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PubMed1992

Eutrophication, marine biotoxins, human health.

Eutrophication phenomena in marine coastal waters can today be explained on the basis of natural or anthropogenic causes. Undesirable effects and also sanitary problems in both types of eutrophication are often produced, but they may differ greatly in frequency and significance. Some algal biotoxins can affect both marine animals and man, whilst others affect man alone. From data currently available it appears that the sanitary state of man can be affected through the digestive, respiratory and cutaneous apparatus. Four main dinoflagellate biointoxications are now recognized: paralytic shellfish poisoning (PSP), neurotoxic shellfish poisoning (NSP), diarrhoetic shellfish poisoning (DSP), and venerupin poisoning. Other biointoxications are due to a diatom bloom responsible for amnesic shellfish poisoning (ASP) and to blue algae blooms which have effects on the skin and the respiratory tract. All these marine toxins are considered and particular attention is paid to: producing organisms, chemistry of the components, compromised sea foods, methods of analysis, occurrence worldwide, human intoxications, toxicology and mechanism of action on a molecular level, therapeutical notes, tolerance levels and remarks on safety. Attention is also paid to the relationship between the anthropogenic eutrophication and PSP and DSP since these are the most widespread biointoxications from toxic marine dinoflagellates in the world today and for which the European Economic Community (EEC) is proposing health legislation such as tolerance limits and methods for official analysis. In view of the harmful potential of coastal anthropogenic eutrophication, the main current committment of various countries concerns control. Finally, it is important to develop a suitable monitor research system using all the specific standards of allowed toxic substances, and also research on effective antiodotes against all biotoxins.

Animals↗

PubMed2004

Concentrations and accumulation profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans in aquatic tissues, and ambient air from South Korea.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/DFs), including 2378-substituted isomers were present in samples of shellfish and fish, and ambient air collected from Masan Bay, and Masan City, South Korea. Total concentrations of PCDDs/DFs in mussel and clam were 750 pg g(-1), lipid weight (lw), and 3418 pg g(-1), lw, respectively. Total concentrations of PCDDs/DFs in mullet, gizzard and flounder were 52, 82, and 122 pg g(-1), lw, respectively. Shellfish tissues contained a greater number of PCDD/DF isomers, contributing greater total concentrations of PCDDs/DFs compared to fish collected from the same locations. The predominance of 2378-substituted PCDDs/DFs in fish is represented in greater total concentrations of 2378-TeCDD equivalents (TEQs), whereas there was very limited occurrence of 2378-substituted isomers in shellfish. TEQ concentrations in samples of mussel and clam were 0.97 and 12 pg g(-1), lw, respectively. Total TEQs in mullet, gizzard and flounder were 12, 22 and 18 pg g(-1), lw, respectively. In fish 2378-substituted PCDDs accounted for 100% of the total concentrations of PCDDs, and 2378-substituted PCDFs accounted from 59% to 73% of the total PCDFs. The 2378-substituted isomers accounted for only 3% of the total PCDDs/DFs in shellfish. Ambient air collected from two sites contained a wide range of isomers of tetra- through heptachlorinated PCDDs/DFs. Even though the total concentration of PCDDs/DFs in ambient air (12.8 pgm(-3)) collected from an industrial area was 2-fold greater than that in air samples (6.3 pgm(-3)) collected from an urban/rural area, total TEQs (0.07 and 0.08 pgm(-3)) there was no statistical difference between the two samples.

Air Pollutants↗

PubMed2005

High pressure-induced inactivation of Qbeta coliphage and c2 phage in oysters and in culture media.

