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PubMed1994

[The detection of viruses in food of animal origin using the polymerase chain reaction--a review].

Conventional methods for the detection of viruses in food are very time consuming and usually not sensitive enough to detect very low amounts of virus. Modern methods, like nucleic acid hybridization and polymerase chain reaction (PCR), may accelerate the diagnostic procedure considerably. The PCR allows the amplification of a specific DNA-segment by the factor 10(6) or more within a few hours and has already been described for the detection of various food-borne viruses. We summarize the use of PCR in the diagnosis of viral food contaminations and also include some results of our work with the detection of pseudorabies virus (PRV) in artificially contaminated sausages. We found that PCR is in some respect advantageous to the classical tissue culture isolation. The detection level of the PCR in samples of different pH values was compared to virus isolation in tissue culture, and it could be shown that the PCR was less affected by extreme pH values than tissue culture.

Animals↗
PubMed2004

Epidemiological evidence of higher susceptibility to vCJD in the young.

BACKGROUND: The strikingly young age of new variant Creutzfeldt-Jacob disease (vCJD) cases remains unexplained. Age dependent susceptibility to infection has been put forward, but differential dietary exposure to contaminated food products in the UK population according to age and sex during the bovine spongiform encephalopathy (BSE) epidemic may provide a simpler explanation. METHODS: Using recently published estimates of dietary exposure in mathematical models of the epidemiology of the new variant Creutzfeldt Jacob disease (vCJD), we examine whether the age characteristics of vCJD cases may be reproduced. RESULTS: The susceptibility/exposure risk function has likely peaked in adolescents and was followed by a sharp decrease with age, evocative of the profile of exposure to bovine material consumption according to age. However, assuming that the risk of contamination was proportional to exposure, with no age dependent susceptibility, the model failed to reproduce the observed age characteristics of the vCJD cases: The predicted cumulated proportion of cases over 40 years was 48%, in strong disagreement with the observed 10%. Incorporating age dependent susceptibility led to a cumulated proportion of cases over 40 years old of 12%. CONCLUSIONS: This analysis provides evidence that differential dietary exposure alone fails to explain the pattern of age in vCJD cases. Decreasing age related susceptibility is required to reproduce the characteristics of the age distribution of vCJD cases.

Adolescent↗
PubMed1987

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) through water and food.

Chronic effects of Cd on reproduction of Polypedilum nubifer (Chironomidae) were investigated by Cd-exposure from the egg stage using a flow-through aquarium. No significant effect of Cd on reproduction was observed in the midge larvae which had been exposed to 10 or 20 microg Cd litre(-1). Emergence of the Cd-exposed larvae peaked several days before that of the control, although growth was impaired in 1st and/or 2nd instars. The percentage emergence success decreased to about 46% of the control at 40 microg Cd litre(-1). However, other reproductive processes (adult sex ratio, oviposition success and egg hatchability) were not impaired. The emergence success decreased to less than 3% of the control at 80 microg Cd litre(-1). The emergence success of midge larvae which had been fed Cd-contaminated food with 220 or 1800 microg Cd g(-1) decreased to nearly 60% of the control. However, other reproductive processes were not impaired. Emergence success of larvae exposed to food containing 22 microg Cd g(-1) was unaffected.

Journal Article↗
PubMedDate not supplied

Food Safety: Bovine Spongiform Encephalopathy (Mad Cow Disease).

Bovine spongiform encephalopathy is just one of a group of diseases known as transmissible spongiform encephalopathies. Only recently has it become recognized that transmissible spongiform encephalopathies are likely due to proteins known as prions. Although it has been recognized that transmissible spongiform encephalopathies may readily spread within species, the recent observations that bovine spongiform encephalopathy in cattle may have originated from another transmissible spongiform encephalopathy in sheep, known as scrapie, is cause for concern. Further, bovine spongiform encephalopathy has now been strongly linked with a universally fatal human neurologic disease known as new variant Creutzfeldt-Jakob disease. Currently the only approach to preventing bovine spongiform encephalopathy, and subsequent new variant Creutzfeldt-Jakob disease in humans, from ingestion of bovine spongiform encephalopathy-infected material is to avoid consumption of contaminated food. Little can be done to treat food that will destroy prions and leave a palatable product. At this stage we are continuing to learn about transmissible spongiform encephalopathies and their implications on human health. This is an ever-changing situation and has an unpredictable element in terms of the extent of the current outbreaks in England and other parts of Europe.

