Wednesday, 5 February 2014

Middle East respiratory syndrome coronavirus (MERS-CoV): summing up 100 weeks

We stand at 182 cases with 78 deaths. The proportion of fatal cases (PFC) stands at 43%.

  • Median age of all cases, including deaths, sits at 53-years (missing data on 13 cases); median age of fatal cases is 60-years
  • 47% of all MERS cases with data are >55-years of age; 36% are >60-years
  • 65% of cases are male (missing data on 18 cases)
  • Underlying comorbidities feature in most severe disease MERS cases
  • Approximately 18% of MERS-CoV cases are in healthcare workers; 2.7% of all fatal MERS cases are HCWs
  • 81% of case are from the Kingdom of Saudi Arabia (KSA); the Arabian peninsula is the zone of case origin
  • Reliable real-time reverse transcription polymerase chain reaction (RT-rtPCR) assays exist for detection, confirmation and genotyping
  • Camels have been found on multiple occasions at multiple sites in the region to have antibodies to an antigenically similar virus to the MERS-CoV and nasal swabs have been found to be MERS-CoV RNA positive, as have humans in contact with the same camels (infection direction unknown). 
  • Camel, goat, monkey, alpaca and human cells lines efficiently replicate MERS-CoV (multiple intermediate sources?)
  • 1 diagnostic sequence of MERS-CoV RNA has been identified in a Taphozus perforatus bat (origin of animal other infections?)
  • MERS-CoV uses DPP4 (CD26) as its receptor on host cells, a molecule found on some cell lines and epithelial cells of kidney, small intestine, liver and prostate. DPP4 has a standard role in hormone and chemokine activation
  • No viable antiviral therapy or cocktail exists to treat infection. No vaccine exists.
  • MERS-CoV replicates well in the lower respiratory tract of lab-infected macaques
  • Person-to-person (p2p) transmission of MERS-CoV is sporadic
  • Genetic variation among MERS-CoV genomes suggests multiple insertions into humans from the source(s)
  • Fever, cough and shortness of breath in >70% of 47 cases in KSA; runny nose in 4%; abnormal chest X-Ray in 100%
  • Sample often, sample lower respiratory tract to increase chance of successful RT-PCR result 
  • Testing 5,065 hospitalized patients, healthcare worker contacts and family contacts found 2% (n=106) positivity over 12-months, in Saudi Arabia 
  • MERS-CoV has circulated in KSA during several mass gatherings (2x Hajj pilgrimages and Umrah) providing ample opportunity for p2p transmission. There has been no evidence for an uptick in p2p transmission. We are nowhere near the verge of a pandemic.