24 Fall Sick From Toxic Fish Caught Near Baja : Poison: None of the tainted fish caught 450 miles south of San Diego are in the commercial marketplace, health department says.

Twenty-four persons have fallen ill from California’s first documented cases of ciguatera poisoning from fish caught off the coast of Baja California, the San Diego County Department of Heath Services announced Friday.

None of the tainted fish, a member of the grouper family, are in the commercial marketplace and the only persons who might be affected are those who fish near Alijos Rocks, an island situated about 450 miles south of San Diego and 100 miles off the coast of Baja California, said Paula Tanner, a county environmental health specialist.

She said the toxin cannot be detected by looking at the fish, smelling it or tasting it, and that cooking will not destroy the toxin.

Symptoms of the illness--which can vary widely from one person to the next--may include nausea, vomiting and diarrhea for up to 24 hours, and can affect the nervous system for up to a month. Those symptoms may include sensitivity to cold, temperature reversal in which, for instance, hot drinks feel cold and vice versa, painful tingling of the palms of the hands and soles of the feet, and diminished reflexes in the knee and heel.

Other symptoms may include an irregular or slow pulse and low blood pressure, difficulty walking, pain in the muscles and joints, dizziness and faintness.

Health officials say that while there is no known cure for the illness, many of the symptoms can be alleviated.

Among the 24 persons identified as having been poisoned, seven have recovered and the remaining 17 remain symptomatic and are expected not to recover for several weeks, Tanner said.

Each of the cases--which have affected one individual, two families and the crew of a commercial fishing boat on a recreational outing--have been traced to flag cabrilla fish, a grouper which weighs 2 1/2 to 3 pounds.

The flag cabrilla fish is not served in area restaurants and is seldom sold in fish markets because of its small size, Tanner said.

The source of the toxin is not known but is believed to come from microorganisms consumed by the fish, she said.