MERS Transmission, Diagnosis, Incubation Period & Symptoms

Middle East respiratory syndrome coronavirus (MERS-CoV) facts

MERS-CoV is a type of coronavirus that spreads through respiratory secretions.

MERS-CoV is a new novel coronavirus that caused severe acute respiratory infection (SARI) first identified in Saudi Arabia in September 2012. The infection appears to be the result of spread of the virus from camels to humans, resulting in limited person-to-person spread but not sustained transmission in humans.
The largest outbreak outside of the Arabian Peninsula occurred in the Republic of Korea in 2015. It was linked to a traveler returning from the Arabian Peninsula.
MERS and Wuhan coronavirus are two other coronavirus types that are related to SARS. They can also cause severe infections in humans.
MERS-CoV is a type of coronavirus, similar to the one that caused SARS (severe acute respiratory syndrome) and the common cold. MERS-CoV has not been previously identified in humans. Like the SARS virus, MERS-CoV is most similar to coronaviruses found in bats. It has been detected in camels, and several cases of MERS-CoV in those who handle camels have been reported. Other livestock do not seem to be affected.
The infection can be spread from person to person through respiratory secretions. It may be transmitted from camels to humans. Those who handle camels are at higher risk of MERS-CoV infection than people who do not have regular close contacts with camels.
Infected people have symptoms of a flu-like illness followed by
- an atypical pneumonia,
- including fever,
- dry cough, and
- severe shortness of breath.
Gastrointestinal symptoms may also occur.
Severely affected people experience respiratory failure and may need mechanical ventilation. Older people and those with underlying illnesses are at higher risk for severe disease.
In 2014, MERS-CoV was diagnosed in the U.S. in two individuals who were not linked to each other. Both were travelers who lived and worked in Saudi Arabia, and both were health-care workers. Other countries, outside of the Arabian Peninsula and surrounding countries, have detected MERS-CoV only in travelers from these areas.
MERS-CoV infection should be suspected in travelers from the Arabian Peninsula or neighboring countries with symptoms compatible with MERS-CoV occurring within 10 days of traveling.
If there are grounds for suspicion, public-health authorities need to be alerted.
Similar to SARS, there is no medication that is known to treat MERS-CoV. Treatment is supportive.
During the 2003 SARS outbreak, approximately 25% of people had severe respiratory failure and 10% died. In contrast, mortality in MERS is higher at about 50%.

What is Middle East respiratory syndrome coronavirus (MERS-CoV)?

MERS-CoV is a coronavirus that can cause severe acute respiratory infection in humans. Confirmed cases of MERS-CoV have originated in the Arabian Peninsula and surrounding areas.

In December 2019, medical professionals noted yet another type of coronavirus outbreak. The new virus, Wuhan virus (also termed 2019-nCoV), is an RNA virus related to both MERS and SARS coronaviruses. It likely originated in infected animals marketed in an open-air food market in Wuhan, China. The virus, like MERS, may cause moderate to severe respiratory problems in individuals and appears to spread from person to person. The majority of patients infected with the Wuhan virus need hospitalization. In 1 month, the virus spread to at least 6 countries, including the U.S.

Symptoms of MERS Virus Infection

A new aggressive pathogen has recently been identified; it’s a coronavirus that causes symptoms of fever, cough, and shortness of breath that may become severe or deadly. The disease is termed MERS (Middle East Respiratory Syndrome or MERS-CoV). Researchers suggest the MERS virus originated in animals (camels) and, like other viruses, mutated to be able to infect humans.

Read more about symptoms and treatment of MERS-CoV »

What causes MERS? How is MERS transmitted?

MERS is caused by a virus referred to as "MERS-CoV" from the coronavirus genus; MERS-CoV means Middle East respiratory syndrome coronavirus. The genus coronavirus includes viruses that infect animals, cause the common cold in humans, and caused the 2003 SARS outbreak in China. However, the MERS-CoV virus is different than other coronaviruses, including SARS-CoV, and had never been identified before 2012. MERS-CoV has been detected in camels in several countries but not in other livestock. It has been detected in camel meat, organs, milk and urine; infected camels may not be observably ill.

MERS-CoV is spread from person to person through respiratory droplet secretions. MERS has also infected people caring for a sick (MERS-CoV-infected) individual. Contact with infected body fluids, respiratory secretions, raw or undercooked camel meat, and unpasteurized dairy products of camels may be other sources of transmission to humans.

MERS-CoV infection should be suspected in travelers who've recently come from the Arabian Peninsula or neighboring countries with a compatible illness occurring within 10 days of traveling.

