MERS-CoV

MERS-CoV is an enveloped, positive-sense, single-stranded RNA virus first identified in Saudi Arabia in 2012. Its receptor, DPP4 (CD26), is expressed on lower respiratory tract epithelium and on kidney, which accounts for the combination of severe pneumonia with acute kidney injury that distinguishes MERS clinically from SARS. Because DPP4 is concentrated in the lower rather than upper airway, the virus transmits relatively poorly between people, and sustained community spread has not occurred; instead, outbreaks are driven by zoonotic exposure to camels and by amplification in hospitals, as in the 2015 South Korean outbreak seeded by a single returning traveller. Incubation is around five days, and presentation ranges from asymptomatic to fever, cough, dyspnoea, gastrointestinal symptoms, ARDS, and multiorgan failure. Case fatality is highest in older patients and those with diabetes or chronic kidney or lung disease. No licensed vaccine or antiviral exists; care is supportive with strict infection control.