High pressure (HP) treatment inactivates bacteria in shellfish, but its effects on viruses in shellfish have not yet been determined, although viral illness is frequently associated with shellfish consumption. The aim of this study was to investigate the baroresistance of two bacteriophage viruses, Qbeta coliphage and c2 phage, in oysters and in culture media. High numbers (>or=10(7) ml(-1) or g(-1)) of both phages were obtained in culture media and in oysters. Samples were HP treated at 200-800 MPa at 20 degrees C for up to 30 min. Little or no inactivation of either phage was observed in oysters or in culture media after treatment at <or=400 MPa. High levels of inactivation of both phages in oysters and in culture medium were observed following treatment at 500-700 MPa. Titres of both phages were reduced to non-detectable levels (up to 8 log inactivation) in oysters and in GM17 broth (for c2 phage) after treatment at 800 MPa. The level of Qbeta coliphage in tryptone soya broth with yeast extract (10(10) PFU ml(-1)) was reduced by approximately 7 log units following treatment of 800 MPa. Levels of inactivation of both phages in oysters were similar to those in culture media. Increasing the duration of treatment at 550 or 600 MPa increased the level of inactivation of both phages in oysters. HP treatment may effectively inactivate phage in shellfish but HP-induced inactivation of human enteric viruses in oysters needs to be studied directly, to more accurately assess the ability of this technology to inactivate these viruses.

Allolevivirus↗

PubMed2026

Culture of infectious human norovirus isolated from live contaminated oysters.

Human noroviruses are a major cause of foodborne outbreaks worldwide. Filter-feeding shellfish, such as oysters, can bioaccumulate these viruses in their digestive tissue when grown in sewage-impacted coastal areas and are often implicated in norovirus foodborne outbreaks. Despite the high sensitivity of current molecular assays, these methods for norovirus detection in shellfish fail to distinguish between infectious and non-infectious particles. Assessing norovirus infectivity in shellfish remains a challenge due to the lack of suitable isolation methods that maintain capsid integrity. In this study, a protocol for isolating infectious norovirus from oyster tissues, based on chloroform-butanol elution and polyethylene glycol concentration (CB-PEG), was optimized for the recovery of human norovirus GI and GII. While CB-PEG method recovered various norovirus GI and GII genotypes, it was less efficient at the genomic level than a protocol based on proteinase K elution (adapted from ISO 15216) and showed genotype-dependent viral recovery rates. By optimizing the flocculation step, we improved the method's compatibility with human intestinal enteroid (HIE) cultures. Using this approach, we successfully quantified infectious norovirus GII.3 titers recovered from artificially-contaminated live oysters. Interestingly, infectious virus was better isolated following a freezing step of the digestive tissues, with titers ranging from 13 to 40 TCID50/mL for positive samples. In conclusion, this study established an optimized methodological approach for the relative quantification of infectious norovirus GII.3 in shellfish, paving the way for future research on viral persistence and inactivation strategies in this foodstuff.

Norovirus↗

PubMed1999

Production and characterization of a monoclonal antibody against domoic acid and its application to enzyme immunoassay.

For production of monoclonal antibodies against domoic acid, a causative agent of amnesic shellfish poisoning, three immunogens, domoic acid conjugated with bovine serum albumin (BSA), ovalbumin (OVA) and human gamma globulin (HGG), were prepared. The antiserum obtained from BALB/c mice immunized with domoic acid-BSA showed the highest affinity for domoic acid. The monoclonal antibody, DA-3, obtained from the mice was highly specific for domoic acid and showed a minor cross-reactivity with the isomers of domoic acid (isodomoic acids B, E, F, G and H), except for isodomoic acid A. Using DA-3 antibody, an indirect competitive enzyme immunoassay (idc-EIA) was developed for measurement of domoic acid. The working range for quantitative measurement of domoic acid and the quantification limit for domoic acid in shellfish were estimated to be 0.15-10 ng/ml and less than 0.04 microg/g, respectively. The mean recovery of domoic acid added to extracts of shellfish at toxin levels of 0.02 to 0.2 microg/ml was 103% with a coefficient of variation of 4.5%. The newly developed idc-EIA seems to be a useful method for monitoring domoic acid in shellfish.

