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PubMed1979

Human enteroviruses in oysters and their overlying waters.

The presence of enteroviruses in oysters and oyster-harvesting waters of the Texas Gulf coast was monitored over a period of 10 months. Viruses were detected in water and oyster samples obtained from areas both open and closed to shellfish harvesting. Viruses were detected periodically in waters that met current bacteriological standards for shellfish harvesting. No significant statistical relationship was demonstrated between virus concentration in oysters and the bacteriological and physiochemical quality of water and shellfish. Viruses in water were, however, moderately correlated with total coliforms in water and oysters and with fecal coliforms in oysters. Total coliforms in water were realted to total coliforms in sediment were related only to total coliforms in sediment. Among the physiochemical characteristics of water, turbidity was related statistically to the organic matter content of water and to fecal coliforms in water. There was a marked effect of rainfall on the bacteriological quality of water. Of a total of 44 water samples, 26 yielded virus in concentrations from 4 to 167 plaque-forming units per 100-gallon (ca. 378.5-liter) sample. Of a total of 40 pools of 10 to 12 oysters each, virus was found in 14 pools at a concentration of 6 to 224 plaque-forming units per 100 g of oyster meat. On five occasions, virus was found in water samples when no virus could be detected in oysters harvested from the same sites. This study indicates that current bacteriological standards for determining the safety of shellfish and shellfish-growing waters do no reflect the occurrence of enteroviruses.

Animals↗

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↗

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↗

PubMed1977

Foodborne disease outbreaks of chemical etiology in the United States, 1970-1974.

In the United States between 1970 and 1974 there was an increase each year both in the absolute number of foodborne diseases outbreaks of chemical etiology reported to the Center for Disease Control and in the proportion of these outbreaks in the total reported foodborne disease outbreaks. Nearly half (48.9%) of these foodborne disease outbreaks of chemical origin were caused by toxic fish or shellfish. Of the rest, 16.5% were caused by poisonous mushrooms, 10.9% by heavy metal poisoning, 7.2% by excessive use in food of monosodium glutamate (the etiologic agent of Chinese Restaurant Syndrome) and 16.5% by miscellaneous chemicals. Practices that contributed to the occurrence of these outbreaks included the inadvertent selection for consumption of toxic fish, shellfish, or mushrooms, storage of fish at improper temperatures, storage of acidic liquids in metal containers, and addition of excessive amounts of monosodium glutamate to foods. Commercially-processed foods were responsible for outbreaks of scombroid fish poisoning, shellfish poisoning, and heavy metal poisoning. Because outbreaks of chemical etiology due to contaminated commercial products do occur, prompt recognition and reporting of outbreaks to public health personnel are essential so that epidemiologic investigations can be conducted and effective control measures promptly initiated.

Animals↗

PubMed1977

Comprehensive evaluation of fatty acids in foods.

Based on production volume and value and on per capita consumption, shellfish are an important food group in the United States. The nutrient composition of shellfish indicates that this food group is low in fat and relatively high in protein. Tabulated data on fatty acids in the different edible portions of seven species of crustaceans and over twenty species of mollusks are presented. The proportionately high level of polyunsaturated fatty acids is shown by the polyunsaturation index calculated for some important species of shellfish.

Animals↗

PubMed1978

Thermal treatment and infectivity of hepatitis A virus in human feces.

The susceptibility of white-lipped marmoset monkeys (Saguinus sp) to human hepatitis A virus (HAV) provides a system for evaluation of thermal inactivation of HAV in feces and contaminated shellfish. Intramuscular or oral administration of HAV derived from feces of four patients with acute hepatitis A induced hepatitis in 28--100% of the inoculated marmosets. A 10% (w/v) fecal pool (GBG-BM) prepared from two patients (GBG and GBM) induced hepatitis in marmosets (2/4 with 1 ml; 2/2 with 3 ml) when given orally as a 1 : 3 dilution. A HAV-baby food raw oyster mixture fed to fasted marmosets induced hepatitis in 1/4 and seroconversion in 2/4 animals. Two groups of oysters were injected with HAV (concentrated 3 : 1 by centrifugation of the GBG-BM pool); one group was treated at 140 degrees F for 19 minutes and the other served as an untreated control. In animals fed the untreated inoculum, 4/6 developed hepatitis and 6/6 seroconverted, whereas of those fed the heat-treated inoculum 1/7 developed hepatitis and 2/7 seroconverted. These data suggest that pasteurization methods could be developed that would eliminate shellfish-associated hepatitis A and retain the palatability of the shellfish.

