Can Borrelia miyamotoi Cause Relapsing Fever?

Borrelia miyamotoi can cause relapsing fever
But the fever does not always relapse
Absence of relapsing fever does not rule it out

Can Borrelia miyamotoi cause relapsing fever? Yes. Borrelia miyamotoi belongs to the relapsing fever group of Borrelia and can cause what is now called hard tick relapsing fever. However, repeated episodes of fever occur in only a minority of reported patients. Many patients experience a single febrile illness rather than the classic pattern of fever disappearing and returning.

This distinction matters clinically. A patient does not need to have repeated fever episodes for Borrelia miyamotoi to be considered. Fever, chills, headache, fatigue, muscle aches, joint pain, and nausea are more common manifestations, while the erythema migrans rash associated with Lyme disease is uncommon.^1,4

What Is Borrelia miyamotoi?

Borrelia miyamotoi is a tick-borne bacterium transmitted by Ixodes ticks, including the same blacklegged ticks that transmit Lyme disease, babesiosis, and anaplasmosis.

Unlike Borrelia burgdorferi, the principal cause of Lyme disease in the United States, B. miyamotoi belongs to the relapsing fever group of Borrelia.^2,4

The infection is found in the northeastern, northern Midwestern, and far western United States as well as parts of Canada. Although considerably less common than Lyme disease, B. miyamotoi is increasingly recognized as an important cause of tick-borne febrile illness.⁴

Does Borrelia miyamotoi Always Cause Relapsing Fever?

No. The name hard tick relapsing fever can create the impression that a patient must experience repeated episodes of fever. Published clinical experience shows otherwise.

In the largest U.S. case series reviewed by Burde and colleagues, only 2 of 51 patients—approximately 4%—experienced relapsing fever. Earlier reports from Russia found relapsing fever in approximately 10% of patients. Across published studies reviewed by the authors, relapsing fever occurred in only a minority of patients.⁴

When fever does relapse, patients may improve for several days before the fever and other symptoms return. Burde and colleagues reported an average interval of approximately 9 days between fever episodes in patients who experienced relapses.⁴

The important clinical point is that absence of relapsing fever should not by itself be used to rule out Borrelia miyamotoi infection.

Why Doesn’t the Fever Always Relapse?

There are several possible explanations.

One is that patients with an acute tick-borne illness may receive antibiotics before another fever episode has time to develop. In the U.S. case series reported by Molloy and colleagues, patients commonly presented with fever and other findings that could prompt empiric treatment for another suspected tick-borne infection.¹

Sudhindra and colleagues described an untreated patient with PCR- and serology-confirmed B. miyamotoi infection who developed relapsing fever. The case demonstrated that recurrent fever can occur when the natural course of the infection is observed without early antibiotic treatment.³

However, treatment alone may not explain why relapses are uncommon. The clinical expression of B. miyamotoi infection varies, and the classic recurring fever pattern associated with other relapsing fever borreliae should not be considered a requirement for diagnosis.

What Are the Symptoms of Borrelia miyamotoi?

Fever is one of the most common manifestations, but patients may have several other nonspecific symptoms.

• Fever
• Chills
• Headache
• Fatigue
• Muscle aches
• Joint pain
• Nausea or other gastrointestinal symptoms

In a 2023 review of North American cases, fever was reported in 94% of patients, chills in 79%, headache in 72%, muscle aches in 71%, fatigue in 69%, and joint pain in 54%. Relapsing fever was reported in only 4% of the U.S. cases summarized in the review.⁴

This illustrates why looking only for recurrent fever can miss the broader clinical presentation.

Does Borrelia miyamotoi Cause a Bull’s-Eye Rash?

Usually not. The erythema migrans rash associated with Lyme disease is uncommon in Borrelia miyamotoi infection.

Burde and colleagues found erythema migrans in only about 4% of cases worldwide and none of the U.S. cases summarized in their review.⁴

A rash in a patient with suspected B. miyamotoi infection may therefore raise the possibility of Lyme disease, simultaneous infection with B. burgdorferi, or another explanation.

How Is Borrelia miyamotoi Different From Lyme Disease?

Both infections can be transmitted by Ixodes ticks, but they are caused by different Borrelia species and may present differently.

• Fever is prominent in B. miyamotoi. Acute fever, chills, headache, and muscle aches are common.
• Erythema migrans is uncommon. Most patients with B. miyamotoi do not develop the characteristic expanding Lyme disease rash.
• Blood abnormalities may occur. Leukopenia, thrombocytopenia, and elevated liver enzyme levels can accompany B. miyamotoi infection.
• Routine Lyme disease testing is not designed to diagnose B. miyamotoi. Different laboratory approaches may be necessary.
• Relapsing fever can occur—but is not required. Many patients have only one recognized febrile episode.

The two infections can nevertheless overlap clinically, and coinfection with B. burgdorferi or other Ixodes-transmitted pathogens has been reported.⁴

How Is Borrelia miyamotoi Diagnosed?

Diagnosis can be challenging because the symptoms overlap with Lyme disease, anaplasmosis, babesiosis, ehrlichiosis, influenza, and other causes of acute fever.

PCR testing of whole blood can be particularly useful during acute illness when organisms are circulating in the bloodstream. Blood smear examination may occasionally identify spirochetes when the organism burden is sufficiently high.⁴

Antibody testing against glycerophosphodiester phosphodiesterase (GlpQ) has also been used to support the diagnosis. However, antibodies may not yet be detectable when patients first become ill.

In the Molloy case series, rGlpQ antibody testing was positive in only 16% of case-patient samples at the initial clinical presentation but became positive in 86% during convalescence.¹

Testing therefore needs to be interpreted in the context of the patient’s symptoms, possible tick exposure, timing of illness, laboratory abnormalities, and previous treatment.

