The measles outbreaks in West Texas and New Mexico have surpassed a combined 350 cases, and two unvaccinated people have died from measles-related causes.

Measles is caused by a highly contagious virus that’s airborne and spreads easily when an infected person breathes, sneezes or coughs. It is preventable through vaccines and has been considered eliminated from the U.S. since 2000.

Already, the U.S. has more measles cases this year than in all of 2024, the U.S. Centers for Disease Control and Prevention said last week. Here’s what else you need to know about measles in the U.S.

How many measles cases are there in Texas and New Mexico?

Texas state health officials said Friday there were 30 new cases of measles since Tuesday, bringing the total to 309 across 14 counties — most in West Texas. Four more people were hospitalized, for a total of 40. Three new Texas counties reported cases: Garza, Hockley and Hale.

New Mexico health officials announced three new cases Friday, bringing the state’s total to 42. Most of the cases are in Lea County, where two people have been hospitalized, and two are in Eddy County.

Oklahoma’s state health department has four probable cases as of this week. Last week, it said the first two probable cases were “associated” with the West Texas and New Mexico outbreaks.

A school-age child died of measles in Texas last month, and New Mexico reported its first measles-related death in an adult last week.

Where else is measles showing up in the U.S.?

Measles cases also have been reported in Alaska, California, Florida, Georgia, Kansas, Kentucky, Maryland, Michigan, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont and Washington

The U.S. Centers for Disease Control and Prevention defines an outbreak as three or more related cases — and there have been three clusters that qualified as outbreaks in 2025.

In the U.S., cases and outbreaks are generally traced to someone who caught the disease abroad. It can then spread, especially in communities with low vaccination rates. In 2019, the U.S. saw 1,274 cases and almost lost its status of having eliminated measles.

Do you need an MMR booster?

The best way to avoid measles is to get the measles, mumps and rubella (MMR) vaccine. The first shot is recommended for children between 12 and 15 months old and the second between 4 and 6 years old.

People at high risk for infection who got the shots many years ago may want to consider getting a booster if they live in an area with an outbreak, said Scott Weaver with the Global Virus Network, an international coalition. Those may include family members living with someone who has measles or those especially vulnerable to respiratory diseases because of underlying medical conditions.

Adults with “presumptive evidence of immunity” generally don’t need measles shots now, the CDC said. Criteria include written documentation of adequate vaccination earlier in life, lab confirmation of past infection or being born before 1957, when most people were likely to be infected naturally.

A doctor can order a lab test called an MMR titer to check your levels of measles antibodies, but health experts don’t always recommend this route and insurance coverage can vary.

Getting another MMR shot is harmless if there are concerns about waning immunity, the CDC says.

People who have documentation of receiving a live measles vaccine in the 1960s don’t need to be revaccinated, but people who were immunized before 1968 with an ineffective measles vaccine made from “killed” virus should be revaccinated with at least one dose, the agency said. That also includes people who don’t know which type they got.

What are the symptoms of measles?

Measles first infects the respiratory tract, then spreads throughout the body, causing a high fever, runny nose, cough, red, watery eyes and a rash.

The rash generally appears three to five days after the first symptoms, beginning as flat red spots on the face and then spreading downward to the neck, trunk, arms, legs and feet. When the rash appears, the fever may spike over 104 degrees Fahrenheit, according to the CDC.

Most kids will recover from measles, but infection can lead to dangerous complications such as pneumonia, blindness, brain swelling and death.

How can you treat measles?

There’s no specific treatment for measles, so doctors generally try to alleviate symptoms, prevent complications and keep patients comfortable.

Why do vaccination rates matter?

In communities with high vaccination rates — above 95% — diseases like measles have a harder time spreading through communities. This is called “herd immunity.”

But childhood vaccination rates have declined nationwide since the pandemic and more parents are claiming religious or personal conscience waivers to exempt their kids from required shots.

The U.S. saw a rise in measles cases in 2024, including an outbreak in Chicago that sickened more than 60.

AP Science Writer Laura Ungar contributed to this report.

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