About Rocky Mountain Spotted Fever
Rocky Mountain spotted fever is caused by Rickettsia rickettsii, a bacterium that infects the cells lining small blood vessels. It spreads through the bite of the American dog tick east of the Rockies, the Rocky Mountain wood tick in the mountain states, and the brown dog tick in parts of the Southwest. It is the most severe of a family of related infections called spotted fever rickettsioses. The milder members include Rickettsia parkeri rickettsiosis, spread by the Gulf Coast tick in the Southeast, and Pacific Coast tick fever in California, Oregon and Washington. Those usually start with a dark scab, or eschar, at the bite, which is rare in Rocky Mountain spotted fever itself. Because antibody tests cannot tell these apart, the CDC counts them together.
The danger is speed. The rash that gives the disease its name appears in 9 of 10 patients eventually, but in fewer than half during the first 3 days, so doctors cannot wait for it. The CDC says doxycycline is the treatment for people of all ages, including children under 8 and pregnant women, that it works best in the first 5 days of illness, and that using any other antibiotic is linked to a higher risk of death. Short courses have not stained children's permanent teeth. Treatment should start on suspicion, before test results come back.
Diagnosis is confirmed afterward with antibody tests on 2 blood samples taken weeks apart, or by PCR on blood or a skin biopsy, though a negative PCR does not rule it out. Survivors of severe disease can be left with amputations, hearing loss or lasting mental changes. There is no vaccine, and antibiotics are not recommended to prevent infection after a bite.
Common Symptoms of Rocky Mountain Spotted Fever
Recognizing the signs of Rocky Mountain Spotted Fever early can lead to faster diagnosis and better outcomes. Symptoms may vary in severity from person to person. If you or a loved one are experiencing any of the following, consider speaking with a specialist.
- Sudden fever and severe headache, 3 to 12 days after a tick bite
- Nausea, vomiting, stomach pain and muscle pain
- A rash that usually appears 2 to 4 days after the fever starts, often beginning on wrists and ankles
- Swelling around the eyes and on the backs of the hands
- Confusion, breathing trouble or kidney failure in severe cases
- A dark scab at the bite site in the milder related infections, which is uncommon in Rocky Mountain spotted fever
Who Rocky Mountain Spotted Fever Affects
Anyone bitten by an infected American dog tick, Rocky Mountain wood tick or brown dog tick. Severe disease is most likely in children under 10, people with G6PD deficiency, and anyone whose treatment starts late. In Arizona and northern Mexico the brown dog tick spreads it around homes year-round, with unusually high death rates, especially among children.
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FDA-Approved Treatments for Rocky Mountain Spotted Fever
There is currently 1 FDA-approved medication for Rocky Mountain Spotted Fever. These therapies represent the current standard of care and may be used alongside or compared against investigational treatments in active clinical trials.
Source: openFDA drug labeling data. This list may not include all treatments. Always consult your doctor.
Help Paying for Rocky Mountain Spotted Fever Treatment
Charity funds and drugmaker programs for Rocky Mountain Spotted Fever, checked at the source.
- Vibramycin (Doxycycline) · Generic from many makers
Side Effect Explorer
Real-world side effect reports from the FDA Adverse Event Reporting System (FAERS). Includes both FDA-approved drugs and investigational therapies from active clinical trials. Click any drug to see what patients reported.
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Diagnosis and Testing
Tick-borne Rickettsia rickettsii infection, diagnosed by paired antibody tests or PCR; not genetic.
Trusted Rocky Mountain Spotted Fever Resources
Reputable organizations and medical references for learning more about Rocky Mountain Spotted Fever, including disease registries, foundation resources, and clinical guidelines.