Health-care workers or contacts of a MERS-infected individual are at risk, as are veterinary, farm, dairy, market, race track, and slaughterhouse workers who handle camels.

Is MERS-CoV contagious?

MERS is contagious (infectious) from person to person by respiratory droplets, either by breathing airborne droplets, or contact of respiratory secretions with moist membranes of the mouth, nose, and eyes. It is contagious from camel to human via respiratory droplets as well as meat, milk, and urine of an infected animal, even though the animal may not appear sick.

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What is the incubation period of a MERS-CoV infection?

The incubation period (the time between infection and start of symptoms) is about five days, but it can occasionally be up range from two to 14 days.

What is the contagious period for a MERS-CoV infection?

The contagious period (the time that a sick animal or human is infectious) for MERS-CoV is not known but may last as long as virus is being shed.

What are risk factors for MERS-CoV infection?

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MERS-CoV can infect a person regardless of his/her health status or age group. Recent travelers from the Arabian Peninsula and neighboring countries who develop severe acute respiratory infection should be tested for MERS-CoV. Elderly people and those with underlying medical conditions such as diabetes, heart disease, or liver disease are at risk of severe infection. Close association with any person infected with MERS-CoV, as in caregivers, health-care workers, or household contacts, is a major risk factor. Contact with camel body fluids, respiratory secretions, raw or undercooked meat, and unpasteurized dairy products likely also poses a major risk of transmission to humans in the Arabian Peninsula and surrounding countries. Thus, those who work in these areas and handle live camels, or camel's meat or milk are at risk, including veterinarians and those who work at markets or race tracks, and those who slaughter, butcher, milk, and cook raw camel products. Cooked meat and pasteurized milk is safe to handle and consume. Not all camels may transmit the disease; Bactrian (Mongolian) camel herds currently show no infections with MERS, but researchers are not sure these camels have ever been exposed to the virus.

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What are MERS symptoms and signs?

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Initially, the illness resembles influenza with fever and a mild cough. The breathing disorder often progresses to severe shortness of breath (dyspnea) and inability to maintain oxygenation (hypoxia). Progression may be rapid, or it may take several days. Severely affected people develop a potentially fatal form of respiratory failure, known as adult respiratory distress syndrome (ARD or ARDS). In addition to attacking the alveoli in the lungs, the virus also infects other organs in the body, causing kidney failure, inflammation of the heart sac (pericarditis), or severe systemic bleeding from disruption of the clotting system (disseminated intravascular coagulation). People with compromised immune systems such as severe rheumatoid arthritis or organ transplantation may not experience respiratory symptoms but can have fever or diarrhea.

What types of specialists treat MERS-CoV infection?

Most people with SARS would see a primary-care provider or an emergency-medicine doctor as illness rapidly progressed. Depending on the stage of illness, they would be admitted to a hospital as oxygen levels decreased. In the hospital, a person with SARS would likely be managed by a hospitalist or critical-care doctor, with consultations to an infectious-disease doctor and lung doctor (pulmonologist).

How do health-care professionals diagnose a MERS-CoV infection?

MERS-CoV is detected using a reverse transcriptase polymerase chain reaction (PCR) test. On June 5, 2013, the FDA issued an emergency-use authorization (EUA) for the CDC Novel Coronavirus 2012 Real-Time RT-PCR Assay. This test detects Middle East respiratory syndrome coronavirus (MERS-CoV), formerly known as novel coronavirus 2012 or NCV-2012, in patients with signs and symptoms of MERS and appropriate risk factors. This assay is distributed by the CDC to qualified laboratories. The PCR is performed on a sample of respiratory secretions or blood.

When the patient's history makes the MERS diagnosis likely, these tests are done with the help of state and local public-health authorities, the CDC, and infectious disease subspecialists. The CDC confirms all positive tests.

ELISA, or enzyme-linked immunosorbent assay, and IFA, or immunofluorescence assay, are tests for antibody to MERS-CoV; they are used for research purposes rather than patient care.

Other tests may be abnormal, but they are not specific for SARS or MERS. The chest X-ray shows pneumonia, which may look patchy at first. Typically, infiltrates may look like "ground glass" on CT scans but may progress to a "white out" appearance. Usually, lymphocyte and platelet counts are decreased while creatinine phosphokinase (CPK) and serum lactate dehydrogenase (LDH) levels may be increased.

