Epidemiology of <i>Brucella</i> Infection in Small Ruminants in the United Arab Emirates

Small ruminants are important livestock species, which function as a major source of protein, in the United Arab Emirates (UAE), although infections such as <i>Brucella</i> infection can hamper their productivity. However, there is currently a paucity of epidemiological data on <i>Brucella</i> infections in small ruminants in the UAE. This study therefore aimed to estimate the seroprevalence of <i>Brucella</i> infection and evaluate the associated risk factors in 272 flocks encompassing 2730 small ruminants in the Emirate of Abu Dhabi. In addition, DNA of the <i>Brucella</i> was tested in seropositive small ruminant. Multispecies competitive enzyme-linked immunosorbent assay (cELISA) and multispecies indirect ELISA (iELISA) were used to detect <i>Brucella</i> antibodies, while real-time quantitative polymerase chain reaction (qPCR) was used to detect the DNA of genus Brucella and its major species (<i>Brucella</i> (<i>B</i>.) <i>abortus</i>, <i>B. melitensis</i>, and <i>B. ovis</i>). Flock seroprevalences of <i>Brucella</i> infection were 13.6% (95% CI: 9.8%-18.3%) and 25.5% (95% CI: 20.3%-31.0%) based on iELISA and cELISA, respectively. While animal seroprevalences were 2.31% (95% CI: 1.8-2.9) and 4.84% (95% CI: 4.1-5.7) on the basis of iELISA and cELISA, respectively. Flock seroprevalence was associated with flock size, whereas animal seroprevalence was associated with region, holding type, species, and age. The genus <i>Brucella</i> DNA was detected in the sera of 28.21% (11/39) of seropositive small ruminants. The 11 <i>Brucella</i> genus positive sera were further identified into three <i>B. ovis</i>, three mixed infections of <i>B. melitensis</i> with either <i>B. abortus</i> or <i>B. ovis</i>, two <i>B. melitensis</i>, and one <i>B. abortus</i>. While the remaining two were not positive for any of the three species. In conclusion, although animal seroprevalences were low by both ELISA tests, flock seroprevalences were relatively high. Besides, <i>B. melitensis</i> was the dominant species that was detected in the sera small ruminants posing zoonotic threat to the public. Therefore, the results of this study warrant for re-enforcement of the control and preventive measures of <i>Brucella</i> infections in small ruminants.