Overview

Causes

RMSF is caused by a specific bacteria from the bite of an infected tick.

Risk Factors

Things that raise the risk of RMSF are:

  • 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, such as bug spray or protective clothing

SymptomsandDiagnosis

Symptoms

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

  • Fever
  • Headache
  • Rash—begins as small, flat pink spots on the wrists and ankles
  • Nausea and vomiting
  • Belly pain
  • Muscle or joint pain
  • Lack of hunger
  • Red eyes
  • Eyes that are sensitive to light
  • Fatigue
  • Changes in mental status
  • Severe bleeding
  • Problems breathing

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

Seek medical care for any fever that happens after getting bit by a tick or spending time in an area known to have ticks.

Immune System Including Spleen and Lymph Nodes
Immune system
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Diagnosis

The doctor will ask about symptoms and past health. Questions may also be asked about any recent tick bites or time spent in areas where ticks are present. A physical exam will be done. This may be enough to suspect the diagnosis.

RMSF can be hard to diagnose. Many conditions cause similar symptoms. The doctor will look for signs of infection. This can be done with:

  • Blood tests
  • A lumbar puncture to test the fluid around the brain and spine

Treatments

Treatment

Early treatment is important. It may be started before the test results are in.

Antibiotics will be given to kill the infection.

Prevention

To lower the risk of tick bites:

  • Wear light colored clothing to make ticks more visible.
  • Tuck pant legs inside socks to stop ticks from crawling up under pantlegs.
  • Use insect repellents that contain DEET. Use sparingly on small children.
  • Check for ticks after returning from outdoor areas.
  • Treat pets for ticks and check them after they have been 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.