Five new measles cases confirmed in Lewis and Clark County; patients seen at St. Peter's

Five new cases of measles were confirmed in Lewis and Clark County this week following reported exposures at the St. Peter’s Emergency Department late Sunday and early Monday morning, Lewis and Clark Public Health officials announced Tuesday.

“Our message remains the same as it was last time – there is no reason to panic. Most of our population is fully immunized against measles. Though it’s always important for residents to stay informed and prepared,” Shelly Maag, LCPH Public Health Nurse Supervisor, said in a statement.

The five cases involved people who were at St. Peter’s ER between 11:20 p.m. March 29 and 3 a.m. March 30, according to a news release from the county health department. According to the Montana Department of Public Health and Human Services' measles tracker, three of the cases involved people aged 20 or older, and two involved people between the ages of 5 and 19.

The cases were not connected to any day cares or schools in or near Lewis and Clark County, health officials reported.

Contact tracing has begun for patients who may have been exposed, Maag said, and those who can be identified will receive a text message or call with further instructions.

Those who were exposed and not immunized against measles are strongly urged to receive the MMR (measles, mumps, rubella) vaccine as soon as possible, the health department said.

Measles confirmed in Lewis and Clark County, no public exposure reported

Measles is a highly contagious viral disease characterized by fever, dry cough and rash that can occur 7-14 days after exposure, the Centers for Disease Control and Prevention (CDC) states. While once extremely common, it was declared eradicated from the United States in 2000 after widespread use of the MMR vaccine.

Lewis and Clark County’s first confirmed measles case in decades was confirmed in August 2025, public health officials previously reported. According to the county tracker at evalue.shinyapps.io/LCPH_Data_Portal/, there were two measles cases reported in the county in 2025.

As of Tuesday morning, Montana has seen 41 measles cases since spring 2025, including three hospitalizations. The new cases in Lewis and Clark County mark the first five in the state since the beginning of the new year.

The Montana Department of Public Health and Human Services recommends anyone eligible to vaccinate in order to protect those who are too young or unable to receive the vaccine.

For those unsure of their vaccination status, the DPHHS offered the following ideas:

• Call the high school, college or university you attended and ask if it has your vaccination records.
• Reach out to your doctor’s office, urgent care, pediatrician or the health department where you grew up. Records can be kept on file years after your last visit.
• Review your home state’s immunization registries.

LCPH considers the following people immune to measles:

• Those with written documentation of MMR vaccination,
• Those who have lab evidence of immunity or prior infection, and
• Those born before 1957.

Because the vaccine is safe, there is no danger for revaccinating already vaccinated people, the CDC said.

If you suspect you have been exposed to measles, LCPS recommends filling the Measles Exposure Self-Referral Form on the LCPH website at lccountymt.gov/Government/Public-Health/Communicable-Disease-Control/2026-Measles-Outbreak-Information.

Lewis and Clark Public Health launches Montana measles outbreak tracker

People who suspect they are exposed or begin to show symptoms should stay at home except for testing or emergency treatment, the public health department said. Common symptoms include fever, white spots in the mouth and a flat, red rash that begins near the hairline and spreads downward around 3-5 days after initial symptoms.

“It is extremely important that you do not enter a clinic building without calling ahead so that precautions can be taken to avoid exposing others," Maag said. "If you are experiencing a medical emergency, please alert staff upon arrival."