The CDC has issued an advisory for people traveling to the Mexican state of Baja California–beware of ticks that could spread Rocky Mountain spotted fever.

The warning comes after someone from the San Diego area recently died from the illness. That person had recently traveled to Tecate, Mexico.

The CDC says that as of December 8, five patients have been diagnosed with confirmed RMSF since late July 2023. All had spent time in Tecate within two weeks of getting sick.

According to the CDC, “RMSF is a severe, rapidly progressive, and often deadly disease transmitted by the bite of infected ticks, although many patients do not recall being bitten by a tick.”

RMSF is endemic in multiple border states in northern Mexico, including but not exclusive to Baja California, Sonora, Chihuahua, Coahuila, and Nuevo León.

Read more about this from the CDC here.

Read NBC News report here.