What characteristic of African horse sickness highlights its transmission method?

The characteristic that highlights the transmission method of African horse sickness is that it is transmitted by biting midges. This disease is caused by a virus that specifically uses these insects as vectors. The biting midge, particularly species from the Culicoides genus, bites infected horses and then carries the virus to other horses when it feeds again. This mode of transmission is crucial for understanding how the disease spreads in equine populations and informs control measures that focus on managing midge populations, especially in areas where the disease is endemic.

In contrast, casual contact does not play a role in transmitting this disease, as it requires a vector for the virus to infect new hosts. The disease does not spread through air currents, which indicates that it does not have airborne transmission capabilities. Additionally, while specific environments can affect the survival of the virus or the breeding of vectors, it is the specific interaction between the midge and the host that is central to its transmission.