A n adult who was infected with measles has died in New Mexico, state health officials announced Thursday, though the virus has not been confirmed as the cause.

The patient tested positive for the infection, but state health officials could not confirm that it was the cause of death.

Nearly 230 measles cases have been identified in outbreaks in West Texas and a nearby county in New Mexico. Experts say the rising totals – and two recent deaths – suggest that cases are vastly undercounted.