There are now more than 120 confirmed measles cases linked to an outbreak in western Texas, the largest such outbreak the state has seen in over 30 years. It's raising questions about vaccine hesitancy in some communities and the growing challenge of these periodic outbreaks.

State medical experts have confirmed 124 cases of measles in Texas. This is the largest measles outbreak in Texas in 30 years. Here is how it started and an overview of the situation, as of Feb. 25.