Transplacental Transmission of Bluetongue Virus 8 in Cattle, UK
Figure. Estimated gestation period at infection of the dam in relation to occurrence of transplacental transmission. Bluetongue virus (BTV) test data for the dams and birth dates of the calves were used to calculate the window of gestation when the dam could have become infected (Technical Appendix, for details). The calculated infection windows are shown in red for BTV-positive calves (transplacental infection did occur) and in blue for BTV-negative calves (transplacental infection did not occur). Because calves were conceived naturally, the exact date of conception is not known, although all were considered to have been born at full term.