A raging measles outbreak in West Texas, which has so far killed one child, has not abated and may have taken root in New Mexico, state health officials reported on Friday.
The outbreak has sickened nearly 200 people — roughly 40 more cases than were reported on Tuesday — and has left 23 hospitalized in West Texas. Local health officials say even that number may be an undercount.
Robert F. Kennedy Jr., the health and human services secretary, has faced criticism for his handling of the worsening outbreak. A prominent vaccine skeptic, Mr. Kennedy has offered muted support for vaccination and has emphasized untested treatments for measles, like cod liver oil.
The outbreak has largely spread within a community of Mennonites in Gaines County, Texas, who historically have had lower vaccination rates and often avoid interacting with the health care system.
Last year, roughly 82 percent of the county’s kindergarten population had received the measles vaccine. Experts say that vaccination rates must reach at least 95 percent to stave off outbreaks in a community.
In a news release on Friday, Texas health officials wrote that more cases are “likely to occur,” because of the contagiousness of the virus.
Health officials in Lea County, N.M. — which borders Gaines County — reported 30 measles cases on Friday, a substantial jump from the nine cases reported on Tuesday.
While the cases in New Mexico have not officially been connected to the Texas outbreak, officials have said a link is “suspected.”
On Thursday, state officials said an unvaccinated person who died in Lea County tested positive for the virus, though they have not yet confirmed that measles was the cause of death.
Most of these cases along the New Mexico-Texas border have involved someone unvaccinated or with unknown vaccine status. Two doses of the measles, mumps and rubella vaccine prevent more than 97 percent of measles infections.
Just 93 percent of kindergarten students nationwide had received the vaccine for measles, mumps and rubella in the 2023-24 school year, down from 95 percent before the pandemic, according to the Centers for Disease Control and Prevention.
While symptoms typically resolve in a few weeks, measles can be extremely dangerous in rare cases. It may cause pneumonia, making it difficult for patients, especially children, to get oxygen into their lungs.
The infection can also lead to brain swelling, which can cause lasting damage, including blindness, deafness and intellectual disabilities. For every 1,000 children who get measles, one or two will die, according to the C.D.C.
The virus also causes “immune amnesia,” making the body unable to defend itself against illnesses it has already been exposed to and leaving patients more susceptible to future infections.
A 2015 study found that before the M.M.R. vaccine was widely available, measles might have been responsible for up to half of all infectious disease deaths in children.
