Rocky Mountain Spotted Fever

What is Rocky Mountain spotted fever?

Rocky Mountain spotted fever (RMSF) is an infection caused by the bite of an infected tick. It may occur anytime the weather is warm, but it most often occurs from April until September. It was first recognized in the Rocky Mountain states. But it may occur throughout the U.S. Most common areas affected are in the southeastern and south central U.S. The disease is spread to humans through a bite from an infected tick. It is not spread from person to person.

What causes Rocky Mountain spotted fever?

RMSF is caused by a bacterium that is spread to people by the bite of an infected tick. In different parts of the U.S., these ticks can transmit the RMSF bacteria:

  • American dog tick

  • Rocky Mountain wood tick

  • Brown dog tick

  • Lone star tick

Who is at risk for Rocky Mountain spotted fever?

People living in or visiting areas where ticks are common, especially the southeastern and south central U.S., are at risk for RMSF. But the illness can also be passed on from ticks in the Northeast, Pacific coast, and other areas.

What are the symptoms of Rocky Mountain spotted fever?

These are the most common symptoms of RMSF:

  • A non-itchy rash that usually starts on the hands, arms, feet, and legs and occurs 5 to 10 days after the bite. The rash consists of flat, pink spots.

  • Fever

  • Headache

  • Confusion

  • Decreased appetite

  • Chills

  • Sore throat

  • Stomachache

  • Nausea or vomiting

  • Diarrhea

  • Body aches

  • Sensitivity to light

RMSF is a serious illness that needs treatment as soon as possible. Death has occurred in untreated cases of RMSF.

Symptoms of RMSF may look like other health problems. See a healthcare provider for diagnosis.

How is Rocky Mountain spotted fever diagnosed?

Diagnosis is based on symptoms and history of a tick bite. How the rash looks is important. Skin samples and lab tests are usually done to rule out other conditions and confirm the diagnosis.

How is Rocky Mountain spotted fever treated?

Treatment will depend on your symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment may include antibiotics (usually doxycycline) until several days after the fever goes away. Efforts to ease symptoms also help.

What are possible complications of Rocky Mountain spotted fever?

RMSF can be cured when treated with antibiotics. But if untreated, serious complications can occur, such as:

  • Nerve damage

  • Hearing loss

  • Incontinence

  • Partial paralysis

  • Tissue death (gangrene) of toes or fingers

  • Rarely, death

Can Rocky Mountain spotted fever be prevented?

Once you’ve had RMSF, you probably won't get it again. To help prevent RMSF, follow these guidelines.

Wearing protective clothing

Ticks can't bite through clothing, so dress in:

  • Light-colored clothing, so you can spot ticks on clothing easier

  • Long-sleeved shirts tucked into pants

  • Socks and closed-toe shoes

  • Long pants with legs tucked into socks

Checking for ticks

It's important to check often for ticks, especially on these parts of the body:

  • Around the joints, such as behind the knees, between fingers and toes, underarms, and groin

  • Other areas where ticks are often found, such as the belly button, in and behind the ears, neck, hairline, and top of the head

  • Areas of pressure points, including anywhere that clothing presses tightly on the skin

  • All other areas of the body and hair. Run your fingers gently over the skin, and run a fine-toothed comb through your hair to check for ticks.

Using insect repellent

Keep these tips in mind: 

  • Products that contain DEET are tick repellents, but may not kill the tick and are not 100% effective. For children, use a children's insect repellent (20% to 30% DEET). If your child is younger than age 1, check with your child's healthcare provider before using.

  • Treat clothing with a product that contains permethrin, which is known to kill ticks on contact. Don't use permethrin on skin.

  • Use any insect repellents safely. Follow instructions on the package.

Other tips

These tips can also help:

  • When possible, walk on cleared paths and pavement through wooded areas and fields.

  • Shower after all outdoor activities are over for the day. It may take up to 4 to 6 hours for ticks to attach firmly to skin. Showering may help remove any loose ticks.

  • Check pets for ticks and treat as needed.

When should I call my healthcare provider?

If your symptoms get worse or you have new symptoms, let your healthcare provider know.

Key points about Rocky Mountain spotted fever

  • RMSF is caused by a bacterium that is spread to people by the bite of an infected tick.

  • Symptoms include a rash, fever, headache, decreased appetite, chills, sore throat, confusion, stomachache, nausea or vomiting, diarrhea, body aches, and sensitivity to light.

  • Treatment includes antibiotics and symptom relief.

  • If RMSF is untreated, serious complications can occur. These include nerve damage, hearing loss, incontinence, partial paralysis, gangrene of toes or fingers, and rarely, death.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

  • Know the reason for your visit and what you want to happen.

  • Before your visit, write down questions you want answered.

  • Bring someone with you to help you ask questions and remember what your provider tells you.

  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

  • Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

  • Ask if your condition can be treated in other ways.

  • Know why a test or procedure is recommended and what the results could mean.

  • Know what to expect if you do not take the medicine or have the test or procedure.

  • If you have a follow-up appointment, write down the date, time, and purpose for that visit.

  • Know how you can contact your provider if you have questions.

Online Medical Reviewer: Barry Zingman MD
Online Medical Reviewer: L Renee Watson MSN RN
Online Medical Reviewer: Raymond Turley Jr PA-C
Date Last Reviewed: 4/1/2021
© 2000-2023 The StayWell Company, LLC. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.