Analysis of small ruminant lentivirus infection in sheep from the Malopolska and Podkarpackie voivodeships

The aim of the present study was to determine the seroprevalence of small ruminant lentiviruses (SRLV) infection in sheep from the Malopolska and Podkarpackie voivodeships in Southern Poland. A total of 1015 serum samples from sheep from 180 flocks were examined. The presence of SRLV antibodies was determined using a diagnostic ELISA kit from Institut Pourqier (Montpellier, France). Out of the 180 flocks investigated, specific antibodies to SRLV were found in 93 flocks (51.7%). When these data were approximated by using beta distribution, the seroprevalence varied from 44.4 to 58.9%. Furthermore, the probability of SRLV seroprevalence was higher in large flock size (>21 animals) (95% CI: 52.5, 89.8) than in flocks with less than 10 animals (95% CI: 4.7, 34.7). Specific antibodies were found in 286 (28.2%) individual sheep out of 1015 tested. The mean true seroprevalence calculated by the Bayesian method was 26.5% (95% CI: 23.6, 29.4). The probability of the incidence of SRLV seropositivity was higher with a large flock size (>21 animals) (95% CI: 21.5, 41.6) than in flocks with less than 10 animals (95% CI: 0.0, 13.6). This study showed a high prevalence of SRLV infection in sheep flocks from both voivodeships at both animal and herd level. Large flocks had higher seroprevalence than smaller ones. The appearance of high seroprevalence of large herd size may be due to horizontal transmission by respiratory secretions when there is a high animal density.