Flu and the mumps that flew

When I was a lad there was no TV. But there was a lot of mumps. Now there's a lot of TV. Mumps -- not so much. But it's still around and it still has something to teach us.

For those who don't know (because the mumps vaccine almost eliminated a reason to know), mumps is caused by a virus. It usually struck in childhood, causing a painful swelling of the salivary glands. If you got it later, as an adult, there was risk it could affect other glands, especially testicles (where it caused a painful inflammation and sometimes sterility), mastitis, oophoritis (inflammation of the ovaries) and occasionally spontaneous abortion. It could also just be a non-specific illness or even asymptomatic. It is spread via the respiratory route or by saliva but has an unusually long incubation period, a couple of weeks. A person is infective up to three days before onset and 9 days after onset. And it is quite contagious. Estimates of the average number of new cases produced by each infective case is ten or more, high compared to influenza (less than four, probably around two), although the shorter serial interval (the time between cases) of influenza also makes flu an efficiently transmissible disease.

Vaccination against mumps started in 1967. It is usually given in childhood in the MMR (Mumps, Measles, Rubella) vaccination. This has had a dramatic effect on its incidence, almost relegating mumps to a rarely seen disease. Almost. Mumps still smolders in our community. In 1968 there were over 150,000 cases per year. Thirty years later there were under 700, and now it is usually around 200 to 300 per year. But now Iowa alone has just had over 600 cases when it usually only sees 5, and neighboring states (Nebraska, Kansas, Minnesota, Wisconsin, Indiana, Michigan, Missouri and Illinois) have more than another 100 between them. New cases in Iowa are still appearing at the rate of about 50 a day.

About a quarter of the cases had been vaccinated, which both raises questions about true vaccination coverage (immunization has been mandatory in school age children since the seventies) and the efficacy of the vaccine. Authorities have understood quarantine is fruitless for this disease (as it would be for influenza), but voluntary isolation of cases will not stop it either, although it may be slowing the spread.

CDC isn't sure what's happening but they are looking at air travel as one possible factor:

To try to keep the outbreak from widening further, the CDC announced yesterday that officials are working to track down 222 airline passengers who sat near two people from Iowa who developed the mumps after traveling on nine flights from March 26 to April 2. One flew from Tucson to Cedar Rapids, Iowa, stopping in Arkansas and St. Louis. The second, a 51-year-old woman on a trip to lobby the Iowa congressional delegation, flew from Waterloo, Iowa, to Washington and back, stopping in Detroit and Minneapolis.

About 17 people who came in contact with her on Capitol Hill have been given vaccine shots as a precaution, health officials said.

"The states where these passengers traveled and landed we'll be watching closely and putting prevention and control activities in place if they start to see some cases," said Jane Seward of the CDC. (WaPo)

This is a dramatic example of how modern means of transportation can also transport diseasel, and an object lesson in what could happen if some other disease -- say avian influenza -- took hold somewhere, even in a distant location. No place is more than 24 hours distant from anywhere else on this planet, and people can be infectious but asymptomatic with influenza for this entire period. It's also a dramatic example of why quarantine is not likely to delay an outbreak for more than a day or two, if that. Conceivably it could hasten spread as people flee to avoid being quarantined.

Maybe now that some CongressThings have been exposed we'll get some action on disease surveillance and immunization programs? I guess some questions answer themselves.