Scientists call residents of St. Thomas to gather information about fish poisoning

CHARLOTTE AMALIE, U.S.V.I. — Don’t disregard the next phone call from an unfamiliar number, because it might not be a telemarketer.

Researchers dialing residents of St. Thomas are trying to determine how many cases of fish poisoning occur during a lifetime among people living on the island.

“In the interviews we’ve already conducted, one in five people reported having an episode of ciguatera fish poisoning,” said Dr. J. Glenn Morris, Jr., a physician who has investigated rates of fish poisoning in the Virgin Islands since the 1980s. “But a significant number of people we talked to did not fully understand what ciguatera was or what causes it.”

The Ciguatera “Fish Poisoning” Monitoring project, or CaribCATCH (, is an ongoing three-year investigation into the effect of Ciguatera Fish Poisoning, or CFP.

When reef fish eat seaweed or algae, they can consume a marine algae known as Gambierdicus toxicus. This algae produces a toxin called ciguatoxin which becomes concentrated as it is passes up the food chain. Large, predacious fish such as barracuda have the greatest risk of toxicity, and scientists are also concerned that warming ocean temperatures increase the production of the toxin, which cannot be removed from fish by cooking or freezing.

Nausea, vomiting and diarrhea are some of the poisoning symptoms that occur within 24 hours of eating fish that have a high accumulation of ciguatoxin, followed by neurological symptoms such as numbness and tingling around the mouth and in the hands and feet. CFP can also cause “temperature reversal” in which hot foods taste cold and cold foods hot.

“Our most recent studies in the community indicate that more than a third of residents on the island question the safety of eating local fish and worry about the risk of fish poisoning,” said Dr. Lynn Grattan, a neuropsychologist with the University of Maryland School of Medicine and a researcher on the project. “And two-thirds of the people surveyed expect our doctors and scientists to succeed in finding a remedy for the problem.”

Poisoning symptoms may become more severe during a person’s lifetime as they continue to consume seafood carrying these toxins. In this next phase of telephone interviews, the researchers want to determine how many people have experienced CFP within the last five years.

Scientists also seek in-person interviews with adult residents of St. Thomas within four days of a person showing symptoms of poisoning. Volunteers will be compensated for their time, and medical information identifying participants will remain confidential. Volunteers who do not speak English may participate in the study if a friend or relative is available to translate during interviews.

CaribCATCH is a collaborative effort by investigators from the Center for Marine and Environmental Studies at the University of the Virgin Islands, St. Thomas, U.S.V.I.; the University of Florida Emerging Pathogens Institute; the University of Maryland School of Medicine; Woods Hole Oceanographic Institution; Schneider Regional Medical Center on St. Thomas; the U.S. Food and Drug Administration, Gulf Coast Seafood Laboratory, Dauphin Island, Alabama; and the Center for Ocean-Atmospheric Prediction Studies at Florida State University. This project is endorsed by the St. Thomas Fishermen’s Association and funded by the Centers for Disease Control and Prevention Climate Change Program.

To obtain more information, or to participate in the study after an acute episode of fish poisoning, please contact:
Margaret Abbott, 340-626-1698, or visit



Claudia Adrien

J. Glenn Morris, Jr.,, 352-273-7526