Using these little bumps, called fusion proteins, measles enters white blood cells and makes copies of itself. As the white blood cells travel throughout the body, they inadvertently spread the viral particles to organs such as the lungs, liver and, in rare cases, the brain.

DALLAS — More than 140 cases of measles have been reported in Texas, including one here in North Texas, and a child in Lubbock has died from the virus, health officials said. The number of cases in the West Texas outbreak increased by 22 when officials released new data Friday, bringing the total to 146.