Ciguatera, an elusive food poisoning carried by fish, has been confirmed in 16 cases from November 22 to December 20, according to the Ministry of Health and Seniors.

A further three people fell ill with ciguatera in January 2016 by eating portions of one fish, a ministry spokeswoman added, while the recent spate was traced back to seven separate fish exposures.

Ciguatera is rare in Bermuda, and there have been no other cases reported in the last five years, although the condition occurs in tropical fisheries worldwide.

The nerve toxin, which is not affected by cooking and cannot be readily detected, causes symptoms ranging from prickling sensations to muscle pains.

A local woman who fell ill last month along with several family members yesterday reported her symptoms abating — but said she was still subject to itches along with “hot and cold burning hands”.

Children and the elderly are often the most sensitive.

The poisons, which do not affect fish, come from reef plankton, and are concentrated as predatory fish feed on smaller species. The local cases have been confined to amber jacks bigger than 20lb, and large yellow jacks. Since jacks are migratory, research is required to determine if the ciguatera is local, or carried by fish from elsewhere.

“Common symptoms experienced in this outbreak include numbness, itching, burning and tingling in fingers, toes and around the mouth, joint and muscle pain, weakness and the reversal of hot and cold sensations,” the spokeswoman said — the last symptoms being “highly indicative” of ciguatera.

“Additional symptoms include gastrointestinal symptoms such as nausea, vomiting, abdominal cramping, and diarrhoea. Symptoms may begin as little as one hour after consuming toxic fish and can persist for an extended period of time. Symptoms may recur with greater severity if additional toxic fish is eaten. Most affected persons recover completely.”

Anyone suspecting ciguatera is advised see a doctor, and keep a frozen sample of the suspect fish.

“The Department of Environment and Natural Resources and the Department of Health are collaborating to develop a plan for broader testing of the local fish species that form the mainstay of our commercial and recreational fisheries,” the spokeswoman added.

Previous studies have found only one ciguatera-carrying plankton species in Bermuda, and the variety carries little to no toxin. More extensive field sampling is planned for the summer of 2017.