Prevalence of bluetongue virus infection among ruminants in Lithuania

Abstract

Bluetongue (BT) disease is a viral noncontagious infection of ruminants. The bluetongue virus (BTV) is transmitted by Culicoides spp. biting midges. The BTV is one of the genus Orbivirus species in the family of Reoviridae, and carries a double-stranded RNA genome. Sheep are considered the most vulnerable species for BT, but other ruminants are known to play a major role in BT epidemiology. There is no published data on BTV distribution in Lithuanian ruminants. The objective of this study was to describe the seroprevalence rate of the BTV in domestic and wild ruminant populations in Lithuania. From 2012 to 2014, blood samples were randomly collected from ruminants in various districts of Lithuania. A total of 15,034 sera samples were collected and tested using an enzyme-linked immunosorbent assay (ID VET Innovative Diagnostics, France). In 2012, serological evidence of the BTV infection was observed in 390 out of 5,278 animals accounting for a 7.5% (CI 6.8–8.2) prevalence rate among various species of ruminants. During 2013, the number of antibody positive samples increased to 26.9% (CI 25.2–28.6; P < 0.01). In 2014, the number of seropositive animals continued to increase to 34% (CI 31.6–36.4; P < 0.01). Also, seropositive individuals were found in populations of sheep and goats, where seroprevalence in 2012–2014 was 1.9% (CI 1.3–2.5). Simultaneously, the study was held for wild ruminants farmed in captivity, such as deer (Dama dama and Cervus elaphus), mouflons (Ovis orientalis), and European bisons (Bison bonasus). It was found that in this group of animals BTV seroprevalence was significantly lower than in the groups of domestic ruminants (0.64%, CI 0.4–0.9, P < 0,0001). Our studies found that the BTV began a rapid spread in the Lithuanian bovine population. BTV seroprevalence among sheep, goats, and wild ruminants was significantly lower.[...].