As the Trump administration moves to dismantle international public health safeguards, pull funding from local health departments and legitimize health misinformation, some experts now fear that the country is setting the stage for a long-term measles resurgence.

If federal health officials do not change course, large multistate outbreaks like the one that has torn through West Texas, jumping to neighboring states and killing two people, may become the norm.

“We have really opened the door for this virus to come back,” said Dr. Thomas R. Frieden, a former director of the Centers for Disease Control and Prevention.

In order for an outbreak to occur in the United States, the virus must first be imported into the country, and it must reach a large, unvaccinated population.

Recent events have made both conditions seem increasingly likely, said Dr. William Moss, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health.

Efforts to control the spread of measles internationally have been disrupted by the Trump administration’s recent decision to withdraw from the World Health Organization, which runs a network of more than 700 laboratories that track measles cases in 164 countries.

The program — which helps to ensure prompt public health responses to emerging outbreaks — relies on the United States to fund its entire $8 million annual budget.

The funds for Gavi were not included on a list the State Department sent to Congress last week of programs it intends to continue to support. But the organization has yet to receive a formal grant termination letter, and its leadership is lobbying the administration to preserve the funding.

Both the W.H.O. withdrawal and the possible loss of Gavi’s funding are likely to cause a surge in measles cases overseas, increasing the likelihood that a U.S. traveler will bring the virus back into the country, said Dr. Walter Orenstein, a professor emeritus at Emory University and the former director of the National Immunization Program at the C.D.C.

“People don’t understand that supporting global immunization not only is good for their countries, but for our country,” he said.

This week’s layoffs at the C.D.C. included staff members who communicate with the public during infectious disease outbreaks and help craft campaigns to encourage vaccination.

Now communications will be centralized at the Department of Health and Human Services, under the control of health secretary Robert F. Kennedy Jr., a vaccine skeptic. The department did not respond to requests for comment.

Dr. Frieden, the former C.D.C. director, described the cuts as “a recipe for disaster.”

The national immunization rate for measles, which fell during the Covid-19 pandemic, has not rebounded to the 95 percent required to stem the spread of the virus in a community. That raises the odds that an imported case will land in a vulnerable population and ignite.

Roughly 93 percent of children in kindergarten had the M.M.R. shot in the 2023-24 school year. But vaccination rates are unevenly distributed; some communities have rates around 80 percent, offset by others where the figure is closer to 99 percent.

Now that H.H.S. has moved to cut billions of dollars to local health departments, they may struggle to quash outbreaks early on, allowing the virus to hop to other unvaccinated communities. (A judge temporarily blocked the funding cuts after a coalition of states sued the Trump administration.)

During infectious disease emergencies, it is local health departments that investigate the source of the pathogen and track down anyone who might have been exposed so they can be quarantined.

The contact-tracing process is time consuming and resource intensive, especially for a virus as contagious as measles.

“A fire is burning and we are at the same time shutting down all the fire departments,” said Jennifer Nuzzo, director of the Pandemic Center at the Brown University School of Public Health.

The current outbreak that began in West Texas shows no signs of slowing. There have been more than 480 cases in the area and 56 hospitalizations since late January. The outbreak has also spread to bordering states, sickening 54 people in New Mexico and 10 in Oklahoma.

Genetic sequencing has suggested that the outbreak is also linked to 24 measles cases discovered in southwest Kansas.

Measles was officially eliminated in the United State in 2000. But the speed at which the Texas outbreak has grown and the fact that it has already jumped to other, under-vaccinated communities makes it very likely that the United States will lose that status, Dr. Nuzzo said.

Measles is no longer considered eliminated if a chain of infections continues for more than twelve months. Public health officials in West Texas have predicted the outbreak will continue for a year.

A large measles outbreak that spread through parts of New York State for nearly 12 months nearly cost the country its elimination status in 2019. The outbreak was contained in large part because of aggressive vaccine mandates, which helped substantially increase childhood immunization rates in the community.

“We just missed it by a hair,” Dr. Nuzzo said. “Where we are now is worse than that.”

Mr. Kennedy has offered muted support for vaccination and has emphasized untested treatments for measles, such as cod liver oil. According to doctors in Texas, his endorsement of alternative treatments has contributed to patients delaying critical care and ingesting toxic levels of vitamin A.

Mr. Kennedy recently tapped a prominent figure in the anti-vaccine movement to work on a study examining the long-debunked theory that vaccines are linked to autism.

If the country does lose elimination status, Dr. Moss said, its unlikely that infection rates will resemble those of the pre-vaccine era, when measles infected nearly every child by age 15.

But it would be likely to mean more frequent and larger outbreaks that make life riskier for society’s most vulnerable: babies too young to be vaccinated, and immunocompromised people.

“There are direct consequences — the health tolls, the long-term health impacts,” Dr. Nuzzo said. “Measles outbreaks are like just incredibly costly and disruptive.”

“It’s also just an embarrassment. It puts the United States on par with some of the most resource-constrained settings in the world, and out of step with most high-income countries.”