Tick Fever and Lyme Disease: How They’re Linked and What It Means for You

When you hear a buzzing sound in the woods, the first thing that comes to mind is probably a mosquito. But for anyone who’s found a tiny, hard‑shelled tick clinging to skin, the thoughts shift to fever, rashes, and a whole list of possible illnesses. Two names surface most often: Lyme disease and tick fever. Though they sound like separate monsters, they share the same culprits - bacteria carried by ticks - and can even show up together in the same patient.

Key Takeaways

• Lyme disease is caused by Borrelia burgdorferi and transmitted mainly by the black‑legged tick (Ixodes scapularis).
• Tick fever, often referring to tick‑borne relapsing fever, is caused by Borrelia hermsii and spread by soft ticks like Ornithodoros hermsi.
• Both illnesses can start with fever, headache, and fatigue, but Lyme disease typically adds a distinctive “bull’s‑eye” rash.
• Co‑infection is possible when a single tick carries both bacteria; this can make symptoms more severe and complicate treatment.
• Early diagnosis and a short course of doxycycline usually clear both infections, but prompt medical attention is crucial.

What Is Tick Fever?

“Tick fever” is a shorthand for several tick‑borne illnesses that cause fever. The most common reference is tick‑borne relapsing fever (TBRF). TBRF is caused by spirochetes of the genus Borrelia, primarily Borrelia hermsii. Unlike the hard‑tick bite that introduces Lyme disease, TBRF is transmitted by soft ticks of the genus Ornithodoros, which feed quickly-often in less than a minute-while the host sleeps.

Symptoms appear 5‑14 days after a bite and come in waves: high fever, chills, muscle aches, and a pounding headache. After a fever spike, the body may experience a brief lull, only for another wave to follow. This “relapsing” pattern is the disease’s namesake and can last weeks if untreated.

What Is Lyme Disease?

Lyme disease is the most prevalent tick‑borne disease in North America and Europe. It’s caused by Borrelia burgdorferi, a spirochete that thrives in the midgut of the black‑legged tick (Ixodes scapularis in the U.S., Ixodes ricinus in Europe). The tick must stay attached for at least 36‑48 hours for transmission to occur.

Early Lyme disease often presents with a red, expanding rash called erythema migrans, sometimes with a bull’s‑eye appearance. Flu‑like symptoms-fever, fatigue, headache, and joint pain-may accompany the rash. If not treated, the infection can spread to joints, the heart, and the nervous system.

How Ticks Transfer Both Pathogens

Although different tick species usually carry different Borrelia species, there are geographic overlaps. In the western United States, for example, the Rocky Mountain wood tick (Dermacentor andersoni) can host both Borrelia burgdorferi and Borrelia hermsii. When a single tick harbors multiple bacteria, a bite may inoculate the host with both, creating a co‑infection scenario.

Co‑infection doesn’t just add up the symptoms; it can amplify them. Patients often report more intense fever, prolonged fatigue, and a higher likelihood of neurological issues. The immune system’s response to one pathogen can inadvertently help the other survive, making diagnosis trickier.

Shared Symptoms and Key Differences

Notice how the rash is a major clue for Lyme disease but is largely missing in tick‑borne relapsing fever. That’s why doctors often rely on a detailed travel and exposure history to differentiate the two.

Co‑Infection Risks and Why They Matter

When a tick carries both Borrelia burgdorferi and Borrelia hermsii, the patient may experience overlapping symptoms. Fever may be higher, the rash may appear alongside relapsing episodes, and neurological signs (like facial palsy) can surface earlier.

Co‑infection also influences treatment decisions. While doxycycline covers both pathogens, clinicians may need to monitor patients longer or adjust dosages if symptoms linger. In rare cases, patients with severe relapsing fever may require intravenous ceftriaxone, especially if central nervous system involvement is suspected.

Diagnosis: Spotting the Connection Early

Because early symptoms mimic flu or common viral infections, many people dismiss a tick bite. Here’s a quick checklist doctors use:

1. Confirm a recent tick bite or exposure to endemic areas.
2. Inspect for erythema migrans or, in the case of relapsing fever, a pattern of fever spikes.
3. Order serologic tests: ELISA and Western blot for Lyme; thick‑blood‑smear or PCR for TBRF.
4. Consider co‑infection if symptoms are atypical or unusually severe.

Timely testing is vital. Serology for Lyme may be negative during the first weeks, so clinicians often start empirical doxycycline if the suspicion is high.

Treatment Pathways

Lyme disease is usually cured with a short course of doxycycline, 100mg twice daily for 2‑3 weeks. For children under eight or pregnant women, amoxicillin is preferred. If neurological or cardiac complications arise, intravenous ceftriaxone for 2‑4 weeks may be required.

Tick‑borne relapsing fever also responds well to doxycycline, but the regimen is slightly shorter-often 7‑10 days. In severe cases, especially with central nervous system involvement, hospitalization and IV antibiotics become necessary.

Because both infections share the same first‑line drug, co‑infection rarely needs separate medication. However, monitoring is essential: lingering fatigue or joint pain after treatment may signal post‑treatment Lyme disease syndrome or a relapse of TBRF.

Prevention: Staying Tick‑Smart

Prevention works on two fronts: avoiding tick bites and reducing tick habitats.

• Wear long sleeves and pants when hiking in forested areas; tuck pants into socks.
• Use EPA‑registered repellents containing 20‑30% DEET or picaridin on skin and clothing.
• Perform a tick check within 30 minutes of leaving the outdoors. Prompt removal (using fine‑point tweezers, pulling upward) cuts transmission risk.
• Keep yards trimmed, remove leaf litter, and apply tick‑control treatments to pets.
• If you find a tick attached for more than 24hours, consider a prophylactic dose of doxycycline (200mg single dose) after consulting a healthcare provider.

These steps dramatically lower the odds of both Lyme disease and tick‑borne relapsing fever, and they’re easy to integrate into weekend adventures.

Quick Checklist for Anyone Who’s Been Bitten

• Remove the tick within 24hours using tweezers.
• Note the date, location, and tick type (hard vs. soft).
• Watch for a bull’s‑eye rash, fever spikes, or flu‑like symptoms for up to a month.
• Seek medical care promptly if any symptoms appear.
• Ask your doctor about testing for both Lyme disease and tick‑borne relapsing fever, especially if you live in overlapping endemic zones.