Warning after puffer fish linked to illnesses
Four cases of puffer fish poisoning in Minnesota in June came from eating dried puffer fish (also known as globefish), said the Morbidity and Mortality Weekly Report (MMWR) dated January 2.
Analysis showed it was highly contaminated with tetrodotoxin, and DNA analysis identified the fish as Lagocephalus lunaris, which is not allowed for import because naturally occurring toxin in its meat make safe preparation impossible.
Details remain unclear
Lack of product labeling and limited information from the two people who went to the emergency department means the exact source and how it was illegally imported is unclear.
The minimum lethal dose of Tetrodotoxin in an adult human is estimated to be 2–3mg. It is a heat-stable and acid-stable, nonprotein, alkaloid toxin found in many species of the fish family Tetraodontidae (puffer fish).
In June last year, two patients went to the Emergency Department in Minneapolis, Minnesota, with symptoms suggestive of tetrodotoxin poisoning (oral paresthesias, weakness, and dyspnea) after eating dried puffer fish purchased in New York City.
The patients said two friends who consumed the same fish had similar, although less pronounced, symptoms and had not sought care.
Investigation and analysis
The Minnesota Department of Health investigated to determine the source of the product and samples were sent to the Food and Drug Administration (FDA) Center for Food Safety and Applied Nutrition (CFSAN) for chemical and genetic analysis.
Seven of the dried, dressed fish were provided to hospital staff by the patients on arrival.
Samples were analyzed for tetrodotoxin by liquid chromatography-electrospray ionization-multiple reaction monitoring mass spectrometry.
All samples were found to contain significant concentrations with a mean of 19.8 ppm and a range of 5.7–72.3 ppm.
A 30 year old man went to the emergency department (ED) with his sister concerned they might have puffer fish poisoning, said the MMWR.
He said the dried fish described as globefish had been purchased from a street vendor in New York City and brought to Minnesota. Six hours before he came to the ED, he rehydrated some fish and ate it with his sister and two friends.
Thirty minutes after, he experienced perioral and tongue numbness, numbness and weakness in his extremities, extreme fatigue, and dyspnea.
Despite self-induced vomiting, his symptoms did not resolve, after which he went to the ED.
Both patients left against medical advice after overnight observation was recommended, said the MMWR.
The report said attempts were made to contact them by telephone but were not successful.
Visits to their home by public health officials and law enforcement found current residents who said they had no knowledge of the patients' whereabouts.
There was no labeling on the fish packaging, and all attempts to determine the source were unsuccessful.
Puffer fish consumption
The puffer fish (also called globefish, fugu, or blowfish) is highly prized in many Asian cultures and is consumed safely in some countries.
It is only safe with specialized training regarding which species to prepare and how because the concentration and tissue distribution of toxin varies greatly among the >180 known species.
The US does not provide this training and tetrodotoxin testing is not done often so only the frozen meat, skin, and male gonad from one species of puffer fish (Takifugu rubripes) from Japan, processed according to Japanese safety guidelines, is permitted to be imported a limited number of times per year, according to an FDA/Japanese government agreement from 1988.
The MMWR said because the fish were reportedly purchased in the US, they pose a substantial health hazard given the potency and high levels of the toxin found in them.
“However, because the two patients provided limited information, the source of the fish and how it was imported, in violation of current FDA import restrictions, could not be determined,” it said.
“Medical professionals who work in EDs or with persons from countries with a tradition of puffer fish consumption should be aware of this potential public health threat and collaborate with local poison centers and health departments to investigate any outbreaks of tetrodotoxin poisoning to determine the source of the product and block additional sales to prevent additional illnesses.”
