Rotavirus excretion in suckling pigs followed under field circumstances.

The enzootic behaviour of porcine rotavirus in swine breeding farms was investigated by determination of the rotavirus excretion pattern in faeces using an enzyme linked immunosorbent assay (ELISA). Three herds were followed for 23, 14 and 9 consecutive weeks respectively and faeces were collected once a week from suckling piglets, weaned pigs and sows. The piglets of nearly all litters were found to excrete rotavirus in faeces before the age of 5-6 weeks. Weaned pigs rarely excreted rotavirus and faeces of sows were always negative. About half of the litters excreted rotavirus during more than one week or showed a recurrent excretion period 3-4 weeks after a first one. The presence of rotavirus group-specific antibodies in milk of sows, as detected by ELISA, did not appear to prevent infection of their piglets. These data may be an indication of the presence of serologically different porcine rotavirus strains within the same herd. Subclinical rotavirus infection occurred often in suckling pigs of all ages. Rotavirus was also found in a high number of fecal samples from pigs with diarrhea, but it was impossible to demonstrate the irrefutable association between the rotavirus infection and the presence of diarrhea.