Submitted to: International Association for Food Protection Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 3/9/2006
Publication Date: 8/12/2006
Citation: Trout, J.M.,Santin, M., Fayer, R. 2006. On Farm Risk: Prevalence of Zoonotic Giardia and Cryptosporidium in Adult Dairy Cows in Severn Eastern States, 53rd Annual Meeting of the International Association for Food Protection, August 12-17, 2006, Calgary, Alberta, Canada. Interpretive Summary:
Technical Abstract: This study was conducted to determine if adult dairy cattle can harbor zoonotic species or genotypes of Cryptosporidium and Giardia, and thus serve as potential sources of water or food contamination. Fecal samples were collected from 541 adult dairy cows (>24 months of age), on two farms in each of the following states: VT, NY, PA, MD, VA, NC, and FL. For analysis by PCR, fifteen gram portions of each fecal sample were mixed with 35 ml water, passed through a 45 micron screen, and concentrated using CsCl density gradient centrifugation. The resulting pellet of material was suspended in 100 microliters of distilled water. Fifty microliters of this suspension was subjected to DNA extraction using a commercial extraction kit. To detect Giardia and Cryptosporidium, PCR amplification was done for the respective ssu-rRNA genes, using nested protocols. PCR products were sequenced, and gene sequences were compared to each other and to previously sequenced Giardia and Cryptosporidium isolates. The average prevalence across all farms was 144/541 (27%) for Giardia and 31/541 (6%) for Cryptosporidium. Of the 144 Giardia positive isolates, 94% belonged to the hoofed-livestock genotype, Assemblage E, whereas 6% were the zoonotic genotype, Assemblage A. Of 31 Cryptosporidium positive isolates, 6% were zoonotic C. parvum, whereas 29% and 65% were host specific C. bovis and C. andersoni, respectively. These results indicates that although adult cows can harbor these parasites, they are generally not a significant source of the species or genotypes that infect humans.