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PubMed1998

An overview of the marine food poisoning in Mexico.

In the course of the last decade, huge events related to harmful algal blooms (HAB) have severely affected the environment in Mexico, even causing several human casualties. The tally of the toxins known up to date in Mexican waters includes: neurotoxin shellfish poisoning (NSP), paralytic shellfish poisoning (PSP), amnesic shellfish poisoning (ASP), tetrodotoxin (TTX) or puffer fish poisoning, ciguatera fish poisoning (CFP) and diarrhetic shellfish poisoning (DSP). Actual epidemiological figures profoundly modified the trends manifested on previous decades. Notwithstanding that the red tides are a long time known phenomena in Mexican coasts, no regular observation of the marine environment has been set up. Although there are monitoring activities for PSP toxins on the shellfish culturing facilities that are exploited for export to the U.S.A., these are only effectively applied on specific spots of the Mexican coasts, implying that the biggest part of the country coastal zones are not formerly surveyed. The misleads caused by the medical conception that food poisoning events are mainly due to microbial contamination, is among the factors why the marine food poisoning events are a neglected disease. In spite of the fact that no official statistics consider HAB related events as a subject of research or further monitoring by the health authorities, sporadic scientific documents related to poisoning events were produced in Mexico. An interesting picture is presented for most of the marine toxins mentioned. Trend and prognosis estimates made with such scarce information, provide a minimum measurement of the reality and urge the need for a permanent monitoring program on the Mexican coasts, a place with one of the greatest marine toxin diversity worldwide.

Animals↗
PubMed1994

An incident of elevated levels of unsaturated free fatty acids in mussels from Nova Scotia and their toxic effect in mice after intraperitoneal injection.

Methanol extracts of the hepatopancreas of mussels (Mytilus edulis) harvested at two locations (Ship Harbour and Wine Harbour) in eastern Nova Scotia, Canada, were found to be toxic to mice after intraperitoneal injection. The commonly known toxins, such as those associated with diarrhetic shellfish poison (DSP), paralytic shellfish poison, and domoic acid, were not present in the extracts. However, they were found to contain elevated levels of free fatty acids. Using a modified DSP extraction procedure the quantities of free fatty acids determined (by latroscan TLC/FID) in the hepatopancreases of mussels were 2.9 mg/g (Ship Harbour 1), 2.2 mg/g (Ship Harbour 2), 1.2 mg/g (Wine Harbour), and 0.15 mg/g (Prince Edward Island, control). After further investigation it was determined that certain unsaturated fatty acids were mainly responsible for the toxicity. These included palmitoleic, linoleic, linolenic, octadecatetraenoic, and eicosapentenoic acids. Artificial mixtures of pure standards of these acids prepared in the same concentrations as found in the shellfish samples were also toxic to mice. These results indicate that elevated levels of free fatty acids in mussel hepatopancreas from locations in eastern Canada can lead to mouse deaths when using the DSP mouse bioassay procedure.

Animals↗
PubMedDate not supplied

A population-based study of paralytic shell fish poisoning in Alaska.

During May and June 1994, the authors interviewed and requested a shellfish sample from a population-based sample of 170 residents from Kodiak and Old Harbor, Alaska. Of 51 Old Harbor and 68 Kodiak residents who had eaten shellfish gathered from Kodiak Island, 18 and 6 percent, respectively, had a history of PSP. We calculated the incidence of paralytic shellfish poisoning in Old Harbor and Kodiak as 15 and 1.5 per 1000 persons per year, respectively. Of 12 butter clam batches collected from residents, 6 had a paralytic shellfish poison toxin level greater than the regulatory limit of 80 micrograms saxitoxin equivalent per 100 g of tissue; one of the 29 people who ate these shellfish developed illness. People who eat shellfish collected from non-commercial beaches have a high rate of paralytic shellfish poisoning. It may be possible to raise the regulatory level for paralytic shellfish poison toxin without affecting the public health.

