MERS-CoV: What you need to know
All known cases so far have been linked to travel or residence in and around the Arabian Peninsula.
Where the Middle East respiratory syndrome coronavirus (MERS-CoV, or MERS) comes from remains a mystery, but it probably started in an animal. It has been found in camels and a bat.
There is currently no vaccine or cure for MERS-CoV, and so far it has been fatal in around 36 percent of cases. As coronaviruses tend to mutate, there are concerns that MERS could become a pandemic.
MERS was previously known as the novel coronavirus (nCoV).
What is MERS?
The MERS coronavirus is related to the common cold.
MERS-CoV belongs to the coronavirus family, the same family of viruses that cause the common cold.
Human coronaviruses were first classified in the mid-1960s, and six of them are known to affect humans, including severe acute respiratory syndrome (SARS) and MERS.
Coronaviruses typically infect a single species or species that are closely related, but SARS-CoV infects both humans and animals. Monkeys, Himalayan palm civets, raccoon dogs, cats, dogs, and rodents are all susceptible.
MERS-CoV has so far been shown to infect humans, camels, and bats. It is believed to have started in bats and then transmitted to camels. From camels, it can pass to humans, but how this happens is also unclear.
MERS-CoV is different from the coronavirus that caused the 2003 outbreak of SARS, but both viruses are similar to the types of coronavirus found in bats.
Two cases of MERS-CoV have so far been confirmed in the United States. One was in Indiana and the other in Florida. Both patients were diagnosed in 2014, both had traveled to Saudi Arabia, and both recovered fully within 3 weeks.
All the cases outside Saudi Arabia were travel-related and originated in in the Middle East.
The most common symptoms of MERS are:
- shortness of breath
Associated symptoms may include:
- chest pain
- body aches
- sore throat
- malaise, a general feeling of being unwell
- nausea and vomiting
Serious complications include:
- organ failure, particularly kidney failure
MERS is a flu-like illness with signs and symptoms of pneumonia. Early reports described symptoms as similar to those of SARS.
Many individuals with MERS may have a mild respiratory illness or no symptoms.
Others will have severe respiratory distress, and they need to spend a long time in the hospital. They may need mechanical ventilation.
MERS-CoV is thought to be a zoonotic virus, which means it can pass from animals to humans.
Camels can carry the virus.
Exposure to camels or camel products appears to be the main source of human infection.
Antibodies to the virus have been identified in camels in Qatar, Egypt, and Saudi Arabia, and in a bat in Saudi. The presence of antibodies indicates that they have been exposed to the virus.
Human-to-human transmission has also been observed, primarily in health care settings rather than in the community.
Goats, cows, sheep, water buffalo, swine, and wild birds have been tested for antibodies to MERS-CoV, but none have yet been detected.
The findings suggest that bats may transfer the virus to camels, and camels transmit it to humans.
Close contact between a person and an infected camel appears to be necessary for the transmission of MERS-CoV. It has been suggested that the virus could infect humans through the air, and through consumption of raw camel milk or uncooked camel meat.
It seems most likely that the virus transmits through the respiratory route, by air, but research suggests that it can survive in raw camel milk marginally longer than in milk of other species.
This has prompted calls for further research into the possibility of it being transmitted through food.
In the case of South Korean, five "super spreaders," who all had pneumonia, transmitted the disease to 153 others. Those with severe coughs spread the disease to more people than those who did not.
Forty four percent of those who contracted the disease were exposed in the hospital, 33 percent were professional caregivers, and 13 percent were healthcare workers.
The following groups of people are more susceptible to MERS-CoV infection and complications:
- people with chronic diseases, such as diabetes, chronic lung disease, and heart conditions
- older people and the very young
- organ transplant recipients who are using immunosuppressive medications to stop their body from rejecting the organ
- those who are taking immunosuppressants, for example, to treat an autoimmune disease
- people whose immune system is weak, such as cancer patients undergoing treatment
Most of those who have died from the virus had other chronic medical conditions.
A doctor will examine the patient and ask about symptoms and about recent activities, including travel.
Samples will be taken from a patient's respiratory tract (RT) for assessment. Polymerase chain reaction testing (RT-PCR testing) can confirm the presence of MERS-Cov.
Tests can detect the relevant antibodies 10 days after the illness starts. If the test is negative 28 days after the onset of symptoms, the person is considered not to have MERS.
Blood tests can determine if an individual has previously been infected, by testing for antibodies to MERS-CoV.
There is no specific treatment or vaccine for the infection, and there is no cure, but supportive medical care can relieve symptoms and reduce the risk of complications.
To reduce the risk of MERS-CoV infection amongst travelers, health authorities have offered the following advice.
They urge travelers to:
Handwashing is an important way to prevent the spread of infectious diseases like MERS-CoV.
- Wash their hands frequently with soap and water, for at least 20 seconds
- Avoid undercooked meat or food prepared under unhygienic conditions
- Ensure fruit and vegetables are properly washed before consumption
- Report any suspected case to the local health authorities to help with worldwide disease monitoring
- Minimize close contact with others if they develop an acute respiratory illness with fever, including wearing a medical mask, sneezing into a tissue and disposing of it properly after use, or sneezing into a sleeve or flexed elbow
- Seek immediate medical attention if an acute respiratory illness with fever appears within 14 days of returning from travel
Travelers with pre-existing chronic conditions, such as diabetes, renal failure, chronic lung disease are at higher risk.
MERS-CoV is contagious, but the virus does not appear to pass between humans without close contact, for example, while caring for a patient without protection.
There are currently no trade or travel restrictions related to MERS.
Saudi Arabia continues to see sporadic cases of the virus. From 16 to 31 December 2016, Saudi Arabia reported 15 new cases, including two fatalities. Another five deaths resulted from previously reported MERS cases.
While the death rate is relatively high for a person who develops symptoms, the chance of contracting the disease remains relatively small.
However, with so little still known about the virus, the situation is open to change.