Evidence for Transmission of Bluetongue Virus Serotype 26 through Direct Contact

Abstract

The aim of this study was to assess the mechanisms of transmission of bluetongue virus serotype 26 (BTV-26) in goats. A previous study, which investigated the pathogenicity and infection kinetics of BTV-26 in goats, unexpectedly revealed that one control goat may have been infected through a direct contact transmission route. To investigate the transmission mechanisms of BTV-26 in more detail an experimental infection study was carried out in which three goats were infected with BTV-26, three goats were kept uninfected, but were housed in direct contact with the infected goats, and an additional four goats were kept in indirect contact separated from infected goats by metal gates. This barrier allowed the goats to have occasional face-to-face contact in the same airspace, but feeding, watering, sampling and environmental cleaning was carried out separately. The three experimentally infected goats did not show clinical signs of BTV, however high levels of viral RNA were detected and virus was isolated from their blood. At 21 dpi viral RNA was detected in, and virus was isolated from the blood of the three direct contact goats, which also seroconverted. The four indirect barrier contact goats remained uninfected throughout the duration of the experiment. In order to assess replication in a laboratory model species of Culicoides biting midge, more than 300 Culicoides sonorensis were fed a BTV-26 spiked blood meal and incubated for 7 days. The dissemination of BTV-26 in individual C. sonorensis was inferred from the quantity of virus RNA and indicated that none of the insects processed at day 7 possessed transmissible infections. This study shows that BTV-26 is easily transmitted through direct contact transmission between goats, and the strain does not seem to replicate in C. sonorensis midges using standard incubation conditions.

Clinical and serological study on bluetongue virus serotype 4 in cattle in Albania

“…Vector-independent transmission of BTV then can occur, although its significance is not fully known. Direct contact transmission of BTV-26, likely by aerosol, between livestock has been demonstrated [8]. In a study conducted in dromedaries in Mauritania slaughterhouse, BTV-26 neutralising antibodies were also found in a high number of animals confirming that horizontal transmission may have occurred in this case at the slaughterhouse, where animals are gathered together for several days before slaughtering.…”

“…In the last years, next to the classical 24 serotypes which are transmitted by vectors, new serotypes, such as, BTV-25, BTV-26, BTV-27 [5][6][7] have been described. The last serotypes are characterized by some addition features, causing asymptomatic infections, being directly transmitted, at least BTV-26 [8] having long viraemia (BTV-250 [9] and using goats as reservoir hosts. Vector-independent transmission of BTV then can occur, although its significance is not fully known.…”

Data collection for risk assessments on animal health (Acronym: DACRAH) : Final Report

“…6 groups with one or more dead animals. (Batten et al, 2014(Batten et al, , 2012Belbis et al, 2013;Breard et al, 2011;Caporale et al, 2014;Coetzee et al, 2013;Planzer et al, 2011;Voegtlin et al, 2013) 1,3,4,7,8,9,10,11,13,14,16,17,18,2,20,21,23 …”

“…The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors. , 1999;Letchworth and Appleton, 1983;Luedke, 1969;Luedke et al, 1976Luedke et al, , 1969Lunt et al, 2006;MacLachlan et al, 2008;Mahrt and Osburn, 1986;Matsuo et al, 2011;McColl and Gould, 1994;Nunamaker et al, 1992;Pages et al, 2014;Pini, 1976;Ramakrishnan et al, 2006;Rasmussen et al, 2013;Richards et al, 1988;Richardson et al, 1985;SanchezCordon et al, 2013;Savini et al, 2007;Shad et al, 1997;Singh et al, 2008;Sluijs et al, 2011Sluijs et al, , 2013aSluijs et al, , 2013bSquire, 1989;Stanislawek et al, 1996;Stott et al, 1985;Tanya et al, 1992;Tessaro and Clavijo, 2001;Tomori, 1980;Umeshappa et al, 2011;Uren and George, 1985;Uren and Squire, 1982;Veronesi et al, 2010;Vosdingh et al, 1968;Waeckerlin et al, 2010;Worwa et al, 2010) Evidence for contact transmission was given in one study in goats (Batten et al, 2014); 3 studies in sheep (Rasmussen et al, 2013;Sluijs et al, 2013b;van der Sluijs et al, 2011); and 1 study in deer (Lopez-Olvera et al, 2010). No contact transmission studies were found in the other species.…”

“…One experimental study was conducted in dogs (Oura et al, 2014). Animals were experimentally infected and RNA was detected from blood from dpi 2 to 14.…”