Officials and the U.S. horse industry are monitoring for African horse sickness, which will put horses at risk if it enters the country. This disease, which has a horse mortality rate of 90 percent, was recently discovered in Thailand. It is believed it was introduced by imported infected zebras. The disease is caused by an Orbivirus that is primarily transmitted by biting midges, small blood-feeding flying insects.
Source: Drovers, July 23, 2020. Link. African horse sickness symptoms are the same as those associated with respiratory and circulatory impairment. At the first signs of the disease, owners are advised to eliminate affected horses and vaccinate noninfected horses with polyvalent vaccine, then let them rest for two weeks.