Saeed Alamian - Brucellosis Department, Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Karim Amiry - Brucellosis Department, Iranian Veterinary Organization, Tehran, Iran
Afshar Etemadi - Brucellosis Department, Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran
Maryam Dadar - Brucellosis Department, Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran

Bovine brucellosis, an infectious disease transmitted by Brucella melitensis and Brucella abortus, presents a significant zoonotic risk for agricultural economics and animal health. The primary objective of this study was to present a comprehensive understanding of the prevalence and features of Brucella strains within the industrial dairy farming sector in Iran. Rose Bengal plate test, standard agglutination test, and indirect enzyme linked immunosorbent assay tests were used to confirm all seropositive animals. A total number of ۱,۳۱۱ bovine samples from seropositive animals including were collected from ۲۲۴ farms in ۲۱ provinces of different regions of Iran and examined. The discovered Brucella isolates were phenotyped and molecularly characterized. The isolates were all B. abortus or B. melitensis. Bacteria analysis revealed that ۷۰.۵۳% of seropositive farms were tested positive for Brucella strains, predominantly B. melitensis biovar ۱ (۴۳.۴۲%) and B. abortus biovar ۳ (۲۷.۱۱%). Geographical distribution revealed that B. melitensis biovar ۱ was the most common in dairy cow farms (۱۶ provinces), followed by B. abortus biovar ۳ (six provinces). Also, the prevalence of B. melitensis biovar ۲, B. melitensis biovar ۳, B. abortus biovar ۱, B. abortus biovar ۲ and RB۵۱ vaccine were restricted to certain provinces. AMOS (abortus melitensis ovis suis)-polymerase chain reaction and Bruce-ladder PCR confirmed species identification. These results highlighted the complexity of bovine brucellosis in Iran and illustrated that B. melitensis was spread from small ruminants to cattle. This study provided important epidemiological insights for targeting future brucellosis control programs in the Iranian dairy farms.

Agricultural economies, Bovine brucellosis, Brucella abortus, Brucella melitensi, Industrial dairy cattle farms