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EPI and UVI Kick Off Ciguatera Fish Poisoning Monitoring

Warming ocean temperatures will bring a slew of environmental changes, and one negative consequence may be an increase in ciguatera fish poisoning in people who dine on reef fish.

To counter an expected rise in cases in the Caribbean, the Emerging Pathogens Institute (EPI) at the University of Florida is teaming up with partners in the U.S. Virgin Islands to launch a Ciguatera Fish Poisoning Monitoring project. Partners include the University of the Virgin Islands, the University of Maryland School of Medicine, Woods Hole Oceanographic Institution, Schneider Regional Medical Center on St. Thomas, the Food and Drug Administration Dauphin Island Lab and Florida State University.

Ciguatera poisoning is caused by a chemical assemblage of naturally-occurring toxins, called ciguatoxins, which are produced by microscopic photosynthetic organisms that live on seaweed and other surfaces within reef communities. When herbivorous fish eat seaweed or algae, they consume the organisms too, and the ciguatoxins accrue in the fish's flesh.

The toxins build up over time in predatory reef fish that feed higher up the food chain. People who rely on reef fish as a staple protein in their diet are at risk for contracting ciguatera poisoning. It is thought that climate change and warming oceans will trigger an increase in harmful algal blooms, with an associated uptick in cases of ciguatera fish poisonings in people who eat fish that feed at affected reefs.

A news conference announcing the start of the Ciguatera Fish Poisoning Monitoring project, and providing more details, will be held in Chase Auditorium (Business building room 110) on the St. Thomas campus of the University of the Virgin Islands on Friday, Dec. 4 at 11 a.m. EPI director Dr. Glenn Morris, will give a short presentation on the project, and there will be time for questions. Dr. Don Anderson of the Woods Hole Oceanographic Institution will also speak about the Gambierdiscus cells that are the source of the ciguatera toxin. Dr. Clayton Wheatley, the chief Emergency Medicine physician at the Schneider Regional Medical Center, will discuss poisoning symptoms.

The study includes reef surveys to better understand why and where Gambierdiscus occurs, and what causes its persistence or overabundance in certain marine communities. For example, warmer ocean temperatures may provide environmental conditions conducive to its growth. But human-caused reef disturbances such as dredging, freshwater runoff, sewage pollution and ship groundings may also play a role in increasing the abundance or distribution of Gambierdiscus. Environmental factors can also alter the patterns of ciguatera fish poisoning, such as pollution and reef damage from storms or coral beaching. Monthly surveys will target two sites south of St. Thomas, an area known to shelter fish that produce ciguatera fish poisoning and fish will be tested for detection of internal toxins.

On land, project staff will work with emergency room doctors at the Schneider Regional Medical Center to track cases of ciguatera poisoning in people admitted for treatment. Staff will also survey local residents and tourists for incidences of ciguatera poisoning to capture cases where people may not have sought medical treatment. The goal of these efforts is to establish the "normal" background levels of ciguatera poisoning, so as to discern if the rates are increasing and what environmental factors are correlated.

Reef fish known to be potential carriers of ciguatoxins include: barracuda, black grouper, blackfin snapper, cubera snapper, dog snapper, greater amberjack, hogfish, horse-eye jack, king mackerel, and yellowfin grouper, according to the CDC.

Classic symptoms of ciguatera poisoning appear within hours to a few days after eating infected fish, and they include electric-shock-like or painful sensation upon exposure to hot and cold, as well as nausea or vomiting. Neurologic symptoms such as intense itching and tingling fingers or toes are also typical. Treatments are available, and the symptoms may pass within a few days to six months.

Ciguatera poisoning is an under-reported public health problem. Some scientists estimate that there are 50,000 to 500,000 poisonings globally each year. In the Virgin Islands and Puerto Rico, it's thought that as many 20,000 to 40,000 illnesses occur annually. The annual incidence rate may approach 10 percent of local island populations. Unfortunately, ciguatera fish poisoning may disproportionately affect certain demographic groups, with subsistence fishermen more susceptible.

Lessons from French Polynesia show a strong correlation between warming ocean waters and an uptick in ciguatera fish poisoning in people. However, data are scarce for the Caribbean. And because the effects of global climate change will vary regionally, the EPI and its partners believe that it is important to get ahead of this problem and better understand the regional ocean ecosystem in the Caribbean in order to predict and understand how ciguatera fish poisonings may change in the future.

Ciguatera poisoning is a major public health problem in the Virgin Islands, Puerto Rico and the Florida Keys. It is also problematic in Hawaii and island protectorates in the South Pacific.

The EPI and its partners desire a high level of communication about this project with local stakeholders, including: residents, fishermen, medical professionals and government officials. All those who experience symptoms that may be ciguatera-related are urged to contact their medical professionals so the team can register the incident and obtain data about the source of the fish, its toxicity and the nature of the illness. The public, stakeholders and local media are encouraged to attend the news conference.

For news conference logistics:
University of the Virgin Islands: Patrice Johnson (Director of Public Relations, Univ. of Virgin Islands):, (340) 693-1058.

For research/project questions:
UF/Emerging Pathogens Institute: Dr. Morris (Principal Investigator),
(352) 273-7526

For medical questions:
Schneider Regional Medical Center: Sam Topp, (340) 776-8311 ext. 2315