Investigation of an outbreak of brucellosis in a dairy mixed farm and evaluation of a proper test and slaughter strategy to release the herd out of the quarantine

An outbreak of brucellosis in a dairy mixed farm with a total of 508 animals at Fayoum governorate, North Upper Egypt was investigated. The present study showed that extensive animal farming was a potential risk factor for interspecies transmission of brucellosis. The seroprevalences of brucellosis using Rose Bengal Test (RBT) and Buffered Acidified Plate Antigen Test (BAPAT) were (9.5%) in cattle, (35%) in sheep, and (50%) in camels. The milk ring test (MRT) identified fewer positive cases than BAPAT and RBPT due to less sensitivity to detect low concentrations of antibodies in milk or due to fat clustering factors. Therefore, MRT cannot be used alone to get rid of the infection inside the farm. A total of 31 Brucella isolates were recovered from cows and sheep on the farm. Bacteriological examination and molecular confirmation of isolated Brucella species using AMOS-PCR confirmed that all isolates were typed as Brucella melitensis biovar 3. AMOS-PCR was a perfect method for rapid, sensitive, and accurate Brucella detection at the species level. The strategy of test and slaughter has been applied to eradicate brucellosis from the farm. The early release of the herd out of the quarantine should be avoided especially under unhygienic conditions and lack of controlled movement of animals. However, the animal population must be subjected to successive serological examinations for the exploration of animals that may be still incubating the disease. Despite 50% of male camels being seropositive, no clinical signs have been reported. Mixed breeding systems have to be avoided and the application of biosecurity practices as well fair compensation policy for owners should be implemented.