Pfiesteria Complex Organisms PCOs

Agents: Pfiesteria piscicida and 10-12 related dinoflagellates, all collectively known as Pfies-teria-Complex Organisms (PCOs). Toxins: (1) Water-soluble, ichthyotoxic neu-rotoxin; (2) lipid-soluble necrotoxin causing "punched out" necrotic fish lesions. LD50: No human fatalities, but neurotoxin is always lethal in fish.

Mechanism: Like brevetoxins, aerosolized neu-rotoxins force open Na channels, prolonging depolarization, especially in brain. Vectors: No seafood vectors; does not enter human seafood chain.

Incubation: 2 weeks after aerosol exposures to PCO toxins.

Symptoms: Confusion and/or memory loss and more than three (3) of the following symptoms: headache, skin rash, conjunctivitis, upper respiratory tract (URT) irritation and sensitivity, muscle cramps, and any type of gastrointestinal symptoms (abdominal cramps, nausea, vomiting, usually no diarrhea). Diagnosis: By history of aerosol exposure only. Treatment: Supportive only. Prognosis: Symptoms resolve in 1-2 weeks. Prevention: Avoid swimming, skiing, fishing, and all other recreational exposures in all waters with extensive fish kills; citizens should immediately report large fish kills to state environmental and public health agencies and to the CDC.

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