Veterinary diagnostics for 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
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.
Middle East respiratory syndrome (MERS) is caused by a previously unknown coronavirus (MERS-CoV). So far, all human MERS-CoV infections have originated in the Middle East. About 40 % of known cases were fatal. The incubation time ranges from less than a week in the majority of cases to up to 12 days in individual cases. Transmission between humans takes place via aerosols and smear infections. Respiratory secretions of the upper respiratory tract of infected persons play a particularly important role as they can be passed on by sneezing, coughing, and via contaminated hands.
Clinical symptoms in camels infected with MERS‑CoV are rare and generally mild. The most reliable laboratory diagnostic methods for confirmation of suspected MERS‑CoV infections in camels include the direct detection of MERS‑CoV using PCR and the detection of antibodies against MERS‑CoV using indirect immunofluorescence (IIFT), ELISA, or neutralisation tests. Cross reactions with other coronaviruses, in particular bovine coronaviruses, need to be taken into account in serological diagnostics. These can be reduced using a specific domain of the recombinant spike protein as the antigen in the ELISA. The IIFT based on MERS‑CoV-infected cells as the substrate provides a highly sensitive screening test that allows qualitative and semiquantitative detection of antibodies against MERS‑CoV. Positive results should be confirmed with another method, ideally by means of a neutralisation test.