Can a Lyme Disease Test Detect Borrelia miyamotoi?

Standard Lyme disease antibody testing is not designed to diagnose Borrelia miyamotoi.

There is another complication: antibodies produced during B. miyamotoi infection may cross-react with the C6 peptide used in some Lyme disease assays. Sudhindra and colleagues described an untreated patient with confirmed B. miyamotoi infection who had positive C6 Lyme serology.³

Burde and colleagues also noted that B. miyamotoi antibody can cross-react with the C6 Lyme antigen. Therefore, a positive C6 result that is not supported by other appropriate Lyme disease testing may require careful interpretation.⁴

A laboratory result should not be interpreted in isolation from the clinical presentation.

Can Borrelia miyamotoi Cause Serious Illness?

Yes, although severe complications appear to be uncommon.

Meningoencephalitis has been reported, particularly among older or immunocompromised patients. Symptoms in reported neurologic cases have included confusion, cognitive slowing, memory problems, headache, dizziness, neck stiffness, hearing changes, and other neurologic findings.⁴

Patients with severe headache, confusion, altered mental status, neck stiffness, new neurologic deficits, or other concerning symptoms require prompt medical evaluation.

Why Borrelia miyamotoi Can Be Missed

Borrelia miyamotoi can be overlooked because its symptoms are nonspecific, the characteristic Lyme disease rash is usually absent, and the term “relapsing fever” may lead patients and clinicians to expect recurrent fever episodes that frequently never occur.

In addition, early antibody testing may be negative, and routine Lyme disease testing is not designed to diagnose the infection.

For a patient with fever, chills, headache, fatigue, muscle aches, abnormal blood counts, or elevated liver enzymes following possible tick exposure, B. miyamotoi may deserve consideration along with Lyme disease, anaplasmosis, babesiosis, and other tick-borne infections.

Frequently Asked Questions

Can Borrelia miyamotoi cause relapsing fever?

Yes. Borrelia miyamotoi can cause hard tick relapsing fever. However, repeated episodes of fever occur in only a minority of reported patients. Many patients experience only one recognized febrile illness.

Can you have Borrelia miyamotoi without relapsing fever?

Yes. The absence of recurrent fever does not rule out Borrelia miyamotoi. In the largest U.S. series summarized in a 2023 review, relapsing fever was reported in only about 4% of patients.

What are the most common Borrelia miyamotoi symptoms?

Common symptoms include fever, chills, headache, fatigue, muscle aches, joint pain, and nausea. The erythema migrans rash associated with Lyme disease is uncommon.

Is Borrelia miyamotoi the same as Lyme disease?

No. Both infections can be transmitted by Ixodes ticks, but Borrelia miyamotoi belongs to the relapsing fever group of Borrelia, while Lyme disease in the United States is caused primarily by Borrelia burgdorferi.

How is Borrelia miyamotoi diagnosed?

Diagnosis depends on the clinical presentation and appropriate laboratory testing. PCR testing of whole blood can be useful during acute illness. GlpQ antibody testing may support the diagnosis later in the illness but can be negative early.

Clinical Takeaway

Borrelia miyamotoi can cause hard tick relapsing fever, but the name can be misleading. Repeated fever episodes occur in only a minority of reported patients. Fever, chills, headache, fatigue, muscle aches, and joint pain are much more common.

Do not rely on the fever having to disappear and return before considering Borrelia miyamotoi. The absence of relapsing fever does not by itself rule out the infection.

Diagnosis requires consideration of the patient’s symptoms, possible tick exposure, timing of illness, laboratory findings, and appropriate testing. Other tick-borne infections should also remain in the differential diagnosis.

Related Articles

Lyme Disease Test Accuracy: Timing, Limitations, and Clinical Diagnosis

Anaplasmosis and Lyme Disease: Symptoms, Lab Findings, and Treatment

Babesia Symptoms and Treatment

Can One Tick Bite Cause Multiple Diseases?

Lyme Disease Misdiagnosis: Why It Happens and What to Know

References

1. Molloy, P. J., Telford, S. R., III, Chowdri, H. R., Lepore, T. J., Gugliotta, J. L., Weeks, K. E., Hewins, M. E., Goethert, H. K., & Berardi, V. P. (2015). Borrelia miyamotoi disease in the northeastern United States: A case series. Annals of Internal Medicine, 163(2), 91–98. https://doi.org/10.7326/M15-0333
2. Telford, S. R., III, Goethert, H. K., Molloy, P. J., Berardi, V. P., Chowdri, H. R., Gugliotta, J. L., & Lepore, T. J. (2015). Borrelia miyamotoi disease: Neither Lyme disease nor relapsing fever. Clinics in Laboratory Medicine, 35(4), 867–882. https://doi.org/10.1016/j.cll.2015.08.002
3. Sudhindra, P., Wang, G., Schriefer, M. E., McKenna, D., Zhuge, J., Krause, P. J., Marques, A. R., & Wormser, G. P. (2016). Insights into Borrelia miyamotoi infection from an untreated case demonstrating relapsing fever, monocytosis and a positive C6 Lyme serology. Diagnostic Microbiology and Infectious Disease, 86(1), 93–96. https://doi.org/10.1016/j.diagmicrobio.2016.06.015
4. Burde, J., Bloch, E. M., Kelly, J. R., & Krause, P. J. (2023). Human Borrelia miyamotoi infection in North America. Pathogens, 12(4), 553. https://doi.org/10.3390/pathogens12040553

This article is for educational purposes and is not intended as medical advice. Diagnosis and treatment decisions should be made with a qualified healthcare professional.

Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.

Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention