We don’t know where the current Minnesota outbreak is going, but there was an outbreak of measles in 2008 that has been studied in a recent paper called “Health Care-Associated Measles Outbreak in the United States After an Importation: Challenges and Economic Impact” by Sanny Chen et. al.

From the abstract:

On 12 February 2008, an infected Swiss traveler visited hospital A in Tucson, Arizona, and initiated a predominantly health care-associated measles outbreak involving 14 cases. … Of 14 patients with confirmed cases, 7 (50%) were aged ?18 years, 4 (29%) were hospitalized, 7 (50%) acquired measles in health care settings, and all (100%) were unvaccinated or had unknown vaccination status. Of the 11 patients (79%) who had accessed health care services while infectious, 1 (9%) was masked and isolated promptly after rash onset. HCP (Health care personnel) measles immunity data from 2 hospitals confirmed that 1776 (25%) of 7195 HCP lacked evidence of measles immunity. Among these HCPs, 139 (9%) of 1583 tested seronegative for measles immunoglobulin G, including 1 person who acquired measles. The 2 hospitals spent $799,136 responding to and containing 7 cases in these facilities.

Suspecting measles as a diagnosis, instituting immediate airborne isolation, and ensuring rapidly retrievable measles immunity records for HCPs are paramount in preventing health care-associated spread and in minimizing hospital outbreak-response costs.

Measles infected between 3 and 4 million Americans a year before vaccines stemmed the disease in the early 1960s. Between 2000 and 2008, between 37 and 140 cases were reported annually in the US. The typical pattern is for an imported case of measles to cause a local outbreak among unvaccinated people. Those unvaccinated people are almost always of two kinds: Those who are not vaccinated because of the Anti-vax movement, or those who were too young to be vaccinated (or who are unvaccinated for some other equally valid reason) and are thus victims of the anti-vaxers.

The study points out that because measles is such a nasty disease, those infected often end up in a health care facility. For this reason, health care professionals have a higher risk of acquiring the disease. The other group at higher risk for getting measles is, of course, patients in the health care facility. Take Patient 4 from the Tucson outbreak:

Patient 4 was an unvaccinated 11-month-old boy who had spent 45 min in an ED room across the hall from patient 2 at hospital A on 24 February. Fever (temperature, 38.9°C) developed on 4 March, and a maculopapular rash developed on 10 March.

And some of those at risk are at risk because their parents chose to put their children at risk:

Patients 5 and 6 were siblings aged 3 and 5 years, respectively, who had not been vaccinated because of parental opposition to vaccination. Both children were exposed to patient 2 while visiting their mother at hospital A on 24 and 25 February. Their fever onsets occurred on 5 March (temperature, 39.5°C) and 6 March (38.9°C), respectively.

And, these accidental accomplices can then put others at risk in a kind of vicious cycle. Consider, for example, Patient 8:

Patient 8 was an unvaccinated 1-year-old girl who was exposed to patient 4 in the pediatrician’s office on 10 March while waiting to receive MMR vaccine. Fever (temperature, 38.5°C) developed on 19 March, a generalized maculopapular rash developed on 20 March, and earache developed on 20 March.

It turns out that in Minnesota, the current outbreak is facilitated in part by misinformation being spread among certain fairly recent immigrants. After arrival in the US, they were indoctrinated into the anti-vax ideology by someone. I’m not sure how this happened exactly, but apparently members of the Somali community are concerned that anti-vax misinformation has been circulated and is causing many individuals to avoid vaccinations. This is being addressed.

In the mean time, get your vaccination and get your children vaccinated.

Chen, S., Anderson, S., Kutty, P., Lugo, F., McDonald, M., Rota, P., Ortega-Sanchez, I., Komatsu, K., Armstrong, G., Sunenshine, R., & Seward, J. (2011). Health Care-Associated Measles Outbreak in the United States After an Importation: Challenges and Economic Impact Journal of Infectious Diseases DOI: 10.1093/infdis/jir115