Experts are tracking a viral outbreak in the Middle East that seemed to worsen over the past weekend, and are watching for signs that it could become a global epidemic.
The World Health Organization
reports 261 cases
of Middle East Respiratory Syndrome
, including 93 deaths, since the disease was first reported in 2012.
The Saudi Arabian Health Ministry
announced over the weekend that they had more than 300 known cases of MERS and put the death toll at more than 100.
The increase in cases in Saudi Arabia that began last week has raised worries among health experts that the virus has mutated into a more spreadable form, which would be a danger sign.
Epidemiologist David Swerdlow (SWERD-low), who heads the U.S. Centers for Disease Control and Prevention
's response to MERS, said German researchers have examined DNA from some of the new Saudi cases.
"The information they have … suggests that there has not been any significant change in the virus,” he said.
"Thirty to 40 percent of people who get [MERS] have died. It's caused illness in multiple countries. The virus clearly spreads from person to person and it's severe and there's no treatment or vaccine. So, we are concerned," Swerdlow said.
The MERS virus first appeared in September of 2012. Saudi Arabia has seen the most cases.
MERS is a member of the coronavirus family, which includes germs that cause the common cold, as well as severe acute respiratory syndrome, or SARS.
That disease popped up in southern China in 2003, infected about 8,000 people in 29 countries and killed about 800 before it was contained.
Amesh Adalja, with the Infectious Diseases Society of America
, said one good thing about MERS is that it does not spread as easily as SARS did.
"With SARS, we saw much more human transmissibility. And we also saw individuals who we called 'super-spreaders,' people who disproportionately spread the virus more than anybody else and were really responsible for how the virus made its way all around the world," Adalja said.
There are no MERS super-spreaders, Adalja said, at least not yet.
That's good news, but Swerdlow said researchers need more data to be sure.
And, he added, they still do not know why the case count spiked in Saudi Arabia.
"Some of this could be seasonality. Some of it could be better surveillance. Some of it could be that there's a large outbreak ongoing in some health care facilities, perhaps," Swerdlow said.
Many of the MERS victims have been health care workers who come in close contact with sick patients. And many of the sickest patients have had other health problems, such as kidney disease, cancer or diabetes.
It is not yet clear where MERS came from originally, but camels are the lead suspect.
NBC News reported that a countrywide survey of camels shows many, if not most, are infected with a strain genetically almost identical to the strain that’s infecting people, a team at Columbia University
, King Saud University
and the EcoHealth Alliance
Unfortunately, there is a lot about MERS that scientists do not know.
What they do know, Adalja said, are lessons that SARS drove home.
"The world is a small place, that borders don't mean anything. And that the total health security of the globe is really tied up in identifying these threats as quickly as possible and then trying to stop them in their tracks," he said.