A measles outbreak that affected 79 individuals (the majority of which (73) were under the age of 10) in the state of Minnesota this spring and summer 2017 was recently declared “over” by the Minnesota Department of Health (MDH). Seventy of these cases occurred in Hennepin County, 3 occurred in Ramsey County, 4 in Crow Wing County, and 2 in Le Sueur. Most of the cases (64) occurred in Minneapolis’ Somali community.
The first case in the outbreak was identified on April 11, 2017, according to a press release
from the MDH. Two incubation periods with no new cases are required to pass before an outbreak can be declared over. Because the incubation period for measles is 21 days, officials waited 42 days after the last case was identified—July 13, 2017—to declare.
A lack measles, mumps, rubella (MMR) vaccinations contributed to the spread of the outbreak
, particularly in the Somali community where, according to the press release, vaccination rates for the MMR in Somali Minnesotan 2-year-olds was about 42% before the outbreak began.
Measles is highly contagious and those communities with low vaccination rates lack the herd immunity that helps prevent major outbreaks. Since the introduction of the MMR in 1963, the United States has seen an almost 100% reduction in annual cases of the infection. Before the vaccine was introduced, up to 4 million cases of measles were reported each year.
According to the MDH, this recent measles outbreak in Minnesota was the largest the state has seen since an outbreak in 1990 that claimed the lives of 3 individuals and sickened 460.
Statistics on this recent outbreak reveal that:
- > 8000 individuals were exposed to the virus
- > 500 individuals were asked to stay home from school, child care, or work because either they were unvaccinated or exposed to an individual who was sick
- A total of 22 individuals were hospitalized
- A total of 71 individuals were unvaccinated for measles
The estimated cost for the multidisciplinary response to the outbreak is about $900,000 for the MDH, and $400,000 for Hennepin County. (Cost estimates for the other counties were not included in the press release.)