Borrelia bavariensis

Borrelia spp. are spirochetes responsible for Lyme disease and relapsing fever, transmitted by ticks and lice. 

While Lyme disease is the most common vector-borne disease in temperate regions, Borrelia species like B. bavariensis have expanded their geographical range, with B. bavariensis now identified as a significant cause of neuroborreliosis in humans.

What is Borrelia?

Borrelia spp. are spirochetes responsible for Lyme disease (LD) and relapsing fever (RF), transmitted by ticks and lice. 

LD, caused by Borreliella spp. (formerly Borrelia), is the most common vector-borne disease in temperate regions. It is primarily caused by B. burgdorferi and B. mayonii, but it is also caused by B. afzelii and B. garinii.

Symptoms include erythema migrans, fatigue, fever, and musculoskeletal pain. Untreated infections can lead to neuroborreliosis, arthritis, and Lyme carditis. 

RF, caused by species like B. miyamotoi, B. hermsii, and Candidatus B. johnsonii, presents with recurring fever, headache, myalgia, and can cause severe complications, including meningitis.

Borrelia spp. are commonly found in ticks that infest rodents, birds, and wild ungulates. The distribution of these ticks, particularly in the Mediterranean and the U.S., has expanded, increasing the prevalence of Borrelia infections. 

A recent study identified five Borrelia species in U.S. patients, including B. burgdorferi and B. mayonii (LD), and B. miyamotoi, B. hermsii, and Candidatus B. johnsonii (RF). The discovery of Candidatus B. johnsonii, previously linked only to bat ticks, suggests it may also cause human illness.

Clinicians should be aware of the distinct clinical features of LD and RF for timely diagnosis and treatment. Preventative measures like tick repellents are foundational in reducing transmission. 

What is Borrelia bavariensis?

Borrelia bavariensis, a spirochete within the Borrelia burgdorferi sensu lato complex, is a tick-borne pathogen primarily associated with small mammals as reservoir hosts. 

First described in 2009, it has spread geographically from Asia to Europe, where it is now found in questing Ixodes ricinus ticks. The species is notably linked to neuroborreliosis in humans and exhibits genomic plasticity, with significant genetic differences between European and Asian strains. 

Despite its low prevalence, its association with neuroborreliosis and genomic adaptability make B. bavariensis a significant concern for clinicians managing Lyme disease.

Symptoms of Lyme Neuroborreliosis

Lyme neuroborreliosis (LNB) is a neurological manifestation of Lyme disease caused by Borrelia bacteria, primarily presenting as polyradiculitis or meningoradiculoneuritis. 

Polyradiculitis and meningoradiculoneuritis, also known as Bannwarth syndrome, commonly present with severe, zoster-like segmental pain, often worse at night and poorly responsive to standard pain relief. 

Patients typically develop neurological deficits, such as flaccid paralysis or segmental sensory disturbances, within 1–4 weeks, with facial nerve involvement leading to peripheral facial palsy in about 60% of cases.

Diagnostic Requirements for Lyme Disease

Diagnosing Lyme disease involves a combination of clinical evaluation, history of tick exposure, and laboratory tests. 

To test for Lyme disease, serologic testing is used. The CDC recommends a two-step process: an enzyme immunoassay (EIA) followed by a Western blot for confirmation. IgM antibodies indicate recent infection, while IgG antibodies appear later.

Early serologic tests may be unreliable, so PCR and CSF analysis are used in suspected neuroborreliosis or Lyme arthritis for various Borrelia species. Early diagnosis and treatment are essential to prevent complications.

Test Procedure and Interpretation

The following section outlines testing procedures and results interpretation for Borrelia bavariensis:

Test Procedure and Preparation Requirements

Borrelia bavariensis testing may require a blood sample, and/or CSF sample if concern for lyme neuroborreliosis is present. 

A blood sample is typically collected via venipuncture. CSF sample collection is more invasive and typically involves a lumbar puncture. 

There are generally no specific preparation requirements for the patient, although it’s always important to confirm this with the ordering provider.

Normal Reference Ranges

Normal reference ranges for Borrelia bavariensis may vary slightly depending on the laboratory performing the test. However, a negative result generally indicates no detectable presence or immune response to B. bavariensis at the time of testing. 

Clinical Implications of Elevated Levels

Elevated Borrelia bavariensis levels typically indicate that the patient is currently experiencing an active infection. Positive antibody responses must be interpreted within the context of the individual’s presentation and medical history.

Positive results, especially the presence of the bacterium in the context of clinical symptoms, indicate a current infection that requires treatment.

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