Analysis of clinical samples of patients with new viral infections is critical to confirm the diagnosis, provide viral load and sequence data necessary for characterizing viral kinetics, transmission and evolution of the virus. We analysed samples from 112 patients infected with the recently discovered Middle East Respiratory Syndrome Coronavirus (MERS-CoV)

METHODS:  Respiratory tract samples from MERS-CoV PCR-confirmed cases were analysed for yields of MERS-CoV viral load and fraction of MERS-CoV genome. These values were analyzed to determine associations with clinical sample type.

RESULTS:  Samples from 112 MERS-CoV PCR-positive individuals were analysed: 13 Sputum samples, 64 Nasopharyngeal swabs, 30 Tracheal aspirates, 3 Broncho-alveolar lavages and 2 were of unknown origin. Tracheal aspirates yielded significantly higher MERS-CoV high viral load when compared with Nasopharyngeal swabs (p=0.005) and to Sputum (p=0.0001). Tracheal aspirates had similar viral load compared to Broncho-alveolar lavage (p=0.3079). Broncho-alveolar lavage samples and tracheal aspirates had significantly higher vital load values than nasopharyngeal swabs (p=0.0095 and p=0.0002) and Sputum samples (p=0.0009 and p=0.0001). The genome yield from tracheal aspirates and bronchoalveolar lavage samples were similar (p=0.1174).

CONCLUSIONS:  Lower respiratory tract samples yield significantly higher MERS-CoV viral load, and genome fractions than upper respiratory tract samples.