Neurologic sequelae of domoic acid intoxication due to the ingestion of contaminated mussels

In late 1987 there was an outbreak in Canada of gastrointestinal and neurologic symptoms after the consumption of mussels found to be contaminated with domoic acid, which is structurally related to the excitatory neurotransmitter glutamate. We studied the neurologic manifestations in 14 of the more severely affected patients and assessed the neuropathological findings in 4 others who died within four months of ingesting the mussels. In the acute phase of mussel-induced intoxication, the patients had headache, seizures, hemiparesis, ophthalmoplegia, and abnormalities of arousal ranging from agitation to coma. On neuropsychological testing several months later, 12 of the patients had severe anterograde-memory deficits, with relative preservation of other cognitive functions. Eleven patients had clinical and electromyographic evidence of pure motor or sensorimotor neuronopathy or axonopathy. Positron-emission tomography of four patients showed decreased glucose metabolism in the medial temporal lobes. Neuropathological studies in the four patients who died after mussel-induced intoxication demonstrated neuronal necrosis and loss, predominantly in the hippocampus and amygdala, in a pattern similar to that observed experimentally in animals after the administration of kainic acid, which is also structurally similar to glutamate and domoic acid. We conclude that intoxication with domoic acid causes a novel and distinct clinicopathologic syndrome characterized initially by widespread neurologic dysfunction and then by chronic residual memory deficits and motor neuronopathy or axonopathy.

Ciguatera fish poisoning: an outbreak associated with fish caught from North Carolina coastal waters

Ten persons who had eaten at a seafood meal in North Carolina had gastrointestinal and neurologic symptoms suggestive of ciguatera fish poisoning. In five persons, the neurologic morbidity lasted 30 days or longer. The meal included barracuda, dolphin fish (mahimahi), and yellow-fin tuna, all of which were caught in North Carolina coastal waters. Analysis of food-specific attack rates implicated the barracuda as the probable cause of the outbreak. We believe this is the first suspected or confirmed report of ciguatera fish poisoning associated with consumption of fish harvested from mainland US coastal waters outside of Florida. Physicians treating patients with a syndrome resembling ciguatera fish poisoning should inquire about consumption of fish not only from areas where the disease is endemic but also from the southeastern US.

[Antidotal effects of sulfhydryl compounds on acute poisonings by sodium ammonium dimethyl-2-(propane-1,3-dithiosulfate) monohydrate, nereistoxin and cartap]

Sodium dimercaptopropanesulphonate (DMPS) and sodium dimercaptosuccinate (DMS) were discovered to be effective antidotes for acute poisoning of insecticides SCD [sodium ammonium dimethyl-2-(propane-1,3-dithiosulfate) monohydrate], nereistoxin (4-N,N-dimethylamino-1,2-dithiolane) and cartap (dihydronereistoxin dicarbamate). In mice, DMPS (250 mg/kg) or DMS (1000 mg/kg) ip 20 min before SCD increased LD50 of ig SCD from 97 to 374 or 251 mg/kg, respectively. The prophylactic effect of DMPS was better than that of DMS. Administration of DMPS prior to cartap increased LD50 of ig cartap from 130 to 375 mg/kg. The therapeutic effect of DMPS was also demonstrated in SCD-poisoned conscious rabbits. DMPS 62.5 mg/kg or DMS 500 mg/kg iv completely antagonized the neuromuscular blockade and respiratory depression caused by SCD, nereistoxin and cartap in anesthetized rabbits. The antagonism of SCD-induced neuromuscular blockade by cysteine (400 mg/kg, iv) was less effective and of shorter duration than that by DMPS and DMS. Dimercaprol 50 mg/kg im showed little effect on SCD-induced paralysis. The antagonistic actions of sulfhydryl compounds on neuromuscular blockade induced by these insecticides probably belong to chemical antagonism.

A toxin profile for shellfish involved in an outbreak of paralytic shellfish poisoning in India

Toxin profiles of clams and oysters involved in the outbreak of paralytic shellfish poisoning in India in 1983 were studied by a liquid chromatographic technique. Gonyautoxins 1, 2, 3, 4 and 8, and 11-epigonyautoxin 8 appeared to be the major toxins along with small amounts of saxitoxin, neosaxitoxin, decarbamoylsaxitoxin, decarbamoylgonyautoxins 2 and 3, C3 and C4. Toxin profile suggests the involvement of Alexandrium spp. in this outbreak.

