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.
Camels are currently discussed as the potential source of sporadic MERS-CoV infections in humans. Antibodies against MERS-CoV were found in camel sera that had already been collected in 1983. This leads to the assumption that the virus has been circulating in the camel population for a long time. The antibody prevalence in adult camels in endemic areas is up to 100 %. In newborn camels, it is assumed that the virus is multiplied and shed, as time is needed to generate neutralising antibodies. During this time the calves might be a source of infection for humans. There is no certified vaccine available.
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.
|Method||Substrate||Diagnostic application||Order number|
|ELISA||Recombinant structural protein of MERS coronavirus (MERS-CoV)||IgG ELISA; first commercially available ELISA for the detection of MERS-CoV in camels, high sensitivity and specificity; reduced cross reactivity; suitable for epidemiological studies and monitoring programmes||EI 2604-9601 GK|
|IIFT||MERS coronavirus-infected and non-infected cells||First commercially available IIFT for the detection of MERS-CoV in camels, highly sensitive screening test; qualitative and semiquantitative detection of|
|FI 2604-1010 GK|