Animals↗

PubMed2001

Pectenotoxins--an issue for public health: a review of their comparative toxicology and metabolism.

Pectenotoxins (PTXs) are a group of toxins associated with diarrhetic shellfish poisoning (DSP) and isolated from DSP toxin-producing dinoflagellate algae. Consumption of shellfish contaminated with PTXs has been associated with incidences of severe diarrhetic illness resulting in hospitalisation. Concern has been raised for public health following the discovery that these toxins are not only hepatotoxic and can cause diarrhetic effects in mammals, but that they are potently cytotoxic to human cancer cell lines and have been found to be tumour promoters in animals. With advances in knowledge and technology, more PTXs are being identified, but little is known of their toxicology and the potential impact these toxins may have on public health in the long term. Without such information, adequate health-risk assessments for the consumption of shellfish contaminated with PTXs cannot be performed. This review gives a brief introduction to diarrhetic shellfish toxins, details the known toxicology and metabolism of PTXs in animals, and discusses known incidences of PTX poisoning in humans.

Animals↗

PubMed2004

Enzyme-linked immunosorbent assay for the detection of yessotoxin and its analogues.

Polyclonal antibodies were produced for the development of competitive enzyme-linked immunoassays for use in quantifying yessotoxins in shellfish, algal cells, and culture supernatants. Immunizing and plate coating antigens were prepared by derivatization of yessotoxin either by ozonolysis or bromination and conjugation to proteins. Two assays that were the most sensitive for yessotoxin were optimized and characterized. Cross-reactivity studies indicated that the antibodies raised have broad specificity and that binding to analogues was strongly affected by changes to the A-ring and, to a lesser extent, the K-ring regions of the toxin molecule. ELISA provides a sensitive and rapid analytical method that is suitable for screening large numbers of samples and detects all the yessotoxin analogues that the European Commission currently requires shellfish to be tested for. The assay limit of quantitation for yessotoxin in whole shellfish flesh is 75 microg/kg; therefore, assay sensitivity is sufficient to measure toxin levels well below the maximum permitted level set by the European Commission. The antibodies produced can be used in additional applications such as the immunolocalization of yessotoxins in shellfish and preparation of immunoaffinity columns.

Antibody Specificity↗

PubMed2006

Production of 7-epi-pectenotoxin-2 seco acid and assessment of its acute toxicity to mice.

Pectenotoxins (PTXs) accumulate in shellfish feeding on dinoflagellates of the genus Dinophysis, so that humans can be exposed to these toxins through shellfish consumption. Some PTXs are toxic to experimental animals, whereas others are of much lower toxicity. Pectenotoxin-2, the most abundant PTX from most Dinophysis spp., is rapidly metabolized by most shellfish to a mixture of pectenotoxin-2 seco acid (2) and 7-epi-pectenotoxin-2 seco acid (1). A mixture of 1 and 2 was produced during purification of an extract from in vitro enzymatic hydrolysis of pectenotoxin-2. These were separated by preparative HPLC, and the structure of 1 was confirmed by one- and two-dimensional 1H and 13C NMR spectroscopy and LC-MS3 analyses. No toxic changes were recorded in mice injected intraperitoneally with 1 or 2 at a dose of 5000 microg/kg. PTX seco acids are therefore unlikely to be of consequence to human consumers at the concentrations found in contaminated shellfish.

Animals↗

PubMed2001

Time course and reversibility of changes in the gizzards of red knots alternately eating hard and soft food.