Ciguatera and mannitol: experience with a new treatment regimen

Ciguatera is a distressing, hitherto-untreatable and not rare disease which results from the eating of ciguatoxin-contaminated fish from tropical and subtropical waters. We report here the results of a pilot study to assess the efficacy of mannitol therapy in ciguatera poisoning. Twelve adult patients (six men) have been treated, five of whom--who were ill acutely--experienced a significant benefit from this therapy, in three cases, with a hitherto-unexperienced dramatic reversal of symptoms. We conclude that an intravenous infusion of 1.0 g/kg of mannitol which is given over 45 minutes, after rehydration if required, can be of significant benefit to at least some acutely intoxicated victims. We postulate either a reduction of axonal oedema, or a scavenger effect, or both, as the mechanism of the beneficial effects of mannitol. Ciguatoxin is rich in hydroxyl groups, and causes microscopic oedema of neural tissue. If our conclusion of the beneficial effects of mannitol therapy is confirmed, this will offer the first effective therapy for acute phases of this disease, and has promise of preventing much long-term morbidity.

Ciguatera fish poisoning

Cases of ciguatera fish poisoning no longer are confined to endemic areas. This makes awareness of this entity important. The diagnosis usually is made by the presence of gastrointestinal symptoms, nausea, vomiting, and diarrhea, and of neurological symptoms such as paresthesias, paresis, and pruritus. The detection of ciguatoxin in the ingested fish by any of the available bioassays, will confirm the diagnosis. The treatment of this food poisoning is supportive, although intravenous mannitol is reported to be safe and effective. The prognosis is good and complete recovery is to be expected. However, relapses can occur, especially on re-exposure to the toxin.

Brevetoxins: unique polyether dinoflagellate toxins

Brevetoxins are lipid-soluble polyether marine toxins of unique structure and pharmacological function. Toxins are active in vivo in the nanomolar to picomolar concentration range and in vitro in isolated neuromuscular or giant axon preparations and in single-cell or subcellular model systems. Their effect is excitatory, mediated by the enhancement of cellular Na+ influx. Brevetoxins bind at site 5 on the voltage-sensitive sodium channel, a specificity shared with ciguatoxin. This site is allosterically linked to other natural toxin binding sites on the channel.

Ciguatera in the Pacific: a link with military activities

Ciguatera fish poisoning is widespread in the Pacific. Outbreaks and the rise in incidence of the disease are related largely to military activities that disturb coral reef ecology. Nuclear test explosions and the setting up of the infrastructure for these tests are major components of such military activity.

Variations in symptomatology of ciguatera poisoning

Ciguatera poisoning reports were examined for patterns of symptomatology when different types of fishes were consumed. Consumption of surgeon fish (Ctenochaetus strigosus), amberjack (Seriola dumerili) and jack (Caranx sp.) resulted in different symptom profiles with a number of statistically significant differences in the reported frequencies of specific symptoms. The results support the contention that the large variability in symptoms associated with ciguatera poisoning is caused by several closely related but distinct toxins.

Histopathological studies on experimental marine toxin poisoning--4. Pathogenesis of experimental maitotoxin poisoning

Repeated injections of 45 ng/kg of maitotoxin into the peritoneal cavities of male ICR mice resulted in marked atrophy of lymphoid tissues, a reduction of lymphocytes in the circulating blood, reduced immunoglobulin M in serum, and an increase of calcium content in the adrenal glands. A single injection of 200 ng/kg of maitotoxin induced a marked increase in total calcium content of the adrenal glands as well as in plasma cortisol concentration (about seven times control) within 1 hr. In contrast, mice pretreated with CoCl2, a calcium channel inhibitor, and/or adrenalectomized mice, showed no discernible changes in the lymphoid tissues after repeated injections of maitotoxin. It is thus suggested that maitotoxin first stimulates calcium influx in the adrenal glands, which then causes the release of cortisol into the blood. The excess amount of cortisol in serum produces acute involution of the thymus and other lymphoid tissues.

Clinical and laboratory findings implicating palytoxin as cause of ciguatera poisoning due to Decapterus macrosoma (mackerel)

A near fatal case of ciguatera-related intoxication following consumption of smoked Decapterus macrosoma is documented. In addition to some of the hallmark symptoms of ciguatera poisoning, the patient exhibited acute respiratory distress and severe muscle spasms. Laboratory results showed large elevations in a number of blood enzymes, indicative of muscle damage. The responsible agent was extracted from corresponding fish samples and identified as palytoxin.

