Middle East Respiratory Syndrome (MERS)

How to Cite This Chapter: Loeb M, Kuś J, Jankowski M. Middle East Respiratory Syndrome (MERS). McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. https://empendium.com/mcmtextbook/chapter/B31.II. Accessed July 18, 2024.
Last Updated: October 20, 2021
Last Reviewed: October 22, 2021
Chapter Information

Definition, Etiology, PathogenesisTop

Middle East respiratory syndrome (MERS) is an infectious disease caused by a zoonotic coronavirus termed MERS­-CoV that emerged in 2012 in Saudi Arabia. Cases of infection have been reported mainly in residents of and visitors to the Arabian Peninsula and Eastern Asia. Transmission is from animals (camels are the suspected source) to humans via unknown route; human-to-human transmission requires close person-to-person contact.

Clinical features range from asymptomatic infection to severe pneumonia with acute respiratory distress syndrome and sepsis. Initial symptoms include fever and cough, often with headache and muscle and joint pain; later patients develop dyspnea, sometimes nausea and vomiting, rarely abdominal pain and diarrhea.


Chest radiographs reveal unilateral or bilateral infiltrates, interstitial changes, and pleural fluid. Laboratory tests show leukopenia with lymphopenia, low platelet counts, and increased lactate dehydrogenase levels.

Diagnostic Tests

1. Polymerase chain reaction (bronchoalveolar lavage fluid, sputum, smear or aspirate from the nasal cavity or oropharynx).

2. Serology (serum sample collected in the first week of illness and 2-3 weeks later).


No antiviral treatment is available. Administer oxygen or use mechanical ventilation when necessary. In the case of bacterial superinfection, administer antibiotics.


While caring for the patient or performing non–aerosol-generating procedures, wear a face mask (procedure or surgical mask; they are as effective as the N95 mask), gloves, gown, and protective goggles or face shield. For aerosol-generating procedures (eg, intubation, manual ventilation, open endotracheal suctioning, cardiopulmonary resuscitation, bronchoscopy, sputum induction, nebulized therapy, noninvasive positive pressure ventilation [continuous or bilevel positive airway pressure]), use a respirator (N95 or equivalent). The patient should be transferred to a hospital equipped with an isolation room that complies with airborne infection isolation room (AIIR) standards.

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