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NPS Arrowhead National Park Service
US Department of the Interior
Office of Public Health 1201 Eye Street, NW
Room 1131
Washington, DC 20005

Phone: 202-513-7215
Fax: 202-371-1349
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Office of Public Health - Pfiesteria Factsheet
Points Of Contact
(202) 513-7217
Assistant to Director for Science
(202) 513-7097
(505) 248-7806
Assistant to Director for Field Operations
(202) 513-7056
National Capitol Region
Northeast Region
(215) 597-5371
Southeast Region
(404) 507-5730
Mid-West Region
(402) 661-1718
Intermountain Region
(505) 988-6040
Pacific West Region
(510) 817-1375
Alaska Region
(206) 220-4270

Pfiesteria is a recently recognized organism first identified in 1991 in North Carolina and this summer in the Chesapeake Bay of Maryland and Virginia. It gained widespread publicity because of large fish kills and many fish developing open sores. It is a very complex organism that can behave both like a plant and an animal. It is a dinoflagellate similar to the marine organism that causes “Red Tide”. Under most conditions, it is innocuous. However, under conditions of high temperature, low dissolved oxygen and high nutrient loading, it produces a powerful toxin.

Human health complaints have occurred as a result of skin contact or inhalation of the toxin. This toxin is not contagious or infectious, and cannot be “caught” like a cold. Well-documented human health effects linked to Pfiesteria have occurred in laboratory conditions, where researchers were working with the organism in close proximity and in high concentrations.

Consistent complaints include memory loss, confusion and/or acute skin burning (on direct contact with water). Other frequent complaints are headache, skin rash, eye irritation, upper respiratory system irritation, muscle cramps and gastrointestinal tract irritation (nausea, vomiting, diarrhea and/or abdominal cramps).

Although there appears to be a causal relationship between Pfiesteria exposure in marine waters and health complaints, this relationship has not yet been verified. Never the less, given the concern raised by these reported health effects, we need to be prudent when potentially exposed to Pfiesteria toxin.

  • Do not to handle fish with lesions unless you have to. If it is necessary, wear impermeable gloves.
  • Avoid swimming or skiing in an area where a fish kill is occurring and/or fish with open lesions are being reported.
  • Because of the uncertainty of consumer health risks, you should take normal precautions and use common sense: never eat fish that exhibit evidence of sores or disease. Do not eat fish that seem diseased or dying when caught.
  • Consumers should completely cook finish and crabs. Normal precautions should be taken when eating raw shellfish.


1. “Pfiesteria Facts”, Bay Journal, Vol 7 (7), October, 1997, Chesapeake Information Management System. Chesapeake Bay Program.
2. “Pfiesteria piscicida, Frequently Asked Questions”, 1997 University of Maryland, School of Medicine, Department of Pathology, Aquatic Pathology Center
3. “Results of the Public Response Pfiesteria Workshop - Atlanta, GA, Centers for Disease Control and Prevention, Morbidity and Mortality Weekly Reports Vol. 46, No. 40, October 10, 1987, pp. 95.

Health Information, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Department of Health and Human Services.

If you have any questions, please contact your nearest Regional Point of Contact, park sanitarian or call WASO Public Health for more information.

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