Thoughts on the recent mumps epidemic

November 2006

As many readers are aware, Iowa was at the center of a mumps epidemic in the spring of 2006. Though we were never able to determine definitively how it started, we believe that it was probably brought in from England (which was experiencing its own outbreak of mumps at the time, with more than 50,000 cases with the same G strain), and probably via a college student or students sometime during the fall of 2005.

The earliest cases probably went unrecognized as mumps. It was not until January that we were able to get laboratory confirmation that mumps was in Iowa and spreading. By the end of February, the number of cases was increasing quickly, and we knew something quite unusual was occurring. Most of Iowa’s cases occurred in March and April, and in young adults (25% of cases occurred in college students). By the fall of 2006, Iowa had almost 2,000 cases of confirmed mumps, and mumps had spread to all of Iowa’s border states and several other states. Although the number of cases declined significantly over the summer, mumps has re-emerged in other states this fall.

Lessons learned

Large outbreaks of mumps had not occurred in the United States since the late 1980s, when school entry requirements meant that most children received two doses of measles, mumps and rubella – not one – before entering kindergarten. This change was due mainly to the measles outbreaks that were occurring. When the Iowa mumps outbreak started, we did not anticipate that an epidemic of this magnitude was possible. This was the first lesson we learned: large outbreaks of mumps can occur, even in highly vaccinated populations. In Iowa, the two-dose school entry requirement began in 1991, and in the 2004-2005 school year, 97% of K-12 students entering school in Iowa had received two doses of MMR vaccine.

The second lesson was that rapid detection and implementation of mass vaccination is needed to control an epidemic of this kind. The third was that the biologic emergency planning at the Iowa Department of Public Health over the past several years was very useful. The incident management system was essential, though to be honest, I wished that we had implemented it about a week sooner in this situation.

Fourth, it is very difficult to motivate college students to take public health actions such as staying isolated in their dorm room for five days if they had mumps, or be vaccinated. It also didn’t help that we were trying to do the vaccine campaigns around final exams week.

Fifth, it was critical to use one proficient lab to do all the testing, which in Iowa was the University Hygienic Laboratory, our public health laboratory. It allowed us to provide free testing to all potential cases, to understand the usefulness of the various tests, as well as to coordinate the case information between the epidemiologists and the laboratorians.

Last, but not by any means least, communication continues to be the biggest challenge. Daily “situation room” briefings, weekly conference calls with local health departments and regular conference calls with all involved states (coordinated by CDC) helped considerably in this regard but there were still communication issues that could have been better.

The vaccination campaign

The mass vaccination program began in early April and reached all 99 counties in Iowa, with almost 10,000 people vaccinated thus far. However, it took more time than we wished to get the finances arranged, to have MMR vaccine ordered and shipped to Iowa, to get appropriate amounts shipped to each county (part of which was determined by location of affected colleges) and for local immunization clinics to be held. The number of cases did begin to drop off after mass vaccinations and colleges began to dismiss students for the summer, which potentially decreased the transmission of mumps virus. Since then, Iowa has only had a few cases of mumps reported each week.

Historically, mumps has shown a pattern of returning in the winter and spring, so we may not be out of the woods yet. An education campaign, using media, letters and e-mails, was conducted in August to remind colleges and their students to ensure that each student has been vaccinated with two doses of MMR before returning for the fall semester. Iowa continues to provide vaccines to anyone between 18 and 46 years of age at no cost or very low cost.

One of the things I found difficult during this situation was dealing with the media. Reporters would call wanting the most up-to-date number of cases, which obviously was changing by the minute. Finally, we put together a schedule for releasing this information, distributed this schedule to the media, and only provided information per the schedule.

Overcoming challenges

One of the most interesting challenges I experienced was being asked by reporters what the most common complication of mumps was. The answer is testicular inflammation. One of the things that we are taught as public health communicators, however, is never to use highly technical medical language. I could never figure out how to say “testicular inflammation” at a sixth-grade level, which could actually be uttered on the news. In this case, I chose to be accurate and let the news outlets worry about the wording.

Some very good things have come out of this experience. Iowa is more confident in its ability to respond to future biologic emergencies, and has been able to address the weaknesses identified during its mumps response. This has made our system stronger. Also, new vaccine recommendations for health care workers have been developed by the ACIP. Lastly, we now know much more about this disease, including how it’s transmitted, the efficacy of the vaccine and what public health actions to take if mumps re-emerges.

Iowa will continue its surveillance efforts to watch for any evidence that the outbreak is starting again; meanwhile we will persist in trying to increase the vaccination rate in our young adults.

For more information:

• Visit Iowa’s Web site for more about this epidemic at www.idph.state.ia.us.
• www.cdc.gov/mmwr/preview/mmwrhtml/mm55d330a1.htm
• www.cdc.gov/mmwr/preview/mmwrhtml/mm55d518a1.htm