Animals↗

PubMed1978

The distribution of Vibrio parahaemolyticus in British coastal waters: report of a collaborative study 1975--6.

A collaborative survey has shown that V. parahaemolyticus is widely distributed in British coastal waters, sediments and shellfish, especially in southern and western areas. The relatively small numbers in the environment do not present significant health hazards from marine products, provided that processing, storage and distribution are adequate. The presence of this organism in small numbers in British coastal waters or in shellfish should not in itself be regarded as cause for concern.

Mollusca↗

PubMed1978

The functional characteristics conserved in tropomyosins.

1. Tropomyosin, one of the regulatory proteins in muscle contraction, was prepared from chickens, rabbits, frogs, shrimps, and shellfish, and conserved characteristics were studied using an enzymological technique. 2. All tropomyosins tested, irrespective of their sources, were found to have the ability to mediate the inhibitory activity of rabbit troponin toward rabbit Mg2+-activated actomyosin ATPase (Mg2+-ATPase) activity in the absence of Ca2+ ions. 3. The effect of tropomyosin on the Mg2+-ATPase activity in the presence of Ca2+ ions varied, depending on the source, and this variation appeared to reflect the evolutionary course of this protein. 4. Tropomyosin from shellfish adductor muscle had the ability to bind to rabbit skeletal muscle troponin and actin. This ability is also considered to be a basic characteristic of tropomyosin which has been conserved during evolution.

Actins↗

PubMed1978

Incidence of Vibrio parahaemolyticus bacteriophages and other Vibrio bacteriophages in marine samples.

Vibrio bacteriophages were isolated by enrichment from 177 of 643 samples of marine molluscan shellfish, crustaceans, seawater, and sediments. The predominant bacteriophage types isolated were specific for some strains of Vibrio parahaemolyticus. A high frequency of phage isolations was also observed with strains of agar-digesting vibrios (21 of 56) and psychrophilic vibrios (14 of 72) that were originally isolated from non-shellfish growing areas. No bacteriophages were isolated against V. alginolyticus and only rarely for V. anguillarum even though these were the two most abundant species found in near-shore environments. No V. cholerae phages were isolated. It was also determined from quantitative studies on the Pacific oyster (Crassostrea gigas) obtained from two environments in Washington and Oregon that the titers of V. parahaemolyticus bacteriophages increased with increasing seasonal water temperatures and that this was proportional to the increase in numbers of mesophilic vibrios and not with the incidence of V. parahaemolyticus. Titers of V. parahaemolyticus bacteriophages occasionally exceeded 10(6) per g of oyster during the summer months. Specific V. parahaemolyticus bacteriophages were also isolated from market seafoods and other marine samples that originated in cold environments where no mesophilic vibrios are expected to be found. The possibility that V. parahaemolyticus bacteriophages originate from Vibrio spp. other than V. parahaemolyticus and the role of these bacteriophages in the ecology of marine vibrios are discussed.

Animals↗

PubMed1978

Steric hindrance as a factor in the reaction of labeled antibody with cell surface antigenic determinants.

The binding of rabbit anti-human IgG labeled with 125I, shellfish glycogen or ferritin to human IgG attached to the surface of rabbit RBC with chromic chloride was studied. Maximum binding was noted with 125I labeled antibody. Slightly but consistently less binding was found with shellfish glycogen labeled antibody. The binding of ferritin labeled antibody was strikingly reduced--usually one-third or less of that found with 125I labeled antibody alone. This suggests that under the conditions of these experiments, the attachment of large labels to antibody molecules results in reduced antibody binding to surface antigen. Steric hindrance is probably at least in part responsible for this reduced binding.

