PREVALENCE AND MOLECULAR TYPING OF BRUCELLA SPP. IN CAMEL HERDS OF DESERT PASTORAL SYSTEMS

Abstract

Brucellosis remains a considerable threat to individuals that reside in desert pastoral systems whereby camels hold great significance to their livelihood.  The aim of this study was to assess the seroprevalence and molecular characteristic of Brucella spp. infection in camel herds.  We checked 450 camels by serology (RBT and CFT), molecular (PCR and multiplex PCR) and genomic (MLST and WGS) tests.  Serology revealed that 29.33 per cent of the samples tested positive (RBT) and 26.22 per cent tested positive (CFT).  PCR targeted to the bcsp31 gene confirmed presence of Brucella DNA in 27.56 percentage of samples.  Species-specific PCR revealed that B. melitensis prevailed (54.84%), followed by B. abortus (33.06%) and multiple infections (12.10%).  MLST revealed that the most prevalent sequence types were ST-8, ST-5 and ST-11. Instead, WGS analysis provided entire genomic portraits that revealed SNPs, indels, and mobile genetic elements associated with regional clusters.  The genes of several of the isolates caused resistance to antibiotics such as tetracycline (70 percent), aminoglycoside (40 percent) and sulfonamide (25 percent).  All the major risk factors of infection were poor biosecurity, shared grazing, and herd mixing.  These findings demonstrate the complexity of the epidemiology of camel brucellosis and highlight the importance of molecular-based surveillance, improved herd management practices, and targeted intervention strategies to reduce the economic and health impact of this disease.