The Minnesota Department of Health has confirmed a 15th case of measles.
Public health officials are contacting people who shared flights with a Minnesota woman in her 20s who developed measles after returning from a trip to India.
Measles is extremely contagious, but State epidemiologist Ruth Lynfield says exposure to an infected person on an airplane doesn't usually lead to a widespread outbreak.
"Typically, it leads to very few additional cases because in the general population immunity is quite high," Lynfield said.
Most of the previous cases were linked to a Somali child who got infected in Kenya. One other case was traced to Florida.
The Health Department says cases have ranged in age from 4 months to 51 years old. At least eleven of the individuals were not vaccinated; some were too young to receive the vaccine. The vaccine status of three others is unknown and one person had been vaccinated.
There have been eight hospitalizations so far and no deaths.