MERS should be suspected in people with the appropriate symptoms who work with MERS-CoV in a laboratory, who are healthcare workers, or potential contacts of a MERS-infected person. It is extremely unlikely that a patient in the U.S. will have MERS without having traveled to the Middle East or caring for an infected returning traveler. In 2014, MERS-CoV infections were diagnosed in two people who had no ties to each other. Both individuals were traveling healthcare workers living and working in Saudi Arabia. None of the staff caring for these individuals nor household contacts became infected with MERS-CoV. In 2016, Saudi Arabia reported another outbreak of the disease.

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What is the treatment for MERS-CoV?

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Because MERS-CoV is caused by a similar virus as SARS, the management of MERS-CoV has been extrapolated from experience with the 2002 SARS outbreak and some limited experimental data. Like SARS, patients with MERS-CoV often require oxygen supplementation, and severe cases require mechanical ventilation and intensive-care-unit support. No medication has been proven to treat MERS-CoV, and treatment is based upon the patient's medical condition. Several medications have been tried in both SARS and MERS-CoV without conclusive benefits, and further research is to be done. Management of the individual with MERS is aided by infectious disease, pulmonary, and critical-care specialists.

What is the prognosis of MERS-CoV? What are complications of MERS-CoV?

MERS is associated with a rapidly progressive severe respiratory illness, and mortality compared to the SARS-CoV outbreak of 2003 is very high. Since 2012, the MERS outbreak in Saudi Arabia has slowly continued with a total of 933 individuals diagnosed with 401 deaths as of March 2015, for a mortality rate of about 50%. Pneumonia and kidney failure are complications of MERS-CoV.

Is it possible to prevent MERS?

Fortunately, MERS-CoV does not appear to spread as easily or rapidly from person to person as the SARS-CoV outbreak of 2003. Travelers to the Arabian Peninsula and surrounding countries, and their close contacts, may protect themselves by taking simple measures that help to prevent the spread of germs. Frequent hand hygiene using soap and water, or an alcohol-based hand sanitizer, avoidance of close contact with sick people, and avoidance of touching one's eyes, nose, and mouth can prevent the spread of viruses. Caregivers of patients who are not hospitalized should perform frequent hand hygiene as stated above and wear a face mask for direct care until the patient has recovered.

In the Arabian Peninsula and surrounding countries where MERS-CoV has been found, the World Health Organization (WHO) recommends precautions in handling live camels or their raw meat and dairy products. Anyone who does so, should frequently wash hands and consider using respiratory protection, as well as barriers to protect skin and clothing. Clothing worn during handling of camels or their products should be kept away from household contacts and washed daily. All products intended for human consumption should be cooked thoroughly or pasteurized.

In the health-care setting, a suspected case of SARS is placed in airborne infection isolation room (AIIR). This is a patient care room used to isolate people with suspected or confirmed airborne infectious diseases. The air is under negative pressure, meaning that contaminated air is continually sucked into the room instead of letting it leak out into the hospital environment. This air is exhausted outside, or it circulates back into the room after passing through a high-efficiency particulate air (HEPA) filter to decontaminate it. If an AIIR not available, the patient must wear a face mask and is isolated in a single-patient room with the door closed. The number of staff assigned and the patient's movements outside of the room must be minimized. Before entering the isolation room, health-care workers caring for the patient must wear a gown, gloves, eye shield, and mask or a portable air purifier that filters out small infectious particles (N95 mask). Before leaving the room, any disposable gear such as gowns, gloves, and mask must be discarded. Hands must be cleansed with soap and water or an alcohol-based hand sanitizer after leaving the room and before attending to another patient.

Local public-health authorities should be consulted promptly when a MERS-CoV diagnosis is considered. Preventing an outbreak requires identification of the first infected patients as soon as possible before the infection spreads further. Those who have been exposed to an infected person should be carefully monitored for fever or respiratory symptoms. Exposure is defined as living with or caring for an infected person, being within 3 feet of the infected person, and exposure to bodily fluids or direct physical contact with an infected person. The Centers for Disease Control and Prevention does not mandate quarantine measures for exposed individuals who are otherwise healthy.

Public-health authorities have taken steps to assure preparedness. In the U.S., the CDC continues to monitor the international situation and issues travel advisories for U.S. travelers to affected areas. The CDC may detain individuals arriving in the U.S. or traveling between states who are believed to be infected with a disease subject to quarantine, including MERS, as of July 31, 2014, per amended U.S. Executive Order 13295.

Is there a vaccine for MERS-CoV?

No vaccine is commercially available at the time of writing.

Where can people get more information about MERS-CoV?

Information on MERS-CoV may be obtained from the CDC at http://www.cdc.gov/
coronavirus/mers/faq.html or the World Health Organization at http://www.who.int/csr/disease/
coronavirus_infections/en/index.html.