CDC update on Midwest mumps outbreak

Yesterday, the MMWR website posted a dispatch with an update on the mumps outbreak in the Midwest followed by a discussion of possible causes.

Through 2 May, 2,597 cases have been reported, 57% of which coming from Iowa. Fortunately, no more than 25 hospitalizations can be attributed to mumps among these cases, with no deaths.

Among the possible causes for the outbreak discussed in an accompanying editorial note are: 1) the close quarters of college dormitories, 2) the absence of 2-dose MMR vaccination requirements for college attendance in 8 of the 11 states affected, 3) delayed recognition of mumps by younger physicians with limited exposure (so to speak) to it or physicians not initially suspecting mumps among vaccinated patients, both leading to more time for transmission to occur, and 4) the long-known fact that the vaccine is less than 100% effective at preventing disease.

Editorial pages weigh in on mumps epidemic

The New York Times offers its take on the mumps epidemic in the Midwest, stressing the continued importance of vaccination efforts and suggesting a closer look should be taken as to whether the vaccine's effectiveness may wane over time. As to the latter, there's no evidence at this point to suggest a booster dose might be necessary, but there is presumably little harm in exploring that possibility. From the editorial...

"Even so, federal and state health officials will need to look hard for any signs that the mumps vaccine is less effective than we previously thought or that its effectiveness diminishes over time. Health officials are wisely urging students and others who are at high risk of exposure and are not fully immunized to get their shots. The current outbreaks would no doubt be much larger — hitting thousands or tens of thousands of people — without the high levels of vaccination already prevalent."

Meanwhile, The Courier News (a suburban Chicago newspaper), published this editorial credited to the St. Louis Post Dispatch (though it appears nowhere on their site). Titled "Halt diseases before they reach the U.S.," the piece relies on a tenuous connection between mumps, avian flu, and 9/11, yet still makes interesting observations about the design of public health efforts and the potential adverse effects of vaccination exemption laws. They write,

"Doctors at the U.S. Centers for Disease Control and Prevention believe the first mumps case was carried to this country by someone traveling from overseas late last year. Two infected airline travelers are believed to have spread it through the Midwest on a total of nine flights.

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It's likely that at least some of the 75 people who have contracted mumps in Missouri and Illinois this year would not be infected if they had received the so-called MMR (measles, mumps and rubella) vaccine. But in recent years, lawmakers in Missouri and several other Midwestern states have expanded options for parents who object to vaccination on religious or philosophical grounds. That policy carries significant public health risks. Many parents probably don't understand the great stakes.

Since the 9/11 attacks, national spending on public health has soared. But much of that has been for work aimed at combating bioterrorism. The greater threat, unfortunately, seems to be from diseases that are far more mundane and easily overlooked."

Latest on Midwest mumps epidemic

We haven't written here yet about the mumps outbreak affecting Iowa and neighboring states in the Midwest, but stories in today's Washington Post and New York Times address the role of the mumps vaccine in the epidemic and also provide good overviews for those who haven't been following the story over the past several weeks. On the vaccine, from the Times...

"(CDC Director Dr. Julie) Gerberding said the disease had spread quickly because of the dense concentration of students in affected cities and because the vaccine is not perfect. It has about an 80 percent efficacy rate for people who have been inoculated with one dose, and a rate of about 90 percent for people who have received the recommended two doses.

'We have absolutely no information to suggest that there's a problem with the vaccine,' Dr. Gerberding said. 'What's going on here is basically a number of people who haven't received both doses, coupled together with people who have received the vaccine but are susceptible anyway, living in crowded conditions like college dormitories or mixing up with other students at spring break or during holidays, and setting up a cascade of transmission that's going to take a while to curtail.'"

The vaccine in question is Merck's M-M-R II, the only licensed mumps vaccine available in the United States. The stories report that CDC will be shipping 25,000 doses of the vaccine from its stockpile to affected areas and Merck will donate another 25,000.

For mumps, there are no specific risk behaviors that increase the likelihood of contracting it (other than not following standard hygiene recommendations -- although people should wash their hands, etc., for many more health reasons than the very slim chance of coming down with mumps). However, the quotes from the general public in both stories reflect near-amazement that it's even possible to get mumps in 2006. While a testament to the effectiveness of decades of vaccination, these views underscore the challenge of stressing the continued necessity of high vaccination rates and the importance of reminding the public that no vaccine guarantees 100% protection against an infection. This second point becomes particularly important when vaccines provide partial protection, as is the case with HPV (which targets viral strains accounting for only 70% of cervical cancers).