Pfiesteria piscicida
Pfiesteria piscicida is a dinoflagellate that some researchers claim is responsible for many blooms in the 1980s and 1990s on the coast of North Carolina.  Pfiesteria is named after Lois Ann Pfiester (19361992), who researched dinoflagellates,  and its species name means "fish-killer." The organism was discovered by JoAnn Burkholder at North Carolina State University. An in-depth story of her and her discovery can be found in And the Waters Turned to Blood by Rodney Barker.

# Life Cycle
While some peer-reviewed research by government and university dinoflagellate experts has shown that its living cycle is extremely complex (these scientists have found at least 24 different stages, spanning from cyst to several amoeba-like forms), other peer-reviewed research by government and university dinoflagellate experts has found only a simple life cycle with no toxic amoebic stage.  The original research claimed that the organism apparently moves through many different stages as environmental conditions require. However, the new research from 2002 claims the cycle is much simpler than previously thought, and that the true Pfiesteria is non-toxic (see external links).

# Toxicity
Some peer-reviewed research based on advanced DNA-analyses shows that the organism lacks certain genetic structure to be capable of making the type of toxic proteins associated with typical dinoflagellates.  Researchers from the NOAA National Centers for Coastal Ocean Science, the National Institute of Standards and Technology, the Medical University of South Carolina, and the College of Charleston (S.C.) have formally isolated and characterized the toxin in the estuarine dinoflagellete Pfiesteria Piscicida and also have identified how the organism transforms from a non-toxic to toxic state. The findings were published in the peer-reviewed science journal, Environmental Science and Technology, on 11 January 2007.

# Human Health
Very little research on the human health effects of Pfiesteria toxins has been conducted. At a multi-state workshop at the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, at the end of September 1997, attendees agreed on clinical symptoms that characterize the adverse health consequences of exposure to Pfiesteria toxins. These clinical features include:
- memory loss
- confusion
- acute skin burning (on direct contact with water); or
- three or more of an additional set of conditions (headaches, skin rash, eye irritation, upper respiratory irritation, muscle cramps, and gastrointestinal complaints (i.e., nausea, vomiting, diarrhea, and/or abdominal cramps).
With these criteria and environmental qualifiers (e.g., 20% of a 50-fish sample, all of the same species, have lesions caused by a toxin), it is likely that Pfiesteria-related surveillance data can better track potential illnesses.
Pfiesteria toxins have been blamed for causing adverse health effects in people who have come in close contact with waters where this organism is abundant. Since June 1997, the Maryland Department of Health and Hygiene has been collecting data from Maryland physicians through a state-wide surveillance system on illnesses suspected of being caused by Pfiesteria toxin. As of late October 1997, illness was reported by 146 persons who had been exposed to diseased fish or to waters that were the site of suspected Pfiesteria activity. Many of these persons are watermen and commercial fishermen.
The strongest evidence of adverse human health effects so far comes from case studies of two research scientists who were both overcome in their North Carolina laboratory in 1993. They still complain of adverse effects on their cognitive abilities, particularly after exercising. Duke University Medical Center researchers conducted experiments on rats, which showed that the toxin appeared to slow learning but did not affect memory.