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

Human coronavirus-EMC (Erasmus Medical Center)

MERS

As of July 2020, there have been 2494 cases worldwide in 27 countries but mostly in the Middle East, with a total of 858 deaths. Outside the Middle East, cases have been travel related and traceable to the Arabian Peninsula.

• The spectrum of disease for MERS ranges from a mild viral respiratory disease to a rapidly fatal viral pneumonia associated with acute respiratory distress syndrome (ARDS) and acute renal failure.
• Patients will present with an influenza-like illness with fever, chills, headache, and a dry cough.
• MERS progresses rapidly to a viral pneumonia within a wk of onset of the infection with bilateral interstitial infiltrates and development of ARDS with severe hypoxemia.
• Other possible symptoms include myalgias, sore throat, vomiting, diarrhea, abdominal pain, and hemoptysis.

• MERS-CoV is closely related to a coronavirus found in bats, which implies that bats may be a reservoir for MERS-CoV. The virus was then transmitted to dromedary camels sometime in the distant past. Camels likely serve as hosts for MERS-CoV for animal-to-human transmission.
• Human-to-human transmission has been documented in various cluster outbreaks and in household contacts.
• While MERS has a high case fatality rate (35%-50%), its transmissibility appears to be modest.
• The median incubation period for human-to-human transmission is 5 days.

• Severe acute respiratory syndrome (SARS), also caused by a novel coronavirus (SARS-CoV), emerged in 2002 in China. The virus also likely originated in bats, and the intermediate host for the virus was the palm civet cat. SARS has a high transmissibility rate but a low case fatality rate.
• Influenza, including pandemic H1N1 influenza and avian influenza H7N9.
• MERS has a high frequency of renal failure, and influenza does not.
• COVID-19: A novel coronavirus that emerged in China in 2019 and spread worldwide, causing a pandemic.

MERS should be considered when there is a direct epidemiologic link with a person with MERS or when a patient resides in or has traveled to the Middle East and presents with a febrile acute respiratory illness.

• Lower respiratory tract specimens such as sputum or BAL should be tested using a real-time reverse-transcriptase polymerase chain reaction test (rRT-PCR), and these test sites appear to be more sensitive than testing of upper respiratory tract secretions via combined nasopharyngeal and oropharyngeal swab with the same rRT-PCR.
• Serology: A serum sample within first 10 to 12 days of onset should be obtained for rRT-PCR and repeated 14 days later.
• Other serologic tests include ELISA screening followed by indirect immunofluorescence.
• Nonspecific laboratory tests with MERS: Leukopenia, relative lymphopenia, and thrombocytopenia.

• Radiographic abnormalities include either unilateral or bilateral airspace opacities, patchy infiltrates, interstitial changes, nodular opacities, reticular opacities, pleural effusions, and even total segmental or lobar opacification.
• ARDS pattern is typically seen with severe cases.

Currently there are no approved treatments for MERS. Experimental therapies include:

• Combination of interferon (IFN)-alpha-2a and ribavirin
• Monoclonal antibodies
• Convalescent serum
• Nitazoxanide: A broad-spectrum antiviral agent
• Steroids are not recommended for use in patients with MERS
• Ongoing placebo controlled trial in Saudi Arabia of oral lopinavir-ritonavir and SQ interferon-beta

There is ongoing research in vaccine development, including camel vaccination, which may be a novel approach to preventing human infection.

If a case is suspected, the local health department should be involved as well as an infectious diseases physician.

• Health care workers are at risk of exposure to the disease and thus should use both contact and airborne precautions in the hospital setting if in close contact with symptomatic individuals or patients with MERS.
• In the Middle East, infection-control practices include prohibiting consumption of unpasteurized camel milk (virus can be found in milk and feces) and use of camel urine, which is believed to have medicinal purposes.