Animals↗

PubMed1979

Food-borne parasitic infections--old stories and new facts.

A review is presented of food-borne parasitic infections. Parasitic infections with public health hazards both from conventional slaughter animals and from seafood (fish and shellfish) are discussed. The former category includes cysticercosis, echinococcosis, and trichinosis, the latter category covers various trematode, cestode, nematode, and possibly also protozoan infections. Examples of trematode infections are heterophyidiasis, transmitted to man by marine fish, and Paragonimus spp parasites, transmitted by crustaceans. Cestode infections include diphyllobothriasis transmitted by both fresh water fish and fish from brackish waters. Special attention is drawn to the condition known as sparganosis. Of the nematode infections, the eosinophilic granulomatous enteritis due to the genera Anisakis, Phocanema, and Contracaecum, transmitted to man by either marine fish or crustaceans, is mentioned. Two other nematode infections. Angiostrongylus cantonensis and Capillaria philippinensis, can also be transmitted to man by marine fish. Free living amoebae (a.o. Naegleria) may be transmitted to man via shellfish as vehicles. Apart from a possible direct effect of these parasites, chemical alterations in seafood resulting from the presence of parasites may also be deleterious to the consumer. Special attention is drawn to a newly developed serological detection method, the enzyme-linked immunosorbent assay, which makes detection of infection possible not only at the slaughterhouse but also at the farm or in large herds. Strategies to control parasitic infections both in conventional slaughter animals and in seafood are discussed.

Animals↗

PubMed1977

Electron capture gas chromatographic determination of Kepone residues in environmental samples.

The pollution of the environment with Kepone (decachlorooctahydro-1,3,4-metheno-2H-cyclobuta[cd]pentalen-2-one) by an industrial manufacturer of the pesticide resulted in the contamination of several terrestrial media, including biological life, near the entry of the insecticide into the ecosystem. The substrata investigated and for which residue methodology was developed included river sediment, soil, water, shellfish, and finfish. Rigorous extraction techniques utilizing the Soxhlet apparatus and the Polytron tissue homogenizer were required for complete removal of Kepone from the samples. Finfish tissue was the most difficult to analyze. For this type of substratum, a preliminary cleanup by gel permeation chromatography was required to remove most of the lipid material followed by a micro Florisil column elution to eliminate polychlorinated biphenyls (PCB'S). Cleanup of shellfish and other environmental samples was accomplished with a micro Florisil column only. Electron capture gas chromatography was used to analyze the sample extracts. Recoveries of Kepone from fortified samples averaged 84% or greater.

Animals↗

PubMed1976

Nondestructive neutron activation analysis of marine organisms collected from ocean dump sites of the middle eastern United States.

The concentrations of eight metals were determined by a nondestructive neutron activation technique for eleven species of fish and shellfish. The marine organisms were collected from ocean dump sites off New York City, off New Haven, Connecticut, and off Delaware Bay. Antimony was not detected in most of the organisms examined in thid study; the detection limit was about 0.02 to 0.05 ppm. Antimony levels ranged from 0.01 to 0.129 ppm in fish that had detectable levels. Cobalt levels were low in all samples with most levels in the range of 0.1 to 0.3 ppm. Chromium concentrations at 0.3 to 1.0 ppm were only roughly quantitated by the procedure employed. Most marine organisms examined had chromium levels at or below these values. Nickel was not detected in any of the organisms examined; the detection limit was in the 3 to 6 ppm range. Rubidium concentrations were 0.6 to 1.5 ppm for most organisms; only rough quantitative measurement was possible at these levels. Selenium levels ranged from about 0.3 to 3.8 ppm in all samples. Silver concentrations were below 0.3 ppm in most organisms. Silver concentrations as high as 10 to 30 ppm, however, were found in the digestive gland of rock crab. Zinc levels in windowpane flounder liver were about 6 to 9 times greater than the 4 to 10 ppm levels found in muscle. Zinc concentrations in rock crab muscle, on the other hand, were only slightly higher than the 15 to 32 ppm concentration found in the digestive gland. Fish other than windowpane flounder had zinc levels that ranged from 4 to 9 ppm in the muscle and 14 to 42 ppm in the liver. Shellfish other than rock crab had zinc levels of 15 to 30 ppm in muscle and 17 to 40 ppm in the digestive gland.

