Cynthia S. Goldsmith; William Bellini/CDC
A look inside a single measles virus particle, or virion, made with an electron microscope.
A look inside a single measles virus particle, or virion, made with an electron microscope. Cynthia S. Goldsmith; William Bellini/CDC
So far this year there have been 118 cases of measles reported in the United States.
Now that may not sound like a whole lot, but that makes this the busiest period for measles since 1996, the Centers for Disease Control and Prevention says. In fact, in the last decade, the median number of cases each year has been only 56.
What's going on?
Well, measles in this country is, thank goodness, no longer an established disease that spreads in a sustained way from person to person. Vaccination in the U.S. was the key to eliminating measles as an everyday infection.
Now, the vast majority of U.S. cases are imported: 105, or 89 percent, of the cases covered in the latest report.
That "unusually large number of importations," as the CDC put it, is tied to an increase in measles cases in countries frequented by U.S. travelers. And the problem in those countries boils down to inadequate vaccination.
The biggest sources of cases cited by the CDC were India (14) and France (11). France, if you didn't know it, has had a large measles outbreak this year, with nearly 5,000 cases reported through the end of March and about 10,000 by then end of April.
So if you're traveling abroad, make sure you've been vaccinated. Same goes, actually, if you're a homebody. "Maintaining high immunization rates with MMR vaccine is the cornerstone of outbreak prevention," the CDC says.
And when there have been outbreaks, the CDC says, "rapid control efforts by state and local public health agencies, which are both time intensive and costly, have been a key factor in limiting" the effects.
How intensive? Check out the story of Matt Kohlstedt, a grad student who ended up sitting near someone infected with measles on flight from Frankfurt to Chicago. The health department in Madison, Wisconsin, tracked him down and threatened to put him in quarantine if he didn't provide proof of immunization.