Journal Article↗
PubMed1999

Use of pyrrolidonyl peptidase to distinguish Citrobacter from Salmonella.

In the routine testing of foods for Salmonella, Citrobacter and other members of the Enterobacteriaceae often produce colonies which are almost indistinguishable from Salmonella on commonly used selective agars. Biochemical confirmation of such colonies can be expensive and time-consuming. It has been suggested that the enzyme pyrrolidonyl peptidase (PYRase) could be used as a rapid test to distinguish Citrobacter colonies (PYRase-positive) from Salmonella (PYRase-negative). Pure cultures of Salmonella, Citrobacter and other Enterobacteriaceae were tested for PYRase activity; all strains of Salmonella tested were PYRase-negative, and all Citrobacter tested were PYRase-positive. Inoculated and naturally contaminated food samples were tested for the presence of Salmonella by a standard cultural method. A PYR test was used to test Salmonella-like colonies isolated on selective agar and potentially, eliminate PYR-positive isolates from further biochemical testing. The test was able to screen out 6% of colonies selected from samples inoculated with Salmonella, and 43% of colonies selected from uninoculated samples.

Bacterial Typing Techniques↗
PubMed1999

Development of digoxigenin-labeled PCR amplicon probes for use in the detection and identification of enteropathogenic Yersinia and Shiga toxin-producing Escherichia coli from foods.

By including digoxigenin-11-dUTP in a polymerase chain reaction (PCR), amplification products were produced that contained nonisotopic markers for use as DNA hybridization probes. Because these labeled amplicons encode pathogenic traits for specific foodborne bacteria, they can be used to detect the presence of potentially virulent organisms that may be present in foods. This technology allows the synthesis of a variety of shelf-stable probe reagents for detecting a number of foodborne microbes of public health concern. We used this technology to detect four genes in two potential pathogens: virF and yadA in enteropathogenic Yersinia and stx1 and stx2 in Shiga-like toxin-producing Escherichia coli. Results of DNA hybridizations of dot blots of 68 Yersinia strains and 24 of 25 E. coli strains were consistent with results of equivalent PCR analyses. DNA colony hybridization with nonisotopic virF probes of colonies arising on spread plates from artificially contaminated food homogenates was able to detect potentially pathogenic Y. enterocolitica. When compared with oligonucleotide probes, amplicon probes are much less sensitive to changes in hybridization and wash temperatures, allowing greater reproducibility. Labeled probe preparations were reused more than five times and have been stored at -20 degrees C for more than 8 months. This method conveniently generates probes that are safe, stable, inexpensive, reusable, and reliable.

Adhesins, Bacterial↗
PubMed2005

Bioaccumulation and the effects of organochlorine pesticides, PAH and heavy metals in the Eel (Anguilla anguilla) at the Camargue Nature Reserve, France.

