REVERSIBLE
ENCEPHALOPATHY FOLLOWING EXPOSURE
TO ESTUARINE WATES CONTAINING PFEISTERIA-LIKE ORGANISMS
Christopher T. Bever*,
Jr., Lynn M. Gratton, C. Civelek, D. Oldach, J.G. Morris
University of Maryland, Baltimore, MD
Pfeisteria piscicida and morphologically
related toxic dinoflagellates are responsible for fish kills in
estuary waters and may cause human illness. We examined 24
exposed symptomatic individuals from the eastern shore of the
Chesapeake Bay starting during the summer of 1997.
Neuropsychological testing showed a deficit in attention and
memory which correlated with the severity of exposure.
Fluorodeoxyglucose positron emission tomography showed
abnormalities in the inferior frontal and temporal lobes of the 8
most severely effected individuals. Follow-up evaluations showed
that the neuropsychological changes were reversible. These
results suggest that toxins produced by Pfeisteria and
Pfeisteria-like organisms may produce a reversible encephalopathy
involving areas of the brain involved in attention and learning.
These findings are provocative both in terms of their
neuropsychological implications and also in terms of potential
pathophysiological mechanisms. (Supported by the Maryland State
Health Department, the National Institute for Environmental
Health, the Center for Disease Control, and the Heinz Family
Foundation.)