Borrelia hermsii - IgG

What Does a Positive or Elevated IgG Result Mean?

A positive or elevated IgG result for Borrelia hermsii may indicate:

• A past infection with B. hermsii, especially if you are no longer experiencing active symptoms

• A resolving or chronic immune response to a prior relapsing fever episode

• In some cases, cross-reactivity with antibodies to other Borrelia species

Because IgG reflects past or longer-standing immune activity, it does not confirm an active infection on its own but strongly suggests prior exposure.

Symptoms of Tick-Borne Relapsing Fever (TBRF)

Symptoms usually appear within a week after a tick bite and may include:

• Recurrent high fever (often cycling every 3–7 days)

• Chills

• Headache

• Muscle and joint aches

• Fatigue

• Nausea or vomiting

• Rash (less common)

Each fever episode typically lasts a few days and then resolves before recurring.

Next Steps

• Speak with your healthcare provider to interpret this result in context. They will assess your clinical history, potential tick exposure, and other lab findings.

• Additional testing may be needed, including IgM or PCR, to determine whether there is an active infection or only past exposure.

• If infection is suspected or symptoms are present, antibiotic treatment is generally effective and can help prevent complications.

Summary

The Borrelia hermsii – IgG marker helps detect past or longer-term exposure to the bacterium that causes tick-borne relapsing fever. A medium or positive result indicates immune system recognition of this pathogen, but it does not confirm a current infection. Clinical symptoms, timing, and further testing are essential to determine whether treatment is needed.

What is Borrelia hermsii – IgG?

Borrelia hermsii is a bacterial species that causes tick-borne relapsing fever (TBRF), a disease characterized by recurring episodes of fever and other flu-like symptoms. It is transmitted to humans by soft-bodied ticks of the Ornithodoros genus, which typically feed quickly and are often found in rodent-infested cabins, campsites, or rustic buildings in the western United States and parts of Canada.

The IgG antibody test for Borrelia hermsii measures your body's longer-term immune response to this pathogen. IgG antibodies typically appear weeks after infection and can remain in the bloodstream for months or years after exposure.

What Does a Medium Result Mean?

A medium IgG result for Borrelia hermsii indicates a moderate level of antibodies, which may reflect:

• Previous exposure to the bacterium

• An early IgG response in the transition from active to resolved infection

• A nonspecific or borderline immune signal, particularly if no symptoms are present

Medium results should be interpreted in the context of your symptoms, risk factors, and other test results, such as IgM antibodies or PCR testing.