Food poisoning caused by fish infected with a toxin is on the rise, an ocean environmentalist warned yesterday.

Chris Flook said cases of ciguatera, which is triggered by the consumption of contaminated fish, had increased in Bermuda.

He added that warming of the oceans, which produces more algae, could be one reason for the increase in confirmed cases.

Mr Flook explained: “It’s always been here, but all of a sudden the climate is changing. The deck has been shuffled and we’re going to see a lot more of this.”

Mr Flook, who is boats and docks supervisor at the Bermuda Institute of Ocean Sciences and former head collector of marine specimens at the Bermuda Aquarium, Museum and Zoo, said that ciguatera appears to have become more common recently.

He explained that certain algae produces the toxin, which is eaten by small fish on the reef that are prey for larger fish eaten by humans such as amberjack, bonita and grey snapper. Other large fish, including barracuda and rockfish, are also possible carriers of ciguatera.

Mr Flook, a board member of the Ocean Support Foundation, said: “It’s also not just a warm-water problem. Ciguatera takes years to build up to toxic levels and won’t improve unless there is a cooling period of several years.

“In the meantime, large reef fish are a risk.”

The toxins do not affect fish, but humans can suffer vomiting, diarrhoea, muscle pain, and numbing and burning sensations. Other symptoms include a reversal of hot and cold sensations, and neurological problems.

Symptoms can start as early as an hour after consumption and can continue in episodes for years.

Department of Health figures released this month showed there have been 25 reported cases since the start of 2016.

Mr Flook said the symptoms were similar to food poisoning, but highlighted nerve damage — paresthesia — as characteristic of the disease.

Alex Hunter, dive safety officer and boats manager at Bios, added that offshore fish were not a problem.

He said: “It’s the predatory reef fish eating other fish that have consumed the algae. Fish with longer life cycles that accumulate the ciguatera are unsafe.”

Patrick Caton said he and his family contracted ciguatera about two weeks ago after they ate bonita caught inshore and bought from an island grocery store.

Mr Caton, from Smith’s and president of an engineering firm, said he, his wife and daughter became “violently ill” after eating fish he had bought the day before.

Mr Caton added: “Since then, we have been dealing with the neurotoxin aftereffects. We have symptoms such as reversal of hot and cold sensations, intense joint pain, and profuse itching.”

He said that their family doctor had prescribed drugs, but they had little effect on the symptoms.

The family was also told to drink a lot of fluids and let the infection run its course.

Mr Caton added: “My wife and daughter were out of work for a week. They were completely incapacitated by it.”

He said that the family still had symptoms and that he knows of other people who had become ill but not reported it.

Mr Caton added: “There’s no real warning. You’ll be fine for a couple of hours and suddenly feel it. “Consumption of various proteins can trigger it and for us, we cannot eat nuts.”

Mr Caton thanked the Department of Health for its fast reaction.

He said: “They have been following up and are looking into treatments.”

He said that the family would not eat fish for at least a year after their health scare.

Mr Flook explained that many people south of Bermuda did not eat large reef fish because of the risk of ciguatera and that many Bermudians were not aware of the disease.

Mr Flook said: “The last thing you want is to poke a hole at our traditional Bermuda fishery, but the proper information needs to get out. People need to be aware.”

He added that the specific reason for the increased presence of the toxin was not clear.

Mr Flook said: “There are all sorts of reasons ciguatera may be more prevalent. People always want simple answers, but there isn’t one.”

The Department of Health added that Bermuda has not had the ciguatera risk experienced by other warm-water countries.

A spokesman said: “Bermudians need to be more aware of ciguatera fish poisoning because we have seen cases in 2018, 2017 and 2016 linked with locally caught fish after decades of only sporadic cases.”

The department added that it aimed to “manage the risk by educating consumers, retailers and fishermen”.