With Measles Spreading, Here’s What to Know About Symptoms.

Well|What You Need to Know About Measles Symptoms and Transmission

One child has died and more than 130 people have fallen ill in measles outbreaks in Texas and New Mexico, raising concerns about the continued spread of the highly contagious virus.

Public health experts have been increasingly concerned about the threat of measles for several reasons. Rates of vaccination against measles, mumps and rubella have been declining. And cases have appeared to rise recently: In 2024, there were 285 measles cases — nearly five times the number seen in 2023, according to the Centers for Disease Control and Prevention.

The latest outbreaks are also unfolding in the first weeks of Robert F. Kennedy, Jr.’s tenure as health secretary. Mr. Kennedy has repeatedly expressed skepticism about the safety and benefit of vaccines, which have been shown to protect against and help limit the spread of measles and other infectious diseases. The majority of people that have been infected this year were unvaccinated or had an unknown vaccination status, according to the C.D.C.

Here’s what to know about how the virus spreads and what its symptoms look like.

How and when measles spreads

Part of what makes measles so tricky to contain is that infected people can easily spread the virus before even realizing they have it. Someone with measles can transmit the infection for up to four days before developing a telltale rash, according to the C.D.C.

Measles spreads when someone who is sick coughs or sneezes, said Dr. Paul Offit, a vaccine expert at the Children’s Hospital of Philadelphia. The virus can linger in the air for up to two hours after an infected person leaves a room. People can also contract measles by touching a surface that a sick person has contaminated and then touching their eyes, nose or mouth. “It’s the most contagious of the vaccine-preventable diseases,” Dr. Offit said.

Symptoms to watch out for

It typically takes one to two weeks for someone to feel ill after coming into contact with the virus. The earliest symptoms tend to be a cough, runny nose, pink eye and a fever. Some people may have a fever that goes above 104 degrees, which can be particularly dangerous for young children. Fewer than one in every 10 people with measles will also develop diarrhea, according to the C.D.C.