Adolescent↗
PubMed1991

Illness associated with seafood.

Seafood is a common vehicle for the transmission of infections and intoxications. The main concerns in the UK are scombroid fish poisoning, viral infections (associated with bivalve molluscs) and bacterial infections (associated with crustaceans). Paralytic shellfish poisoning (PSP) and red whelk poisoning occur sporadically, and ciguatera has started to appear associated with imported fish. The appearance in coastal waters of marine algae associated with diarrheic shellfish poisoning (DSP) has increased the likelihood of outbreaks of this toxic syndrome. The dinoflagellates causing neurotoxic shellfish poisoning and amnesic shellfish poisoning have not been detected in UK fishing waters but the fluctuating distribution of algal populations makes their appearance a possibility. The Food Hygiene Laboratory and the Torry research station of the Ministry of Agriculture, Fisheries and Food provide a reference service for scombrotoxin, ciguatera, DSP, PSP and red whelk poisoning in the UK.

Cross-Cultural Comparison↗
PubMed1989

Kynurenic acid protects against gastroduodenal ulceration in mice injected with extracts from poisonous Atlantic shellfish.

1. Mice were treated with an extract prepared from poisonous Atlantic mussels. 2. Gastric and duodenal ulcers, duodenal hyperemia and peritoneal ascites resulted from administration of the shellfish extract, with an LD84 of 1.0 ml. 3. Kynurenic acid, an antagonist at excitatory amino acid receptors, protected significantly against gastroduodenal ulcers, ascites and hyperemia when given at 60 or 75 min post-extract. 4. It is likely that the gastrointestinal damage evoked by this extract is due to its domoic acid content and that kynurenic acid may prove useful against domoic acid-induced gastropathy.

Animals↗
PubMed1992

Detection of the marine toxins okadaic acid and domoic acid in shellfish and phytoplankton in the Gulf of Mexico.

Liquid chromatographic analyses of extracts from shellfish and phytoplankton from the Gulf of Mexico indicated the presence of the marine toxins okadaic acid (0.162 microgram/g shellfish) and domoic acid (2.1 pg/cell phytoplankter). These toxins are causative agents of diarrhetic shellfish poisoning (DSP) and amnesic shellfish poisoning (ASP), respectively. The presence of DSP and ASP toxins in a region with no previous record of outbreaks may indicate a potential for human poisoning under conditions appropriate for accumulation of these toxins in shellfish.

Animals↗
PubMed1997

Seafood-associated diseases and control in Canada.

Paralytic shellfish poisoning (PSP) has been documented for two centuries and control programmes have been operated for fifty years. Although some illnesses are reported almost every year, the last known death from PSP occurred in 1981. In more recent years, amnesic shellfish poisoning, ciguatera poisoning, diarrhoetic shellfish poisoning, scombroid (histamine) poisoning and tetramine poisoning have been documented. The most frequently observed of these diseases is scombroid poisoning from improperly stored fish, but PSP and ciguatera poisoning have the most serious consequences. Vibrio infections arising from naturally-contaminated shellfish are virtually unknown, and viral illnesses from polluted harvested waters are rare. Control is achieved through monitoring of waters for indicators of human pathogens. Inspection systems based on the hazard analysis and critical control point principles are being introduced into all areas of fish and shellfish harvesting. The Inspection Directorate of the Department of Fisheries and Oceans joined the new Canadian Food Inspection Agency in 1997, which co-ordinates all Federal control measures for food in Canada.

Amnesia↗
PubMed2000

The marine toxin domoic acid may affect the developing brain by activation of neonatal brain microglia and subsequent neurotoxic mediator generation.

