infectious diseases
Coronaviruses and Acute Respiratory Syndromes (MERS and SARS)
Middle East Respiratory Syndrome (MERS)
Middle East respiratory syndrome (MERS) is a severe, acute respiratory illness caused by the MERS coronavirus (MERS-CoV). MERS-CoV infection was first reported in September 2012 in Saudi Arabia, but an outbreak in April 2012 in Jordan was confirmed retrospectively. Through 2021, worldwide, over 2500 cases of MERS-CoV infection (with at least 850 related deaths) have been reported from 27 countries; all cases of MERS have been linked through travel to or residence in countries in and near the Arabian Peninsula, with > 80% involving Saudi Arabia. The largest known outbreak of MERS outside the Arabian Peninsula occurred in the Republic of Korea in 2015. The outbreak was associated with a traveler returning from the Arabian Peninsula. Cases have also been confirmed in countries throughout Europe, Asia, North Africa, the Middle East, and the United States in patients who were either transferred there for care or became ill after returning from the Middle East. Only a handful of cases have been reported since 2019 ( Reference ). Preliminary seroprevalence studies indicate that the infection is not widespread in Saudi Arabia. The World Health Organization considers the risk of contracting MERS-CoV infection to be very low for pilgrims traveling to Saudi Arabia for Umrah and Hajj. Median age of patients with MERS-CoV is about 50 years, and patients are predominantly male. Infection tends to be more severe in older patients and in patients with a preexisting disorder such as diabetes, a chronic heart disorder, or a chronic renal disorder. MERS-CoV may be transmitted from person to person via direct contact, respiratory droplets (particles > 5 micrometers), or aerosols (particles < 5 micrometers). Person-to-person transmission has been established by the development of infection in people whose only risk was close contact with people who had MERS. The reservoir of MERS-CoV is thought to be dromedary camels, but the mechanism of transmission from camels to humans is unknown. Most reported cases involved direct human-to-human transmission in health care settings. If MERS is suspected in a patient, infection control measures must be initiated promptly to prevent transmission in health care settings. 1.World Health Organization: Middle East respiratory syndrome coronavirus (MERS-CoV) situation update---Feburary 2022. The incubation period for MERS-CoV is about 5 days. Most reported cases have involved severe respiratory illness requiring hospitalization, with a case fatality rate of about 35%; however, about 21% of patients had mild or no symptoms ( Symptoms and signs reference ). Fever, chills, myalgia, and cough are common. Gastrointestinal symptoms (eg, diarrhea, vomiting, abdominal pain) occur in about one third of patients. Manifestations may be severe enough to require treatment in an intensive care unit, but the proportion of such cases has declined sharply over time. 1. World Health Organization:MERS Global Summary and Assessment of Risk - July 2019 Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) testing of upper and lower respiratory secretions and serum MERS should be suspected in patients who have an unexplained acute febrile lower respiratory infection and who have had any of the following within 14 days of symptom onset: Travel to or residence in an area where MERS has recently been reported or where transmission could have occurred Contact with a health care facility where MERS has been transmitted Close contact with a patient who was ill with suspected MERS MERS should also be suspected in patients who have had close contact with a patient with suspected MERS and who have a fever whether they have respiratory symptoms or not. The most recent recommendations are available from the Centers for Disease Control and Prevention (CDC) (MERS: Interim Guidance for Healthcare Professionals). Testing should include real-time RT-PCR testing of upper and lower respiratory secretions, ideally taken from different sites and at different times. Serum should be obtained from patients and from all, even asymptomatic close contacts, including health care workers (to help identify mild or asymptomatic MERS). Serum is obtained immediately after MERS is suspected or after contacts are exposed (acute serum) and 3 to 4 weeks later (convalescent serum). Testing is done at state health departments or the CDC. In all patients, chest imaging detects abnormalities, which may be subtle or extensive, unilateral or bilateral. In some patients, levels of LDH and AST are elevated and/or levels of platelets and lymphocytes are low. A few patients have Acute Kidney Injury (AKI) . Supportive Treatment of MERS is supportive. To help prevent spread from suspected cases, health care practitioners should use standard, contact, and airborne precautions. There is no vaccine. The following are English-language resources that may be useful. Please note that THE MANUAL is not responsible for the content of these resources. CDC: Middle East Respiratory Syndrome (MERS) information for healthcare professionals World Health Organization: Middle East respiratory syndrome coronavirus (MERS-CoV) 