Gaines County is a vast, flat expanse far in the west of Texas: more than 1,500 square miles of sparsely populated farmland. And right now, this is the epicenter of a measles outbreak the likes of which this state hasn’t seen in more than 30 years.

Measles is highly contagious and can spread from one person to nine out of 10 people close to them, according to the CDC, which notes a person infected with measles can spread it to others four days before through four days after the rash appears. Measles can spread through coughing, sneezing and infected surfaces.