Molecular Prevalence and Risk Factors Analysis of Asymptomatic Infection with Anaplasma marginale and Theileria annulata in Egyptian Cattle

Abstract

Awareness of the epidemiology of Anaplasma marginale ( A. marginale ) and Theileria annulata ( T. annulata ) in the asymptomatic carriers is integral for developing efficient control in tropical and subtropical countries. The endemic status of both pathogens among asymptomatic carrier cattle in Egypt is poorly investigated. This study was conducted to detect the prevalence of A. marginale and T. annulata infections in apparently healthy cattle from six Egyptian provinces based on specific polymerase chain reaction (PCR) assays and to assess its associated risk factors. Two hundred seventy-eight blood samples were collected from cattle in 24 farms and four abattoirs in Beheira, Damietta, Cairo, Fayoum, Qena, and Luxor. DNA was extracted, and A. marginale msp4 and T. annulata tams-1 genes were amplified using Real-Time PCR assays. The overall prevalence of A. marginale and T. annulata were 39.6% and 5.8%, respectively. Meanwhile, the prevalence of co-infection was 2.5%. The prevalence of A. marginale (0.0% - 65.1%) and T. annulata (0.0% - 25.0%) greatly varied between provinces. Statistical analysis of risk factors indicated that female cows (49.7%; OR = 3.4; p = < 0.0001), Mixed breed (47.4%; OR = 3.6; p = 0.03), dairy (48.2%; OR = 3.7; p = < 0.0001), and small-size farms (60.2%; OR = 4.6; p = < 0.0001) showed a significantly higher risk for A. marginale compared to the references. Meanwhile, for T. annulata, cattle from Luxor (25.0%; OR = 10.3; p = 0.03) and ages < 2 years (16.7%; OR = 4.6; p = 0.038) had a significantly higher risk against the references. These findings highlight the endemic status of A. marginale and T. annulata in asymptomatic cattle and analyze the risks influencing their prevalence in Egyptian cattle.