The New Mexico health department reported 30 measles cases in the state, an increase of 20 cases from its previous count.

All the cases were reported in Lea County, that is located adjacent to Gaines County, Texas, where more than 100 cases and one death in an unvaccinated child have been reported.

The increase in the reported cases comes a day after a deceased resident of New Mexico tested positive for measles, marking the second measles-related death in the U.S. in more than a decade.

The unvaccinated adult patient did not seek any medical care before death, and the cause of the death was still under investigation by the state medical examiner.

Half of the patients in New Mexico are 18 years of age or older, data from the state health department showed on Friday. Three of the patients are up to 4 years of age and eight patients are aged between 5 and 17 years.

The outbreak, one of the largest the U.S. has seen in the past decade, has put U.S. Health Secretary Robert F. Kennedy Jr., a longtime vaccine skeptic, to the test.