Amnesic shellfish poisoning, one of the shellfish poisoning syndromes, is caused by the marine diatom toxin domoic acid (DOM). While in adult rats, mice, monkeys and humans DOM poorly penetrates the blood-brain barrier, DOM has been shown to be very toxic to fetal in newborn mice, because the blood-brain barrier is incomplete during neurodevelopment. This fact may explain why neonates show a higher sensitivity to neurotoxins like DOM as compared to adult animals. Mechanistic studies on DOM's neurotoxicity have mainly concentrated on the investigation of DOM's effect on neuronal tissue. Recent studies have shown that glia is also involved in DOM's neurotoxicity to the adult as well as the developing nervous system. The scientific literature strongly supports the hypothesis that the microglia may play a critical role in mediating DOM's neurotoxic effects. However, the effect of DOM on microglia has not been systematically investigated. The literature supporting our hypothesis is presented and discussed.

Animals↗
PubMed1989

Neurotoxicity and lethality of toxic extracts from Atlantic coast shellfish.

1. HCl-extract of poisonous shellfish was injected i.p. into Swiss-Webster mice. 2. Behavioral effects (sluggishness, scratching, huddling, clonic convulsions, respiratory distress and mortality) were noted. 3. Infant mice were more sensitive than were the adults to XTRT toxicity. Estimated LD50 values were; adult: 34.8 ml/kg i.p., infant: 9.6 ml/kg i.p. 4. The mouse model of shellfish-toxicity offers the advantages of a degree of similarity with the human clinical situation and a rapid time course for screening antagonists against shellfish poisoning.

Aging↗
PubMed1992

Phycotoxins in seafood--toxicological and chromatographic aspects.

Two typical clinical types of algae-related seafood poisoning have attracted medical and scientific attention: paralytic shellfish poisoning (PSP) and diarrhetic shellfish poisoning (DSP). Therefore, it became necessary to establish methods for the evaluation of possible hazards caused by contamination of seafood with these phycotoxins. Bioassays with mice or rats are the common methods for the determination of the toxin content of seafood. However, biological tests are not completely satisfactory because of a lack of sensitivity and pronounced variations. Additionally, there is growing opposition against animal testing. Therefore, many efforts have been undertaken to determine phycotoxins by chromatographic methods. PSP determination is mainly based on high-performance liquid chromatographic (HPLC) separation by ion-pair chromatography followed by postcolumn oxidation of the underivatized toxins in alkaline solution and fluorescence detection. HPLC methods for the determination of the DSP toxins okadaic acid (OA) and dinophysistoxin-1 (DTX-1) are characterized by precolumn derivatization with 9-anthryldiazomethane (ADAM) and/or 4-bromomethyl-7-methoxycoumarin (Br-Mmc), followed by chromatographic separation of the DSP esters formed and fluorescence detection. The chromatographic methods discussed in this review allow the rapid, sensitive and non-ambiguous determination of individual species of the two most important phycotoxins in seafood, PSP and DSP.

Animals↗
PubMed1995

Urinary elimination of saxitoxin after intravenous injection.

Paralytic shellfish poisoning is a serious public health concern throughout the world. An analytical method with diagnostic potential was used to isolate and measure saxitoxin, the most potent and studied paralytic shellfish poisoning toxin, in the urine of rats injected i.v. with sublethal doses (2 micrograms/kg) of saxitoxin. Urine was collected at intervals between 4 and 144 hr after injection. Saxitoxin was isolated from urine with an ion-exchange procedure, identified, and measured with a precolumn-oxidation-HPLC procedure coupled with fluorescence detection. The identity of oxidized saxitoxin was confirmed with electrospray ionization mass spectrometry. Four hours after injection, approximately 19% of the injected saxitoxin dose was excreted. By 24 hr, approximately 58% of the administered dose was excreted. Average total urinary excretion of administered saxitoxin was approximately 68% for the full study period. These results demonstrate that small quantities of unmetabolized saxitoxin can be detected in rat urine up to 144 hr after i.v. administration, and that the analytical method may have diagnostic potential for saxitoxin intoxication and paralytic shellfish poisoning.

