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This award-winning blog supplements the articles in Hospital Infection Control & Prevention.

CDC takes MERS fight to Saudi epicenter

The Centers for Disease Control and Prevention is bolstering its presence in Saudi Arabia, sending additional scientists and epidemiologists to try to determine more about MERS and stop it before it spreads beyond the Middle East.

"We have sent additional staff to Saudi Arabia in conjunction with the World Health Organization to learn more about the virus to try to understand where it comes from and what the risk factors for acquiring it are,” Tom Frieden, MD, MPH, CDC director, said at a May 12 press conference. “This work is really vital because there's no way we can effectively protect Americans only by working within the U.S. borders. That's one of the reasons we focus on helping other countries find and stop emerging infections such as MERS promptly and preventing them wherever that's possible."

Genetic sequencing of the MERS coronavirus that infected the first U.S. case in Indiana shows no indication of a mutation that would make it more transmissible, he noted.

“That's important to us in public health because with the increase in reported cases from the Arabian Peninsula over the past weeks and months, one of the essential questions to ask is did the virus change?” Frieden said. “And the answer to that seems to be probably not. It doesn't appear that it has --that's reassuring.”

SARS – a similar novel coronavirus that emerged rapidly in 2003 – mutated and became more transmissible before the epidemic ended and the virus disappeared. If MERS has not accomplished a similar feat, the increase in cases is likely due to improved surveillance and case identification, particularly in patients with milder symptoms.

“That is consistent with what we're seeing from the Arabian Peninsula, Saudi Arabia and elsewhere which is an increased proportion of asymptomatic or more mildly symptomatic patients,” Frieden says. “We think that at least some of the increase in cases that we're hearing about from the Middle East [has] to do with better monitoring and tracking. And that's a good thing. That means that we're able to find patients earlier, protect them and others from spread and get a better handle on how to stop the disease transmission”

Like SARS, MERS has been found in bats. There is growing evidence that the MERS coronavirus has moved from bats to camels, following the classic pattern of an emerging zoological infection jumping from a rarely encountered animal to establish a reservoir in a domesticated beast that has contact with the human population.