Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/21/2008
Publication Date: 11/21/2008
Citation: Callicott, K., Haroardottir, H., Georgsson, F., Reiersen, J., Frioriksdottir, V., Gunnarsson, E., Michel, P., Bisaillon, J., Kristinsson, K.G., Briem, H., Hiett, K.L., Needleman, D.S., Stern, N.J. 2008. Broiler Contamination and Human campylobacteriosis in Iceland. Applied and Environmental Microbiology. 74(21):6483-6494. Interpretive Summary: We wanted to determine if there was a relationship between the levels of Campylobacter on contaminationed poultry products and human disease. To test this hypothesis we counted Campylobacter on a representative number of ~85% of all the raw broiler carcasses processed and distributed in Iceland. All human cases of campylobacteriosis from 2001 through 2004 yielded isolates which were then genetically typed and compared for identity with isolates from carcasses having been processed within approximately 2 weeks time of the disease occurrence. If isolates weer identical and, the disease occurred within the designated time frame, the broiler process lots were placed into the "implicated" process lot designation. Statistical analysis showed that implicated product lots had significantly higher median levels of contamination (~3,600 cells per carcass) than did the non-implicated lots (~525 cells per carcass). Our results suggest that broiler borne campylobacterosis may occur in clusters and that the difference in mean contamination levels may provide a basis for regulatory action beyond that of a presence/absence standard.
Technical Abstract: To examine whether there is a relationship between the degree of Campylobacter contamination observed in product lots of retail Icelandic briler chicken carcasses and human disease, 1617 isolates from 327 individual product lots were genetically matched (using flaA Short Variable Region) to 289 isolates from cases of human campylobacteriosis whose onset was within approximately two weeks from the date of processing. When there was genetic identity between broiler isolates and human isolates within the appropriate time frame, a retail product lot was classified as implicated in human disease. From this anaylsis, there were multiple clusters of human disease linked to the same process lot or lots. Implicated and non-implicated retail product lots were compared for four lot descriptors: lot size, prevalence, mean contamination, and maximum contamination (as characterized in the laboratory by rinse-direct plating). For retail product distributed fresh, Mann-Whitney U tests showed that implicated product lots had significantly hgher mean contamination (P=0.055; median = 3.56 log cfu per carcass) than non-implicated lots (2.72 log cfu). For frozen retail product, implicated lots were significantly larger than non-implicated lots (P=0.0281). When the time frame was lifted, retail product lots containing Campylobacter flaA SVR alleles also seen in human disease had significantly higher mean and maximum contamination than lots containing no alleles seen in human disease for both fresh and frozen product. Our results suggest that broiler-borne campylobacteriosis may occur in clusters and that differences in mean contamination levels may provide a basis for regulatory action other than a presence/absence standard.