RAY SUAREZ: It's the largest mumps epidemic in this country in more than two decades, with confirmed cases in at least eight states, most in the Midwest. The bulk of cases are in Iowa, where up to 975 people have been affected, and the virus is spreading.
Some 350 additional cases have been reported in seven nearby states: Illinois, Kansas, Minnesota, Wisconsin, Missouri, Nebraska and Oklahoma. Seven more unidentified states are investigating possible outbreaks.
For more on the mysterious reappearance of the virus and the public health response, I'm joined by Dr. Julie Gerberding.
What is mumps?
JULIE GERBERDING, Director, Centers for Disease Control and Prevention: Well, mumps is a disease caused by a virus, and it presents initially with the same symptoms that you see with any viral affection, but it uniquely can infect the salivary glands. So the characteristic is tenderness near the angle of the jaw, a lot of fatigue, and a lot of muscle aches go along with that.
RAY SUAREZ: And how long does it take to run its course?
JULIE GERBERDING: Usually, people are sick for about a week; sometimes there are serious complications, though. A few people develop meningitis. Among kids who are older than adolescents, up to about 10 percent of people will develop that complication, and that's the most serious thing.
Many young men after adolescence will also develop inflammation of the testicles, a condition we call orchitis. Rarely, that can lead to sterility.
And there are a few other serious complications, as well. So while it's generally annoyance, it can have serious outcomes.
RAY SUAREZ: People of my generation remember it as a childhood disease. It sounds like it's more dangerous when an adult gets it.
JULIE GERBERDING: Well, I'm not sure that it's always more dangerous, but some of these complications don't occur in children. And so it's something that we want to be sure people are vaccinated effectively for, if we can avoid it at all costs.
RAY SUAREZ: Now, in recent years, mumps has been referred to as a disease that's been effectively suppressed in the United States. How does it get started again?
JULIE GERBERDING: You know, suppression is a good word, but it's never been completely eliminated, unlike some other vaccine-preventable diseases.
What happens is, really, an interplay of three things: We've got people who haven't received both doses of the vaccine, so they're uniquely susceptible.
Then, we have people who have had two doses, which is what it takes to get the best possible immunity. But even with two doses, about 10 percent of people are still susceptible, because their immune system just doesn't respond.
And then the third factor is somebody arrives who's bringing the virus in from somewhere else, and they can set off this cascade. That is especially likely to occur in conditions of crowding, like college dormitories or when people are co-housed together.
RAY SUAREZ: Well, you mentioned college dormitories. The Iowa cases, the most heavy clustering is between 18 and 22. So is that a marker for what's going on here?
JULIE GERBERDING: Well, right now the available evidence is still being discovered by the people in Iowa, who are responsible for the health investigation. But our best bet is that it probably did start on a couple of college campuses, lots of transmission among students, and then spilling over from those students into their families and communities, as they went home for holidays, or spring breaks, and so forth.
Now that network seems to be cascading outward, sometimes directly linked to students and, in other cases, the linkage as it moves forward in the community hasn't been discovered yet.
RAY SUAREZ: So the path to those other states now you're piecing together?
JULIE GERBERDING: That's exactly what's undergoing investigation in all of these states. They're not only looking for cases, which by the way is a bit of a trick here, because a lot of clinicians haven't seen mumps in a long time and they're not making the diagnosis. So that's one of the major efforts we're making, is to be everyone can understand the disease and look for it.
But we're also tracing back to try to see who got it from whom, and can we link cases together, and make sure that we're not overlooking another hot spot where we need to specifically target the vaccine effort.
RAY SUAREZ: So with so many cases clustered in one state, what's the best response to sort of shut off the spread?
JULIE GERBERDING: Well, the most important thing is to get everybody adequately vaccinated, to get up to the two doses, although that alone is not going to be effective, because, as I said, there are still some people with vaccine who remain vulnerable.
So the other thing that has to be done is to isolate the people while their infectious. That, too, is a bit tricky, because they can be infectious a few days before they actually develop the mumps symptoms.
So shutting this down is going to take some time. We've had this experience before, and other countries have seen it even on a bigger scale. It's a bit unstable as we start off with these immunization programs, but over time, I'm fairly optimistic we'll be able to contain it.
RAY SUAREZ: Would you want people, especially in those high-contact ages, to check their own records and see if they had the second shot of the two in the course?
JULIE GERBERDING: That's a great idea. Anybody who's not sure about their mumps vaccine status should check. If you've had mumps when you were a child, you don't have to worry about this, because you are highly likely to be completely protected.
But often people don't know the details of their vaccine history, and that's useful information to have anyway. Right now, you know, most states are going to be targeting their efforts on the people who are in the groups where the transmission is the most aggressive, but anyone who hasn't had both mumps shots really should get their second shot.
RAY SUAREZ: And if you don't know and you're in one of these states that has an outbreak, is there any harm to being multiply vaccinated?
JULIE GERBERDING: We don't know of any harm associated with it, but we'd like to concentrate our vaccine efforts on the people that we know are the most vulnerable.
And the state and local officials are posting independent guidelines about who should be vaccinated, because these situations aren't the same in every community, and they're really in the best position to know who should go first in a particular outbreak situation.
RAY SUAREZ: Now, does this have any seasonal response? Will this sort of burn itself out, or do you have to worry about something that will continue to reoccur throughout the year now?
JULIE GERBERDING: Usually in the past, mumps has died off during the summer. And so, if Mother Nature is on our side, we may see some curtailment of this by natural reasons. The seasonality of it would be on our side, but we're not sure about that.
And until we know, we need to be aggressive about getting people vaccinated, and, again, recognizing cases, and getting them isolated so that we can help contain this through those means.
RAY SUAREZ: Dr. Julie Gerberding, thanks for being with us.
JULIE GERBERDING: You're welcome. Glad to be here. Thank you.