SEAFOOD POISONING
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A Review From Sharky's Dive
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Approximately 500 species of marine fishes are known to be toxic, or may on ingestion be poisonus to man. Most but by no means all, of these species are found in the coral-reef belt. Four general types of fish poisoning are recognized: Ichthyosarcotoxins, of which there are at least nine kinds: Ichthyotoxism: hthyohemotoxism; and Ichthyoacanthotoxism.
1. Ciguatera:
A type of fish poisoning characterized by certain gastrointestinal-neurological manifestations. * The commonest form of fish poisoning that occurs in the Caribbean area is called ciquatera. ( It also occurs in other areas.) * This syndrome is usually, but not always,caused by the meat of the moray eel or Sphyraena barracuda and is due to a toxin produced by benthic blue-green algae which is ingested by the small herbivores of the reef which in turn are eaten by carnivorous fish. * A fat-soluble,heat-stable toxin has been isolated from the flesh of barracudas. Mammals which ingest fish containing the ciguatera poison develop muscular weakness, particularly in the hind legs first, muscular incoordination and ataxia, vomiting, diarrhea, and increased parasympathetic activity. If lethal amounts are consumed, marked respiratory distress, vomiting, salivation, cyanosis and prostration are often seen prior to death. Deep reflexes are usually hypoactive, and in the more severe cases of poisoning the animal loses its righting reflex.
SYMPTOMS:
The first symptoms and signs of ciguaters poisoning are usually evident within thirty minutes to 4 hours after ingestion of the offending fish. The symptoms consist of nausea, vomiting, diarrhea, abdominal cramps, circumoral tingling,about the mouth, tongue and throat, or sometimes over the face and distal parts of the fingers and toes, chills, If the poisoning is severe the victim may also complain of severe malaise, muscle weakness and incoordination, chills and fever restlessness, insomnia and dyspnea. Increased sweating and hypotension are sometimes observed during the acute illness. * The victim often experiences parasthesia which is almost classical in type : hot objects feel cold and cold objects feel hot. * In fatal poisoning the above findings progressively worsen, severe muscular weakness and muscular incoordination develop and walking becomes difficult. Pruritus, often limited to the palms of the hand and soles of the feet become intense, breathing becomes labored and cyanosis may develop. * A second poisoning in a patient previously stricken within 6 months, or perhaps even a year, is more likely to be more serious than the same poisoning in a patient not previously exposed to the toxin.
SYMPTOMS:
The symptoms and signs of ciguatera poisoning appear to be very similar to those of paralytic shellfish poisoning, and it is possible that the components f the two toxins are related.
TREATMENT:
Is mainly symptomatic and supportive; however, recent experimentation has demonstrated that cholinesterase activity is definitely inhibited by the toxin and that the administration of pralidoxime chloride,a cholinesterase reactivator, is an effective antidote. * The consumption of mussels (shellfish) has sporadically given rise to epidemics of poisoning apparently caused by an allergic idiosyncrasy; in other, infection with Salmonella organisms; and in many, poisoning due to toxic compounds (saxitoxin), probably quaternary or tertiary amines. (See Shellfish poisoning.)
2. TETRAODON:
Tetraodon, puffer or fugu poisoning may occur following the ingestion of certain puffers. They are known in various parts of the world as Globefishes, Blowfishes, Balloonfishes, Swellfishes, Toadfishes, Blasers or Tambores. Of the approximately 100 species of these fish, over 50 have been involved in poisonings to man. Tetraodon poisoning is the most dangerous form of ichthyosarcotoxism. According to Halstead (1964), Japanese statistics show a mortality rate of 61.5% for this type of poisoning. Approximately twenty persons a year die of the poisoning in Japan.
SYMPTOMS:
Weakness, dizziness, pallor and paresthesia about the lips, tongue and throat. The paresthesia is usually described as "tingling or pricking sensations" and often in the limbs, particularly the fingers and toes. A potent emetic, and nausea is often one of the presenting symptoms, vomiting doses not occur in most cases. In those cases in which it does, the vomiting develops during the first hour of the illness.
SEVERE POISONING:
" Numbness all over", giving rise to a feeling of "floating on air", sweating, increased salivation, pain on inspiration, changes in oral temperature and in the pupils, and hypotension with a weak but increased heart rate. In the more severe cases the muscular fasciculations may be seen, and respiratory distress, chest pain and cyanosis are usually present. Petechial hemorrhages may develop. Paralysis involving the body musculature, the larynx and the extra ocular muscles is found in the most severe cases. Death is attributed to "respiratory paralysis", and occurs 6-24 hours following ingestion of the toxic fish.
3.SCOMBROID POISONING:
Is caused by a histamine-like substance called saurine, instances of scombroid poisoning following the ingestion of spoild mackerel-like fishes. If scombroid are inadequately preserved, a toxic substance is formed within the body musculature, and toxic components may not be histamine When histidine is acted upon by bacteria, as may occur when these fish are exposed to the sun or left to stand at room temperature for an extended period of tome, saurine is produced.
