SINGAPORE – African horse sickness (AHS) was spotted in Thailand last year (2020), and it came as a shock to officials there and their counterparts in other Asean countries.
Said Dr Charlene Judith Fernandez, director of the Centre for Animal and Veterinary Sciences: “That was utterly unexpected; nobody in their wildest dreams would have ever thought that (AHS) would ever come to our region. It had never been seen outside of Africa.”
Before Thailand reported the virus outbreak in horses bred there to the World Organisation for Animal Health, it had already notified its Asean counterparts as this would affect the movement of horses within the region.
The National Parks Board (NParks) reached out to Thailand to see if it could do any sort of collaboration in researching the virus, which affects only horses.
A lab in Thailand then made arrangements to send spleen tissues and blood samples to NParks’ lab in Singapore.
Ms Wendy Sng, deputy director of Veterinary Health Management at the Animal and Veterinary Service, said: “There are nine serotypes of AHS and we had to identify which it was, so that we have the right vaccine later on and other mitigation aspects can be adjusted accordingly.”
Research revealed that AHS is a vector-borne disease spread through biting midges of the culicoides species.
Ms Sng said: “The virus is transmitted through a specific species of culicoides. We have culicoides in South-east Asia, so it became a very huge concern to us.”
Understanding whether this region has the specific culicoides species became paramount, and that is yet to be established.
Before the spread of AHS, NParks had been in discussions with the National Environment Agency (NEA) on how they could address the various gaps in biosurveillance in Singapore, such as vectors.
Ms Sng said: “NEA was already modifying their existing mosquito traps to capture biting midges… So when (the AHS outbreak in Thailand) happened, we quickly mobilised our counterparts from NEA and we went down to places in Singapore where there are horses – like turf clubs – to set up the traps.”
No case of AHS was found in Singapore. But thanks to the collaborative effort with NEA and their counterparts from Thailand, NParks has been able to collect samples of midges and tissues of infected horses.
NParks has since kick-started the process of identification and detailed genetic characterisation of the AHS virus. The research is ongoing.