Giardia duodenalis and Cryptosporidium spp. in meat purchased at retail in Canada.

The enteric protozoan parasites, Giardia duodenalis and Cryptosporidium spp., or their DNA, have been reported in surveillance studies on fresh produce and in shellfish worldwide, but have been reported only rarely in meat or on the carcasses of meat animals. The objective of the present study, therefore, was to determine the prevalence of G. duodenalis and Cryptosporidium spp. in retail meat purchased in three Canadian provinces as part of FoodNet Canada's (Public Health Agency of Canada) retail surveillance activities. Packages containing chicken, beef, pork or veal were purchased at grocery stores in FoodNet Canada sentinel sites. Following DNA extraction from the meat samples, nested-PCR and DNA sequencing were used to detect parasite-specific sequences. Giardia duodenalis DNA was detected in 1.5% of 468 meat packages, while Cryptosporidium spp. DNA was present in 2.1% of 468 packages. Parasite DNA was detected in meat purchased in all three Canadian provinces sampled, with no apparent seasonal variation in prevalence. The presence of G. duodenalis and Cryptosporidium spp. DNA in retail meats was unexpected, but does not necessarily confirm the presence of viable parasites. It does, however, suggest possible cross-contamination either at the abattoir or during processing. Considering that the meats tested in this study are very often cooked before consumption, the risk of meat-borne transmission of these parasites is likely minimal.