I attended a lecture yesterday given by Patty Quinlisk, Iowa’s state epidemiologist. The bad news: there have been over 500 reported cases of mumps as of Monday, April 10, with more cases in neighboring states (30-50 in Nebraska, for example). She did, however, give a bit more history on the epidemic, described below.
The outbreak can be traced back to last December, when 2 cases were found to be IgM-positive for mumps. (IgM is the first type of antibody produced to a new infection; therefore, this is diagnostic of a current infection, whereas looking at a different type of antibody–IgG–shows a prior exposure). In January 2006, an unrelated case of mumps was cultured at the state hygienic laboratory. These weren’t exactly surprising; Iowa generally has around 5 cases of mumps every year, and most occur in winter, so 3 in 2 months’ time was about normal. However, cases continued to roll in, and in mid-February active surveillance was begun in 7 Iowa counties. So far, there’s no signs yet of the epidemic slowing.
Again, mumps is often thought of just as a mild childhood disease, but as with any pathogen, the larger the number of infections, the greater the potential for a serious manifestation of disease to occur. In the case of the current epidemic, there is at least one potential case of encephalitis, a swelling of the brain that can lead to permanent impairment. Mumps is also notorious for causing testicular swelling (“orchitis”) in pre-pubescent males. This can manifest in up to 30-40% of male cases, and has the potential for permanent consequences (luckily, rare). Women aren’t off the hook, either: infection with mumps during the first trimester of pregnancy results in spontaneous abortion in 20-25% of such pregnancies. Indeed, the virus can be totally asymptomatic in a similar number of patients–but as I mentioned with chicken pox, it’s a mistake to dismiss it as “just a mild childhood infection.”
Currently, officials are recommending that patients with the mumps isolate themselves for at least 5 days following the onset of symptoms in an effort to stem the epidemic. No other measures (such as quarantine of exposed individuals) have been put in place yet, and it’s hoped they won’t be necessary.