WEDNESDAY, April 19 (HealthDay News) -- The outbreak of mumps striking the Midwest -- the largest number of cases to hit the United States in two decades -- continues to spread, according to federal officials.
There have been more than 1,000 cases reported so far; the bulk of them, 815, have been in Iowa. The remaining cases have been reported in seven other states -- Illinois, Kansas, Minnesota, Missouri, Nebraska, Oklahoma and Wisconsin, according to latest information from the U.S. Centers for Disease Control and Prevention.
The disease has been seen largely among people in their late teens and early 20s, officials said at a news conference Wednesday.
"This is the largest outbreak of mumps that we have seen in this country in more than 20 years," said CDC Director Dr. Julie Gerberding. "There have been more than 1,000 cases reported from more than eight states. There are ongoing investigations in seven more states," she added.
So far, 20 people have been hospitalized with mumps, Gerberding said.
A major outbreak of more than 100,000 cases of mumps in England has led to speculation that the U.S. outbreak had its origins abroad. "It is possible," Gerberding said, "but we don't have any proof of that at this time."
Gerberding noted that, given the nature of mumps and the continued progression of the outbreak, officials expect more cases in more states. There has been a vaccine for mumps since 1967 that has largely eliminated frequent outbreaks of the disease, she said.
"Fortunately, mumps is not usually a serious disease," Gerberding said. "But in some people it can have serious complications." Up to 10 percent of people with mumps develop encephalitis (inflammation of the brain) and others can develop an inflammation of the testes, which can lead to infertility. Mumps has also been associated with spontaneous abortion and deafness, Gerberding said.
An acute viral illness caused by the mumps virus, the disease typically causes fever, headache, muscle aches, tiredness, and loss of appetite, followed by swelling of the salivary glands, according to the CDC.
"The best protection against mumps is the vaccine," Gerberding said. "There is confusion right now if whether or not this outbreak is related to some problem with the vaccine," she said. "I want to emphasize that we have absolutely no information that there is any problem with the vaccine."
Gerberding said that, despite the availability of the vaccine, people in the age group who are getting sick may not have had the recommended two doses of inoculation and are not completely vaccinated, leaving them susceptible to the disease.
"This is a good vaccine, but it's not perfect," Gerberding said. "About 10 percent of people who get both doses of the vaccine still remain susceptible to mumps."
She said the CDC will send another 25,000 doses of measles-mumps-rubella (MMR) vaccine from the the agency's stockpile to Iowa, the state hit hardest by the outbreak. Merck & Co., which markets the vaccine, is providing another 25,000 doses to the CDC for distribution to other states, Gerberding said, according to the Associated Press.
She recommended getting vaccinated if you haven't had the two doses. "For individuals who are in the school-aged population or individuals who are post-high school in college, and especially for health-care workers, it is very important that you get your second dose," she said.
One vaccine critic said there may be a problem with the longevity of immunity offered by the current vaccine.
"This isn't the first time there has been a problem with a vaccine not being effective," said Barbara Loe Fisher, co-founder and president of the National Vaccine Information Center. "There was a problem with the mumps, measles, rubella vaccine in the late '80s and early '90s that caused the CDC to say that kids had to have a second dose of it."
"We are now finding that the mumps part of it, even in two doses, is not holding in some children," Fisher said. Old vaccines only provide a temporary immunity, which is inferior to the immunity you get after having had the disease, she said.
The CDC can tell you more about mumps.