Scientists who discovered pfiesteria in the early 1990s believe the one-celled organism has existed for centuries, usually remaining in a nontoxic form that feeds on bacteria and algae. Researchers suspect that animal wastes and fertilizers running from farms and poultry houses into the Pocomoke's slow-moving, shallow waters encourage the pfiesteria to multiply. The microorganism secretes a toxin that subdues the fish until it can attach to their skin and feed on their tissue and blood. Some 11,000 fish died in the river last month. A smaller kill, stretching over a larger area, occurred in the Pocomoke last week.
Scientists believe that the watermen are falling ill from direct contact with the water.
North Carolina health officials said Tuesday they will conduct a study similar to Maryland's, even though problems linked to pfiesteria, including rumors of human illnesses, have been going on there for several years. Pfiesteria has been blamed for killing millions of fish in North Carolina's Neuse and Pamlico rivers, both located off Pamlico Sound, which separates the state's mainland from the Outer Banks. Researchers at North Carolina State University suffered nausea, memory loss and respiratory problems while working with pfiesteria. One worker crawled out of the lab on his hands and knees, vomiting. His nephew, Tom, didn't have that luxury.