Epidemiology of Brucella Infection in Small Ruminants in the United Arab Emirates

TL;DR

This study examines the spread of Brucella infection in small ruminants in the UAE, finding significant flock-level infection rates and identifying B. melitensis as a major concern.

Contribution

The study provides the first detailed epidemiological data on Brucella infections in small ruminants in the UAE.

Findings

Flock seroprevalence of Brucella was 13.6% using iELISA and 25.5% using cELISA.

B. melitensis was the dominant species detected, posing a zoonotic risk.

Animal seroprevalence was low, but flock-level infection rates were relatively high.

Abstract

Small ruminants are important livestock species, which function as a major source of protein, in the United Arab Emirates (UAE), although infections such as Brucella infection can hamper their productivity. However, there is currently a paucity of epidemiological data on Brucella infections in small ruminants in the UAE. This study therefore aimed to estimate the seroprevalence of Brucella 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 Brucella was tested in seropositive small ruminant. Multispecies competitive enzyme-linked immunosorbent assay (cELISA) and multispecies indirect ELISA (iELISA) were used to detect Brucella antibodies, while real-time quantitative polymerase chain reaction (qPCR) was used to detect the DNA of genus Brucella and its major species (Brucella (B.) abortus, B. melitensis, and B. ovis). Flock seroprevalences of Brucella 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 Brucella DNA was detected in the sera of 28.21% (11/39) of seropositive small ruminants. The 11 Brucella genus positive sera were further identified into three B. ovis, three mixed infections of B. melitensis with either B. abortus or B. ovis, two B. melitensis, and one B. abortus. 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, B. melitensis 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 Brucella infections in small ruminants.

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