Shedding of rotavirus in feces of sows before and after farrowing.

The purpose of this study was to determine whether sows shed rotavirus near the time of farrowing. Twelve sows purchased from a common source and seropositive for rotavirus were housed in isolation in farrowing crates from 5 days before to 3 weeks after farrowing. Fecal samples were collected at 3- to 4-day intervals and examined for the presence of rotavirus by direct electron microscopy. Samples were also treated with pancreatin and inoculated onto monkey kidney cells. Rotaviral antigens were detected by a direct immunofluorescence technique, and selected positive cultures were examined by immunoelectron microscopy. Rotavirus was detected in the feces of 5 of 12 sows as early as 5 days before to 2 weeks after farrowing. Diarrhea related to rotavirus developed in 4 of 12 litters. Two of these four litters were farrowed by sows which shed rotavirus at 7 and 10 and 14 days after farrowing. The results of this study indicate that sows immune to rotavirus can shed virus in their feces at a time when piglets are particularly susceptible to infection and that adult swine are of primary importance in the epidemiology of rotavirus as initiators of infection.