A resurgence of infectious diseases including measles and pertussis has been reported in parts of Mexico and Guatemala amid concerns over health care budget cuts. In Mexico City, measles cases first appeared in mid-August, with infections confirmed in the boroughs of Coyoacán, Gustavo A. Madero, and Tlalpan. In response, the city has launched a vaccination campaign and the federal health authority is providing telephone guidance to help residents locate vaccination sites. Meanwhile, in Quetzaltenango, Guatemala, 12 cases of pertussis have been identified, primarily affecting children under one year and school-aged populations. A medical student at Hospital Roosevelt who was treating patients tested positive for pertussis and has been isolated, with preventive testing conducted on 13 contacts. These outbreaks occur alongside warnings that U.S. funding cuts may threaten progress in combating globally burdensome diseases.