New findings of Enterocytozoon bieneusi in beef and dairy cattle in Brazil.

Microsporidia are widely recognized as important human pathogens with Enterocytozoon bieneusi as the most common species infecting humans and animals, including cattle. Although Brazil has the second largest cattle herd in the world and it is the largest exporter of beef there are no data on the presence or impact of E. bieneusi on this important population. To fill this knowledge gap, fecal specimens were collected from 452 cattle from pre-weaned calves to adult cattle in the state of Rio de Janeiro. Host factors including age, gender, dairy/beef, body composition, and fecal consistency were included in the study. Using molecular methods, E. bieneusi was found in 79/452 (17.5%) fecal specimens. This represents the first report of this parasite in Brazilian cattle. A significantly higher prevalence was found in calves less than 2 months of age (27.6%) and those 3-8 months of age (28.8%) versus heifers (14.1%) and adults (1.4%) (P<0.05). Dairy cattle (26.2%) had a higher prevalence than beef cattle (9.7%) (P<0.001). No correlation was found between infection and gender, body composition, and fecal consistency. Molecular characterization of the internal transcribed spacer (ITS) revealed 12 genotypes; five previously reported in cattle (BEB4, BEB8, D, EbpA and I), and seven novel genotypes (BEB11-BEB17). A phylogenetic analysis showed that 6 genotypes (D, EbpA, BEB12, BEB13, BEB15, and BEB16) identified in 18 animals clustered within the designated zoonotic Group 1 while the other 6 genotypes (I, BEB4, BEB8, BEB11, BEB14, BEB17) identified in 61 animals clustered within Group 2. The identification of genotypes in Brazilian cattle that have previously been reported in humans highlights the potential risk of zoonotic transmission and suggests that the role of cattle in transmission of human infections requires further study.