Mississippi officials say they’re investigating whether a traveler passing through Mississippi may have infected people with measles.

State Health Officer Dr. Thomas Dobbs said Friday that the traveler was contagious and visited a Subway restaurant in Hattiesburg on April 9 and a Raising Cane’s Chicken Fingers in Hattiesburg on April 10.

Mississippi hasn’t reported any cases of measles despite a nationwide outbreak.

Health officials on Monday said 555 measles cases have been confirmed in the U.S. so far this year, on pace for the most in 25 years.

Dobbs warns unvaccinated people have a 90 percent chance of infection. He says anyone exposed should take immediate precautions.

Anyone who may have been exposed should contact a physician or emergency room before going there to ensure precautions to prevent further infections.