African horse sickness

Two new African horse sickness (AHS) outbreaks have occurred in Thailand, affecting horses and zebras, according to a report issued by the World Organisation for Animal Health (OIE) on 14 October 2020.

The outbreak of African horse sickness (AHS) in Thailand was first reported in March 2020, and was the first time AHS had occurred outside the African region in 30 years. Thailand has now associated the outbreak with the importation of zebras from South Africa.

  • Thailand commenced vaccinating horses against AHS in mid-April, using an attenuated live polyvalent vaccine from South Africa.
  • Between April and July 2020, Thailand reported no new cases of AHS.
  • The new cases of AHS in Thailand were diagnosed in August (horses) and September (zebras).
  • In early September 2020, AHS was also diagnosed in five horses in Malaysia. According to Malaysian reports to the OIE, the affected horses were destroyed and no further cases have been reported.
  • The AHS virus is transmitted by biting Culicoides midges that feed on horses, and therefore the spread of the virus can difficult to control where such midges are abundant.

AHA is conducting a review of the AUSVETPLAN disease strategy for African horse sickness.


Control measures

What to look for