The ability to change organ size reversibly can be advantageous to birds that perform long migrations. During winter, red knots (Calidris canutus) feed on shellfish and carry a muscular gizzard that weighs 10% of their body mass. Gizzard size decreases when these birds eat soft foods, e.g. while breeding in the tundra. We studied the reversibility and time course of such changes using ultrasonography. Two groups of shellfish-adapted knots (N=9 and N=10) were fed alternately a hard and a soft food type. Diet switches elicited rapid reversible changes. Switches from hard to soft food induced decreases to 60% of initial gizzard mass within 8.5 days, while switches to hard food induced increases in gizzard mass to 147% within 6.2 days. A third group of knots (N=11), adapted to soft food for more than 1 year, initially had very small gizzards (25% of the mass of shellfish-adapted gizzards), but showed a similar capacity to increase gizzard size when fed shellfish. This is the first non-invasive study showing rapid digestive organ adjustments in non-domesticated birds.

Adaptation, Physiological↗

PubMed2003

Hepatitis A virus detection in oysters (Crassostrea gigas) in Santa Catarina State, Brazil, by reverse transcription-polymerase chain reaction.

Shellfish are readily contaminated with viruses present in water containing sewage because of the concentration effect of filter feeding. Hepatitis A virus (HAV) is the main cause of acute hepatitis worldwide and may lead to severe illness or even death. It is transmitted through fecal and oral routes and causes widespread endemic and asymptomatic infections in young children. Here we describe a method for the detection of HAV RNA in shellfish involving the extraction of total RNA from oyster meat followed by reverse transcription-polymerase chain reaction (RT-PCR). Virus recovery from oyster extracts artificially seeded with HAV strain HM 175 was examined by RT-PCR. The minimum detection limit was 3.3 focus-forming units of HAV, and the recovery rate was 75.7%. This method was used to assess the viral contamination of four shellfish beds in Santa Catarina State, Brazil, over a 1-year period. Six (22%) of 27 samples collected in autumn and winter from one shellfish bed tested positive for HAV.

Animals↗

PubMed2001

Are Pyrodinium blooms in the Southeast Asian region recurring and spreading? A view at the end of the millennium.

Pyrodinium bahamense (var. compressum) has been the only dinoflagellate species that has caused major public health and economic problems in the Southeast Asian region for more than 2 decades now. It produces saxitoxin, a suite of toxins that cause Paralytic Shellfish Poisoning (PSP). A serious toxicological problem affecting many countries of the world, mild cases of this poisoning can occur within 30 minutes while in extreme cases, death through respiratory paralysis may occur within 2-24 hrs of ingestion of intoxicated shellfish. Blooms of the organism have been reported in Malaysia, Brunei Darussalam, the Philippines and Indonesia. The ASEAN-Canada Red Tide Network has recorded 31 blooms of the organism in 26 areas since 1976 when it first occurred in Sabah, Malaysia. As of 1999, the most hard hit country has been the Philippines which has the greatest number of areas affected (18) and highest number of Paralytic Shellfish Poisoning (PSP) cases (about 1995). Malaysia has reported a total of 609 PSP cases and 44 deaths while Brunei has recorded 14 PSP cases and no fatalities. Indonesia, on the other hand has a record of 427 PSP cases and 17 deaths. Studies on ecological/environmental impacts of these blooms have not been done in the region. Estimates of economic impacts have shown that the loss could be up to USD 300,000 day-1. Most of the data and information useful for understanding Pyrodinium bloom dynamics have come from harmful/toxic algal monitoring and research that have developed to different degrees in the various countries in the region affected by the organism's bloom. Regional collaborative research and monitoring efforts can help harmonize local data sets and ensure their quality and availability for comparative analysis and modeling. Temporal patterns of the blooms at local and regional scales and possible signals and trends in the occurrence/recurrence and spread of Pyrodinium blooms could be investigated. Existing descriptive and simple predictive models of Pyrodinium blooms can be improved and refined to help in the management of the wild harvest and aquaculture of shellfish in a region where the people are dependent on these resources for their daily food sustainance and livelihood.

Animals↗

PubMed2003

[Risk to human health associated with marine toxic algae].

