Surveillance systems to detect CFP ‘essential’ after diagnosis failure

By Joseph James Whitworth contact

- Last updated on GMT

Ciguatoxin retains toxicity regardless of freezing or cooking. This outbreak was linked to black grouper
Ciguatoxin retains toxicity regardless of freezing or cooking. This outbreak was linked to black grouper

Related tags: Health care

Food recalls are likely to be inefficient in response to Ciguatera fish poisoning (CFP) outbreaks, according to researchers.

They found surveillance systems detected an outbreak last year after patients sought medical attention but a diagnosis of CFP was not made.

The Florida Department of Health in Orange County (DOH-Orange) received a report in November 2014 describing paresthesias and numbness that suggested CFP, which had occurred on October 31, the day after eating two fish meals.

The same day, DOH-Orange interviewed the person and determined the illness met the CFP case definition. Five additional cases were identified with help from surveillance systems.

Failure to detect ciguatoxin in FDA-tested fish heads samples taken from the lot that five of six intoxicated patients ate is not inconsistent with the sporadic nature of disease occurrence, or the fact that not all fish of a given species or from a given location are toxic, found the outbreak review.

CFP is acquired by eating reef fish that have accumulated naturally occurring ciguatoxins found in several dinoflagellate (algae) species through their diet.

Toxin retention

Ciguatoxin retains toxicity regardless of freezing or cooking. There are no FDA-cleared or approved clinical tests for CFP.

Investigations at two restaurants, one grocery store, two fish distributors, and one fish supplier identified the outbreak source.

The six people with CFP had eaten black grouper at a local restaurant or from a grocery store; the fish was traced back to an international distributor.

No laboratory tests were ordered, and no medication was prescribed; the patients were discharged with diagnoses of gastroenteritis. 

“Although CFP is a reportable disease in Florida, none of the five patients who sought medical care received a diagnosis of CFP, nor was suspected CFP reported to DOH by health care providers,” ​said the report.

“Despite the fact that five of the six patients described in this report saw a health care provider, and at least four reported that they had eaten fish before becoming ill, the cases were only detected by DOH-Orange through an online self-reporting consumer complaint system and a syndromic surveillance system.”

Two outbreaks into one

Patients ranged in age from 36 to 64 years and four were male. All experienced paradoxical temperature perception, nausea, paresthesias, numbness, abdominal pain, diarrhea, arthralgias, and myalgias.

The black grouper appears to have originated from Mexico but it was not possible to determine whether the implicated filet and any of the fish heads came from the same fish.

No leftover fish from the meals that caused the illnesses was available for laboratory analysis and testing by FDA did not detect ciguatoxin.

Black grouper fish heads from the same lot that patients ate were collected from a grocery store.

During 2012–2014, 137 CFP cases were reported in Florida, 109 (80%) of which were initially identified by surveillance and consumer complaint systems, 19 (14%) by health care providers, and nine (7%) via other, non-described methods.

Researchers said syndromic surveillance systems capable of detecting CFP are essential public health tools to identify outbreaks and enhance investigations. 

“Medical and public health practitioners should be educated to inquire about recent fish consumption when evaluating patients with clinically compatible signs and symptoms to allow for prompt treatment, and report suspected CFP cases to public health authorities to facilitate source-food traceback efforts.  

“Public education on avoidance of consumption of relatively large predatory reef fish species known to be from ciguatoxic-endemic areas might reduce the risk for CFP.”

Related topics: Food Safety & Quality

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