Risk factors associated with small-ruminant lentiviruses in sheepfold buildings.

INTRODUCTION: Small-ruminant lentivirus (SRLV) infection is widespread across Europe. It causes substantial economic losses in sheep breeding. The main route of SRLV infection is through the mother's milk, especially colostrum However, infection can also occur via contact between infected and healthy animals. It should be noted that the mechanisms of contact infection are still relatively poorly understood. The virus can also spread through a flock via an aerogenic mechanism. OBJECTIVE: Due to the increased risk of SRLV infection in sheep bred in an alcove system, this study sought to define the effect of various selected factors associated with alcove breeding on the frequency of SRLV infection in sheep. MATERIAL AND METHODS: Risk factors associated with small-ruminant lentivirus (SRLV) infection were analyzed among flocks of sheep in central-eastern Poland. Ninety-eight sheep flocks were selected for detailed investigation and included 6,470 ewes and 15 breeds and lines. Serologic testing of blood samples was used to identify infected animals and evaluate the epidemiologic status of particular flocks. Specific antibodies for Maedi Visna Virus (MVV) were detected via ELISA. Questionnaires were used to gather information concerning risk factors. RESULTS: The study's results indicate that factors associated with environmental conditions under which sheep are kept play a significant role in determining the risk of SRLV infection. CONCLUSIONS: Special attention should be focused on airborne contamination associated with the technologies used in sheep breeding. Breeding technologies that limit airborne contamination in farm buildings should be employed. In developing programmes to eliminate SLRV in sheep flocks, improvement of zoohygenic conditions should also be considered.

Risk factors associated with small ruminant lentivirus infection in eastern Poland sheep flocks.

An analysis of the risk factors for ovine lentivirus infection was performed in sheep flocks located throughout the central-eastern region of Poland. Here, we report the infection details for 98 flocks with a total of 6470 ewes, 15 sheep breeds. The identification of infected animals and a review of the epidemiological status of each flock were based on an evaluation of serological tests performed on collected blood serum samples. Blood for examination was obtained from 2925 ewes of the 98 flocks under observation. Specific antibodies for Maedi Visna Virus (MVV) were detected via ELISA. Data illustrating the conditions at each sheep farm were obtained through questionnaires completed by farmers, as well as observations, measurements, and breeding records that were available. These observations were used to assess risk factors contributing to small ruminant lentivirus (SRLV) infection in sheep flocks. It was found that both sheep flock size and the type of management system had a significant effect on the increased risk of lentiviral infection. In addition, we demonstrate that there is a significant (p<0.0001) relationship between the occurrence of mastitis (OR 2.01, CI: 1.55-2.61) and diarrhea (OR 4.22, CI: 3.30-5.39) with SRLV infection in the observed sheep. Additionally, the infection rate of the animals translated directly to an impaired physical condition. Notably, the risk of infection could potentially be reduced if sheep producers are further acquainted with SRLV detection and invoke a control program based on diagnostic tests. Moreover, marketing approval should be granted for solely SRLV-seronegative animals.