" What was causing this mayhem? How was it spreading from one horse to another, or anyway getting into so many of them simultaneously? One possibility was a toxic contaminant in the feed supply. Or maybe poison, maliciously introduced. Alternatively, Reid began wondering whether there might be an exotic virus at work, such as the one responsible for African horse sickness (AHS), a disease carried by biting midges in sub-Saharan Africa. "

― David Quammen , Spillover: Animal Infections and the Next Human Pandemic