Detection of African horsesickness (AHS) in recently vaccinated horses with inactivated vaccine in Qatar.

This research focuses on the detection of African Horsesickness (AHS) in two Arabian horses in Qatar that had been recently vaccinated with an inactivated form of the vaccine. The source of the infection is unclear, and could either be due to the natural presence of the virus in the country, or residual infection from the vaccine itself.

Research Method and Findings

• The research was initiated after two 7-year old Arabian racing horses in Qatar exhibited signs of African Horsesickness (AHS) and subsequently died.
• These horses had been recently vaccinated against AHS with an inactivated vaccine, approximately 10 days prior to showing symptoms.
• Blood samples were collected from these horses and the AHS virus was isolated from one of the samples.
• The isolation was achieved by inoculating the sample into suckling mice intracerebrally, a common method used to identify the presence of viruses.
• Once the virus was isolated, its identity was confirmed to be AHS using a complement fixation test (CFT). This test used the virus antigen and reference type 9 of AHS virus hyperimmune serum which are known to create a reaction in the presence of AHS.

Identification of the Virus Serotype

• The serotype, a variant within a species of the isolated AHS virus, was identified using the serum neutralization test (SNT).
• This test uses reference types of the AHS virus to determine which specific strain of the virus is present.

Source of Infection

• The researchers suggest two possibilities for the original source of this infection.
• The first possibility considers the endemic occurrence of AHS in Qatar. The virus might be naturally present in the country and hence causing infections.
• The second hypothesis puts the inactivated vaccine under scrutiny. There could have been residual infectious virus present in the inactivated vaccine given to the horses. If this were true, it could indicate a major issue in the vaccination procedure possibly leading to more cases of similar nature.