Isolation and identification of Brucella abortus and B. melitensis in ruminants with a history of abortion: the first report from Eritrea

Abstract

Brucella species have never been isolated or documented in Eritrea. The present study was initiated to isolate and identify Brucella species that infect livestock in Eritrea. A total of 316 blood sera, 137 milk, 71 vaginal swabs, a placental cotyledon, and a fetal stomach content were sampled from 208 goat, 102 sheep, and 6 cattle. Series testing protocol starting with Rose Bengal plate test, followed by c-ELISA, culturing, and then multiplex AMOS-PCR was followed. The purpose-sampling strategy was applied, and animals with a history of abortion in the last three weeks were sampled to increase the probability of capturing Brucella species. Isolation was conducted on Burcella media agar, and Brucella broth was added with Brucella selective supplement containing 2,500IU polymyxin B, 12,500IU bacitracin, 50.0 mg cycloheximide, 2.5mg nalidixic acid, 50,000 IU nystatin, and 10.0 mg vancomycin. Accordingly, 41 animals were positive for a series of serological tests. The overall Brucella seropositive detection proportion was 13.0%, and goats constituted the majority 78% (n=32). The highest number of positive samples were from the Maekel region. Six Brucella organisms were successfully isolated from two milk samples, two vaginal swabs, one placental cotyledon, and one fetal stomach content obtained from seropositive animals. Among the  Brucella isolates, five were B. melitensis, while the remaining one was B. abortus as per the multiplex AMOS- PCR assay. The present  study documented the first B. abortus and B. melitensis isolates in Eritrea. Milk, vaginal discharges, placental cotyledon, and aborted  fetus were identified as sources of Brucella for livestock and livestock keepers. Besides, the findings highlight a reasonable proportion of  the reproductive disorders in cattle and small ruminants could be due to brucellosis. This calls for public sector intervention to control the  diseases in animals and to enhance community awareness of good practices such as drinking boiled milk and avoiding contact with  infected tissues and body discharges to prevent potential public health risks from zoonosis.