were simply poor test takers.

Oldach was headed for West Ocean City because he thought they could find the perfect control group. Dozens of commercial fishermen motored out everyday headed out for fishing waters well beyond the beaches and boardwalks and high-rise hotels of Ocean City. He knew from experience they worked as hard as watermen on the Pocomoke — but had no exposure to the Pocomoke or other estuarine waters with Pfiesteria-like dinoflagellates that might cause memory problems. Screening a group of these fishermen could verify (or falsify) their findings about a Pfiesteria-connected health problem.

To test fishermen, they first had to find them. When they drove up to the work docks at West Ocean City, Grattan, at least, was still nervous. They had no hotel rooms booked and no testing appointments lined up. What they had was Oldach's optimism and chutzpah. When the boats pulled up, he began walking the docks asking fishermen, most of them back from a long work day, if they could hang around for another hour or more. He wanted them to sit for a medical interview evaluating their medical status and then take neuropsychological tests measuring their mental status.

His straightforward approach worked. None of the fishermen were happy about the Pfiesteria controversy, but nearly all of them agreed to testing. Grattan was able to give eight ocean fishermen the same screens and mind games she gave the Pocomoke watermen. While the tests were the same, the results were different. The ocean fishermen scored remarkably well on the same tests that befuddled the Bayside watermen. Something peculiar to the Pocomoke must be causing memory loss among watermen and state workers.

With findings from the control study, the case for Yes, the science case for a Pfiesteria health syndrome, got a little stronger. officials were soon listing 31 diagnosed cases.

There were other holes in the science case: Where in the Bay was Pfiesteria living? What kind of toxin, if any, did it make? What was the route of exposure? Were there other toxic-forming dinoflagellates out there? Elsewhere in the country, other dinoflagellates were known to cause devastating diseases like Paralytic Shellfish Poisoning, Neurotoxic Shellfish Poisoning and, more recently, Amnesiac Shellfish Poisoning. Was Pfiesteria the new toxic threat?

Flush with that first excitement of a new discovery, the medical team went after the illness question with high hopes and research smarts. Led by Morris, Oldach, and Grattan, the team went into the medical tool box of the time and pulled out a number of techniques, some classic, some cutting edge. In addition to control studies, they tried brain scans, rat studies, cohort studies, and a new, high-tech gene probe. Not every question, they found, had an answer.

Development of the gene probe by Oldach was an early breakthrough. His technique could find Pfiesteria and find it fast, primarily by detecting its DNA fingerprint in water and sediment. As a medical researcher at the Institute of Human Virology, a high-tech department of the University of Maryland Biotechnology Institute, Oldach was familiar with new techniques that doctors were using to track fast-changing viruses in the human body. By collaborating with aquatic biologists in Maryland, North Carolina, and Norway, he was able to adapt these medical techniques and create a probe that marine scientists could use to track dinoflagellates in water bodies like the Chesapeake Bay.

The probe produced an immediate and practical payoff: Pfiesteria could now be identified in hours instead of weeks. When state workers began using it, however, they came up with an unwelcome payoff. They began detecting the DNA of Pfiesteria nearly all over the Bay.

That discovery raised the stakes for everybody. Pfiesteria was not some rare, perhaps alien species that somehow snuck into the Pocomoke and a few distant Eastern Shore rivers. The organism was clearly at home all around the Chesapeake. What showed up in the water down in the Pocomoke could show up in Baltimore Harbor.