PROTOZOAN PARASITES AFFECTING FOOD ANIMALS, FOOD SAFETY, AND PUBLIC HEALTH
Title: A LONGITUDINAL STUDY OF ENTEROCYTOZOON BIENEUSI IN DAIRY CATTLE
Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 6, 2009
Publication Date: June 1, 2009
Citation: Santin, M., Fayer, R. 2009. A longitudinal study of Giardia duodenalis genotypes in dairy cows from birth to 2 years of age. Veterinary Parasitology. 162(1-2):40-45.
Interpretive Summary: There are now over 80 genotypes of the parasite Enterocytozoon bieneusi, the species of Microsporidia reported most frequently in human infections. They have been found in a wide variety of livestock, domesticated animals, and wild mammals and many appear host specific. There are reports of E. bieneusi-infected cattle in Germany, Korea, Portugal, and the United States, all of which present data acquired on farms at one moment in time. The present study was conducted to determine if genotypes are present in cattle that represent a public health risk and to determine the duration of any such infections. This is the first longitudinal study to determine the presence of E. bieneusi-related genotypes in the same cattle on a single farm over time. An extremely high prevalence of infection with E. bieneusi was found in 30 calves, each examined at 33 intervals from 1 week to 24 months of age. The cumulative prevalence of infection increased from 33% in pre-weaned calves (1-8 weeks of age) to 100% in post-weaned calves (3 to 12 months of age) and then decreased to 80% in heifer calves (13-24 months of age). Three genotypes were found, none of which appear to be represent a public health risk since they have not been found in humans or other animals.
Feces from each of 30 Holstein cattle on a Maryland dairy farm were examined at weekly, bimonthly, and then monthly intervals from 1 week to 24 months of age for the presence of Enterocytozoon bienesusi. DNA was extracted from spores cleaned of fecal debris, and a two-step nested PCR protocol was used to amplify a fragment of the internal transcriber spacer (ITS) region of the rRNA gene. All PCR-positive specimens were sequenced to determine the genotype of E. bieneusi. The overall prevalence was 24% (239/990) with a lower prevalence in pre-weaned calves (less than 8 weeks of age) (11.7 %) and heifers (13-24 months of age) than post-weaned calves (3-12 months of age) (44.4%). Over the course of 24 months the cumulative prevalence of E. bieneusi was 100% since all 30 calves shed spores at some time during the study. One or more of 3 genotypes of E. bieneusi, J, I and BEB4, were detected in all 30 animals. Genotype I was detected in all 30 cattle between 1 week and 22 months of age with some cattle remaining infected as long as 17 months. At 4 months of age 28 cattle were infected with genotype I. Genotype BEB4 was detected briefly in 7 cattle, most between 15 and 20 months of age. Genotype J was detected in 8 cattle, all between 16 and 24 months of age. This longitudinal study strongly supports the findings of point prevalence, multiple farm studies in which genotypes J, I, and BEB 4 were found. These genotypes appear to be cattle-specific and have not been found in humans or other animals.