WASHINGTON, United States (AFP) — A measles outbreak in the southwestern United States has killed two people and infected more than 200, prompting a top health agency to issue a travel warning.

As of Friday, Texas had reported 198 cases and New Mexico 30, bringing the total to 228. Each state confirmed one death, and both were unvaccinated.

The Texas patient was a child while the New Mexico patient was an adult who tested positive for measles after death.

Although the official cause of the adult’s death has not been released by the New Mexico Office of the Medical Investigator, the Centers for Disease Control and Prevention (CDC) has classified it as a measles-related fatality.

“More cases are expected as this outbreak continues to expand rapidly,” the CDC warned in a Health Alert Network advisory to healthcare workers, public health officials and potential travelers.

“With spring and summer travel season approaching in the United States, CDC emphasizes the important role that clinicians and public health officials play in preventing the spread of measles,” the agency said.

“They should be vigilant for cases of febrile rash illness that meet the measles case definition and share effective measles prevention strategies, including vaccination guidance for international travelers.”

Measles is highly contagious, spreading through respiratory droplets and lingering in the air for up to two hours after an infected person leaves an area. The disease causes fever, respiratory symptoms, and a rash -- but can also lead to severe complications, including pneumonia, brain inflammation, and death.

Vaccination remains the best protection. The measles vaccine, required for children 12 months and older, confers 93 percent lifetime immunity after one dose, rising to 97 percent after two.

But immunization rates have been declining in the US, particularly since the Covid-19 pandemic fueled a surge in vaccine misinformation.

The CDC recommends a 95 percent vaccination rate for herd immunity, but nationwide coverage among kindergartners had slumped to 92.7 percent by 2023to 2024.