Merck Manual

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Coronaviruses and Acute Respiratory Syndromes (MERS and SARS)

By

Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Apr 2022
CLICK HERE FOR THE PROFESSIONAL VERSION

Coronaviruses are a large family of viruses that cause respiratory illness ranging in severity from the common cold to fatal pneumonia.

There are many different coronaviruses. Most of them cause illness in animals. However, 7 types of coronaviruses are known to cause illness in humans.

However, 3 of the 7 human coronavirus infections can be much more severe and have recently caused major outbreaks of deadly pneumonia:

These coronaviruses that cause severe respiratory infections are transmitted from animals to humans (zoonotic pathogens).

Middle East Respiratory Syndrome (MERS)

Middle East respiratory syndrome is a coronavirus infection that causes severe flu-like symptoms.

The MERS virus was first detected in Jordan and Saudi Arabia in 2012. As of 2021, worldwide, there were over 2,500 confirmed cases of MERS, with at least 850 related deaths. Most occurred in Saudi Arabia, where new cases continue to appear. 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 occurred in countries throughout Europe, Asia, North Africa, the Middle East, and the United States in people 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.

In several countries in the Middle East, dromedary camels are suspected of being the primary source of infection for people, but how the virus spreads from camels to people is unknown.

The infection is more common among men and is more severe in older people and in people with an underlying chronic disorder such as diabetes or a heart or kidney disorder. The infection has been fatal in about one third of infected people.

The MERS virus is spread through close contact with people who have MERS or through airborne droplets that were coughed or sneezed out by an infected person. People are not thought to be contagious until symptoms develop. Most cases of person-to-person spread have occurred in health care workers caring for infected people.

Symptoms usually appear about 5 days (but anywhere from 2 to 14 days) after people are infected. Most people have a fever, chills, muscle aches, and cough. About one third have diarrhea, vomiting, and abdominal pain.

Diagnosis of MERS

  • Testing of fluids from the respiratory tract

  • Blood tests

Doctors suspect MERS in people who have a lower respiratory tract infection and have traveled to or reside in an area where they could have been exposed to the virus or who have had recent close contact with someone who may have had MERS.

To diagnose MERS, doctors take a sample of fluids from several places in the respiratory tract at different times and test it for the virus. They also do blood tests to detect the virus or antibodies to it. Blood tests are done on all people who have had close contact with someone who may have MERS.

Treatment of MERS

  • Drugs to relieve fever and muscle aches

  • Isolation

There is no specific treatment for MERS. Acetaminophen or a nonsteroidal anti-inflammatory drug (NSAID) such as ibuprofen are given to relieve fever and muscle aches.

Precautions are taken to prevent the spread of the virus. For example, the person is isolated in a room with a ventilation system that limits the spread of microorganisms in the air. People who go into the room must wear a special mask, eye protection, and a gown, cap, and gloves. Doors to the room should be kept closed except when people enter or leave the room, and people should enter and leave as few times as possible.

Severe Acute Respiratory Syndrome (SARS)

Severe acute respiratory syndrome is a coronavirus infection that causes flu-like symptoms.

  • No cases had been reported worldwide since 2004.

  • Symptoms of SARS resemble those of other more common respiratory viral infections (such as fever, headache, chills, and muscle aches) but are more severe.

  • Doctors suspect SARS only if people may have been exposed to an infected person.

  • If doctors think a person may have SARS, the person is isolated in a room with a ventilation system that limits the spread of microorganisms in the air.

Severe acute respiratory syndrome (SARS) was first detected in China in late 2002. A worldwide outbreak occurred, resulting in more than 8,000 cases worldwide, including Canada and the United States, and about 800 deaths by mid 2003. No cases had been reported worldwide since 2004.

Although no new cases have been reported since 2004, SARS is not considered eliminated because the virus has an animal reservoir from which it conceivably could reemerge.

The immediate source was presumed to be civets, cat-like mammals, that were being sold in live animal markets as exotic food. How civets became infected is unclear, though bats are thought to be the reservoir host of the SARS virus in nature.

SARS is spread from person to person through close contact with an infected person or through airborne droplets that were coughed or sneezed out by an infected person.

Symptoms of SARS

Symptoms of SARS resemble those of other more common respiratory viral infections but are more severe. They include fever, headache, chills, and muscle aches, followed by a dry cough and sometimes difficulty breathing.

Most people recovered within 1 to 2 weeks. However, some developed severe difficulty breathing, and about 10% died.

Diagnosis of SARS

  • A doctor's evaluation

  • Tests to identify the virus

SARS is suspected only if people who may have been exposed to an infected person have a fever plus a cough or difficulty breathing.

Tests can be done to identify the virus.

Treatment of SARS

  • Isolation

  • If needed, oxygen

  • Sometimes a ventilator to help with breathing

If doctors think a person may have SARS, the person is isolated in a room with a ventilation system that limits the spread of microorganisms in the air. In the first and only outbreak of SARS, such isolation kept the virus from being transmitted and eventually eliminated it.

People with mild symptoms need no specific treatment. Those with moderate difficulty breathing may need to be given oxygen. Those with severe difficulty breathing may need mechanical ventilation to aid breathing.

NOTE: This is the Consumer Version. DOCTORS: CLICK HERE FOR THE PROFESSIONAL VERSION
CLICK HERE FOR THE PROFESSIONAL VERSION
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