Neurotoxic Shellfish Poisoning

Abstract

Neurotoxic shellfish poisoning (NSP) is caused by consumption of molluscan shellfish contaminated with brevetoxins primarily produced by the dinoflagellate, Karenia brevis. Blooms of K. brevis, called Florida red tide, occur frequently along the Gulf of Mexico. Many shellfish beds in the US (and other nations) are routinely monitored for presence of K. brevis and other brevetoxin-producing organisms. As a result, few NSP cases are reported annually from the US. However, infrequent larger outbreaks do occur. Cases are usually associated with recreationally-harvested shellfish collected during or post red tide blooms. Brevetoxins are neurotoxins which activate voltage-sensitive sodium channels causing sodium influx and nerve membrane depolarization. No fatalities have been reported, but hospitalizations occur. NSP involves a cluster of gastrointestinal and neurological symptoms: nausea and vomiting, paresthesias of the mouth, lips and tongue as well as distal paresthesias, ataxia, slurred speech and dizziness. Neurological symptoms can progress to partial paralysis; respiratory distress has been recorded. Recent research has implicated new species of harmful algal bloom organisms which produce brevetoxins, identified additional marine species which accumulate brevetoxins, and has provided additional information on the toxicity and analysis of brevetoxins. A review of the known epidemiology and recommendations for improved NSP prevention are presented.

Dinoflagellates: Ecological Approaches and Spatial Distributions in Malaysia Waters

“…[40] Diarrheic Shellfish Poisoning (DSP) Okadoic acids Dinophysis, Procentrum [41] Neurotoxic Shellfish Poisoning (NSP) Brevetoxin Karenia brevis [42] Ciguatera Shellfish Poisoning (CFP) Ciguatoxin Gambierdiscus toxicus [43] the onset of paralysis. Blocking of sodium conductance eventually generates symptoms of numbness, tingling sensation of the oral parts and nausea to the patient.…”

“…Neurotoxic shellfish poisoning is known for causing failure of both gastrointestinal and neurological functions [42]. There is no lethal case reported to date during the outbreak of NSP.…”

The Shellfish Biotoxins

“…This poisoning is caused by species from dinoflagellate group, Karenia brevis (Watkins et al, 2008). This species produced toxins belong to bravetoxins group, and its can form aerosol.…”

“…Symptoms of poisoning (gasrointestinal and neurological) in humans appear 3-4 hours after consummation: nausea, vomiting, diarrhea, loss of taste, numbness of the lips and face, dilated pupils, alternating sensations of cold and heat. The maximum allowable concentrations of these toxins should not exceed 80µg/100g shellfish meat (Watkins et al, 2008). Detection of toxins can be done by liquid chromatography.…”

ASIANetwork Exchange: A Journal for Asian Studies in the Liberal Arts, Volume 21, Number 1 (2013)

“…In Asia, it is common to consume whole fish, rather than fillets, exposing consumers to the liver and stomachs, where the fish would have the highest level of toxins. 100 Some of the symptoms associated with toxin poisoning from Karenia-affected seafood include, "nausea, vomiting, diarrhea... numbness and tingling in the lips, mouth and face, as well as numbness and tingling in the extremities… [Moreover,]... overall loss of coordination, and partial limb paralysis may also occur... [as well as] slurred speech, headache, pupil dilation, and overall fatigue... and more severe clinical progression that often involves paralysis, respiratory distress and death if undiagnosed and untreated. " 101 Because many of these symptoms are common to many intestinal or neurological illnesses, the effects of Karenia-toxin poisoning are typically underreported and misdiagnosed not only in Asia but in other regions of the world where this species also occurs.…”