Pesticides (organochlorines-OC), polycyclic aromatic hydrocarbons (PAH) and heavy metals are toxic to fish and may be taken in through gills, skin and contaminated foods. Here we measure concentrations of OC, PAH and heavy metals, and their effects in the eel Anguilla anguilla from three locations in the Camargue Reserve in southern France. The Camargue Biosphere Reserve is the largest coastal wetland in Western Europe, and A. anguilla is a common predator at the top of the food chain. Livers and spleens were analyzed for histopathological, chemical and organo-somatic (HSI and SSI) effects. Gill, liver and spleen samples were collected for histopathological studies. Livers and muscles were sampled for metabolic parameters and persistent organic pollutant analysis. Total lipids were estimated by spectrophotometry and lipid-free residues were used in protein and glycogen analysis. OC pesticides were extracted from lipids of muscles and livers, analyzed by gas chromatography, and PAH from bile were analyzed by fixed wavelength fluorescence spectrofluorimetry. Heavy metals were measured by inductively coupled plasma with optical or with mass spectrometers. High concentrations of contaminants were found in eel tissues. La Capelière had the greatest OC and PAH concentrations; unexpected lesions in gills, livers and spleens were more common at the other sites. Liver and spleen tumors and lipidosis in livers were associated with chronic, and gill lesions with acute exposure. High pesticide and PAH concentrations and lesions in eels from the Camargue reserve demonstrate the contamination of the area. A more complete study in the Camargue reserve is necessary to better understand the impact on wildlife and humans. Also, this study suggests that eel biology must be better understood before continued use of this species as a biomonitor of polluted areas.

Analysis of Variance↗
PubMed1999

Detection of Salmonella spp. in food by a rapid PCR-hybridization procedure.

A rapid and sensitive PCR-hybridization procedure for detection of Salmonella serovars in food samples was developed. This method is based on three subsequent steps: (1) extraction of nucleic acids from a 2 ml aliquot of the pre-enrichment medium used for the conventional culture method after 6 h of incubation at 37 degrees C; (2) amplification with primers selected from the sequences of invE and invA genes; (3) Southern blot and hybridization with a biotin labeled oligonucleotide probe. The entire procedure requires 30 h. The PCR-hybridization assay was able to detect as little as 50 fg of purified chromosomal DNA of S. typhimurium and 0.2 cfu g-1 of an artificially contaminated food sample. Of 245 food samples analyzed by culture and PCR-hybridization, 20 were positive by both methods and 16 were positive by PCR-hybridization only. None of the 209 PCR-negative samples tested positive by culture. The sensitivity, specificity, alpha and beta error values of the results of the PCR-hybridization procedure, compared with those of culture, were 100, 92.9, 0 and 7.1%, respectively. These results indicate that a short pre-enrichment and PCR-hybridization could be used as a screening test for the detection of Salmonella in food samples.

Animal Feed↗
PubMed2004

[Parasitic zoonoses transmitted by drinking water. Giardiasis and cryptosporidiosis].

Nowadays, the parasitic zoonose organisms Giardia lamblia und Cryptosporidium spp. are among the most relevant pathogens of drinking water-associated disease outbreaks. These pathogens are transmitted via a fecal-oral route; in both cases the dose of infection is low. Apart from person-to-person or animal-to-person transmissions, the consumption of contaminated food and water are further modes of transmission. The disease is mainly characterized by gastrointestinal symptoms. In industrialized countries, the prevalence rate of giardiasis is 2-5 % and of cryptosporidiosis 1-3%. Throughout the world, a large number of giardiasis and cryptosporidiosis outbreaks associated with drinking water were published; in 2001 the first case in Germany was identified. Giardia and Cryptosporidium are detected in surface water and sporadically in unprotected groundwater. Use of these waters for drinking water abstraction makes high demands on the technology of the treatment process: because of the disinfectant resistance of the parasites, safe elimination methods are needed, which even at high contamination levels of source water guarantee safe drinking water. Further measures for prevention and control are implementation of the HACCP concept, which includes the whole chain of procedures of drinking water supply from catchment via treatment to tap and a quality management system.

Communicable Disease Control↗
PubMed1979

Effect of food toxicants on voluntary wheel running in rats.

Voluntary wheel running in rats in reaction to a dietary deficiency of iron or food toxicants of natural (dioscin) and environmental (cadmium) origins was used to develop a behavioral model by which rapid detection of food contaminants was accomplished following induction of spontaneous activity by techniques of feed restriction. High levels of voluntary wheel running in reference controls were followed by significant depressions in running activity in animals fed the dietary toxicants. Analyses of blood and liver tissues and depressions of testes size confirmed the presence of the insults to metabolism.