SYMPTOMS: Are similar to those of histamine poisoning. Within a few minutes after eating the toxic fish, which reportedly has a "peppery" or sharp taste, nausea and vomiting, diarrhea, flushing of the face, intense headache, epigastric pain, burning of the throat with difficulty in swallowing, thirst, and swelling of the lip. Soon they also develop massive red welts and intense itching. The signs and symptoms usually appear within 2 hours of the meal and subside within 16 hours. TREATMENT: should encompass evacuation of the stomach contents and catharsis. Administration of one of the common antihistamines will relieve the victim's distress .
4. CLUPEOID:
Following ingestion of certain herring-likefish of the tropical Pacific. Clupeidae havve been found to be toxic at one timeor another. * Like ciguatera poisoning this form occurs sporadically and over an extensive area. While the symptoms and signs provoked by the toxin are slightly different from those in cigatera poisoning, it has not yet been definitly established that the toxic is indeed different from that responsibl for ciguatera poisoning.
5. CYCLOSTOME:
The slime and flesh of certain lampreys and hagfish appears to contain a toxin which may produce gastrointestinal signs and symptoms. * The chemical and toxicological nature of the toxin is unknown.
6. ELASMOBRANCH:
Musculature of the Greenland shark(Somniosus microcephalus) has caused poisoning in both human and dogs.* The livers of several species of tropical sharks have caused severe poisoning and even death.
SYMPTOMS:
Poisoning from the eating of toxic shark liver is characterized by nausea, vomiting, abdominal pain, diarrhea, headache and parasthia about the mouth. These manifestations are sometimes evident within 30 min following ingestion of the organ. Malaise, weakness, muscle cramps and respiratory distress may develop. The pulse is usually weak and rapid; reflexes are hypoactive and the victim complains of visual disturbances and a sensation of "heaviness". Ataxia, severe respiratory distress and coma usually precede death. In most cases complete recovery requires 5-20 days.
7. Hallucinatory Fish Poisoning:
This type of poisoning is characterized by centeral nervous system signs and symptoms, and by the lack of gastrointestinal manifestations. * It has occurred following the ingestion of certain mullet and surmullet (goatfish). * These fish appear to be toxic only in certain specific areas and only durning c ertain times of the year, usually June, July and August.
SYMPTOMS:
The onset of symptoms occurs 10-90 min. following ingestion of the toxic fish. The victim complains of light-headedness or dizziness, weakness muscular incoordination and sometimes ataxia, hallucinations and depression. In severe cases, there may be parasthesia about the mouth, and some muscular paralysis and dyspnea. The agonal period is usually of short duration,2-24 Hr.
8. SHELLFISH POISONING:
A. Gastrointestinal:
Shellfish poisoning is characterized by nausea, vomiting, abdominal pain, weakness and diarrhea. The onset of symptoms generally occurs 8-12 hr. following ingestion of the offending mollusc. Intoxication is caused by bacterial pathogens, It rarely persists for more than 48 h.
B. Erythematous: (Allergic shellfsih poisoning)
Allergic response, The onset of symptoms and signs occure 30 min to 6 h r. after ingestion of the molluse to which the individual is sensitive. The usual persenting signs and symptoms are diffuse erythema, swelling , urticaria and pruritus involving the head and nech, and then spreading to the body. Headache, flushing, epigastric distress and nausea are occasional complaints. In more severe cases, generalized edema, severe pruritus, swelling of the tongue and throat, respiratory distress and vomiting sometimes occur.
C. PARALYTIC:
This shellfish poisoning is known variously as gonyaulax poisoning, or mytilointoxication. Pathognomonic symtpoms develop within the first 30 min following ingestion of the molluse.Parasthesia, described as tingling, burning or numbness is noted first aboutthe mouth, lips and tongue; is then spreads over the face, scalp, and neck, and to the finger tips and toes. Sensory perception and proprioception are affected to the point that the individual moves incoordinately. Complaints of dizziness, tightness of the throat and chest and some pain on deep inspiration, thirst, and nausea and vomiting may be present. The puls is usually thready and rapid; the superficial reflexes are often absent and the deep reflexes may be hypoactive. If muscular weakness and respiratory distress grow progressively more severe during the first 8h, death may ensue. If the victim survives the first 10-12 h the prognosis is good. Death is usually from 1 to 10%.
B. ICHTHYOOTOXIC FISH.
A number of fresh-water fish and a few marine species produce a toxin which appears to be restricted to their gonads. In these fish the body musculature and even the gastrointestinal organs are edible.* Poisoning is characterized by the rapid onset of nausea, vomiting and epigastric distress. Diarrhea, dryness in the mouth, thirst, tinnitus and malaise sometimes occur. In the more severe cases, syncopy, respiratory distress, chest pain, convulsions and coma may ensue. Complete recovery usually occurs within a few days.
C. ICHTHYOHEMOTOXIC FISH.
A toxic substance has been found in the blood of many pecies of fish, although the principal contributions to our knowledge of the toxin have come to us through studies on the bloods of the eels.
SYMPTOMS:
In these cases there is some nausea, vomiting, epigastric distress, increased salivation, urticaria and generalixed weakness. Parasthesia about the mouth, respiratory distress, paralysis and death have been reported.
