Abstract
Brucellosis is the most widespread zoonosis in the world and is responsible for significant economic losses, particularly in bovine and water buffalo herds. The causative agent of the disease is Brucella spp. which can infect humans and numerous animal species, including cattle, water buffalo, sheep and pigs. In animals the main clinical manifestation of infection is abortion. The pathogen can be transmitted through direct contact with infected animals and parturition products or through consumption of contaminated raw milk and/or dairy products. The genus Brucella is characterized by a high level of homology of DNA. For this reason, advanced molecular methods are very useful tools for the characterization of field isolates and the identification of sources of infection. The aim of this study was to characterize by whole genome sequencing (WGS) Brucella strains isolated from water buffalo farms in the Campania Region in order to perform epidemiological trace-back studies. This study was carried out on 41 strains of Brucella abortus bv.1 isolated from lymph nodes of as many water buffaloes from 40 different farms in the Campania Region. All strains were sequenced for whole genome characterization. The obtained results showed very high homogeneity of the strains under study. Indeed they exhibited a unique MLST (ST1) genetic profile and 4 distinct MLVA genetic profiles. These data indicate a very low level of genetic variability of the analyzed Brucella strains and suggest an epidemiological situation characterized by the persistence of a few bacterial strains in close geographical areas, characterized by intense inter-human and commercial exchanges. This evidence suggests an inter-herd diffusion probably due to environmental factors associated with few sources of infection, likely common to most of the farms included in this study.
