By Neha Mukherjee, CNN

(CNN) — The measles outbreak in West Texas is linked with cases in New Mexico, officials said Tuesday, as well as new cases reported in Oklahoma. This brings the total number of cases to 258 across three states.

In West Texas, 223 cases have been reported, according to a Tuesday update from the Texas Department of Health Services – 25 more confirmed cases since an update on Friday.

New Mexico’s Department of Health reported 33 measles cases as of Tuesday, three more than last week, and says it now considers the outbreak there to be connected to the one in West Texas.

“We consider this a regional outbreak of measles that has been linked geographically and by the strain identified through genome sequencing,” said Robert Nott, communications director for the New Mexico Department of Health.

Two cases of measles were also reported in Oklahoma, the Oklahoma State Department of Health said Tuesday. The infected people reported “exposure associated with the Texas and New Mexico outbreak.”

Even with climbing case counts, experts say these numbers are a severe undercount.

“The issue is when it spreads to communities that don’t have high vaccination rates,” said Dr. Catherine Troisi, infectious disease epidemiologist with UTHealth Houston. “So it depends on where the infected person goes to spread measles, to see how far and how many other cases are going to result from it.”

Measles is a highly contagious airborne virus that can stay in the air or on surfaces for up to two hours after an infected person has left the room. It also has a fairly long incubation period, which makes contact tracing and identifying exposures very difficult, according to Troisi.

In Texas, 29 patients have been hospitalized, six more than previously reported. Cases have been identified in nine counties.

The bulk of the cases, 156, are in Gaines County, where the outbreak was first identified.

Although most of the cases are in patients who were unvaccinated or who have unknown vaccination status, five cases were found in people who said they have been vaccinated with at least one dose.

Last month, Texas announced the outbreak’s first death in a school-age child who was not vaccinated and had no underlying conditions.

The US Centers for Disease Control and Prevention has been on the ground in Texas since last week.

“They’re advising our physicians and epidemiologists,” said Katherine Wells, director of Lubbock Public Health. “As this moves on, you end up with … really interesting scenarios of whether or not someone’s exposed. … So they are helping us work through that.”

Lea County is the focus of the outbreak in New Mexico, with 32 cases reported. Tuesday’s update also adds a case in Eddy County. One person who became ill reported getting at least one dose of the measles vaccine, 27 others were unvaccinated, and the vaccination status was unclear for five cases.

“Because measles is so contagious, additional cases are likely to occur in Lea County and the surrounding communities,” the state said in its update.

Health officials in New Mexico said last week that they are investigating the cause of death of an unvaccinated person who tested positive for measles. The Lea County resident had not sought out health care.

Texas and New Mexico are expected to update their numbers again Friday.

With the latest numbers, measles cases for 2025 are already approaching last year’s total of 285 cases in the US, according to the CDC.

“This is a virus that will spread, certainly, until mid-May. So we have a couple more months of this. We are certainly going to exceed last year’s levels massively,” Dr. Paul Offit, director of the Vaccine Education Center at the Philadelphia Children’s Hospital, told CNN.

The-CNN-Wire
™ & © 2025 Cable News Network, Inc., a Warner Bros. Discovery Company. All rights reserved.