FLORA LICHTMAN, HOST:
This is SCIENCE FRIDAY. I'm Flora Lichtman, filling in for Ira Flatow. Ten years ago, a virus called SARS starting spreading through Asia. Nearly 8,000 people got sick with flu-like symptoms, and almost 800 people died. Now a new virus similar to SARS, another coronavirus, is emerging. The virus is causing what's called Middle East Respiratory Syndrome, or MERS.
There have been about 90 documented cases so far, and about half of those who've been diagnosed with the disease have died. Where did this virus come from? How does it spread? What can we do about it? That's what we're talking about today. Let me introduce my guest. Martin Cetron is director of the Division of Global Migration and Quarantine at the Centers for Disease Control and Prevention in Atlanta. He's also on the World Health Organization's emergency committee concerning MERS, and he joins us by phone.
Welcome to the show.
MARTIN CRETON: Hi. Thank you for having me.
LICHTMAN: So your committee, this WHO committee this week, said that MERS is serious and of great concern, but it doesn't rise to the level of a global public health emergency. But at the same time, it does seem scary. Can you put it in context for us?
CRETON: Yes. I think that, you know, when we did a risk assessment and looked at all the data that were available, I think it's clear that this is something to pay very close attention to. It's not a time for complacency. It's a time for heightened vigilance. But at this point in time, it doesn't reach the threshold of being an international emergency.
And I think that the distinction may be subtle, but it's a time of preparedness, alertness, enhanced preparation, but not necessarily a time to be overly concerned in that regard.
LICHTMAN: The disease has about a 50 percent mortality rate. Is that right?
CRETON: Among those cases that have been reported, half of them have died. And that's quite concerning. And that's a reason, again, to be alarmed. High case fatality rates at the beginning or at the emergence of a new problem are often, you know, sort of a distorted picture, because we don't really know the true number of cases that are fully out there, or the number of people who could be infected with mild symptoms or asymptomatic.
So among those that are reported and where we're mostly looking now is those with serious respiratory conditions that are hospitalized in intensive care units. The case fatality rate has been very high.
LICHTMAN: And is there any trend emerging in the people who are being infected, who we know about?
CRETON: Yes. I think it's fair to say that among the cases that are reported so far, many of them are elderly and have underlying chronic health problems, whether that be heart disease, immune-compromising conditions, serious kidney disease or things like that. There have been clusters of this outbreak that are associated with hospitals and healthcare facilities.
And, again, so having an emerging infection and a serious virus affect those who are already sick or already in hospitals may also be contributing to why the high case fatality rate is reported in the onset of this emerging infection.
LICHTMAN: Hmm. How is it transmitted?
CRETON: You know, I wish we knew a lot more about it. We really have much, much to learn. It's not actually clear how it's transmitted or exactly what the original source of the virus is. We presume that it might have its origins in an animal reservoir, because it's related genetically to a bat coronavirus. But much remains unknown, including where it's coming from and how it's transmitted.
LICHTMAN: What about how long people are contagious? Any idea of that?
CRETON: Yeah. We're still trying to learn those kinds of questions, too, as well as, you know, what's the actual incubation period. There are several studies that are providing an insight into that. It looks like the mean period of time between exposure and onset of symptoms, or the incubation period, is somewhere around five or six days.
But it can range anywhere from just a few, all the way up to two weeks. And if it's like other coronaviruses, people tend to be more contagious when they're quite sick, as opposed to being contagious maybe before they get sick. But we really don't know the degree or the length of time that somebody would be contagious with this virus. So there's much that remains to be learned.
LICHTMAN: Can we learn the answers to those questions before the horse is out of the barn, so to speak?
CRETON: I think we can. And this is why, for over a year now, CDC, together with many of its international partners in other countries where the virus has been appearing, have been actively involved in investigations to look at these cases, the clusters around those cases, the outbreak situation, and try to learn as much as we can about the virus, both the virus characteristics, its genetics, where it's coming from, how it's evolving, as well as the type of people who are at risk of getting infected, and how much spread there is to secondary cases, either household contacts or inside health care facilities to both other patients and healthcare workers. These are the basis of what is an intense global effort right now in the public health community.
LICHTMAN: Saudi Arabia, where the virus was first spotted last year, is expecting an influx of people for the pilgrimage to Mecca. And you actually studied a paper looking at how flight and travel patterns and trying to predict how MERS could spread during this time. What did you find?
CRETON: Well, we're trying to do a risk assessment to appreciate how connected the world is globally by international air travel and one of the world's largest mass gathering events, which includes these pilgrimages. As you know, right now we're in Ramadan, and it's a particularly auspicious to have the Umrah pilgrimage to the holy sites. And then in the fall, in October, is the hajj pilgrimage that goes over a period of five days.
And during that time, millions of people will congregate in the kingdom for pilgrimage. And so what we wanted to do is analyze: Where are pilgrims coming from? Where is the international travel coming in and out of the kingdom of Saudi Arabia? And how can we anticipate in advance the potential pathways of the virus, if it were to begin to accelerate in its transmissibility or communicability? Where might it move next?
And so what we've found that is concerning, in addition to the very large volume of people that gather for these mass gatherings, is that the countries that have the greatest connectivity - both in number of pilgrims, as well as in commercial air travel in and out of Saudi Arabia - are some countries which may not have as sophisticated a public health infrastructure for early detection or for containment.
And so it's really important as we prepare and increase our vigilance to make sure that these countries are well aware, understand what the symptoms are like, how to make the diagnosis, have the laboratory capacity to find cases, and also have the infection control capability in the hospital facilities in order to contain outbreaks and keep them small and keep them from spreading.
LICHTMAN: And who helps with that educational effort? Does that fall to the WHO?
CRETON: That's a global responsibility. You know, we live in a global village, and a pathogen in one place in the globe can be anyplace in just a matter of hours. And I think we have a collective - and have appreciated that we have a collective responsibility. So that work is going on as part of a global community under umbrella efforts at WHO, but also through bilateral efforts between countries.
The CDC has been heavily engaged in this type of in distributing test kits and having training sessions to enhance surveillance, in putting out guidance documents. WHO is a world leader in taking this responsibility, as well, and both on the part of countries that have a lot of connectivity, as well as countries that have more capacity.
I think the international health regulations from 2005 really clearly identify our collective global responsibilities for disease control and containment.
LICHTMAN: And in the 30 seconds I have left, is there anything that individuals should be thinking about or doing to keep them...
LICHTMAN: ...keep this virus from spreading?
CRETON: I think that that's really important. And we have on our website - which I encourage people to visit, as does WHO - things for people to do before they travel, during their travel and after they get back. And this includes, you know, commonsense infection controls things like washing your hands, coughing or sneezing into a Kleenex, staying home when you're sick, not traveling or engaging in international travel when you're feeling ill.
And if you do get symptoms, being able to report those quickly to a healthcare provider and alert the healthcare provider that you may have been in an area where MERS is spreading, so that people can take the appropriate steps to contain that, and that you don't spread that to friends, family or other folks in a healthcare facility.
LICHTMAN: Thank you, Martin Cetron, for joining us today.
CRETON: Thanks for having me.
LICHTMAN: Martin Cetron is director of the Division of Global Migration and Quarantine at the Centers for Disease Control and Prevention and a member of the WHO's emergency committee concerning MERS. Transcript provided by NPR, Copyright NPR.