Investigation of risk factors associated with infections caused by small ruminant lentiviruses

An epidemiological study was conducted to identify risk factors related to small ruminant lentivirus (SRLV) infection in the central region of Spain. Between October 1998 and October 2000, a total of 194 sheep from 10 flocks and 163 goats from three flocks were tested for SRLV antibodies, resulting in 65.5% and 8.0% of seroprevalence, respectively. The relationship between differences in prevalence of SRLV, geographical location of the flock, and possible factors related to the flock that could enhance transmission were studied. Results of multivariable analysis showed an association between SRLV infection and geographical location of the flock and the rearing system. In addition, the differences in the productivity between infected and non-infected animals were explored. The productivity parameters were measured in 62 sheep and 28 goats. All productivity parameters studied (milk production, number of milking days, and lambing rate) appeared to be reduced in the SRLV-seropositive group in both goats and sheep. Even though, these differences were not statistically significant, it seems that animals infected are less productive than these non-infected. Statistical analyses comparing infected and non-infected sheep showed no statistical relationship between SRLV infection and milk quality.