Animals↗
PubMed2004

Development of an indirect competitive ELISA for detection of Campylobacter jejuni subsp.jejuni O:23 in foods.

An indirect enzyme immunoassay for rapid detection of Campylobacter jejuni subsp. jejuni 0:23 has been developed. Optimum concentrations of immobilized cells, polyclonal chicken IgY, and rabbit anti-IgY antibody-horseradish peroxidase conjugate were 3.1 CFU/nL, 10 microg/mL, and 8 microg/mL, respectively. Under such conditions, the detection limit reached 50 CFU/microL, limit of quantification being 480 CFU/microL. By testing 5 chromogens, viz. 1,2-benzenediamine, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid), 3,3',5,5'-tetramethylbenzidine, bi(4,4'-anisidine) and 3-methyl-2-benzothiazolinone hydrazone, in horseradish peroxidase substrate, 1,2-benzenediamine or 3,3',5,5'-tetramethylbenzidine as H-donors in the enzyme substrate provided the highest ELISA sensitivity. The applied polyclonal antibody was specific for homogeneous antigen. The cross-reactions were observed only with one strain of C. sputorum subsp. sputorum (21.5 %) and with G+ bacterium Micrococcus luteus (6.1 %). Preliminary tests have been performed with a limited number of artificially contaminated food samples. No matrix effects on the ELISA sensitivity were observed. The results (by means of ELISA) were comparable with those given by both a standard cultivation method performed according to CSN ISO 10272 and commercially available Singlepath Campylobacter GLISA-Rapid Test.

Animals↗
PubMedDate not supplied

[Outbreak of Salmonella enteriditis food poisoning at a dining hall facility].

BACKGROUND: An outbreak of Salmonella enteriditis food poisoning having occurred at two banquet halls, affecting eight groups of guests, is described. This research was aimed at determining the food by means of which this illness was transmitted. METHODS: An analysis was conducted of the food processing procedures subject to having caused the outbreak. The association of the foods with the illness was analyzed by means of a case and control design. The adjusted Odds Ratio (aOR) and the 95% confidence intervals (C195%) were calculated by logic regression. RESULTS: The guests totalled 1771 in number, being divided up into 13 groups for three days running. A total of 629 individuals (36%) were surveyed The probable cases totalled 250 in number, 61 confirmed by Salmonella enterica. The glazed biscuit (dessert with raw egg having undergone no heat processing) showed the highest adjusted Odds Ratio (aOR = 20.40; CI95%:7.52-55.30) and tested positive for Salmonella enterica of the enteritidis serotype. CONCLUSIONS: Epidemiological and laboratory evidence supports the glazed biscuit having been the contaminated food having caused the outbreak. The research stressed as contributing factors: the use of raw egg, the production of large quantities ahead of time, prior to the time at which the food item in question was to be eaten.

Adolescent↗
PubMedDate not supplied

[Principal serotypes of Salmonella identified in 10703 strains in Mexico from 1982 to 1993].

From 1982 to 1993, 10703 Salmonella strains from The National Network of Diarroheal Laboratories of Mexico were sent to the Enteric Bacteriology Laboratory of INDRE. The strains were confirmed by serology and 119 different Salmonella serotypes were found. The most frequent serotypes were as follows: S. typhimurium, S, enteritidis, S. agona & S. typhi. The strains were classified according to the source of isolation as follows: 6671 strains (62.33%) from clinical samples, mainly of faecal origin; 2903 (27.1%) from food for human consumption; 425 from food for animal consumption, 665 (6.21%) from environment or fomites and 39 (0.36%) from animals. The most frequent serotype in clinical samples was S. typhimurium among 96 different serotypes. The main serotype from blood cultures was S. typhi although 27 other serotypes were found. Of thirteen serotypes related to diarrhoeal outbreaks the higher frequency of S. typhimurium was observed but S. typhi caused more outbreaks. A frequency of 119/> 2000 serotypes was observed, that means less than 5% of Salmonella known serotypes. A yearly variability on serotype predominance was observed as well as changes on source of isolation. This results suggest that epidemiological surveillance of salmonellosis should be continued and improved, looking for cases, asymptomatic carriers and contaminated food for human consumption.

