Analysis of Cured Meat Products for Cryptosporidium Oocysts following Possible Contamination during an Extensive Waterborne Outbreak of Cryptosporidiosis
Parasitology Laboratory, Section for Microbiology, Immunology, and Parasitology, Department of Food Safety and Infection Biology, Norwegian School of Veterinary Science, P.O. Box 8146 Dep, 0033 Oslo, Norway.Journal of food protection (Impact Factor: 1.85). 05/2012; 75(5):982-8. DOI: 10.4315/0362-028X.JFP-11-525
An outbreak of waterborne cryptosporidiosis in a town in northern Sweden during winter 2010 resulted in the potential exposure of cured meat products to Cryptosporidium oocysts during their manufacture. The purpose of this work was to develop a method for analyzing cured meat products for contamination with Cryptosporidium oocysts and use this method to analyze potentially contaminated product samples. A simple method of elution, concentration, separation, and detection was used, based on work with other food matrices but adapted for the relatively high fat content of cured meat surfaces. Using spiking experiments, the recovery efficiency of this method was found to be over 60%. In the analysis of the potentially contaminated products, only one putative Cryptosporidium oocyst was detected, and this was sufficiently deformed so that it could not be confirmed as an oocyst; if it was an oocyst, it was considered to have been probably deformed and inactivated prior to analysis. Based on the results of the analyses, together with data on the probable extent of contamination of the products and on our knowledge of factors, such as water activity, which affect oocyst survival, the products were safely released to the market.
- [Show abstract] [Hide abstract]
ABSTRACT: We report the results of interlaboratory collaborative trials of methods to detect oocysts of the protozoan parasite Cryptosporidium parvum on lettuce and raspberries. The trials involved eight expert laboratories in the United Kingdom. Samples comprised 30 g lettuce, and 60 g raspberries. Lettuce samples were artificially contaminated at three levels: low (8.5-14.2 oocysts), medium (53.5-62.6 oocysts), and high (111.3-135.0 oocysts). Non-contaminated lettuce samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated lettuce samples) of 89.6%, and a specificity (correct identification of non-contaminated samples) of 85.4%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 30.4%. The method was just as reproducible between laboratories, as repeatable within a laboratory. Raspberry samples were artificially contaminated at three levels: low (8.5-26.8 oocysts), medium (29.7-65.7 oocysts), and high (53.9-131.3 oocysts). Non-contaminated raspberry samples were also tested. The method had an overall sensitivity (correct identification of all artificially contaminated raspberry samples) of 95.8%, and a specificity (correct identification of non-contaminated samples) of 83.3%. The total median percentage recovery (from all artificially contaminated samples) produced by the method was 44.3%. The method was just as reproducible between laboratories, as repeatable within a laboratory. The results of the collaborative trial indicate that these assays can be used effectively in analytical microbiological laboratories.International Journal of Food Microbiology 07/2006; 109(3):222-8. DOI:10.1016/j.ijfoodmicro.2005.12.014 · 3.08 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: This paper describes the first reported method for the recovery and detection of Cryptosporidium parvum oocysts from beef carcasses. C. parvum oocysts were mobilized from beef surfaces into phosphate buffer saline-Tween 80, and subsequently recovered from this suspending medium by membrane filtration. Oocysts were removed from the membrane, concentrated by centrifugation, labelling with an FITC conjugated monoclonal antibody and enumerated using fluorescence microscopy. The study compared 'pulsification', a novel method, with 'stomaching' an established method, as processes for resuspending the target microorganisms from beef. Both yielded similar levels of recovery of oocysts, but pulsification produced less suspended sample debris, allowing easier oocyst detection. Membrane filter pore size (0.45, 1.0 or 3.0 mm) did not significantly affect the number of oocysts detected (P > 0:05). Centrifugation at 2500g for 15 min using a swing out no brake (SONB) during deceleration rotor gave higher recoveries than a fixed angle with braking (FAB) rotor during centrifugation (Po0:05). Using inocula containing 2000 oocyst cm À2 , the optimized method (pulsification, filtration, SONB centrifugation and FITC labelling) allowed recovery and detection of 85.4% of inoculated oocysts from fat beef tissue and 128.4% from lean beef tissue. The developed method will be of value in establishing the incidence of C. parvum on beef and in future research on this parasite.Food Microbiology 06/2004; 21(3):275-282. DOI:10.1016/j.fm.2003.08.005 · 3.33 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Recent waterborne outbreaks have established Cryptosporidium as an emerging enteric pathogen, but foodborne transmission has rarely been reported. In October 1993, an outbreak of cryptosporidiosis occurred among students and staff attending a 1-day school agricultural fair in central Maine. Environmental/laboratory investigation and cohort study. Attendees of the fair and their household members. Clinical or laboratory-confirmed cryptosporidiosis. Clinical cryptosporidiosis was defined as 3 days of either diarrhea (three loose stools in a 24-hour period) or vomiting. Surveys were completed for 611 (81%) of the estimated 759 fair attendees. Among attendees who completed the survey, there were 160 (26%) primary cases. Cryptosporidium oocysts were detected in the stools of 50 (89%) of 56 primary and secondary case patients tested. The median incubation period was 6 days (range, 10 hours to 13 days); the median duration of illness was 6 days (range, 1 to 16 days). Eighty-four percent of primary case patients had diarrhea and 82% had vomiting. Persons drinking apple cider that was hand pressed in the afternoon were at increased risk for cryptosporidiosis (154 [54%] of 284 exposed vs six [2%] of 292 unexposed; relative risk, 26; 95% confidence interval, 12 to 59). Cryptosporidium oocysts were detected in the apple cider, on the cider press, and in the stool specimen of a calf on the farm that supplied the apples. The secondary household transmission rate was 15% (53/353). This is the first large cryptosporidiosis outbreak in which foodborne transmission has been documented. It underscores the need for agricultural producers to take measures to avoid contamination of foodstuffs with infectious agents common to the farm environment.JAMA The Journal of the American Medical Association 11/1994; 272(20):1592-6. DOI:10.1001/jama.272.20.1592 · 35.29 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.