Seroprevalence and Molecular Characterization of Brucella Species in Naturally Infected Cattle and Sheep

Brucellosis is one of the most economically significant infectious diseases in Egypt. The study aimed to assess the seroprevalence by indirect ELISA by examining serum samples from 720 cattle and 320 sheep and detection and characterization of Brucella spp. from 24 clinical samples (placenta) by bacterial culture (BC) and PCR targeting bcsp31 gene. The seroprevalence was 16.7% and 16.25% in cattle and sheep, respectively. There was a significant association (P < 0.05) between the seroprevalence of brucellosis and sex at the level of cattle and age at the sheep level, where seroprevalence was 18.7% in female cattle and 22% in sheep > 2 years. Likewise, seroprevalence was significantly (P < 0.05) different among locations for cattle. Of the 24 clinical samples tested by BC, B. abortus was isolated and identified in 100% of clinical samples. Using PCR, all Brucella strains were positive (100%) regarding bcsp31gene. Nucleotide analyses of seven bcsp31 sequences of the identified strains revealed 99.3-100% identity, with one nucleotide divergence. These results provide an insight into the brucellosis, particularly with the detection of B. abortus from sheep, therefore, further wide epidemiological studies are needed to develop appropriate prevention and control strategies.