Ciguatera fish poisoning

Ciguatera fish poisoning (CFP), also known as ciguatera, is a foodborne illness caused by eating tropical reef fish contaminated with ciguatoxins.<ref>Template:Cite journal</ref><ref name="Yellow2018" /> Such individual fish are said to be ciguatoxic. Symptoms may include diarrhea, vomiting, numbness, itchiness, dysesthesia, sensitivity to hot and cold, dizziness, and weakness with lethargy.<ref name="Fri2017" /><ref name="Yellow2018" /> The onset of symptoms varies with the amount of toxin absorbed. If a large quantity of toxins is consumed, symptoms may appear within half an hour. At lower amounts, symptoms may take a few days to appear.<ref name="FAO2004" /> Diarrhea may last up to four days.<ref name="Fri2017" /> Symptoms may last a few weeks to a few months.<ref name="FAO2004" /> Heart problems such as slow heart rate and low blood pressure may occur.<ref name="Yellow2018" />

The specific toxins involved are the ciguatoxins and maitotoxin.<ref name=Yellow2018/> They are made by a small marine organism, Gambierdiscus toxicus, that grows on and around coral reefs in tropical and subtropical waters.<ref name=Yellow2018/> These are eaten by herbivorous fish which in turn are eaten by larger carnivorous fish.<ref name=Yellow2018/> The toxins become more concentrated as they move up the food chain.<ref name=FAO2004>Template:Cite book</ref> The fish most often implicated include barracuda, grouper, moray eel, amberjack, sea bass, and sturgeon.<ref name=Yellow2018/> Diagnosis is based on a person's symptoms together with having recently eaten fish.<ref name=Fri2017/> If a number of those who eat the same fish develop symptoms the diagnosis becomes more likely.<ref name=Fri2017/> If some of the fish they had previously eaten is available this can also be tested to confirm the diagnosis.<ref name=Fri2017/>

Preventive efforts include not eating reef fish, not eating high-risk fish such as barracuda, and not eating fish liver, roe, or fish heads.<ref name=Yellow2018/> Ciguatoxin has no taste or smell, and cannot be destroyed by conventional cooking.<ref name=Yellow2018/> There is no specific treatment for ciguatera fish poisoning once it occurs.<ref name=Yellow2018>Template:Cite webTemplate:PD-notice</ref> Mannitol may be considered, but the evidence supporting its use is not very strong.<ref name=Fri2017>Template:Cite journal</ref> Gabapentin or amitriptyline may be used to treat some of the symptoms.<ref name=Yellow2018/>

In 2017, the United States Centers for Disease Control (CDC) estimated that around 50,000 cases occur globally each year.<ref name=Yellow2018/> Other estimates suggest up to 500,000 cases per year.<ref name=Fri2017/> The risk of death from poisoning is less than 1 in 1,000 according to the CDC.<ref name=Yellow2018/> It is the most frequent seafood poisoning.<ref name=FAO2004/> It occurs most commonly in the Pacific Ocean, Indian Ocean, and the Caribbean Sea between the latitudes of 35°N and 35°S.<ref name=Yellow2018/> The risk of the condition appears to be increasing due to coral reef deterioration and increasing trade in seafood.<ref name=Yellow2018/> Descriptions of the condition date back to at least 1511.<ref name=FAO2004/> The current name, introduced in 1787, is of Cuban Spanish origin and originally referred to the gastropod Cittarium pica.<ref name=FAO2004/>

Signs and symptoms

Hallmark symptoms of ciguatera in humans include gastrointestinal, cardiovascular, and neurological effects.<ref name=Isbister-2005>Template:Cite journal</ref><ref name=uhm>Template:Cite journal</ref> Gastrointestinal symptoms include nausea, vomiting, and diarrhea, usually followed by neurological symptoms such as headaches, muscle aches, paresthesia, numbness of extremities, mouth and lips, reversal of hot and cold sensation,<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> ataxia, vertigo, and hallucinations.<ref name=Swift-1993>Template:Cite journal</ref><ref name=uhm /> Severe cases of ciguatera can also result in cold allodynia, which is a burning sensation on contact with cold.<ref name=Isbister-2005 /> Neurological symptoms can persist and ciguatera poisoning is occasionally misdiagnosed as multiple sclerosis.<ref>Template:Cite journal</ref> Cardiovascular symptoms include bradycardia, tachycardia, hypotension, hypertension, orthostatic tachycardia, exercise intolerance, and abnormal electrocardiograms.<ref>Template:Cite journal</ref> Death from the condition can occur, but is very rare.<ref name=Telegraph-2016-10-13 />

Dyspareunia and other ciguatera symptoms have developed in otherwise healthy males and females following sexual intercourse with partners suffering ciguatera poisoning, signifying that the toxin may be sexually transmitted.<ref>Template:Cite journal</ref> Diarrhea and facial rashes have been reported in breastfed infants of poisoned mothers, suggesting that the polyether toxins partition into breast milk.<ref>Template:Cite journal</ref>

