Seroprevalence and risk factors associated with maedi visna virus in sheep population in southwestern Croatia

The objective of this cross-sectional study was to detect the presence of maedi visna virus (MVV) infections in sheep in three counties in southwestern Croatia: Istria County, Primorje-Gorski Kotar County and Lika-Senj County, and to estimate the influence of geographical location, breed, age and gender as risk factors on the prevalence rate. A total of 460 randomly selected sheep were tested using a commercially available ID Screen?? MVV/CAEV Indirect screening test, VISNAS-5P (ID.VET, Grabels France) for detection of antibodies against the Maedi-Visna virus. The prevalence rate for the entire population was 10.00 % (95 % 7.26 -12.74 %), The highest seroprevalence of MVV was found in Istria County (19.02%, CI 95% 13.35-24.70%), followed by Lika-Senj County (5.43 %, CI 95 % 2.17-8.70) and Primorje-Gorski Kotar County (1.07 %, CI 95 %-1.03 -3.17) (P<0.01). When comparing the seroprevalence among breeds, statistically significant differences were observed. The largest number of positive sheep was found in the following breeds: Istrian Pramenka (22.97%, CI 95% 13.39 -32.55%), Jezersko-Solcava sheep (23.53%, CI 95% 11.89 -35.17%%), Pramenka (13.16%, CI 95% 2.41 -23.91%) and Lika sheep (9.78%, CI 95% 3.71-15.85%). Prevalence rates in other examined breeds (Krk sheep, Pag sheep and Romanov sheep) were lower than 2 % (P<0.01). No statistically significant differences in seroprevalence between sex and age were found. According to risk estimation, the main risk factors were found to be geographical location and breed. In Istria County, seroprevalence was 4.77 ( CI 95 % 2.67 -8.54) higher than in other examined areas (OR = 5.66, CI 95 % 2.97-10.79) (P<0.01). As for breeds, significant differences were observed between Jezersko-Solcava sheep and Lika sheep (OR = 2.84, CI 95% 1.13-7.14) and Istrian Pramenka in relation to Pag sheep (OR 22.51,, CI 95% 16.99-119.73), Krk sheep (OR 19.53, CI 95% 5.80-108.27), and Lika sheep (OR 2.35, CI 95% 1.17-6.47). This cross-section study indicates the circulation of MVV in this sheep population in Croatia, and represents the first research into the risk factors for MVV in sheep in southwestern Croatia.