Another outbreak of a virus with no treatment or cure is making headlines.
At least nine people have died and more than 3,000 are quarantined as an outbreak of Middle East respiratory syndrome (MERS) surfaces in South Korea.
As the virus slowly spreads, inevitable comparisons arise to the Ebola crisis that struck Africa earlier this year.
But how do Ebola and MERS really compare? And should you be concerned about the current MERS outbreak?
How Similar Are MERS and Ebola?
“MERS and Ebola are both emerging infectious diseases,” said Dr. Amesh Adalja, an infectious disease physician and a member of the public health committee of the Infectious Diseases Society of America. “However, they are from two different viral families and are very different in the way that they spread between people.”
MERS is a respiratory virus that is spread through sneezes, coughs, and droplets of saliva and mucus. It first appeared in 2012.
Ebola spreads through blood and body fluids. It’s been around for almost four decades.
As a respiratory virus, MERS causes mainly respiratory symptoms — fever, cough, and shortness of breath.
MERS also belongs to the coronavirus family, along with severe acute respiratory syndrome (SARS), which caused an outbreak in 2003. The common cold is also included in this family of viruses.
“MERS is a very severe form of coronavirus that’s new,” said Adalja, “and hasn’t really had the time to adapt to humans in the way that the other common cold-causing coronaviruses have.”
Ebola can be caused by five separate species of viruses, leading to a general infection in the body, along with vomiting and diarrhea. Some people also develop internal or external bleeding.
In spite of their differences, MERS and Ebola may have a similar origin.
“Interestingly, both of these viruses are spillovers from animals,” said Adalja. “We believe both of them actually have their origin in bats.”
Other animals, though, play a role in transmitting these viruses to people. In Ebola, this includes monkeys, chimpanzees, and gorillas. With MERS, the intermediate animal species is camels, which remain a source of the virus for future outbreaks.
How Serious Are These Illnesses?
With more than 27,000 cases of Ebola reported to the World Health Organization (WHO) in the current outbreak and more than 11,000 related deaths, the severity of Ebola far outnumbers MERS.
The MERS outbreak in South Korea is not the first. The disease was identified in 2012 in Saudi Arabia. Since then more than 1,200 cases have been confirmed by the WHO globally, with at least 448 related deaths. This puts the death rate from MERS around 37 percent.
“We’re finding more and more evidence that mild infections occur with MERS,” said Adalja.
Ebola has been around for much longer — first identified in 1976. But it has a higher death rate, with around 50 percent of people infected with Ebola dying.
Will MERS Spread Like Ebola Did?
Because these infections cause different symptoms, “they’re spread by two different mechanisms,” said Adalja. “Where Ebola is blood and body fluids, in MERS it’s respiratory secretions.”
Although it takes a very small amount of Ebola virus to infect someone, the virus is limited in how it moves between people — only through blood and body fluids.
As a respiratory illness, though, MERS may be more of a risk for spreading between people.
“The fact that it’s spread through respiratory secretions — coughs, sneezes — makes it much more of a contagion threat than Ebola ever could be,” said Adalja, “because Ebola is blood and body fluids.”
A MERS infection also starts out similar to a common cold, so people who are sick may interact with more people before they’re diagnosed properly.
In spite of that, new MERS infections are restricted to certain settings.
“MERS spreads very well in hospitals and healthcare systems,” said Adalja, “but what we’ve seen so far with MERS is that it is really unable to sustain community-wide transmission.”
That means the people at greatest risk of MERS are healthcare workers and people caring for sick family members.
“So the panic that you’re seeing in South Korea in the general public really isn’t warranted,” said Adalja, “because this is something restricted to the hospitals.”
MERS Is Already Outside South Korea
Although much media attention has focused on whether the MERS outbreak in South Korea will spread to other countries, this disease is already global.
“The epicenter of the MERS outbreak is the Middle East, where cases have been occurring since 2012,” said Adalja. “But we’ve had importations to several different countries outside of the Middle East, including the United States.”
Since 2012 most cases of MERS have occurred in the Middle East. Travelers to that area can easily bring MERS back to their country, especially given that the early symptoms resemble a cold.
The first case in South Korea was a 68-year-old man who had traveled to Saudi Arabia, Qatar, the United Arab Emirates, and Bahrain.
And in 2014 two cases of MERS were confirmed in people who had traveled from Saudi Arabia to the U.S. Both people were treated and released, without spreading the infection to others.
What Steps Are Countries Taking to Contain MERS?
One similarity between Ebola and MERS is that there is no vaccine or specific treatment for either disease. Infected patients are provided supportive care to manage their symptoms. They are also isolated to prevent the infection from spreading to others.
Although some countries have already issued advisories against nonessential travel to South Korea, the WHO is advising against travel restrictions.
Because of the ease with which people infected with MERS can travel, it may be impossible to prevent cases from popping up in new countries. But previous small outbreaks in France and England were still not able to sustain themselves in the community.
“That shows that when hospitals are doing the appropriate infection control,” said Adalja, “these outbreaks can easily be controlled.”
This includes quickly identifying people with MERS and isolating them, making sure that healthcare workers are properly trained in preventing infections, and ensuring that proper protective gear is used.
The bottom line is that the world is a much smaller place, with people traveling frequently.
Without a vaccine available for MERS — and other infectious diseases — the best protection is for countries and healthcare facilities to stay alert for new cases.
“We have to be prepared,” said Adalja, “that as the MERS outbreak continues in the Middle East — which is where the real focus should be — that we will start to see some cases in travelers.”