The symptoms can last from weeks to years, and in extreme cases as long as 20 years, often leading to long-term disability.<ref>Template:Cite journal</ref> Most people do recover slowly over time.<ref>Template:Cite journal</ref>

Cause

Gambierdiscus toxicus is the primary dinoflagellate responsible for the production of a number of similar polyether toxins, including ciguatoxins, maitotoxin and possibly palytoxin.<ref name=Identifying>Faust, MA and Gulledge RA. Identifying Harmful Marine Dynoflagellates. Smithsonian Institution, Contributions from the United States National Herbarium. Volume 42:1-144. 2002.</ref><ref name=WHOI>National Office for Harmful Algal Blooms, Ciguatera Fish Poisoning. Woods Hole Oceanographic Institution.</ref> Other dinoflagellates that may cause ciguatera include other Gambierdiscus species and members of the genera Fukuyoa and Ostreopsis.

Diagnosis

Diagnosis is based on a person's symptoms together with having recently eaten fish.<ref name=Fri2017 /> If a number of those who eat the same fish have symptoms the diagnosis becomes more likely.<ref name=Fri2017 /> If some of the fish they had previously eaten is available this can also be tested to confirm the diagnosis.<ref name=Fri2017 /> Other potential causes such as paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), scombrotoxin fish poisoning, and pufferfish poisoning should be excluded.<ref name=Fri2017 />

The reversal of hot and cold sensations is an occasional symptom of CFP that may help differentiate it from norovirus.<ref>Template:Cite journal</ref>

Treatment

There is no known effective treatment or antidote for ciguatera poisoning. The mainstay of treatment is supportive care. There is some evidence that calcium channel blockers like nifedipine and verapamil are effective in treating some of the symptoms that remain after the initial sickness passes, such as poor circulation and shooting pains through the chest. These symptoms are due to vasoconstriction caused by maitotoxin.<ref name=uhm /><ref>Template:Cite book</ref><ref>Template:Cite web</ref><ref>Template:Cite book</ref> Ciguatoxin lowers the threshold for opening voltage-gated sodium channels in synapses of the nervous system. Opening a sodium channel causes depolarization, which could sequentially cause paralysis, heart contraction, and changing the senses of hot and cold. Some medications such as amitriptyline may reduce some symptoms, such as fatigue and paresthesia,<ref>Template:Cite journal</ref> although benefit does not occur in every case.<ref>Template:Cite journal</ref>

Mannitol

Mannitol was once used for poisoning after one study reported symptom reversal.<ref name=uhm /><ref>Template:Cite journal</ref> Follow-up studies in animals<ref>Template:Cite journal</ref> and case reports in humans<ref>Template:Cite journal</ref> also found benefit from mannitol. However, a randomized, double-blind clinical trial found no difference between mannitol and normal saline.<ref>Template:Cite journal</ref> Despite this its use may still be considered.<ref name=Fri2017 />

Epidemiology

The current estimated global incidence annually is 20,000 to 50,000 people, though a large number of cases are believed to go unreported.<ref name="UpToDate 06-04-2015">Template:Citation</ref>

Due to the limited habitats of ciguatoxin-producing microorganisms, ciguatera is common only in subtropical and tropical waters, particularly the Pacific and Caribbean, and usually is associated with fish caught in tropical reef waters.<ref name=Isbister-2005 /> Exportation of reef fish, as well as tourism, often account for cases that develop in other regions.<ref name="UpToDate 06-04-2015"/>

Ciguatoxin is found in over 400 species of reef fish. Avoiding consumption of all reef fish is the only sure way to avoid exposure.<ref name=Schep>Template:Cite journal</ref> Imported fish served in restaurants may contain the toxin and produce illness which often goes unexplained by physicians unfamiliar with the symptoms of a tropical toxin.<ref name=Schep /><ref>Template:Cite journal</ref> Ciguatoxin can also occur in farm-raised salmon.<ref>Template:Cite journal</ref> Furthermore, species substitution, labeling a reef fish as a non-reef fish at restaurants and retail, can complicate efforts by consumers to avoid ciguatera.Template:Citation needed

