A federal health agency has told the nation's doctors to watch for problems that could be associated with Pfiesteria, the microorganism blamed for sickening Chesapeake Bay watermen two years ago. The alert from the Centers for Disease Control and Prevention was not prompted by a specific public health concern - it comes as warmer, drier weather arrives to make conditions ripe for Pfiesteria piscicida.

The CDC published a similar alert last year before the fishing and crabbing season began.

Pfiesteria piscicida is an estuarine dinoflagellate that has been associated with fish kill events in estuaries along the eastern seaboard and possibly with human health effects. CDC, in collaboration with other federal, state, and local government agencies and academic institutions, is conducting multistate surveillance, epidemiologic studies, and laboratory research for possible estuary-associated syndrome (PEAS), including possible pfiesteria-related human illness.

The surveillance system tracks PEAS rather than pfiesteria-related illness because a pfiesteria toxin(s) has not been identified and therefore a biomarker of exposure has not been developed. Detection of pfiesteria or fish with lesions in water has been used as evidence of suspected pfiesteria toxin(s). However, pfiesteria has been found in waters where there were no reports of harm to fish or persons. In addition, lesions on fish can result from various biologic, physical, and environmental factors. Therefore, detecting pfiesteria or observing fish with lesions may not be indicative of the presence of putative pfiesteria toxin(s).

PEAS surveillance criteria resulted from a series of CDC-sponsored multistate workshops and differ from criteria developed in 1997. Persons are considered to have PEAS if 1) they report developing symptoms within 2 weeks after exposure to estuarine water; 2) they report memory loss or confusion of any duration and/or three or more selected symptoms (i.e., headache, skin rash at the site of water contact, sensation of burning skin, eye irritation, upper respiratory irritation, muscle cramps, and gastrointestinal symptoms) that--with the exception of skin rash at the site of water contact and sensation of burning skin--persist for greater than or equal to 2 weeks; and 3) a health-care provider cannot identify another cause for the symptoms.

It is unclear whether persons exposed to pfiesteria while swimming, boating, or engaging in other recreational activities in coastal waters are at risk for developing illness. PEAS is not infectious and has not been associated with eating fish or shellfish caught in waters where pfiesteria has been found. However, persons should avoid areas with large numbers of diseased, dying, or dead fish and should promptly report the event to the state's environmental or natural resource agency. In addition, persons should not go in or near the water in areas that are closed officially by the state and should not harvest or eat fish or shellfish from these areas. Persons who experience health problems after exposure to estuarine water, a fish-disease event, or a fish-kill site should contact their health-care provider and state or local public health agency.

Several states have established PEAS information lines:

• Delaware, (800) 523-3336;
• Florida, (888) 232-8635;
• Maryland, (888) 584-3110;
• North Carolina, (888) 823-6915;
• South Carolina, (888) 481-0125;
• and Virginia, (888) 238-6154.