Animal Feed↗
PubMed2000

An outbreak of Salmonella infection after a Chinese year-end party in central Taiwan.

An outbreak of food poisoning caused by Salmonella O7 serogroup C1 and O8 serogroup C2, occurred in Taichung City after a Chinese year-end buffet party with 127 attendees including employees, relatives and guests of the Psychiatry Department of Changhua Christian Hospital (CCH). Among the 114 attendees interviewed, 96 (84.2%) reported developing symptoms within 120 h after the dinner on February 4, 1999. The time of onset ranged from 2 h to 101 h after the dinner with an average of 20 +/- 16 h. The median and mode incubation periods were 17 h and 16 h, respectively. Salmonella C1 and C2 serogroups were isolated from the stool samples of 45 attendees. Based on the results of interview questionnaire, the most likely contaminated food was eel kabayaki (OR = 4.8, 95% CI:1.6-14.9, p < 0.01) followed by baked mussels (OR = 4.04, 95% CI:1.3-12.1, p = 0.01). However, this result could not be confirmed by food sample investigation due to the lack of leftover food. Possible techniques for the prevention of food-borne disease transmission, enhancement of communication about foodborne disease outbreaks within the health reporting system, and the reduction of response time during an outbreak of infection are required.

Adult↗
PubMed1993

[Epizootiology and pathogenesis of avian mycobacteriosis in the house sparrow (Passer domesticus) and tree sparrow (Passer montanus)].

The occurrence and extension of avian mycobacteriosis in house-sparrows (P. domesticus) and mountain-sparrows (P. montanus) have been followed under different epidemiological conditions. Out of 2.929 totally examined house-sparrow pathological changes of tuberculosis were found in 3 (0.10%) animals and in 14 (0.48%) animals the mycobacteria were isolated. By an examination of 544 mountain-sparrow the mycobacteria in 12 (2.20%) cases and in 1 case were isolated and the mycobacteria were found in the intestinal contents. Out of 11 different locations the mycobacteria were found only in places where a contact between sparrows and poultry contaminated by TBC was possible. In some cases the sparrow could be a source of mycobacteria for cattle as well. Simultaneously, the occurrence of TBC in sparrows out of cattle stables correlated with high incidence of avian tuberculin reactions in cattle stabled there. The sparrow could be here not only the source but also an indicator of mycobacteria environment infection. All isolated strains of mycobacteria were virulent for poultry. In experimental infections there was proven a high sensitivity of both species of sparrows to M. avium. After intramuscular infection of M. avium suspension the histological changes in liver have been observed after 12 days, the microscopic changes after 21 days and miliary TBC after 35 days. Peroral infection by food contaminated by TBC poultry livers caused TBC changes in liver and spleen with clinical symptoms and death after 91 days. After free contact between TBC poultry and healthy sparrows the tuberculous changes of parenchymatous organs in sparrows were found after 180 days. There was no difference in sensitivity between the house-sparrow and mountain-sparrow. The transfer of M. avium from TBC-infected sparrows to pigs and poultry was successful. After 45 days of join contact among TBC sparrows, healthy pigs and poultry in stables and after further stay of pigs and poultry in contaminated surroundings there was found an allergy to tuberculin after 65 or 178 days, respectively. Simultaneously, the TBC liver and spleen in poultry were found. The house-sparrow and mountain-sparrow are very sensitive to the M. avium infections. The occurrence and extension of TBC infections in sparrows depends first of all on the possibility of contacts with TBC-infected poultry. Infected sparrows can be an important source of M. avium for other species of animals.

