MEXICO CITY (AP) — Mexico’s most populous state said Monday it was stepping up health screening at schools and recommended the use of face masks for students and staff as the country confronts a growing measles outbreak.

The decision by Mexico state followed similar measures announced last week in the western state of Jalisco, site of the country’s largest outbreak, where masks are now required in the schools of its capital Guadalajara, Mexico’s second-largest city.

Through Feb. 6, there were 2,143 confirmed measles cases nationwide and nearly 6,000 suspected cases. Jalisco was home to more than half of Mexico’s confirmed cases, but there are confirmed cases from Mexico’s northern border to its southern border.

The health department of Mexico state, which hugs Mexico City on three sides, said students’ temperatures will be taken at school entrances and the state will push a vaccination campaign.

Measles cases began surging last year in the northern border state of Chihuahua. Officials traced that outbreak that began in March 2025 to an 8-year-old unvaccinated Mennonite boy who visited relatives in Seminole, Texas — at the center of the U.S. outbreak.

The Chihuahua outbreak has since been controlled, but there are confirmed measles cases now in all of Mexico’s 32 states.

Mexico state Health Secretary Macarena Montoya Olvera said Monday that the outbreak in the state is under control and that the cases have so far been light. The federal government has confirmed 40 cases there.

Neighboring Mexico City has launched an aggressive vaccination campaign. As of last Friday, there were 166 confirmed cases.

The Pan American Health Organization issued an epidemiological alert last week following a surge of measles cases across the Americas.

Canada lost its measles-free status in November and the same could happen to the United States and Mexico.