Abstract

Isolation of Brucella organism is considered as the gold standard diagnostic method for brucellosis since it is specific and allows biotyping of the isolate, which is relevant for control of brucellosis using vaccination. Serological studies revealed that brucellosis is endemic in bovines in Ethiopia. Even though seroprevalence of brucellosis is established in different species of animals, so far there was no successful attempt to isolate and identify Brucella spp. in dairy cattle at farm level in the country. Therefore, the endeavor of the present study was to isolate Brucella spp. from seropositive cattle with a history of abortion. A total of 570 dairy cattle from 35 herds were screened serologically by Rose Bengal plate test based on the history of abortion in the farm. Among the tested samples 13 (2.28%) were found positive by Rose Bengal plate test screening while 33 samples were found sero negative upon serological screening test but were collected from the cattle with history of recent abortion. Forty six clinical samples were cultured which were both from Brucella seropositive and seronegative (dairy cattle with history of abortion) upon Rose Bengal plate test screening. Three (6.52%) samples were Brucella culture positive and further characterization of all the three isolates based on biochemical tests result confirmed that the pathogen was Brucella abortus. Brucella abortus was isolated from placental cotyledon 1/9 (11.1%) and vaginal swab 2/23 (8.69%) while no isolate was obtained from milk and fetal abomasal contents (abomasal aspirate) of aborted fetus. Our finding revealed the occurrence of B. abortus in dairy cattle of Ethiopia through isolation of the organism for the first time from seropositive dairy cattle with a history of abortion. The organisms were isolated from placental cotyledon (one isolate) and vaginal swab (two isolates) while no isolate was obtained from milk and fetal abomasal contents (abomasal aspirate) of the aborted fetus. Hence, the bacteriological isolation and identification of Brucella abortus from dairy cattle indicates the importance of brucellosis in dairy cattle industry of the area and potential public health implication for human population in the study areas.

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