Brucellosis in camels

Brucellosis is a zoonotic disease which is caused by gram‑negative bacteria from the Brucella genus. Brucella is classified as risk group III by the WHO. The species Brucella abortus and Brucella melitensis were identified in camels. The disease was first described in 1931. Even though clinical symptoms are generally mild in camels, Brucella can be transmitted to humans via fresh milk or raw meat and turn into a serious health problem in the affected regions.

Camels of the species Camelus bactrianus and Camelus dromedarius are often infected with Brucella, especially if they live in direct vicinity of infected ruminants such as cattle, sheep or goats. Entry sites for Brucella are the lungs, intestinal tract, mucous membranes and skin. The pathogen travels via the blood to various organs such as liver, spleen, or the haematopoietic system. Experimental infection of camels with Brucella abortus led to mild clinical symptoms, e.g. inappetence, minimal lameness due to arthritis, and bilateral lacrimation. Orchitis and epididymitis occurred with Brucella abortus and Brucella melitensis. Retained placenta (retentio secundarium), placentitis, infections of the urogenital tract, abortion with mummification, and infertility were also observed. The economic loss due to miscarriage, decreased milk production and reduced fertility is significant.

Reliable diagnosis can only be achieved by direct detection of Brucella in the affected tissue, e.g. from the placenta or lymph nodes. This procedure, however, is complicated, and also constitutes a potential infection risk for the laboratory staff. For this reason, various serological test systems for the detection of antibodies against Brucella have been developed, including the complement fixation test (CFT) and Rose Bengal test (RBT). But these tests are time-consuming and limited with respect to sensitivity and standardisation. The RBT can only be used for monitoring in Brucella-free regions. The World Organisation for Animal Health OIE (“Office International des Epizooties”) names various serological tests for the diagnosis of bovine antibodies against Brucella, including the above-mentioned CFT and RBT, as well as ELISA. However, the organisation also points out that a positive result should always be verified using a confirmatory test. ELISAs based on a large antigen spectrum offer a high sensitivity and are therefore ideally suited for screening.

• Anti-Brucella ELISA Camel (IgG)