Pfiesteria complex organisms and human illness.

Pfiesteria piscicida and look-alike dinoflagellates are collectively known as Pfiesteria complex organisms (PCOs). The purposes of this paper are to evaluate the threat that PCOs pose to human health and to clarify some common misconceptions concerning these organisms. References about P piscicida and PCOs were identified and reviewed using MEDLINE, Sea Grant databases, and other sources obtained from various Internet sites. Researchers exposed to aerosols of water containing P piscicida in a laboratory setting exhibited a variety of symptoms, including reversible cognitive impairment and loss of short-term memory. This led to multiple biologic, animal model, and epidemiologic studies that are reviewed and discussed. Exposure to P piscicida and possibly other PCOs can cause human illness. Until further isolation and purification of toxins from PCOs allows for development of tests to detect these toxins, predicting and documenting toxic PCO fish kills as well as potential PCO-related illness will be difficult.