About Tick-Borne Relapsing Fever
Tick-borne relapsing fever, which the CDC now calls soft tick relapsing fever, is caused by several Borrelia species that are relatives of the Lyme disease bacterium but behave very differently. They are spread by soft-bodied ticks that live in the nests of rodents such as chipmunks and squirrels, often inside the walls and under the floors of rustic cabins. The bacteria repeatedly change their surface proteins to escape the immune system, which is why the fever comes back in waves.
Symptoms begin 4 to 21 days after exposure. Each fever episode lasts about 3 days, separated by about a week without fever. Because the bacteria are present in large numbers in the blood during a fever, the diagnosis is usually made by looking at a stained blood smear under a microscope, something most hospital labs can do. PCR is available from some commercial labs. One trap: relapsing fever can cause a false positive Lyme disease antibody test, so a positive Lyme test in someone with cyclic fevers after a cabin stay deserves a second look.
Treatment for adults is 10 days of doxycycline, or azithromycin, penicillin G or ceftriaxone, with intravenous beta-lactam antibiotics first for pregnant patients or anyone with neurological involvement. Up to half of patients have a Jarisch-Herxheimer reaction within hours of the first dose, a sudden spike of fever, chills and low blood pressure as bacteria die, so the CDC advises observing patients for the first 4 hours. The infection can cross the placenta, and pregnant women who may have been exposed should be evaluated promptly.
Common Symptoms of Tick-Borne Relapsing Fever
Recognizing the signs of Tick-Borne Relapsing 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.
- Fever of around 3 days, then about 7 days without fever, then fever again, sometimes several times
- Headache, muscle aches and chills during each fever
- Dizziness, joint pain, nausea and loss of appetite
- Shaking, drenching sweats and low blood pressure as each fever breaks
- Rarely, facial paralysis, eye pain or vision changes
- Pregnancy loss, premature birth or severe newborn infection when it occurs in pregnancy
Who Tick-Borne Relapsing Fever Affects
People who sleep in rodent-infested cabins and vacation homes in the mountains of the western states, where Borrelia hermsii is carried by Ornithodoros hermsi ticks, and people who explore caves in Texas, where Borrelia turicatae is carried by Ornithodoros turicata. The bites are painless, last under half an hour and usually happen at night, so most patients never saw a tick. Exposure is most common in summer but can happen in winter when cabins are heated.
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FDA-Approved Treatments for Tick-Borne Relapsing Fever
There is currently 1 FDA-approved medication for Tick-Borne Relapsing 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 Tick-Borne Relapsing Fever Treatment
Charity funds and drugmaker programs for Tick-Borne Relapsing 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
Bacterial infection (Borrelia hermsii or B. turicatae) from soft tick bites, diagnosed by blood smear or PCR; not genetic.
Trusted Tick-Borne Relapsing Fever Resources
Reputable organizations and medical references for learning more about Tick-Borne Relapsing Fever, including disease registries, foundation resources, and clinical guidelines.