Molecular identification of Brucella abortus in secondary hosts of goats and sheep in Magelang, Central Java,...

Brucella abortus is primarily associated with cattle; however, its detection in small ruminants has been increasingly reported, raising concerns about interspecies transmission and public health risks.

This study aimed to detect and genetically characterize B. abortus in goats and sheep using molecular techniques, assess genetic variation within the IS711 gene, and evaluate phylogenetic relationships among isolates.

Blood samples were collected from 102 small ruminants (32 goats and 70 sheep) with a history of reproductive disorders in Magelang District, Central Java, between October and December 2024. DNA was extracted and analyzed using Abortus, Melitensis, Ovis, Suis Polymerase Chain Reaction (AMOS)-PCR targeting the IS711 gene. Positive amplicons were sequenced and subjected to BLAST analysis, phylogenetic reconstruction (MEGA 12), and genetic distance estimation using the Kimura-2 parameter.

AMOS-PCR was used to detect B. abortus Deoxyribonucleic acid in 40 animals (39.2%). Sequencing showed >99% identity with reference B. abortus strains. Phylogenetic analysis revealed low genetic divergence (0.000-0.004), indicating a common infection source. Notably, several isolates exhibited limited sequence variation, including a double guanine insertion at positions 8-9 and a C→T transition at position 40 of IS711.

This study demonstrates that B. abortus can infect small ruminants through interspecies transmission under mixed grazing systems. The findings emphasize the need to expand surveillance and control efforts beyond cattle to include sheep and goats, strengthening brucellosis management within a One Health framework.