Middle East respiratory syndrome coronavirus (MERS-CoV)

Middle East respiratory syndrome (MERS) is a viral respiratory disease caused by a novel coronavirus (Middle East respiratory syndrome coronavirus, or MERS-CoV) that was first identified in Saudi Arabia in 2012

• MERS-CoV is a zoonotic pathogen that causes respiratory infection in humans, ranging from asymptomatic to severe pneumonia (1)
  • in dromedary camels, the virus only causes a mild infection but it spreads efficiently between animals
  • the dromedary camel is the only animal species that has been reported to transmit this virus to humans
  • although the clinical manifestations, as well as transmission, are remarkably different in MERS-CoV-infected humans and dromedary camels, the viruses isolated from these two species are highly similar, if not indistinguishable
    • indicates that host factors play a significant role in MERS-CoV pathogenesis and transmission
      
      
• Coronaviruses are a large family of viruses that can cause diseases ranging from the common cold to Severe Acute Respiratory Syndrome (SARS)
  
  
• transmission:
  • most of human cases of MERS-CoV infections have been attributed to human-to-human infections in health care settings - however current scientific evidence suggests that dromedary camels are a major reservoir host for MERS-CoV and an animal source of MERS infection in humans (1,2)
    • however, the exact role of dromedaries in transmission of the virus and the exact route(s) of transmission are unknown - strains of MERS-CoV that are identical to human strains have been isolated from dromedaries in several countries, including Egypt, Oman, Qatar, and Saudi Arabia
    • the virus does not seem to pass easily from person to person unless there is close contact, such as occurs when providing unprotected care to a patient
    • health care associated outbreaks have occurred in several countries, with the largest outbreaks seen in Saudi Arabia, United Arab Emirates, and the Republic of Korea
      
      
• clinical features:
  • typical MERS symptoms include fever, cough and shortness of breath. Pneumonia is common, but not always present. Gastrointestinal symptoms, including diarrhoea, have also been reported
    • some laboratory-confirmed cases of MERS-CoV infection are reported as asymptomatic, meaning that they do not have any clinical symptoms, yet they are positive for MERS-CoV infection following a laboratory test
      • most of these asymptomatic cases have been detected following aggressive contact tracing of a laboratory-confirmed case
        
        
• prevention and treatment:
  • no vaccine or specific treatment is currently available - however several MERS-CoV specific vaccines and treatments are in development
  • treatment is supportive and based on the patient's clinical condition
    
    
• prognosis:
  • approximately 35% of reported patients with MERS-CoV infection have died (2)

Reference:

• Widagdo W et al. Host Determinants of MERS-CoV Transmission and Pathogenesis.Viruses. 2019 Mar 19;11(3)
• World Health Organization. Middle East respiratory syndrome coronavirus (MERS-CoV) (Accessed 19/3/19).