Bluetongue virus infection in cattle: serosurvey and its associated risk factors

Bluetongue virus (BTV) is a vector-borne virus that primarily affects sheep. However, the disease is usually asymptomatic in cattle without obvious clinical signs related to BTV infection. Although there is evidence of BTV antibodies through serology in Egypt, it is still unknown whether Egyptian cattle have ever been exposed to the virus in the north or south of the country. The study's aims were to determine the seroprevalence of BTV and evaluate the potential risk factors for BTV infection in cattle in Egypt. We used a competitive ELISA to screen 690 healthy cattle for BTV-specific immunoglobulin G (IgG) antibodies in four governorates in Egypt. A total seroprevalence of BTV antibodies in examined cattle was 51.47%, 95%CI: 48.01-55.45. The odds of BTV seropositivity were higher in Aswan (OR=1.30, 95%CI: 0.71-2.36), females (OR=3.29, 95%CI: 1.87-5.79), and elder cattle >8 years (OR=12.91, 95%CI: 6.63-25.13). Moreover, cattle contacted with other animals (OR=1.40, 95%CI: 0.94-2.10), with history of abortion (OR=4.88, 95%CI: 3.14-7.59), and those living with presence of insects (OR=12.34, 95%CI: 8-19.30) were more likely to be infected with bluetongue (BT). To effectively predict and respond to a potential BTV outbreak in Egypt, surveillance for BTV infection should be expanded to cover other susceptible ruminants and the range of the insect vectors.