Greece experienced in August 1999 a fresh outbreak that continued through December. Three serotypes were in play, numbers 9 and 4 and another that resembled number 13. The latest epizootic phase featured serotype 2. The disease is ordinarily vectored by a small biting fly called the midge, which travels en masse, creating a virtual insect cloud. Thus, the spread east to west in the Mediterranean may have been facilitated by wind.
Bluetongue is an important disease of economic consequence.
Tens of thousands of sheep have been destroyed in the Mediterranean over the past two years. In addition, it can be transmitted vertically to fetal calves and cause congenital deformities. In sheep, the virus produces lesions in the respiratory tract and in the vascular system, where it can lead to hemorrhage. Highest mortality rates are seen in white-tailed deer, pronghorn sheep and bighorn sheep. It does not affect humans and is not passed as a contagious disease from animal to animal.