Retrospective study of rotavirus infection in cattle herds of São Paulo State, Brazil
Rotaviruses are the major agents of neonatal diarrhea in cattle worldwide, leading to significant economic losses. This study aimed to determine the occurrence of rotavirus infection in 48 herds of dairy and beef cattle, from 21 municipalities in the Northern region of the São Paulo State, between 2006 and 2010. Thus, 803 fecal samples of calves, aging from one to 90 days, were analyzed by polyacrylamide gel electrophoresis (PAGE), which indicated positive animals in 33.3% (16/48) of the herds and 6.1% (49/803) of the samples. Of the 326 samples from calves with diarrhea, 12.6% (41/326) were positive, while 1.7% (8/477) was positive on PAGE of the 477 samples from animals without clinical signs. The results showed that there is a statistically significant association between the presence of diarrhea and rotavirus infection. In the 35 dairy herds studied, 34.3% (12/35) were positive for rotavirus, corresponding to 3.3% (23/689) of positive samples. Among the diarrheic samples, 5.6% (15/269) were positive, while 1.9% (8/420) was positive in non-diarrheic samples. Chi-square analysis showed a significant association between rotavirus detection and the presence of diarrhea in dairy herds; however, there was no statistical difference related to the age of the calves and the rotavirus infection. Of the 13 beef herds sampled, 30.8% (4/13) presented positive animals, corresponding to 22.8% (26/114) of the samples, all of them diarrheic (26/57), which resulted in undefined statistical association. However, the frequency of positives was higher in calves aging one to 30 days (p <0.05). According to the migration of the rotavirus genome in the PAGE, it was possible to identify seven distinct electrophoretic profiles, characteristic of group A rotavirus, showing differences among the field strains. Therefore, the presence of rotavirus infection in the studied regions emphasizes the importance of control measures and prevention, since the agent is in constantly evolution in cattle herds.
Copyright (c) 2019 Heloisa Pinto de Godoy
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