The outbreak has sickened nearly 200 people in Gaines County, Texas. A neighboring county in New Mexico has seen 21 new cases since Tuesday.

Nearly 230 measles cases have been identified in outbreaks in West Texas and a nearby New Mexico county. One hundred ninety-eight measles cases have been reported in the West Texas outbreak, the Texas Department of State Health Services said in an update Friday — 39 more confirmed cases since an update on Tuesday.

A historic measles outbreak in West Texas is just short of 200 cases, Texas state health officials said Friday, while the number of cases in neighboring New Mexico tripled to 30. Most of the cases across both states are in people younger than 18 and people who are unvaccinated or have an unknown vaccination status.