Northern Mexico's Rocky Mountain Spotted Fever Outbreak Causing Illness and Death

The U.S. government has issued a Level 1 Travel Health Notice regarding an outbreak of Rocky Mountain spotted fever (RMSF) in northern Mexico, specifically in the states of Baja California, Sonora, Chihuahua, Coahuila, and Nuevo León, which has been causing Illness and death in late 2025.

As of December 23, 2025, the Centers for Disease Control and Prevention (CDC) announced that ticks carrying the bacteria that cause RMSF have been found in several cities in northern Mexico.

These cities include Tecate, Tijuana, Ensenada, and Mexicali in Baja California, as well as Hermosillo in Sonora, Ciudad Juárez, and Chihuahua City in Chihuahua. The CDC warns that RMSF can be deadly if not treated promptly.

A similar CDC advisory was issued in 2023.

In the U.S., RMSF cases vary, but typically range from a few hundred to several thousand, says the CDC.

Since no protective vaccines are available as of 2025, travelers to these affected areas must take precautions. People can protect themselves by using a registered insect repellent on exposed skin and clothing.

Additionally, it is essential to check their bodies and their children's bodies for ticks daily, as well as their clothing. Ticks can be tiny, and their bites may be painless, so it is possible to overlook a tick bite. If you find a tick on your body, the CDC advises removing it as soon as possible.