MERS typically starts with a fever (> 38°C, 100.4°F), chills, cough and shortness of breath. In some cases, individuals with MERS may also experience muscle and joint pain, nausea and diarrhea.
Although reports of asymptomatic and mild cases exist, the disease quickly progresses to pneumonia in the majority of cases.1 Severe cases often result in respiratory failure requiring mechanical ventilation and support in an intensive‐care unit. Septic shock and organ failure, especially of the kidneys, have also occurred.2
Findings on chest x-rays appear rapidly and are consistent with viral inflammation of lung tissue and Acute Respiratory Distress Syndrome (ARDS). Lower lobes appear more affected than upper lobes early in the course of illness.3
People with pre-existing medical conditions or weakened immune systems appear to be more susceptible to MERS infection and more prone to experience severe, including fatal, disease. Pre-existing conditions among reported cases include diabetes; cancer; and chronic lung, heart, and kidney disease.4 One or more additional disorders have been present in most hospitalized MERS-CoV patients.5
The time between when a person is exposed to MERS-CoV and when symptoms appear is approximately two (2) to 14 days (five to six days average).6,7 The infectious period for individuals with MERS-CoV is likely to extend from the onset of fever until 10 days after fever resolution.8 A preliminary epidemiological assessment of the MERS-CoV outbreak in South Korea found no evidence that infectiousness preceded symptom onset.9
There is no specific drug (i.e., antiviral) treatment for MERS and no vaccine available to protect against the disease. Medical management of patients with confirmed MERS focuses on symptom relief, supportive management of complications, and implementation of recommended infection prevention and control measures. WHO's interim guidance document, Clinical management of severe acute respiratory infections when novel coronavirus is suspected: What to do and what not to do, provides further information.
The search for effective treatments is ongoing. Scientists at the National Institutes of Health (NIH), National Institute of Allergy and Infectious Diseases (NIAID) are screening drugs approved by the Food and Drug Administration (FDA) while others study the classes of drugs possibly able to halt the infection in patients. The NIH is also involved in vaccine studies to protect against MERS-CoV.
Polymerase chain reaction (PCR) tests are performed to confirm MERS infection. Respiratory samples enable rapid detection for active MERS-CoV infection. The CDC Laboratory Testing for MERS-CoV web page and the Interim Guidelines for Collecting, Handling, and Testing Clinical Specimens from Patients under Investigation (PUIs) for Middle East Respiratory Syndrome Coronavirus (MERS-CoV) – Version 2.1 provide detailed guidance on laboratory testing.
The CDC web page, Interim Guidance for Healthcare Professionals, provides assistance on evaluation and management of close contacts, reporting requirements and laboratory testing.
1 W.A. Rutala, D.J. Weber, and the Healthcare Infection Control Practices Advisory Committee (HICPAC), "Guideline for Disinfection and Sterilization in Healthcare Facilities", Centers for Disease Control and Prevention, U.S. Department of Health and Human Services (2008).
2 World Health Organization, "Frequently Asked Questions on Middle East Respiratory Syndrome Coronavirus (MERS‐CoV)."
3 A. Zumla, D. Hui, and S. Perlman, "Middle East Respiratory Syndrome," Lancet 386, 1997, p. 995-1007 (2015).
4 Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, "Patient Under Investigation (PUI)."
5 Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, "People Who May Be at Increased Risk for MERS."
6 Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, "Patient Under Investigation (PUI)."
7 National Institute of Allergy and Infectious Disease, National Institutes of Health, "Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Research."
8 A. Zumla, D. Hui, and S. Perlman, "Middle East Respiratory Syndrome," Lancet 386, 1997, p. 995-1007 (2015).
9 B.J. Cowling, M. Park, V.J. Fang, P. Wu, G.M. Leung, J.T. Wu, "Preliminary epidemiological assessment of MERS-CoV outbreak in South Korea, May to June 2015," Euro. Surveill., 20, 25 (2015).