Borrelia afzelii DbpA IgG

Borrelia afzelii is a key bacterium in Lyme borreliosis, particularly in Europe and Asia, where it is primarily transmitted by Ixodes ticks. 

Borrelia afzelii DbpA IgG is a serological marker used for diagnosing Lyme disease, indicating past or present infection, but its interpretation must consider the patient's symptoms and clinical history.

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 of LD 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. 

Ongoing surveillance and rapid intervention are essential for understanding and managing Borrelia infections.

What is Borrelia afzelii?

Borrelia afzelii is a species of Borrelia burgdorferi sensu lato (B. burgdorferi s.l.), and is a primary cause of Lyme disease (LD) in Europe. Predominantly transmitted by Ixodes ricinus ticks, it is found in regions including Spain, France, Italy, Slovenia, Croatia, Greece, Turkey, and Egypt. 

It is particularly linked to dermatological manifestations like erythema migrans, borrelial lymphocytoma, and acrodermatitis chronica atrophicans (ACA). The species tends to cause localized skin infections rather than systemic symptoms like neuroborreliosis or arthritis, which are more commonly associated with other species like Borrelia burgdorferi sensu stricto (B. burgdorferi s.s). 

B. afzelii is the most prevalent Borrelia species in European ticks, with minimal transmission time from tick bite to infection. Genetic diversity within B. afzelii has been noted, with multiple genotypes identified, which may influence transmission and virulence. 

What is Borrelia afzelii DbpA?

Decorin-binding proteins (Dbps) are surface proteins on Borrelia bacteria, such as Borrelia burgdorferi sensu stricto and Borrelia afzelii, that facilitate attachment to decorin, a protein found in the extracellular matrix of tissues like the skin, joints, and brain. DbpA is one type of decorin-binding protein present on B. afzelii.

This interaction is essential for bacterial adhesion and spread, contributing to the pathogenesis of Lyme disease. 

Borrelia afzelii DbpA, in particular, binds weakly or not at all to decorin compared to other species like B. burgdorferi s.s. and B. garinii. This limited decorin binding may explain why B. afzelii is primarily associated with skin-related conditions like acrodermatitis chronica atrophicans, rather than neuroborreliosis or arthritis. 

What is Borrelia afzelii DbpA IgG?

Borrelia afzelii DbpA IgG is a type of antibody produced by the immune system against DbpA. These antibodies remain detectable long after the infection resolves, serving as markers of past or present infection.

While IgG antibodies to B. afzelii can be present in both active and past infections, their presence alone does not confirm active disease. 

Who Should Get Borrelia afzelii DbpA IgG Tested?

Common symptoms of Borrelia afzelii infection that should prompt testing include skin issues like erythema migrans (a red, circular rash often with a "bull's-eye" appearance) and acrodermatitis chronica atrophicans (ACA), which starts as red-blue swelling and may lead to skin thinning and atrophy, usually on the hands and feet. 

Another symptom is borrelial lymphocytoma, a small, bluish-red nodule that typically appears on the ear or breast.

These symptoms, combined with a history of potential tick exposure in endemic areas, warrant testing for B. afzelii and other related Borrelia species.

In regions where B. afzelii is common, such as parts of Europe, testing for this specific biomarker is especially relevant. Additionally, individuals with persistent symptoms despite negative Lyme disease testing may benefit from further evaluation, as initial tests can yield false-negative results, especially in the early stages of infection.

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 afzelii DbpA IgG:

Test Procedure and Preparation Requirements

Borrelia afzelii DbpA IgG testing requires a blood sample, typically collected via venipuncture. 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 afzelii DbpA IgG may vary slightly depending on the laboratory performing the test. However, a negative result generally indicates no detectable immune response to B. afzelii at the time of testing. 

Positive results, especially in the context of clinical symptoms, suggest past or ongoing infection.

Clinical Implications of Elevated Levels

Elevated Borrelia afzelii DbpA IgG levels typically indicate that the patient has been exposed to B. afzelii in the past or is currently experiencing an active infection. However, since IgG antibodies can persist after infection has cleared, high levels do not necessarily confirm active disease. 

Elevated IgG levels should be interpreted alongside the patient’s clinical history and symptoms, with further diagnostic tests, such as IgM testing or PCR, used to confirm the diagnosis.

Order Lyme Disease Testing

Click here to compare testing options and order tests for Lyme disease.