For the fourth time this year (that would be one per month, if anyone is counting), there is news of a measles outbreak in the US. This one bears particular significance to me, and has the potential to repeat history from the Disneyland outbreak a few months back. The patient, an unvaccinated student, lives in Massachusetts but visited Kittery, Maine and Portsmouth, New Hampshire last week in the prodromal (or pre-symptomatic) phase of her disease. This is notable and concerning for three reasons:
1.) Measles can be transmitted from an infected person up to four days before the characteristic rash appears. Patients can mistake their symptoms for a case of the sniffles, or worse, not show any symptoms at all. In other words, an infected person may not know to avoid public places or those with compromised immune systems (you know, such as babies or grandmas). This is a problem.
2.) Portsmouth and Kittery are highly popular shopping and dining destinations for locals and vacationers alike, and last week was vacation week here in the Northeast. In other words, the patient potentially exposed not only many people local to the area, but potentially exposed many people from other regions. Should anyone have become infected, it is predictable that "satellite" (non-localized) cases will occur. The patient visited some of the more popular spots in Kittery. As measured by base reproductive value (R0), a measure of how "transmissible" and able to sustain an epidemic a pathogen is, measles is the most contagious infectious disease known to humanity.
3.) I wrote about this a few months back during the Disneyland outbreak, and it bears repeating now: many parts of Maine (notably the Southeastern coastal region) have immunization rates below herd immunity level. In other words, there are enough unvaccinated or partially vaccinated individuals for an outbreak to become an epidemic because there are enough people lacking sterilizing immunity to allow efficient person-to-person transmission to occur.
So...should we all start panicking? Or should we all roll our eyes because measles is no big deal? As always, the reality is somewhere in the middle. First and foremost, measles is not trivial. Though most infected children do recover, some don't. Some develop encephalitis (an inflammation of the brain) or pneumonia, both of which can be fatal. Others recover, but are left with life-long consequences such as hearing loss, vision loss, or cognitive impairment. So no, measles is not necessarily "no big deal".
So we should all panic?? No, not really. If yours and your children's MMR immunizations are up to date, there is nothing to worry about. The MMR vaccine has an excellent safety and efficacy profile, and a person who has received the recommended doses can be expected to be protected from infection. If you or your children are only partially immunized or unimmunized and are fully eligible to receive the MMR, now would be the moment to get on that. If your child is not old enough to receive the MMR, which is the situation I found myself in last fall during the Boston outbreak, take particular care to clean public surfaces that your baby may touch. Try as best you can to avoid anyone with respiratory symptoms until this whole thing blows over.
Remain calm, and take advantage of the opportunity modern medicine has afforded you and your children.
Quarantine sign on a front door following a measles case (Image: National Library of Medicine)