An 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 person who died was unvaccinated and did not seek medical care, a state health department spokesperson said in a statement. The person’s exact age and other details were not immediately released.

The person was from Lea county, just across the state line from the west Texas region where 159 measles cases have been identified and a school-age child died last week. New Mexico health officials have not linked the outbreak there to the Texas cases.

The person is the 10th in Lea county to have a confirmed measles infection. Seven were unvaccinated. The vaccination status of the other three is unknown. Six of the cases are in adults and the rest are in children younger than 17.

On Tuesday, the US Centers for Disease Control and Prevention announced that they were sending a team to Texas to help local public health officials respond to the outbreak, which began in late January.

Measles is a respiratory virus that can survive in the air for up to two hours. Up to nine out of 10 people who are susceptible will get the virus if exposed, according to the CDC.

The measles, mumps and rubella vaccine is safe and highly effective at preventing infection and severe cases. The first shot is recommended for children aged 12 to 15 months, and the second for those aged four to six.

“We don’t want to see New Mexicans getting sick or dying from measles,” said Dr Chad Smelser, the deputy state epidemiologist. “The measles-mumps-rubella vaccine is the best protection against this serious disease.”