Among the about 5000 of marine algal species, some 75 produce algal toxins. These latter mainly belong to the taxa first of dynoflagellates and then diatomes. The so far known human intoxications have been associated with mollusc consumption. The main poisoning syndromes have been termed, on the basis of the observed symptoms, as paralytic, diarrhetic, neurotoxic and amnesic and shorthened as: PSP (paralytic shellfish poisoning), DSP (diarrhetic shellfish poisoning), NSP (neurotoxic shellfish poisoning), ASP (amnesic shellfish poisoning), respectively. This paper is a review of the problem of human health implications associated with marine toxic algae, with particular reference to the situation of the Mediterranean and the Italian coastal areas.

Animals↗

PubMed1978

[Program for the production of mollusks in Venezuela].

This paper discusses an integrated project in Venezuela, planned and designed to ascertain the best procedures required for production of large quantities of shellfish, including: selection and maintenance of pollution-free growing areas; the best harvesting methods; and the safest and most economical marketing procedures. The major problems involved in producing safe, wholesome and nutritious shellfish are primarily those of sanitation and adequate preservation of the foods until they finally reach the consumer. Therefore, it is essential that these products be produced and handled in a sanitary manner on a continuous basis. There are numerous codes of recommended handling practices for shellfish, most developed only after many technical conferences were organized to evaluate all of the available scientific evidence. Therefore, for producing safe shellfish in Venezuela, this publication recommends the adoption of these sanitary and handling practices, designed and tested by the faculty and staff personnel of Universidad Simón Bolívar.

Animals↗

PubMed2001

Evidence for PSP in mussels in Trinidad.

Herein we present the first evidence for the presence of Paralytic Shellfish Poison (PSP) in Trinidadian waters. The toxin was found in a meat extract of the mussel, Perna viridis. PSP has not previously been demonstrated in the shellfish of Caribbean islands. The presence of PSP in Trinidad is therefore significant in that it presents an opportunity to better understand the dynamics of PSP and algal blooms in both a region and island environment not normally associated with PSP.P. viridis is not native to Trinidad, but rather originates from eastern Asia. It presented itself only recently in Trinidadian waters. Interestingly, shellfish consumption and algal blooms have had a long history of coexistence in Trinidad without any record of human intoxications. In this context, potential Public Health implications of finding PSP in a non-native shellfish species are briefly discussed.

Animals↗

PubMedDate not supplied

Do saxitoxin-like substances have a role in scombrotoxicosis?

Evidence is presented which establishes that mackerel fed in captivity can, by relay from contaminated shellfish via sand eels, accumulate paralytic shellfish poisons (PSP) in the edible flesh at a level (250 micrograms saxitoxin equivalents per kg) similar to that in the contaminated shellfish. Data from ELISAs performed independently in two laboratories show that commercial mackerel fillets which have been associated with incidents of scombrotoxicosis contained 0.02-1.30 micrograms saxitoxin equivalents per kg, concentrations some two to four orders of magnitude below that normally detectable by the mouse bioassay. The doses, expressed as saxitoxin equivalents, administered inadvertently during volunteer testing of such fillets ranged up to 0.5 ng/kg bw, at least four orders of magnitude less than the fatal oral dose for an adult. The doses associated with the rapid induction of nausea/vomiting and/or diarrhoea, 0.11-1.0 ng/kg bw, could not be distinguished from the doses which failed to produce such symptoms in susceptible volunteers (up to 0.5 ng/kg bw). Factors that might explain this lack of correlation between dose (saxitoxin equivalents) and volunteer response are discussed along with previously published reports of PSP relay through the food web. It is suggested that the relay of algal toxins, particularly PSP, but possibly in combination with diarrheic shellfish poisons, may be responsible for scombrotoxicosis.

Animals↗

PubMedDate not supplied

Surveillance programmes for managing risks from naturally occurring toxicants.

