ARI SHAPIRO, HOST:
There's been an increase in the number of cases of the mumps this year in the United States. The disease is not as dangerous as it was decades ago. Still, health officials are reacting strongly to several big outbreaks of the mumps. NPR's Richard Harris reports.
RICHARD HARRIS, BYLINE: Most years, health officials report a few hundred cases of mumps. But this year, the total has topped 4,000. Most are in large outbreaks in Iowa, Illinois and, worst of all, Arkansas, which has more than 2,000 cases.
DIRK HASELOW: Our outbreak started back in August, and it's been going strong for five months.
HARRIS: Dr. Dirk Haselow is the Arkansas state epidemiologist.
HASELOW: Mumps is a highly infectious disease. People who cough or sneeze can spread it to people in their general area. But what really caused it to take hold in our outbreak was sort of population density and poverty.
HARRIS: The disease spreads easily through schools and colleges. In northwestern Arkansas, those kids often live in close quarters with their families, so the disease keeps on spreading. And it spreads more when residents go to churches and community centers. Its classic symptom is swollen glands under the ears. Fortunately, it's a much milder form of the disease than what caused so much concern decades ago. Mumps can lower sperm count and affect fertility.
HASELOW: We have seen markedly lower levels of the complications that you might see with mumps in the absence of vaccination.
HARRIS: Haselow said just eight men out of more than a thousand had the most common serious complication, swollen testicles. And he's seen no cases of potentially serious brain inflammation.
HASELOW: So it's very, very clear that the vaccine is actually helping to make the mumps disease that we see milder than expected.
HARRIS: About 90 percent of young people in Arkansas have had the MMR vaccine which protects against mumps as well as measles and rubella. But Dr. Manisha Patel at the federal Centers for Disease Control and Prevention says the mumps vaccine isn't quite as potent as those for measles and rubella. It's about 88 percent effective.
MANISHA PATEL: So what that means is if you have a hundred people in a room and all of them have been vaccinated and then they all get exposed to mumps, you'll still get 12 people that come down with mumps.
HARRIS: Not perfect but good enough to put an end to mumps epidemics which swept the United States until the 1960s.
PATEL: There were millions of cases of mumps that were ongoing at that time, and now we're reaching anywhere from a couple hundred depending on the year to a couple of thousand. But CDC is concerned why we're having a large number this year, and we're working very closely with states to better understand why that's happening.
HARRIS: In the worst-hit state, Arkansas, Dr. Haselow says the outbreak seems to be easing.
HASELOW: We're very hopeful that the holidays will help this slow down.
HARRIS: Kids will not only get a break from class. They'll be less likely to pick up each other's germs. Richard Harris, NPR News.
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