Residential and recreational acquisition of possible estuary-associated syndrome: a new approach to successful diagnosis and treatment.

Evidence suggests that the estuarine dinoflagellates, Pfiesteria piscicida Steidinger & Burkholder and P. shumwayae Glasgow & Burkholder, members of the toxic Pfiesteria complex (TPC), may release one or more toxins that kill fish and adversely affect human health. In the current study we investigated the potential for undiagnosed cases of possible estuary-associated syndrome (PEAS), as termed by the Centers for Disease Control and Prevention (CDC), in a population that had residential and/or recreational exposure to TPC-affected estuaries, but that did not have direct contact with fish kills or lesioned fish. Age-adjusted visual contrast sensitivity (VCS) was significantly lower and the presence of PEAS-associated symptoms was much higher in the estuary cohort (n = 77) than in combined-control cohorts (n = 87), one without exposure to bodies of water (n = 53) and one with exposure to marine waters (n = 34). In the estuary cohort, 37 individuals met the CDC case definition for PEAS and had significantly lower VCS than non-PEAS cases. The VCS improved and symptoms abated after 2 weeks of treatment with cholestyramine. Cholestyramine, the original drug approved for treatment of hypercholesterolemia, has previously been reported to enhance the elimination rates of a variety of toxins, presumably by interruption of enterohepatic recirculation through toxin entrapment in its polymeric structure and/or anion-exchange process. Control studies showed that repeated VCS testing alone did not improve VCS scores and that cholestyramine treatment did not affect VCS in patients with elevated cholesterol levels. These results suggested that a) susceptible individuals may acquire PEAS through residential and/or recreational contact with TPC-affected estuaries in the absence of an active fish kill; b) VCS is a useful indicator in PEAS diagnosis and treatment monitoring; and c) PEAS can be effectively treated with cholestyramine. Because the study did not use population sampling techniques, the results do not indicate PEAS prevalence. Furthermore, definitive diagnosis of PEAS and association with TPC toxin(s) must await identification of, and a serologic test for, the putative TPC toxin(s).