Animals↗
PubMed1989

Respiratory effects of brevetoxin and saxitoxin in awake guinea pigs.

Ptychodiscus brevis toxin (brevetoxin) is associated with 'Florida red tide' and cause neurotoxic shellfish poisoning. Saxitoxin is the agent of paralytic shellfish poisoning. Clinical reports of human intoxication suggest that both toxins affect the respiratory system. The toxins were administered by slow intravenous infusion. The effects of the toxins on respiratory function of awake guinea pigs in a pressure plethysmograph were studied. Both toxins caused lactic acidosis of unknown etiology, which was compensated for by increased minute volume with brevetoxin (PbTx-3)- but not with saxitoxin-intoxicated animals. In general, brevetoxin increased ventilation, before respiratory failure, while saxitoxin had a depressive effect on ventilation. Airways resistance was not increased, nor was dynamic compliance decreased during intoxication, although the data suggest that respiratory system failure was the primary cause of death. The responses seen in these experiments are consistent with the dissimilar molecular actions of these toxins.

Animals↗
PubMed1988

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.

Animals↗
PubMed1994

Redtide in the Philippines.

1. Redtide is a marine phenomenon that poses great risk to the health and economic livelihood of people in coastal areas. Paralytic shellfish poisoning develops when a person consumes molluscs containing toxic dinoflagellates and suffers neurological and/or gastrointestinal manifestations. 2. Four redtide incidents in the Philippines are presented. The manner in which the problems were managed are described. 3. The clinical features of redtide poisoning in the Philippines included gastro-intestinal and neurological features with deaths secondary to ventilatory failure. Mortality ranged from 0% to 12% in the different redtide episodes. 4. There are many lessons to be learned in handling this kind of natural disaster. For an effective toxicovigilance programme, there must be a central co-ordinating responsible organization, a clear definition of roles and functions and good inter-agency co-operation. Appropriate surveillance procedures, resources to intensify surveillance at times of risks, prompt warning system, and the ability to impose bans on consumption are also necessary. 5. Poisons centres can play an important role during times of redtide. This may include toxicovigilant activities, such as early warning and educational campaigns to consumers, and seminars in the recognition and management of paralytic shellfish poisoning. 6. The contribution of the epidemiologists in investigating and monitoring the extent of public health damage and patterns of poisoning in a coastal community is emphasized.

Animals↗
PubMed1998

Pseudo-nitzschia in New Zealand and the role of DNA probes and immunoassays in refining marine biotoxin monitoring programmes.

Domoic acid (DA) was first detected in shellfish in New Zealand after the implementation of a comprehensive biotoxin monitoring programme for amnesic, paralytic, diarrhetic and neurotoxic shellfish toxins, following a suspected neurotoxic shellfish poisoning (NSP) event in early 1993. Both phytoplankton monitoring and shellfish flesh testing programmes have led to an extensive database which has helped link species of Pseudo-nitzschia to specific DA outbreaks. In 1994, P. pungens and P. turgidula were associated with DA contamination of shellfish, and cultured isolates of these species proved to be toxin producers. During 1996 the use of species-specific ribosomal RNA (rRNA)-targeted oligonucleotide probes and DA immunoassays led to the discovery of toxin production by P. fraudulenta, and showed the nontoxic P. heimii to be a major bloom former. Pseudo-nitzschia delicatissima, P. pseudodelicatissima and P. multiseries, also identified using rRNA-targeted probes, have been linked to DA contamination of New Zealand shellfish; P. australis is the main cause of DA in scallops. The relative amnesic shellfish poisoning (ASP) risk associated with different species, largely determined by DA immunoassays of cultured isolates, is now used by some regulators to refine risk assessments. Species identification is therefore vital so that shellfish growers, and health and industry officials, can make safe and economically sound harvesting decisions. The development and field trialling of DNA probes is proving invaluable in this context.

