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 in a day 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.

Texas and New Mexico on Friday reported an additional 59 cases of measles for a total of 228 known infections in those states, where an outbreak that began in West Texas in late January has spread, causing the first U.

Nearly 230 measles cases have been identified in outbreaks in West Texas and a nearby county in New Mexico. Experts say the rising totals – and two recent deaths – suggest that cases are vastly undercounted.