Molecular detection and risk factors of African horse sickness virus (AHSV) in different governorates of Sudan

Abstract

African horse sickness (AHS) is one of the most prevalent vector born viral diseases that threaten the equine industry in Sudan. A study was carried out during fall 2018 and 2019 to estimate the prevalence of the disease in horses, to detect the virus in Culicoides spp. (Diptera: Ceratopogonidae) pools and assess the contribution of major risk factors for the occurrence of the disease in horses. Whole blood samples (n=184) were collected randomly from horses from two governorates in Khartoum state and three provinces in Southern Darfur state. In addition, 1916 insects in 18 pools, the pool range 70-150 non-engorged females of different species of Culicoides biting midges were collected from Khartoum governorate and tested for the presence of ribonucleic acid of African horse sickness virus (AHSV) using one-step reverse transcriptase polymerase chain reaction technique. The obtained results revealed that the overall prevalence of AHSV in horses was 38.5% and from the 18 pools of Culicoides spp. the virus was detected in 6 pools (33.3%). Furthermore, in the univariate analysis, risk factors such as locality (p = 0.0001), age (p = 0.018) and sex (p = 0.011) were significantly associated with the prevalence of AHSV in horses. However, the breed of horses did not show statistically significant associations (p>0.05). In the multivariate analysis, locality (OR = 28.271, p = 0.0002) was found to be the most statistically significant risk factor for the occurrence of AHSV. The results of this study highlight that the overall prevalence of AHSV was high in the areas surveyed. The high abundance of the Culicoides recognized as potential AHSV vectors, suggests possible risk of the emergence of AHSV as pandemic in the study area.