Prophylactic and therapeutic use of an anti-brevetoxin (PbTx-2) antibody in conscious rats

A polyclonal antiserum was investigated for prophylactic and therapeutic use in the treatment of brevetoxin intoxication. Conscious, tethered male rats were pre-treated with 1 ml of anti-brevetoxin IgG (PbAb) or control IgG by a 10 min infusion, then given brevetoxin (25 micrograms/kg) by a 1 hr infusion. Rats pre-treated with control IgG demonstrated signs of brevetoxin intoxication; these signs were absent in rats pre-treated with PbAb. In therapy studies, rats were infused for 1 hr with 100 micrograms/kg brevetoxin, followed immediately by 2 ml of either PbAb or control IgG. During toxin infusion, both groups showed signs of brevetoxin intoxication. Rats treated with control antibody died within 6 hr. In rats treated with PbAb, respiratory rates began to return toward baseline almost immediately, and fewer neurological signs developed. After 24 hr, nearly all neurological signs had disappeared and both core and peripheral temperatures had returned to normal. There was a time differential between two groups of signs, suggesting high and low accessibility compartments for the antibody. These compartments probably represent central and peripheral nervous system. All animals treated with PbAb survived at least 8 days. These results suggest that PbAb has both therapeutic and prophylactic potential in the treatment of brevetoxin intoxication. Further, because of the differential in efficacy in reversing central and peripheral nervous system signs of brevetoxin intoxication, it provides useful new information on the mechanism of action of this toxin.

Can ciguatera be a sexually transmitted disease?

Ciguatera is a type of food poisoning associated with the consumption of contaminated marine fish. We report two cases in which painful ejaculation in an affected male and dyspareunia in an unaffected female following her partner's ejaculation suggest the sexual transfer of the responsible agent, ciguatoxin (CTX). Immunoassay of semen samples for CTX were not diagnostic, but the sensitivity and timing of the test employed may have precluded detection of small quantities of the toxin. We conclude that CTX may be present in the semen of men affected with ciguatera toxicity and be capable of producing symptomatology in both males and females during sexual intercourse.

Histopathological studies on experimental marine toxin poisoning--III. Morphological changes in the liver and thymus of male ICR mice induced by goniodomin A, isolated from the dinoflagellate Goniodoma pseudogoniaulax

The i.p. LD50 values of goniodomin A, a novel polyether macrolide, in male ICR mice were 1.2 and 0.7 mg/kg at 24 and 48 hr, respectively. Histologically, perihepatitis, non-fatty vacuoles in the hepatocytes, central necrosis of the liver and massive necrosis of lymphocytes, in the cortical layer of the thymus, were prominent.

Ciguatera-like poisoning in the Mediterranean

A case of group poisoning from the consumption of the fish Sarpa salpa, caught in the Mediterranean coastal waters of Israel, is presented. Mullets and rabbitfish caught at the same site caused no harm. This is the third case of ciguatera poisoning in the region and the first to be transferred by a fish which is not a Red Sea immigrant. It implies that toxic algae dinoflagellates, originating from the Red Sea, crossed the Suez Canal and found their way to the Mediterranean coastal waters.

Polyneuropathy secondary to ciguatoxin poisoning

Following ingestion of marine fish in Thailand this patient complained of gastrointestinal and neurological disturbances, marked by severe, mainly motor, demyelinating polyneuropathy, which worsened on her return to Italy a few days later. The clinical pattern, electromyography, cerebrospinal fluid test and sural nerve biopsy by electronmicroscopy permitted the diagnosis of polyneuropathy secondary to ciguatoxin poisoning.

Successful treatment of ciguatera fish poisoning with intravenous mannitol

Twenty-four patients with acute ciguatera fish poisoning were treated with intravenous mannitol, and each patient's condition improved dramatically. All exhibited marked lessening of neurologic and muscular dysfunction within minutes of the administration of mannitol. Gastrointestinal symptoms disappeared more slowly. Two patients in coma and one in shock responded within minutes, with full recovery after infusion. Although these observations were empiric and uncontrolled and the mechanism of action of mannitol in this disease is unclear, mannitol should be considered for initial use in patients with significant illness and morbidity from ciguatera fish poisoning.

Anticholinesterase poisonings in dogs from a cyanobacterial (blue-green algae) bloom dominated by Anabaena flos-aquae

Cyanobacteria (blue-green algae) implicated in the deaths of 9 dogs at Richmond Lake, SD, on Aug 26, 1985, were analyzed. The dominant cyanobacterial species from the water sample was Anabaena flos-aquae. The lyophilized bloom material or the high-performance liquid chromatography purified toxin peak, when administered to mice IP, induced clinical signs of salivation, lacrimation, urinary incontinence, defecation, convulsion, fasciculation, and respiratory arrest. Further comparison of the semipurified bloom toxin with an irreversible anticholinesterase anatoxin-a(s), produced by A flos-aquae strain NRC-525-17, revealed the bloom toxin and anatoxin-a(s) had similar properties on high-performance liquid chromatography and on the inhibition of electric eel acetylcholinesterase (EC 3.1.1.7).

