WASHINGTON, United States (AFP) — A measles outbreak in the southwestern United States (US) 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 10, bringing the total to 208. Each state confirmed one death. Both were unvaccinated, and the New Mexico patient tested positive for measles posthumously.

Although their official cause of death has not been released, 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 immunisation 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 2023-2024.

Current Health Secretary Robert F. Kennedy Jr. spent decades falsely linking the measles, mumps, and rubella (MMR) vaccine to autism — a claim thoroughly debunked by scientific research.

Since the outbreak expanded, he has softened his stance, recommending vaccination while simultaneously promoting treatments such as vitamin A and steroids.

While these treatments are medically valid, experts warn that emphasising them may divert attention from the urgent need to boost immunisation rates.

Before this outbreak, the last US measles-related death was in 2015, when a Washington state woman died from virus-induced pneumonia while on immunosuppressive medication. The previous fatality was in 2003.