A measles outbreak in the southwestern United States has infected nearly 100 people in recent weeks. The deadly illness has sickened dozens of people in west Texas and New Mexico since late January. The Texas Department of State Health Services confirmed 90 cases of measles,

Texas' measles outbreak is now at 90 cases, the highest yearly case count since 1992. Experts say the number is likely to grow more. Here's why.

Over the past month, the virus has spread in areas with low vaccination rates, and most of those affected are minors.