Scombroid poisoning

The symptoms of scombroid poisoning resemble an acute allergic reaction. Tuna, albacore, mackerel and bonito are implicated, as are nonscombroid fish such as mahi-mahi and bluefish. The histamine content of affected fish is high, but the pathophysiology is more complex than the mere ingestion of histamine. Antihistamines and cimetidine appear to be effective in controlling symptoms. Prevention consists of prompt and adequate refrigeration of dark-meated fish.

Mussel mystery: "the more you know, the more you don't know"

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Pelagic paralysis

Three conditions that may occur after consumption of seafood--puffer fish poisoning, ciguatera, and paralytic shellfish poisoning--are caused by a group of poisons that block voltage-gated sodium channels in myelinated and non-myelinated nerves. The conditions cannot be distinguished clinically and so constitute an entity for which the name pelagic paralysis is proposed. Variations in the clinical features can be accounted for by large differences in the amount of toxin present in the seafood.

Human fatality due to ingestion of the crab Demania reynaudii that contained a palytoxin-like toxin

Clinical accounts of a human fatality resulting from ingestion of the crab Demania reynaudii are documented. The causative toxin was suggested to be palytoxin on the basis of dose-death time relationships and chromatographic properties.

Histopathological studies of experimental marine toxin poisoning. II. The acute effects of maitotoxin on the stomach, heart and lymphoid tissues in mice and rats

Maitotoxin, one of the causative agents of ciguatera isolated from marine dinoflagellate, Gambierdiscus toxicus, induced severe pathomorphological changes in the stomach, heart and lymphoid tissues in mice and rats. Multiple erosions were observed in gastric mucosa accompanied by a marked increase in total calcium content 24 hr after i.p. injection of 200 or 400 ng/kg of maitotoxin. In contrast, there was no close temporal association between the accumulation of calcium and the morphological appearance of dead cells in the heart and thymus. Within 30 min of administration of 200 or 400 ng/kg of maitotoxin, a marked swelling was seen in the endothelial lining cells of blood capillaries between cardiac muscle fibers, followed by the cell death of the fibers. Injection of maitotoxin at a dose of 200 ng/kg or higher also resulted in necrosis of lymphocytes in the cortex of the thymus at 4 hr and in the medulla at 8 hr.

A theoretical discourse on the pharmacology of toxic marine ingestions

The known and theoretical pharmacology of poisons involved in toxic marine ingestions has assisted in the development of specific therapeutics for these afflictions. The clinical manifestations of several toxic marine ingestions have suggested toxins/cogeners that may be involved in the poisoning process, providing direction for the development of diagnostic laboratory tests, including those for cyclic ethers. Future investigations should involve utilization of acetaminophen and indomethacin for chronic ciguatera fish poisoning, and the evaluation of the role of polycyclic ethers in the temperature sensation reversal phenomenon of both ciguatera and neurotropic shellfish poisoning.

Intoxications from the seas: ciguatera, scombroid, and paralytic shellfish poisoning

Sporadic cases and outbreaks of intoxications borne by fish and shellfish have increased in frequency during recent years. Ciguatera, scombroid, and paralytic shellfish poisoning account for nearly 16 per cent of all reported foodborne outbreaks of disease in the United States. Fishborne ciguatera and paralytic shellfish poisoning are characterized by gastrointestinal and neuromuscular manifestations attributable to toxins of dinoflagellates. These toxins impair sodium transport in cell membranes. Treatment is primarily supportive. Scombroid fish intoxication resembles histamine poisoning and may be treated effectively with antihistamines or cimetidine. Prevention of these intoxications at present depends upon avoidance of potential vectors.

Prostaglandin associated mortality following intravenous injection of catfish epidermal secretions in rabbits

Toxicity of soluble protein extracts from epidermal gel secretions of the catfish, Arius thalassinus, was examined in rabbits. Intravenous injections containing doses as low as 2 mg protein/kg body weight caused mortality in all animals tested. An increase in plasma levels of thromboxane B2 (TXB2) and of 6-keto prostaglandin F1 alpha (6-keto PGF1 alpha) were observed following injections. Both the mortality and prostaglandin release were prevented by pretreatment of rabbits with either indomethacin or hydrocortisone. A similar indomethacin sensitive induction of prostaglandin release was noted following the in vitro treatment of arterial tissue sections with gel. Lethality appears to result from gel substances stimulating phospholipase activity to yield arachidonic acid, which is then metabolized to give toxic levels of prostaglandins.