Twenty-three measles cases have been reported in Kansas, and the state health department said they could be linked to an ongoing outbreak that has infected at least 379 people across Texas, New Mexico and Oklahoma.

State health officials worry that declining vaccination rates have left many communities vulnerable nationwide.

A measles outbreak in Kansas doubled in less than a week to 23 cases and has “a possible link” to outbreaks in Texas and New Mexico that have sickened more than 370, the state health department said Wednesday.

A person with highly-contagious measles took an Amtrak train to Washington, DC, last week, health officials said Tuesday, warning others may have been exposed on the train, at Union Station, or at an urgent care center.

A measles patient traveled from New York to Washington, DC, on an Amtrak train on the evening of March 19, exposing people along the heavily traveled route to the highly infectious disease.