20th and 21st centuries

• In 1994, Nobel-Prize winning novelist Saul Bellow nearly died from ciguatera after eating red snapper on vacation in St. Martin, fictionalized in his last novel Ravelstein.<ref>Leader, Zachary, The Life of Saul Bellow: Love and Strife 1965-2005, p. 528.</ref>
• In 2007, ten people in St. Louis, Missouri developed the disease after eating imported fish.<ref>Template:Cite web</ref>
• In February 2008, the U.S. Food and Drug Administration (FDA) traced several outbreaks to the Flower Garden Banks National Marine Sanctuary in the northern Gulf of Mexico, near the Texas–Louisiana shoreline. The FDA advised seafood processors that ciguatera poisoning was reasonably likely to occur from eating several species of fish caught as far as Template:Convert from the sanctuary.<ref>Template:Cite press release</ref>
• From August 2010 to July 2011, there were eight outbreaks of ciguatera fish poisoning in New York City. Outbreaks were linked to barracuda and grouper purchased at a fish market in Queens, New York.<ref>Template:Cite journal</ref>
• In the first quarter of 2012, two restaurants in Lanzarote, Canary Islands are thought to have been the source of ciguatera poisoning, leading to new fishing regulations issued 18 April 2012. The first outbreak was reported in February 2012. Diners suffered with vomiting, diarrhoea and abdominal pain several hours after eating amberjack. The second case was in early April affecting six people who live in Lanzarote and had all eaten amberjack at a local restaurant.<ref>Template:Cite news</ref>
• In March 2014, nine people were hospitalised near Macksville, New South Wales, Australia after a recreational fisherman caught a Template:Convert Spanish mackerel (Scomberomorus commersoni) off Scotts Head (NSW) and then shared it among his friends and family.<ref>Template:Cite news</ref>
• In April 2015, fourteen crew members of a potash ship were hospitalized in Saint John, New Brunswick, Canada after consuming tropical fish obtained from international waters.<ref>Template:Cite news</ref> After the incident, Marine Catering Services issued a reminder to seafarers that the UK Food Act makes it illegal for crews to fish for food from their vessels.<ref>Template:Cite news</ref>
• In September 2016, a British holidaymaker died while on honeymoon in Mexico after consuming fish contaminated with the algae that causes ciguatera poisoning.<ref name=Telegraph-2016-10-13>Template:Cite newsTemplate:Cbignore</ref>
• During October 2016, more than 100 people suffered from ciguatera poisoning after eating fish heads supplied by an export firm in Mangalore, India.<ref>Template:Cite news</ref>

History and folklore

Ciguatera was first described by one of the surgeon's mates, William Anderson, on the crew of Template:HMS in 1774.<ref>Template:Cite news (The New York Times incorrectly gives William Anderson's first name as John.)</ref>

Researchers suggest that ciguatera outbreaks caused by warm climatic conditions in part propelled the migratory voyages of Polynesians between 1000 and 1400 CE.<ref>Template:Cite journal</ref><ref>Template:Cite news</ref>

Folk tales

Template:More citations needed section In Northern Australia, where ciguatera is a common problem, two different folk science methods are widely believed to detect whether fish harbor significant ciguatoxin. The first method is that flies are supposed not to land on contaminated fish. The second is that cats will either refuse to eat or vomit/display symptoms after eating contaminated fish.

On Grand Cayman and other islands the locals will test barracuda by placing a piece of the fish on the ground and allowing ants to crawl on it. If the ants do not avoid the flesh and will eat it, then the fish is deemed safe.Template:Citation needed

In Dominican Republic, another common belief is that during months whose names do not include the letter "R" (May through August), it is not recommended to eat certain kinds of fish, because they are more likely to be infected by the ciguatera toxin.

The validity of many of these tests has been scientifically rejected.<ref>Template:Cite book</ref>

Folk remedies

Leaves of Heliotropium foertherianum (Boraginaceae) – also known as octopus bush – are used in many Pacific islands as a traditional medicine to treat ciguatera fish poisoning. Senescent octopus bush leaves contain rosmarinic acid and derivatives, which are known for their antiviral, antibacterial, antioxidant, and anti-inflammatory properties.<ref>Template:Cite journal</ref> Rosmarinic acid may remove the ciguatoxins from their sites of action, as well as being an anti-inflammatory.

An account of ciguatera poisoning from a linguistics researcher living on Malakula island, Vanuatu, indicates the local treatment: "We had to go with what local people told us: avoid salt and any seafood. Eat sugary foods. And they gave us a tea made from the roots of ferns growing on tree trunks. I don't know if any of that helped, but after a few weeks, the symptoms faded away".<ref>Template:Cite journal</ref>

Various Caribbean folk and ritualistic treatments originated in Cuba and nearby islands. The most common old-time remedy involves bed rest subsequent to a guanabana juice enema.Template:Citation needed In Puerto Rico, natives drink a tea made from mangrove buttons, purportedly high in B vitamins, to flush the toxic symptoms from the system.Template:Citation needed There has never been a funded study of these treatments. Other folk treatments range from directly porting and bleeding the gastrointestinal tract to "cleansing" the diseased with a dove during a Santería ritual.Template:Citation needed

See also

• Algal bloom
• Red tide
• Scombroid food poisoning
• Yessotoxin

References

• Ciguatera fish poisoning, CDC
• Template:Cite journal