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September 22, 1998, Tuesday

SECTION: Local; Pg. B1

LENGTH: 687 words

HEADLINE: FISH-KILLING MICROBES LINKED TO HUMAN SIGHT LOSS

BYLINE: Andrew Conte of the News staff

BODY:

A federal scientist has found preliminary evidence of long-term neurological damage from exposure to fish-killing microbes in North Carolina, but the symptoms have not been identified among people in contact with this year's high incidence of fish disease in the St. Lucie River and Indian River Lagoon. Fourteen North Carolina men infected by the microbe Pfiesteria piscicida had diminished ability to see contrasting patterns, said Kenneth Hudnell, a neurotoxicologist with the U.S. Environmental Protection Agency.

Previous studies found that exposure to Pfiesteria might cause short-term memory loss, confusion and headaches, but the new study is the first indication that exposure to the micro-organism can cause long-term effects. However, the finding could mean little for people who have come in contact with Cryptoperidiniopsis, a microbe blamed for causing fish disease in the St. Lucie River and Indian River Lagoon. Although similar, the two microorganisms, called dinoflagellates, might trigger different responses in humans, Hudnell said.

Since the outbreak of sick fish in March, five people on the Treasure Coast have been diagnosed with estuarine syndrome illness, a medical condition resulting from contact with water containing diseased fish. The symptoms were similar to those resulting from exposure to Pfiesteria, as well as extra sensitivity to light. In a test similar to the North Carolina study, one of the five people was tested for diminished ability to distinguish patterns, but the person had not developed the problem, said Dr. Ronald Frenkel, a Stuart ophthalmologist. Researchers plan to contact the other four to see whether they are willing to undergo the contrast sensitivity test, a simple procedure.

Although the Florida test did not produce a positive result, researchers familiar with human health effects related to sick fish outbreaks in Florida, North Carolina and Maryland are optimistic that Hudnell's finding could lead to better understanding in each of the places. "It gives us ... a new way to look at exposure," said Dr. Ritchie Shoemaker of Pocomoke City, Md., who diagnosed the five Treasure Coast cases. He said he hopes the study will lead to a qualitative test to evaluate people's exposure to water with diseased fish. Researchers still don't know why some exposed people show symptoms and others do not. "Some people may be exposed and have no symptoms at all," he said. "Some have symptoms that go away in a month and some have symptoms that don't go away at all after a few months. There are still some people who are sick four years after."

In the North Carolina study, Hudnell focused on two groups of fishermen: 22 who had spent considerable time in estuary waters where fish kills occurred and 20 who had stayed in coastal waters where exposure was less likely. Members of the first group had 30 percent reduction in their ability to see the contrast between dark and light bars in a pattern. Because the men did not have optic nerve damage, the effects probably were neurological, Hudnell said. He compared the effects with a contrast knob on a television set, which can make objects more or less difficult to distinguish. The health effects in the anglers were similar to those in people who have had long-term exposure to cleaning solvents and are a serious health risk, he said. "It takes them longer to see and react to visual stimuli," Hudnell said. "It puts them at increased risk for accidents." The contrast sensitivity test will be used in a regional study by the Centers for Disease Control and Prevention to look at possible associations between human health effects and Pfiesteria next year. The study will track 100 individuals who have been exposed to the microorganism and 100 people who have not been exposed. Last month, a study published in the medical journal Lancet found that 19 people exposed to Pfiesteria in Maryland showed attention and learning deficits compared with a control group. The longer the exposure at the time Pfiesteria was active, the more severe the problems appeared to be.