ARS | Publication request: Prevalence and genotypes of enterocytozoon bieneusi in weaned beef calves on cow-calf operations in the United States

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 21, 2011
Publication Date: December 7, 2011
Citation: Santin, M., Dargatz, D., Fayer, R. 2011. Prevalence and genotypes of enterocytozoon bieneusi in weaned beef calves on cow-calf operations in the United States. Parasitology Research. 110(5):2033-2041.

Interpretive Summary: Microsporidia are microscopic fungi that infect all major animal groups from invertebrates to fish to birds and mammals, including domesticated animals and humans. Enterocytozoon bieneusi is the species found most frequently in humans, mainly associated with diarrhea. Enterocytozoon bieneusi has been identified in water as well as in wild, domestic and food-producing farm animals, raising concerns of water-borne, food-borne and zoonotic transmission. To determine the prevalence and genotype distribution of Enterocytozoon bieneusi in beef calves in the United States, fecal samples were collected from 819 calves (6-18 months of age) from 49 operations. Parasite spores were concentrated, DNA was extracted, and subjected to the polymerase chain reaction (PCR) to amplify the complete internal transcriber spacer (ITS) from each sample. All PCR-positive specimens were sequenced to determine the genotype(s) present. Overall, E. bieneusi was detected in 34.8% of the 819 samples. The highest prevalence was found in the Midwest region (42.7%) followed by the South (35.8%), and the West (23.2%). The prevalence of E. bieneusi varied considerably from operation to operation (0-100%). A prevalence of 100% was observed in 3 operations, one in the Midwest and two in the South; E. bieneusi was not found in six operations, three in the South and three in the West. Sequence analysis revealed the presence of six genotypes, four previously reported (I, J, BEB4, and Type IV) and two novel genotypes (BEB8 and BEB9). The identification in this study of the three most common genotypes of E. bieneusi of cattle (I, J, and BEB4), now found in humans, changes the paradigm from genotypes thought to be cattle-specific to genotypes with potential to infect humans.

Technical Abstract: To determine the prevalence and genotype distribution of Enterocytozoon bieneusi in weaned beef calves in the United States, fecal samples were collected from 819 calves (6-18 months of age) from 49 operations. Feces were sieved and subjected to density gradient centrifugation to remove fecal debris and to concentrate spores. DNA extracted from each sample was subjected to the polymerase chain reaction (PCR) to amplify the complete internal transcriber spacer (ITS). All PCR-positive specimens were sequenced to determine the genotype(s) present. Overall, E. bieneusi was detected in 34.8% of the 819 fecal samples. The highest prevalence was found in the Midwest region (42.7%) followed by the South (35.8%), and the West (23.2%). The prevalence of E. bieneusi varied considerably from operation to operation (0-100%). A prevalence of 100% was observed in 3 operations, one in the Midwest and two in the South; E. bieneusi was not found in six operations, three in the South and three in the West. Sequence analysis revealed the presence of six genotypes, four previously reported (I, J, BEB4, and Type IV) and two novel genotypes (BEB8 and BEB9). Mixed infections were identified in 5 specimens, three contained I and BEB4 and two contained J and BEB4. Most of the positive calves (238 of 285) harbored genotypes with zoonotic potential including I (59), J (108), BEB4 (65), Type IV (1), mixed I/BEB4 (3), and mixed J/BEB4 (2).