Bluetongue in Cattle
Bluetongue (BT) is a viral disease that is spread mainly by one specific type of gnat. Other gnats and blood sucking insects may occasionally transmit BT, but they are much less important in its transfer. Cattle are the main reservoir for overwintering of the virus in temperate climates. The gnats become infected from cattle and then spread the disease to other cattle and sheep as they take blood meals. It is also spread through infected semen and may be spread by blood sucking lice and a soft tick. It is possible that biting flies and contaminated needles may also spread it mechanically.