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Rocky Mountain Spotted Fever (RMSF)

Rocky Mountain spotted fever (RMSF) is a tickborne disease caused by the bacterium Rickettsia rickettsii. This organism is a cause of potentially fatal human illness in North and South America, and is transmitted to humans by the bite of infected tick species. In the United States, these include the American dog tick (Dermacentor variabilis), Rocky Mountain wood tick (Dermacentor andersoni), and brown dog tick (Rhipicephalus sanguineus).  Typical symptoms include: fever, headache, abdominal pain, vomiting, and muscle pain. A rash may also develop, but is often absent in the first few days, and in some patients, never develops.  Rocky Mountain spotted fever can be a severe or even fatal illness if not treated in the first few days of symptoms. Doxycycline is the first line treatment for adults and children of all ages, and is most effective if started before the fifth day of symptoms.   The initial diagnosis is made based on clinical signs and symptoms, and medical history, and can later be confirmed by using specialized laboratory tests.  RMSF and other tickborne diseases can be prevented.

Rocky Mountain Spotted Fever Topics

rash on arm from rmsf
Symptoms, Diagnosis, and Treatment

Signs of illness, what to expect from your physician…

pie chart
Statistics and Epidemiology

Incidence, Geography, seasonality, and more…

In-Depth Information

Guidelines and Recommendations…

Doxycycline saves lives

Research of Doxycycline and Safe Use in Children…

RMSF News & Highlights

Related Tick Topics

woman spraying tick repellant on her arm
Avoiding Ticks

Avoid getting infected…
On CDC's Ticks website

people, deer, fox
Tick Lifecycle and Hosts

How ticks spread disease…
On CDC's Ticks website

removing a tick from the skin with tweezers
Removing a Tick

How to remove a tick…
On CDC's Ticks website

tick on a blade of grass
Other Diseases Caused by Ticks

Learn more about other tickborne diseases that can affect your health…
On CDC's Ticks website

Contact Us:
  • Centers for Disease Control and Prevention
    Rickettsial Zoonoses Branch
    Mail Stop G-44
    1600 Clifton Rd
    Atlanta, GA 30333
  • 800-CDC-INFO
    TTY: (888) 232-6348
  • Contact CDC–INFO
Doxycycline saves lives The U.S. Government's Official Web PortalDepartment of Health and Human Services
Centers for Disease Control and Prevention   1600 Clifton Road Atlanta, GA 30329-4027, USA
800-CDC-INFO (800-232-4636) TTY: (888) 232-6348 - Contact CDC–INFO
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