Prevalence of bluetongue virus infection and associated risk factors among cattle in North Kordufan State, Western Sudan

Background: Bluetongue virus causes febrile disease in sheep and a fatal hemorrhagic infection in North American White-tailed deer. However, in cattle the disease is typically asymptomatic and no clinical overt disease is associated with bluetongue infection. Bluetongue virus activity has been detected in Khartoum, Sennar and South Darfur states of the Sudan. Currently, no information is available in regard to previous exposure of livestock to Bluetongue virus in North Kordufan State, the largest livestock producing region in the country. The present study was conducted to determine the prevalence of bluetongue antibodies and to identify the potential risk factors associated with the presence of bluetongue antibodies among cattle in North Kordufan State, Sudan. A total of 299 bovine blood samples were collected randomly from six localities in North Kordufan State and were tested by enzyme-linked immunosorbent assay (ELISA) for detection of BTV-specific immunoglobulin G (IgG) antibodies. Results: The serological evidence of Bluetongue virus infection was observed in 58 out of 299 cows, accounting for a 19.4% prevalence rate among cattle in North Kordufan State. Older cattle (> 2 years of age) had four times the odds to be infected with BTV compared to young cattle (OR = 4.309, CI = 1.941-9.567, p-value = 0.01). Application of preventive measures, such as spraying or dipping with insecticide protects cattle against Bluetongue infection. Application of vector control measures decreased the odds for bluetongue seropositivity by 7 times (OR = 7.408, CI = 3.111-17.637, p-value = 0.01). Conclusions: The results of this study indicated that age and application of routine insecticides are influential risk factors for seroprevalence of Bluetongue in cattle. Surveillance of Bluetongue virus should be extended to include other susceptible animals and to study the distribution of the insect vectors in the region to better predict and respond to BTV outbreak in the State of North Kordufan, Sudan.