title: Prevalence and genotypes of Giardia duodenalis in 1-2 year old dairy cattle.
abstract: To determine the prevalence of Giardia genotypes in 12-24 month old dairy heifers, fecal specimens were collected from two farms each in Vermont, New York, Pennsylvania, Maryland, Virginia, North Carolina, and Florida. Specimens, cleaned of fecal debris and concentrated using CsCl density gradient centrifugation, were subjected to PCR and DNA sequence analysis. Prevalence of Giardia infection, ranged from 11% to 75% on 14 farms with an average prevalence of 36% (204 positive cattle out of 571 examined). DNA sequence analysis of the 16S rRNA gene revealed 91% of the 204 Giardia isolates were Assemblage E, and 9% were Assemblage A. The prevalence of these genotypes varied greatly from farm to farm, with four farms having exclusively Assemblage E Giardia. Overall, Assemblage E was present in 33% of all animals tested and Assemblage A was present in 3% of the animals. Thus, while many of the heifers were infected with a genotype that is not known to be infectious for humans, 1-2 year old heifers on 10 of 14 farms did harbor zoonotic Assemblage A Giardia. Therefore, heifers cannot be overlooked as a potential source of human infectious cysts in the environment, with some farms representing a much higher risk than others.
authors.affiliation: Environmental Microbial Safety Laboratory, Animal and Natural Resources Institute, Agricultural Research Service, US Department of Agriculture, Beltsville, MD 20705, USA. jtrout@anri.usda.gov
authors.forename: James M
authors.initials: JM
authors.lastname: Trout
authors.forename: Mónica
authors.initials: M
authors.lastname: Santín
authors.forename: Ellis C
authors.initials: EC
authors.lastname: Greiner
authors.forename: Ronald
authors.initials: R
authors.lastname: Fayer
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001483:Base Sequence; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000469:parasitology; D016054:DNA, Protozoan / Q000737:chemistry; D005243:Feces / Q000469:parasitology; D005260:Female; D005838:Genotype; D005872:Giardia / Q000235:genetics* / Q000302:isolation & purification*; D005873:Giardiasis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D015995:Prevalence; D015144:Southeastern United States / Q000453:epidemiology
chemical_list: D016054:DNA, Protozoan