An unvaccinated person who died in New Mexico has tested positive for measles, state health officials said on Thursday, possibly the second such fatality in a growing outbreak that began in West Texas.

The officials have not yet confirmed that measles was the cause of death, and said the person did not seek medical treatment before dying.

The announcement came a little over a week after a child died of measles in Gaines County, Texas, the first such death in the United States in 10 years.

Ten cases of measles, six adults and four children, have been reported in Lea County, N.M., which borders Gaines County, the epicenter of the West Texas outbreak.

This outbreak has been a trial by fire of the new secretary of health and human services, Robert F. Kennedy Jr., a prominent vaccine skeptic. His equivocal response has drawn harsh criticism from scientists, who say he has offered muted support for vaccination and has emphasized untested treatments for measles like cod liver oil.

Instead of broadly lauding the safety and efficacy of vaccines, as past H.H.S. secretaries did, Mr. Kennedy has said that vaccines help protect against measles but that the decision to vaccinate “is a personal one.”

Thank you for your patience while we verify access. If you are in Reader mode please exit and log into your Times account, or subscribe for all of The Times.

Thank you for your patience while we verify access.

Already a subscriber? Log in.

Want all of The Times? Subscribe.