During an Iowa winter, which disease would NOT spread through a stable from a single infected horse?

• A. Equine influenza
• B. African horse sickness
• C. EHV-4
• D. NONE of the above; they would all spread

Answer: (B)

Understanding transmission routes and seasonality helps explain why some diseases spread in a stable while others don’t. Equine influenza and EHV-4 spread mainly through direct horse-to-horse contact, respiratory droplets, and contaminated surfaces, so a single infected horse can pass the infection to others in the same stable, especially when horses are in close quarters and indoors. African horse sickness, on the other hand, is primarily transmitted by Culicoides midges. In a cold Iowa winter, these vectors are not active, so the virus cannot spread from one horse to another within the stable. Without the biting insects to bridge infections, AHS would not propagate in that setting, making it the correct choice.