Animals↗
PubMed2000

Standardized growth toxicity testing (Cu, Zn, Pb, and pentachlorophenol) with Helix aspersa.

Juvenile Helix aspersa (1 month, 1 g) were exposed for 4 weeks to food contaminated with copper, zinc, lead, and pentachlorophenol. At concentrations observed in contaminated soils, two essential metals at low levels (Cu and Zn) had a dose-dependent sublethal action on growth. Copper inhibited growth dose-dependently between 1000 and 2000 microg small middle dotg(-1) (EC(50)=1200 microg small middle dotg(-1)), whereas zinc had a toxic effect from 4000 microg small middle dotg(-1) (EC(50)=5500 microg small middle dotg(-1)) on. Lead, a nonessential metal, had no negative effect on growth, unlike cadmium (EC(50)=140 microg small middle dotg(-1)), as reported previously. Pentachlorophenol inhibited growth at a concentration of 500 microg small middle dotg(-1) from the fourth week and 1000 microg small middle dotg(-1) from the first week on. The results obtained with these key organisms in the food chain (consumers) complement those obtained with other land invertebrates (earthworms, springtails, wood-lice, etc.). The findings of the present study and those of earlier studies indicate that juvenile snails are useful organisms for testing the sublethal toxicity of chemicals acting via the food, i.e., the main route of toxicant uptake in land animals.

Animals↗
PubMed1998

RESEARCH: Perceptions of Risk Associated with Use of Farm Chemicals: Implications for Conservation Initiatives

/ Data were collected from 245 farmers within the Darby Creek hydrologic unit in central Ohio to assess perceptions of risk associated with use of farm chemicals. Farmers were asked to evaluate the level of risk associated with use of agricultural chemicals for water quality, food safety, food quality, health of applicator, health of farm animals, wildlife, beneficial plants, beneficial insects, and human health. Study findings revealed that respondents perceived use of farm chemicals posed little or no threat to any of the assessed items. A composite index was formulated from the responses to the nine items and was titled Perceived Risk. Variance in the Perceived Risk index was regressed against social learning variables. The findings revealed that approximately 32% of the variance was explained by the predictive variables included in the model. It was concluded that the theoretical perspective was somewhat useful for understanding perceptions held about agricultural chemical use at the farm level. The findings are discussed in the context of future conservation and educational-information programs within the study region.KEY WORDS: Risk perception; Risk assessment; Groundwater; Pesticide contamination; Food safety; Environmental quality

Journal Article↗
PubMedDate not supplied

Insecticide urinary metabolites in nonoccupationally exposed populations.

The wide use of insecticides in agricultural and residential settings has resulted in environmental contamination, leading to increased concern about exposure of the population and possible chronic effects on health. This review summarizes the studies that have measured urinary metabolites to assess exposure of nonoccupationally exposed population to nonpersistent insecticides, organophosphates (OPs), carbamates, and pyrethroids. Electronic search yielded 36 different studies performed in a small number of countries for the last 20 years, most of them dealing with OP urinary metabolites. Dialkylphosphates, specific metabolites of OPs, and specific metabolites of pyrethroids or carbamates, have been investigated. Results indicate that a wide range of the population, adults as well as children, is exposed to OPs and to a lesser extent to pyrethroids and carbamates. Levels are one to several orders of magnitude lower than those in occupational studies. The contribution of the different sources of insecticide exposure remains uncertain. Food contamination, as well as environmental and residential contamination, appears to influence exposure, especially in the case of children. Residential use of insecticides, having pets, and living near gardens or fields have all been inconstantly related to higher urinary metabolite levels. Occupational exposure of the parents, especially of the agricultural workers, seems to be a predictive factor of higher exposure of their children. More studies investigating every source and pathway of exposure of randomized population samples and in other countries than the United States, in particular in developing countries, could improve our knowledge of factors influencing insecticide exposure of the population.

Animals↗