Health officials in New Mexico are investigating the cause of death of an unvaccinated person who tested positive for measles, the state health department said Thursday.

New Mexico health officials say an unvaccinated adult has died after a measles infection, though the virus has not been confirmed as the cause. The death comes as cases rise in Texas and New Mexico, prompting the CDC to send a response team.

An unvaccinated adult in Lea County, New Mexico, died recently and tested positive for measles afterward, the state’s Department of Health disclosed Thursday.