Animals↗

PubMed1977

Potential for employing the distribution of anomalous non-methylene-interrupted dienoic fatty acids in several marine invertebrates as part of food web studies.

A group of homologous, nonmethylene-interrupted dienoic fatty acids (NMID) recently reported in oysters has been found in several other shellfish species and also in other marine phyla. The distribution of most other "normal" fatty acids among several species of shellfish is basically similar but mantle lipids from two other molluscan species, both squid, differ radically. The squid mantle fatty acids do not include NMID, suggesting that in molluscs NMID may accumula-e primarily in filter-feeders or herbovores. The distribution of these anomalous fatty acid components in higher species suggests that they reflect invertebrates in the diet and are biochemically inert.

Animals↗

PubMed1975

Uptake and elimination of poliovirus by West Coast oysters.

Accumulation of poliovirus Lsc-2ab by West Coast oysters was determined by using a stationary seawater system, and depuration was determined by using both stationary and free-flow systems. Results indicate that these shellfish have the same pattern of accumulation and localization of viruses as do East Coast species. However, uptake appeared to occur more rapidly than described for East Coast shellfish. There appeared to be a gradual diffusion of virus from the digestive area into the body. Depuration was found to occur more rapidly and completely under free-flow conditions than in a stationary system.

Animals↗

PubMed1979

Influences of oyster or clam feeding on lipid metabolism in rats.

Rats were fed on three kinds of diets for two weeks: (I) basal diet, (II) containing 0.1% cholate and (III) containing 0.1% cholesterol and 0.1% cholate. Each dietary group was further divided into subgroups to whose diet was added 0, 5 or 10% (dry weight) of minced oyster (Callocorchina) or clam (Tapes japonica). The serum and liver cholesterol levels of the rats fed the basal diet were reduced by feeding oyster or clam. The serum and liver triglyceride levels of all dietary groups were lowered markedly by feeding oyster or clam. The activities of glucose-6-phosphate dehydrogenase, malic enzyme and acetyl-CoA carboxylase were markedly reduced in the basal groups fed oyster or clam. These effects were observed in 5 and 10% shellfish feeding. These shellfish may be considered hypolipidemic foods.

Acetyl-CoA Carboxylase↗

PubMed1978

Viruses in water.

Attention is drawn in this paper to the increasing problem of viral contamination of water and shellfish, particularly since growing demands for available water resources by a rising world population and expanding industry will make the recycling of wastewater almost inevitable in the future. The problem of eliminating viruses pathogenic for man from water is considered in the light of present water treatment procedures, which are often inadequate for that purpose. Man may be exposed to waterborne viruses through the consumption of contaminated water, shellfish, or crops, as a result of recreational activities involving water, or from aerosols following the spraying of crops with liquid wastes. Physical and chemical methods of eliminating viruses from water are discussed.

Humans↗

PubMed1979

Cholera in the Gilbert Island. I. Epidemiological features.

An explosive epidemic of cholera due to Vibrio cholerae, biotype El Tor, serotype Inaba, was centered on the coral atoll of Tarawa, Gilbert Islands. This outbreak was a unique experience in the South and Central Pacific region. The principal mode of spread during the peak of the outbreak was probably through contamination of the main water supply. Tarawa lagoon water and shellfish were found to be contaminated with V. cholerae and ingestion of raw fish and shellfish from the lagoon also served as a source of transmission. This outbreak raises the concern of Rother outbreaks of cholera occuring on remote and poorly equipped Pacific islands where the environmental circumstances are conducive to cholera spread.

Antibodies, Bacterial↗