Morning Report: 3/8/2013

Here’s Dr. Basile with today’s Morning Report!

Ciguatera Poisoning

– One of the most common reported forms of vertebrate fishborne poisonings in the United States (more than half of the reported cases)

– Endemic to warm-water, bottom-dwelling shore reef fish living between 35 degrees south and north latitude (Indian Ocean, South Pacific, Caribbean, etc.)

– 90% of all cases in the US are reported in Hawaii and Florida (May through August)

– Most common fish are barracuda, sea bass, parrot fish, red snapper, grouper, amber jack, kingfish, and sturgeon (large size)

– 50,000 cases are reported worldwide annually

– 5-70 cases per 10,000 in the US in ciguatera-endemic areas

– It is believed to be underreported (only 2-10% of cases reported)

Ciguatoxin:

– Found in blue-green algae, protozoa, and free algae dinoflagellates

– These are nutritional source for smaller herbivorous fish which are then the food source for the larger carnivorous fish–> increases the ciguatoxin concentrations

– Heat stable, lipid soluble, acid stable, odorless, and tasteless

Humans:

– Binds to voltage-sensitive sodium channels

– Causes a shift in the voltage dependence of channel activation, which opens the sodium channel leading to depolarization and action potentials (alters the voltage necessary for depolarization)

– One of the most potent natural substances known –> risk at low concentrations (0.08-0.1 ug/kg)

– Can be afflicted after eating fresh or frozen fish that was prepared by boiling, baking, frying, stewing, or broiling

– Appearance, taste, and smell unremarkable

Symptoms:

– Majority of symptomatic episodes begin 2-6 hours after ingestion, 75% within 12 hours and 96% within 24 hours

– Cardiovascular and Neurologic symptoms can last for several days to weeks

– No documented deaths in the US, but deaths have been reported internationally due to respiratory paralysis and seizures (Severe dehydration or cardiovascular collapse also possible)

– Eating fish organs or viscera is associated with more severe toxicity (higher concentration)

GI:

– Abdominal pain with cramps, nausea, vomiting, profuse watery diarrhea

– Develop within 6-24 hours and usually resolve spontaneously within 1-4 days

Cardiovascular:

– Bradycardia and orthostatic hypotension

Neurologic and Neuropsychiatric:

– Most characteristically is reversal of temperature discrimination

– Peripheral dyesthesias and paresthesias predominating

– Sensation of loose or painful teeth, watery eyes, tingling, metallic taste

– Numbness of tongue, lips, throat, and perioral area

– Myalgias, arthralgias, ataxia, weakness, vertigo, seizures, and visual disturbances

– Anxiety, depression, subjective memory loss, hallucinations, giddiness

Treatment:

– Supportive care (IVF, electrolyte replacement, pressors, mechanical ventilation)

– Elimination of toxin is accelerated if vomiting and diarrhea have occurred

– Bradycardia with atropine and/or cardiac pacing

– Mannitol for neurologic and muscular symptoms (Controversial if it works and can cause hypotension)–> thought to work by osmotic reduction of neuronal edema, scavenger of free radicals produced by the toxin, and reduction in the action of the toxin at the channel

– Inconsistency in the literature about the effectiveness, but there does seem to be some benefit

– Mannitol only recommended if fish was consumed within 48-72 hours

– For chronic symptoms SSRIs may help

– Should avoid dehydration for 3-6 months until all symptoms have resolved as dehydration worsens symptoms

– Should avoid alcohol and particular foods (caffeine, nuts, chicken, pork) for 3-6 months if exposure worsens or causes recurrence symptoms (based on anecdotal information)

References:

Centers for Disease Control and Prevention Cluster of ciguatera fish poisoning in North Carolina, 2007. MMWR Morb Mortal Wkly Rep. 2009;58:283–285.

Friedman MA, Fleming LE, Fernandez M, Bienfang P, Schrank K, Dickey R, et al. 2008. Ciguatera fish poisoning: treatment, prevention and management. Mar Drugs 6:456–479.

Tunik MG. Chapter 45. Food Poisoning. In: Hoffman RS, Nelson LS, Goldfrank LR, Howland MA, Lewin NA, Flomenbaum NE, eds. Goldfrank’s Toxicologic Emergencies. 9th ed. New York: McGraw-Hill; 2011. http://www.accessemergencymedicine.com/content.aspx?aID=6513232. Accessed December 19, 2012.