Animals↗
PubMed1992

Comparison of liquid-junction and coaxial interfaces for capillary electrophoresis-mass spectrometry with application to compounds of concern to the aquaculture industry.

The application of capillary electrophoresis-mass spectrometry (CE-MS) to the analysis of compounds of concern to the aquaculture industry is reported. Two different approaches to coupling the CE column to an IonSpray atmospheric pressure ionization (API) interface, viz., a liquid-junction and a coaxial arrangement, are describe and compared with regard to ruggedness, ease of use, sensitivity and electrophoretic performance. The different injection modes used in three commercial capillary electrophoresis systems were also evaluated for their applicability to CE-MS. The use of CE-MS for the analysis of a variety of classes of antibiotics used in the fish aquaculture industry, such as the sulfonamides and their potentiators (e.g., trimethoprim), is demonstrated and was used to confirm the presence of these components in shellfish extracts at the low ppm level. CE-MS was also applied to the analysis of marine toxins such as saxitoxin and its analogues which are associated with paralytic shellfish poisoning, and also the toxins responsible for amnesic and diarrheic shellfish poisoning. Tandem mass spectrometry (MS-MS) was used to provide structural information on these analytes, and the ability to distinguish isomeric compounds based on their different migration and fragmentation characteristics using CE-MS-MS is demonstrated.

Anti-Bacterial Agents↗
PubMedDate not supplied

Modified immunoassays for polyether toxins: implications of biological matrixes, metabolic states, and epitope recognition.

Polyether marine toxins are responsible for the seafood intoxication phenomena known as neurotoxic shellfish poisoning (due to brevetoxins), ciguatera (due to ciguatoxin), and diarrheic shellfish poisoning (due to okadaic acid). Using traditional techniques of hapten (pure toxin) conjugation to protein to create complete antigen, animal immunization and antibody isolation, and specific antibody subpopulation purification, discriminating antibodies have been isolated that detect brevetoxins and ciguatoxin, but not okadaic acid, in a dose-dependent fashion. Using microorganic chemistry and purified toxins, a unique set of tools has been created for the study of polyether ladder toxin accumulation; depuration; and specific site localization in tissues, food sources, and clinical samples. Developed test protocols can detect toxin in dinoflagellate cells, in extracts from food sources, in seawater and culture media, and in human serum samples. Enzyme-linked immunosorbent assay protocols developed for eventual collaborative testing have been successful in limited applications within the laboratory (correlation coefficient of 0.92 excluding 2 outliers), and alternative formats are being developed to optimize the basic test for use in research laboratories, regulatory laboratories, and field inspections.

Antibodies↗
PubMed2001

Determination of paralytic shellfish toxins in Portuguese shellfish by automated pre-column oxidation.

Automated pre-column oxidation (the method of Lawrence) was implemented on a routine basis since the end of 1996 to study paralytic shellfish poisoning (PSP) toxins in Portuguese shellfish. Liquid chromatography confirmed the presence of PSP toxins when the known toxic algae were present: Gymnodinium catenatum and/or Alexandrium cf. lusitanicum. On the other side, it has eliminated PSP toxins as a possible recurrent contaminant in oysters from Sado estuary. These oysters were already known to contain high levels of some metals (mainly zinc, copper and cadmium) due to their location in a contaminated area and their particular physiology prone to accumulate metals. The presence of PSP toxins in Scrobicularia plana from Mondego estuary and Tellina crassa from the northern coast, during the absence of the above toxic microalgae in the water column, was confirmed. Unlike other shellfish, these two genera have the feeding habit of aspirating more sediment than organisms in suspension, and probably ingest from the sediment resting cysts of PSP producing microalgae. This is another route of contamination that may help to explain why after a bloom certain shellfish species maintain toxicity for long periods. The method revealed to have a fast implementation on a daily basis, short analysis time (around 20 min between samples), high sensitivity and robustness, and therefore, it is one of the best HPLC methods for screening a large number of shellfish samples for monitoring purposes.

Animals↗