CDC Response to Rocky Mountain Spotted Fever

The Current U.S. Situation

Rocky Mountain Spotted Fever (RMSF) is a critical public health concern caused by the bite of an infected tick. Since July 2023, 5 patients have been diagnosed with RMSF, including 3 deaths. Four of the patients were under the age of 18 and all had travel to, or residence in, Tecate, in the state of Baja California, Mexico.

RMSF is spread to humans and dogs through tick bites. While ticks are commonly found in places like hiking trails and wooded areas, the risk for RMSF is particularly high in regions with stray dogs, as they can carry infected ticks year-round.

What CDC is Doing

In December 2023, CDC warned travelers to seek medical attention if they develop RMSF symptoms during travel to Tecate or another area in northern Mexico or within 2 weeks of returning to the United States.

CDC also issued an alert in December 2023 encouraging healthcare providers to be aware of RMSF as a possible diagnosis in patients seeking medical care in the United States who had recent travel to, or lived in, Tecate, Mexico or other areas of northern Mexico, and who have the disease signs or symptoms.

In summer 2023, CDC updated a web-based clinician training and toolkit for healthcare providers, epidemiologists, and public health practitioners on the diagnosis and treatment of Rocky Mountain spotted fever (RMSF) in the United States. CDC’s free clinical module helps frontline providers recognize and treat RMSF early to reduce severe disease and death.

RMSF Basics

Early signs and symptoms are not specific to RMSF (including fever and headache). However, the disease can rapidly progress to a serious and life-threatening illness.

Signs and symptoms can include:

• Fever
• Headache
• Rash
• Nausea
• Vomiting
• Stomach pain
• Muscle pain
• Lack of appetite
• Rash

Developing a rash is a common sign in people who are sick with RMSF. The rash, which may look different for different people, may develop 2-4 days after you have a fever. While almost all patients with RMSF will develop a rash, it often does not appear early in illness, which can make RMSF difficult to diagnose.

Prevent Tick Bites

Ticks, small eight-legged arachnids that are related to spiders, can spread multiple diseases, including Lyme disease and tularemia, in addition to RMSF. To safeguard against tick bites at home and while traveling, CDC recommends

• Using Environmental Protection Agency (EPA)-registered insect repellent on exposed skin and clothing.
• Checking your body, your child’s body, and your clothing for ticks after going outdoors.
• Using tick preventatives on pets.

Treatment of RMSF

Early detection is crucial and saves lives. RMSF responds well to the antibiotic doxycycline if diagnosed within the first week of symptoms. Doxycycline is the recommended antibiotic for people of all ages, including children and pregnant people.

What To Do If Bitten

If bitten by a tick, carefully remove the tick with tweezers and consider saving it for identification, as only specific ticks carry RMSF.

If a rash or fever develops after you’ve been bitten by a tick, call your doctor immediately. Informing the doctor about the tick bite, its timing, and location is important for accurate diagnosis and treatment.