Aflatoxins are potent carcinogenic, mutagenic and teratogenic metabolites produced by moulds that grow on food and feed. Their toxicity has caused severe health and economic problems worldwide. Other mycotoxins which have been associated with human health risks include ergot alkaloids, citreoviridin, trichothecenes, ochratoxins, citrinin, tremorgenic mycotoxins and the fumonisins. Many phycotoxins have also been associated with human illnesses; these phycotoxins include paralytic shellfish poisons, diarrhoeic shellfish poisons, ciguatera-related toxins, neurotoxic shellfish poisons, tetrodotoxin and, the more recently discovered, domoic acid which is associated with amnesic shellfish poisoning. Human exposure to these naturally occurring toxins can be from direct consumption of contaminated commodities or from foods derived from animals previously exposed to these toxins in their feed. Food safety monitoring programmes for selected toxins have been established for raw and finished products susceptible to contamination. Components of these control programme include the establishment of regulatory limits or guidelines, monitoring susceptible products for specific compounds, and the diversion of the contaminated products to lower-risk uses and/or decontamination procedures.

Consumer Product Safety↗

PubMed2000

Vibrio ocular infections on the U.S. Gulf Coast.

PURPOSE: To describe the epidemiology of Vibrio eye infections. METHOD: We reviewed the records of a patient from our institution with V. vulnificus keratitis and conducted a literature search for other cases of ocular infections with Vibrio species. RESULTS: A 39-year-old fisherman was struck in his left eye with an oyster shell fragment, developed suppurative V. vulnificus keratitis, and was successfully treated with combined cefazolin and gentamicin. Including our patient, 17 cases of eye infections with Vibrio spp. have been reported, and 11 (65%) involved exposure to seawater or shellfish. Of the seven cases due to V. vulnificus (six keratitis and one endophthalmitis), six had known exposure to shellfish or seawater along the U.S. coast of the Gulf of Mexico. Of five cases of V. alginolyticus conjunctivitis, three had been exposed to fish or shellfish. Three infections with V. parahaemolyticus (one keratitis and two endophthalmitis) were reported; two of these occurred in people exposed to brackish water on or near the Gulf Coast. Two cases of postsurgical endophthalmitis, one with V. albensis and one with V. fluvialis, also were reported. CONCLUSIONS: In addition to septicemia, gastroenteritis, and wound infections, halophilic noncholera Vibrio species can cause sight-threatening ocular infections. Ocular trauma by shellfish from contaminated water is the most common risk factor for Vibrio conjunctivitis and keratitis. Nearly one half of reported Vibrio infections of the eye occurred along the U.S. coast of the Gulf of Mexico.

Adult↗

PubMed2000

Contributions of 18 food categories to intakes of 232Th and 238U in Japan.

Daily intakes of 232Th and 238U and contributions of food categories to those nuclide intakes in Japanese were estimated using a market basket study for 18 food categories. Food categories having higher 238U contents (per g-fresh) were found to be as follows: seaweeds 1,140 microBq; fishes and shellfishes 37 microBq; nuts and seeds 11 microBq; bean products 8.6 microBq; and cooked meals 7.3 microBq. Big contributors to the daily 238U intake in Japan were as follows: seaweeds (50%); fishes and shellfishes (26%); and bean products (4.3%). For 232Th, higher contents (per g-fresh) were found as follows: seaweeds 28 microBq; fishes and shellfishes 13 microBq; nuts and seeds 8.2 microBq; green vegetables 3.9 microBq; cooked meals 3.5 microBq; and bean products 2.9 microBq. Big contributors to the daily 232Th intake were as follows: fishes and shellfishes (44%); green vegetables (11%); bean products (7.4%); and seaweeds (6.0%). For both nuclides, marine food products were big contributors, while minor contributors were oil and fats, eggs, and cooked meals. Daily intakes of 232Th and 238U in Japan were estimated to be 2.7 mBq and 14 mBq per person from the intakes of the 18 categories, respectively. Annual effective doses were estimated to be 232Th, 2.2 x 10(-7) Sv, and 238U, 2.2 x 10(-7) Sv.

Diet↗