Figure 4From: Quantification of the increase in the frequency of early calving associated with late exposure to bluetongue virus serotype 8 in dairy cows: implications for syndromic surveillance Raw frequencies of early calving per calving month from October 2005 to September 2009. (A) 34 248 cows in 2616 reported case herds with clinical signs in 2007; (B) 209 231 cows in 9540 unexposed herds located in Brittany; (C) 26 701 cows in 1498 unexposed herds located in the Southwest of France. B and C composed the unexposed population BTV-8 in 2007; (D) 17 139 cows in 2616 herds that reported clinical signs in 2007 exposed during the last 10 weeks of pregnancies. Population D is a subset of the population A. (E) 20 139 cows in 4008 herds for which a date of exposure was interpolated during the last 10 weeks of pregnancies. These herds were non-reported during the 2007 outbreak but located in the outbreak area. The two red vertical lines correspond to the 2007 outbreak period in France.Back to article page