Evidence of equine influenza A (H3N8) activity in horses from Eastern and Central Saudi Arabia: 2013-2015.

This research was carried out to determine the prevalence of Equine Influenza A (H3N8) — a common cause of respiratory ailments in horses — in horse populations in Eastern and Central regions of Saudi Arabia.

Objective

• The study sought to determine the prevalence of equine influenza in horses in Eastern and Central Saudi Arabia, an area where little was previously known about EIV, particularly the H3N8 serotype.

Method

• A cross-sectional study was conducted, in which 145 serum samples, 323 nasal swabs, and 323 rectal swabs were collected from horses in six major cities across Eastern and Central Saudi Arabia.
• None of these horses had been vaccinated against EIV.
• The serum samples were tested using ELISA assays for influenza A type-specific antibodies, and by haemagglutination inhibition (HI) tests for equine H3N8.
• All the swabs were tested with a RT-qPCR assay targeting a conserved region of the influenza A matrix gene, which detects all subtypes of influenza A viruses.

Results

• None of the swabs tested showed detectable influenza A virus RNA.
• Out of the 145 serum samples tested using the ELISA method, 81 (55.9%) tested positive.
• Out of these 145 samples, 98 (67.6%) tested positive for equine H3 when tested with the HI method.

Conclusions

• The results of the study underscored the researchers’ inability to detect and sequence any EIV, thereby hindering the identification of the lineage of the virus that prevails in Saudi Arabia.
• The research affirmed that EIV H3N8 is indeed present in Saudi Arabia, hence it should be considered as a potential cause while investigating cases of horses with respiratory diseases in this region.