'Localized Measles Outbreak' Underway In Western Riverside County: Health Department

RIVERSIDE COUNTY, CA — Two more measles cases have been reported in western Riverside County, prompting officials to warn of a "localized measles outbreak."

On Friday, the Riverside University Health System — Public Health system announced that a western Riverside County adult and child tested positive for measles, bringing the total known infections to three people countywide.

The latest infections may be linked to the county's first measles case of 2026, which was also reported in western Riverside County, according to RUHS.

"This marks a localized outbreak of three total confirmed cases of measles in Riverside County for 2026," RUHS reported.

The first 2026 measles case was a child who underwent testing last month for the highly contagious virus.

How that child became infected could not be verified. RUHS officials said the minor had not traveled out of the country, or even out of the state, in the last several months.

All of the patients are recovering at their respective homes, according to RUHS.

"These additional cases of measles underscore the disease’s highly contagious nature,” said Riverside County Public Health Officer Dr. Jennifer Chevinsky.

Measles lives in the nose and throat mucus of an infected person. It can spread to others through coughing and sneezing.

If other people breathe the contaminated air or touch an infected surface, then touch their eyes, noses or mouths, they can become infected.

Measles can live for up to two hours in an airspace after an infected person leaves an area, according to RUHS.

Infection symptoms typically develop seven to 21 days after exposure and often begin with fever, cough, runny nose and red eyes.

Within a few days, a red, blotchy rash appears, usually starting on the face and spreading downward to the rest of the body.

People with measles can be contagious four days before the onset of rash and four days after.

Measles can lead to serious health complications, including ear infections, lung infections, diarrhea, and in rare cases, brain swelling or death.

If someone has measles, up to 90% of people close to them — who are not immune — will also become infected, RUHS reported.

Additionally, some vaccinated people may still get measles if they are exposed or have prolonged, close contact with someone infected with the virus. This can occur if their immune system’s ability to fight infection has decreased over time or doesn’t respond to the vaccine as it should, according to RUHS.

Measles symptoms are generally milder in vaccinated people.

“Now is the perfect time to make sure you and your family are vaccinated against measles,” Chevinsky said.

Southern California is seeing an increase in measles cases.

People who shopped at an Ontario Walmart store last month were advised by health officials that they may have been exposed to measles after a child who was at the retail location later tested positive for the viral infection.

The case, involving an unvaccinated minor visiting California from another state, was announced Friday, Feb. 6, by the San Bernardino County Department of Public Health. The infected child was at the Walmart Supercenter, 1333 N. Mountain Ave. in Ontario, between noon and 3 p.m. on Jan. 29.

The child was infectious from Jan. 26 through Feb. 3, according to the county health department.
Shoppers who were at the Walmart store during the exposure timeframe were at risk of developing measles, especially if unvaccinated, immunocompromised or pregnant, according to the county health department.

The measles case was the first confirmed in San Bernardino County since 2023.

The San Bernardino County Department of Public Health said the case is unrelated to the measles exposure at Disneyland that was reported.

As of Monday, Feb. 16, 19 confirmed measles cases have been reported in California during 2026, according to the California Department of Public Health. In addition to Orange, Riverside and San Bernardino counties, cases have been reported in Los Angeles, Napa, San Mateo and Shasta counties.

Health officials statewide are urging residents to stay up to date on vaccines, especially before traveling, including international travel and travel to domestic areas with measles outbreaks. It is also important to be up to date before visiting places or events where there are many people from other countries or regions of the United States, such as large sporting events, theme parks or airports, officials said.

If you’re unsure of your vaccination status, you can check out the CA Digital Vaccine Record (DVR) or ask your healthcare provider.

"If no records exist, getting vaccinated is highly recommended," according to RUHS.

For questions and locations of public health clinic locations that offer vaccinations, call 951-358-7125 or visit www.ruhealth.org/vaccineclinics