Overview on CommonPathological Changes and Diagnostic Methods of Caprine and Ovine Brucellosis

Brucellosis is one of the common bacterial zoonosis in the worldwide caused by organisms belong to the genus Brucella. Brucellosis in sheep and goats is an important animal disease which affects many regions where small ruminants are the predominant species of domestic animals. It is widely distributed around the world, which causes great economic losses in farm animals due to abortion, the slaughter of infected animals, birth of weak animals, decrease in milk production, and infertility. It is a disease of sexually matured animals and commonlytransmitted to other animals by direct or indirect contact with infected animals or discharges such as aborted fetuses, placental membranes or fluids. Brucella melitensis (biovars 1,2,3) is the main causative agent of caprine and ovine brucellosis. Sporadic cases caused by B. abortus have been observed, but cases of natural infection are rare in sheep and goats. Clinically, the disease is characterized by abortion, retainedplacenta, orchitis, epididymitis and, rarely, arthritis, with excretion of the organisms in uterine discharges and in milk. Brucella infected animals generally develop granulomatous inflammatory lesions which frequently are found in lymphoid tissues and organs such as reproductive organs, udder, supramammary lymph nodes and sometimes joints and synovial membranes. Diagnosis depends on the isolation of Brucella from abortion material, udder secretions or from tissues removed at postmortem. Rose Bengal plate test, complement fixation test, and ELISA have been used for the serological diagnosis of brucellosis in sheep and goats. Direct proof of Brucella infection requires isolation of bacteria with well-established methods or detection of bacterial genome by application of polymerase chain reaction. Humans become infected indirectly through contact with infected animals or by animal products consumption. Control of brucellosis in animals requires a correct diagnosis, culling of infected animals, and permanent monitoring of brucellosis-free herds.