The department said the first Michigan measles case was tied to travel to Florida, and the additional linked cases show how quickly the virus can spread among people who are not immune.
Michigan health department declared a measles outbreak in Washtenaw County on Thursday after three linked cases were reported since March 12.
The department said the first Michigan measles case was tied to travel to Florida, and the additional linked cases show how quickly the virus can spread among people who are not immune.
"Measles cases are spreading like wildfire this year, and with families traveling over spring break the risk of exposure increases," said Dr. Natasha Bagdasarian, Michigan's chief medical executive.
Officials urged families to check that they are up to date on the MMR vaccine, especially as many prepare to travel during spring break.
Vaccination rates falling sharply in Michigan
Vaccination rates in the state have fallen over the past year, the state department said, leaving children and young adults at risk.
Earlier this week, Reuters analysis also showed that vaccination rates among young children in Michigan dropped sharply during the first year of the Trump administration, providing an early indication of how vaccine-skeptic Health Secretary Robert F. Kennedy Jr. is influencing immunization practices in the United States.
As of March 12, 1,362 measles cases were reported in the United States in 2026, CDC's latest data showed.