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