Mumps Outbreak in Midwest Could Have Been Worse

By Steven Reinberg
HealthDay Reporter
Thursday, April 10, 2008; 4:00 AM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

WEDNESDAY, April 9 (HealthDay News) -- In 2006, the largest U.S. outbreak of mumps in 20 years swept across eight Midwestern states, but a new study claims things could have been much worse.

The scope of outbreak was limited, because the number of people in the United States who have been vaccinated against mumps is very high, explained study co-author Amy A. Parker, from the U.S. Centers for Disease Control and Prevention.

There were total of 6,584 cases scattered across Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, South Dakota and Wisconsin. Eighty-five people were hospitalized, but fortunately there were no deaths. However, 11 people lost their hearing and 22 developed meningitis, according to the report in the April 10 issue of the New England Journal of Medicine.

"The outbreak affected mostly college-age students who had two doses of the mumps vaccine," Parker said. "If that vaccination coverage drops, and a case of mumps is imported, then the spread can occur like wildfire."

Currently, mumps is not well-controlled around the world, Parker noted. "At the time of this outbreak, the United Kingdom was having an outbreak, and they saw over 70,000 cases of mumps," she said. "Most of these cases were among people who were not vaccinated."

In the United States, the mumps vaccine is part of the combination vaccine that includes mumps, measles and rubella (MMR). The vaccination rate against mumps in this country is robust: About 87 percent of adolescents have had two doses of the mumps vaccine, and more than 90 percent of 1-year-olds have had one dose.

"So, even though our outbreak was large, it wasn't of the same proportion as the one in the U.K.," Parker said.

She noted that the strain of mumps in the United Kingdom was identical to the one that spread across the United States. "It's likely this was the source, because the strains matched," she said.

Since the 2006 outbreak, there hasn't been another of the same proportion in the United States, Parker added.

However, the CDC has set a goal of eliminating mumps in the United States by 2010. Although the current vaccine was able to limit the scope of the outbreak, it is only 90 percent effective after two doses, Parker said. "So, even if you had a 100 percent vaccination rate, you would still have 10 out of every 100 people susceptible to mumps," she explained.