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Rocky Mountain Spotted Fever

Rocky Mountain Spotted Fever (RMSF) is a disease caused by the bacteria Rickettsia rickettsii. It is transmitted by the bite of an infected tick. In British Columbia, there are 0 – 3 cases of RMSF each year. In northwestern US and western Canada, it is spread by the Rocky Mountain wood tick - Dermacentor andersoni. In eastern North America, the American dog tick, D. variabilis, is responsible for spread.

Information for Health Professionals

RMSF is spread to humans through the bite of ticks.

RMSF is a potentially fatal but curable tick-borne disease. Symptoms typically appear within 2-14 days after a tick bite and may include:
  • Fever 
  • Headache
  • Nausea with or without vomiting
  • Rash (90% of cases have a rash)
  • Muscle and joint pain
  • Fatigue
Although less common, illness can progress and cause:
  • Breathing problems caused by fluid in/around the lungs
  • Irregular rhythm of the heart 
  • Enlargement of the liver and spleen
  • Bleeding abnormalities
  • Skin inflammation and damage
  • Neurological problems such as inflammation of the brain
Overall, the fatality rate varies and is generally low, especially with treatment. It increases with age and can be much higher if left untreated.

If you suspect you have been exposed to ticks and are experiencing symptoms consistent with RMSF, it is important to seek medical attention promptly. 
The following tests are available:
  • Nucleic Acid Amplification test (NAAT)
  • Serology (identifying antibodies in the blood)

Treatment of RMSF is with antibiotics. Awareness and avoidance are best to prevent this disease. If RMSF is diagnosed or suspected, your doctor may prescribe antibiotics to ensure the best possible result.


Find more information about prevention of RMSF on the main tick-borne diseases page.


SOURCE: Rocky Mountain Spotted Fever ( )
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