Prevalence of African Horse Sickness in Donkeys in Three Northern Regions of Cameroon

Abstract

African Horse Sickness (AHS) is a non-contagious viral disease that is endemic in sub-Saharan Africa countries and poses an important production and health threats of equines. AHS can induce up to 95% mortality in horses and 10% in donkeys. However, there is dearth of information of its epidemiology in donkeys in Cameroon. This study was therefore carried out to determine the prevalence and associated risk factors of AHS in donkey in three Northern regions of Cameroon. Donkey sera were subjected to the ELISA blocking test for the determination of antibodies against African Horse Sickness Virus (AHSV) and positive samples were subjected to Capture-ELISA to determine the presence of antigens. Spleen samples were collected from fifteen donkey carcasses, of unknown causes of death, were screened using capture ELISA and positive reactors confirmed using conventional PCR. Potential risk factors associated with AHS were assessed based on the information collected in the field. The Chi-Square test and the Odd ratio were used to test the association between prevalence and the different variables. Of the 266 sera obtained, 219 were positive for anti-AHS virus antibodies corresponding to a sero-prevalence of 82.33% [95%CI: 77.30 – 86.44] and no antigen detected from the corresponding whole blood. Locality (p<0.001, χ2= 22.96) and age (p<0.001, χ2= 24.31) significantly influenced sero-positivity of the donkeys. The sero-prevalence was higher (p<0.05) in the North (87.18% [95%CI: 81.03 – 91.55]) and Far North regions (84.81% [95%CI: 75.30 – 91.09]) than in the Adamawa region (51.61% [95%CI: 34.84 – 68.03]). Donkeys that were at least 3 years old (89.42% [95%CI: 84.22 – 93.05]) were at higher risk of AHS (p<0.0001, χ2 = 22.54, OR: 4.56 [95%CI: 2.36 – 8.82]) compared to young animals of less than 3 years old (32.14% [95%CI: 27.15-37.13, OR: 0.15]). The study highlights that AHS is highly endemic in all age groups and both sexes of donkey populations in Northern Cameroon and donkeys maybe playing important roles in the maintenance of the disease in equine populations in the country.