Overview

Causes

RMSF is caused by a specific bacteria. An infected tick can spread it through a bite.

Risk Factors

Factors that increase your chance of RMSF include:

  • Being outdoors in areas known to have RMSF especially from April to September
  • Exposure to tick-infested areas such as long grass, weeds, or low brush
  • Exposure to dogs
  • Not using preventive steps like bug spray or appropriate clothes

SymptomsandDiagnosis

Symptoms

The first symptoms of RMSF often occur within 2 to 14 days after a tick bite. Symptoms may include:

  • Fever
  • Headache
  • Rash—begins as small, flat pink spots on wrists and ankles
  • Nausea and vomiting
  • Abdominal pain
  • Muscle or joint pain
  • Lack of appetite
  • Red eyes
  • Light hurting the eyes
  • Fatigue
  • Altered mental status
  • Severe bleeding
  • Difficulty breathing

If left untreated, RMSF can cause severe problems. Other symptoms will depend on which organs are involved.

See your doctor if you have a fever after:

  • Tick bite
  • Being in an area likely to have ticks
Immune System Including Spleen and Lymph Nodes
Immune system
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Diagnosis

You will be asked about your symptoms and health history. A physical exam will be done. RMSF can be hard to diagnose. There are many conditions that cause similar symptoms. You may also be unaware of a tick bite. The rash may not be present yet.

The doctor may suspect RMSF based on your symptoms. A blood test may be done. They will help to find more signs of this infection.

A spinal tap may be done to look for infection around the brain.

Treatments

Treatment

Early treatment is important. Treatment may be started before all your tests come back.

RMSF is treated with antibiotics. Doxycycline is first choice. Make sure to take all of the medicine as advised.

Prevention

Tick bites can cause a number of infections. If you are in an area that may have ticks:

  • Wear light-colored clothing. You will be better able to see ticks.
  • Tuck pant legs inside socks. This will stop ticks from crawling up under your pants.
  • Use insect repellents with DEET. Apply to exposed skin. Permethrin can be put on clothing.
    • DEET should be avoided or used sparingly for small children. Follow the directions on the label.
  • Carefully check your entire body for ticks after returning from outdoor areas.
  • Treat your pets for ticks. Check pets for ticks after being outdoors.

This content is reviewed regularly and is updated when new and relevant evidence is made available. This information is neither intended nor implied to be a substitute for professional medical advice. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with questions regarding a medical condition.

Edits to original content made by Denver Health.