Pima County health officials are urging parents to stay current on their children’s vaccinations after confirming two measles cases in recent weeks.
In a letter to parents dated Jan. 26, the county health department said two cases had been identified since last month and emphasized that immunization remains the best protection against the virus. Schools and childcare facilities are being asked to review the immunization status of all staff, students and children, the letter said.
“The most effective way to prevent measles is vaccination,” the letter said.
Measles is a highly contagious infection that can cause brain damage, vision and hearing loss, lifelong complications — and, in some cases, death.
Arizona law requires children to have proof of immunization or a completed exemption form on file with their school.
The warning comes as Arizona faces its largest measles outbreak in more than 30 years.
The state first reported four measles cases in June in Navajo County. By the end of 2025, the outbreak grew to 220 cases statewide. The vast majority — 214 cases — occurred in Mohave County, largely within the geographically isolated community of Colorado City.
Earlier this month, the Pima County Health Department reported that an individual who traveled across the southern border into Arizona was hospitalized for measles in Tucson. County officials said they worked with the Arizona Department of Health Services to investigate the case and that the patient was quickly isolated.
Health officials later confirmed a second measles case weeks later involving a Tucson resident who developed symptoms after returning from international travel.
Symptoms typically begin seven to 14 days after exposure but may take up to 21 days to appear. The illness often starts with a high fever, red watery eyes, cough and runny nose. A rash that is red, raised and blotchy usually follows several days later, beginning on the face before spreading to the body and arms.
People with measles are considered contagious from four days before the rash appears until four days afterward.
Health officials say two doses of the measles, mumps and rubella (MMR) vaccine are about 97% effective at preventing infection.
