The IgG antibodies against Borrelia burgdorferi in cerebrospinal fluid (CSF) test are primarily used in the diagnosis of Lyme neuroborreliosis, a neurological manifestation of Lyme disease that results from central nervous system infection by the spirochete. It is particularly valuable in cases where neurological symptoms such as facial palsy, meningitis, encephalitis, or radiculoneuritis are present and Lyme disease is suspected based on clinical or epidemiological evidence. The detection of specific IgG antibodies in CSF supports the diagnosis of chronic or subacute infection within the central nervous system. It aids in distinguishing Lyme neuroborreliosis from other inflammatory or infectious conditions of the brain and spinal cord.
Borrelia burgdorferi is a spirochetal bacterium transmitted to humans through the bite of infected ticks from the Ixodes genus. Once introduced into the host, the bacterium may disseminate from the initial site of infection and invade various tissues, including the nervous system. Neuroborreliosis develops when Borrelia bacteria cross the blood-brain barrier and induce an immune response within the central nervous system. The presence of IgG antibodies in the cerebrospinal fluid is indicative of this intrathecal immune response, which reflects local antibody production in response to persistent antigenic stimulation from Borrelia antigens.
Elevated IgG levels against Borrelia burgdorferi in CSF suggest a sustained and active immune response to infection within the central nervous system. These antibodies typically appear several weeks after the initial infection and may persist for months or even years, depending on the duration of the disease and the host’s immune status. The interpretation of IgG positivity in the CSF is most meaningful when considered alongside serum antibody levels and other indicators of intrathecal synthesis, such as the antibody index or the presence of oligoclonal bands. High levels of specific IgG in CSF, in combination with clinical signs and inflammatory changes in CSF (e.g., pleocytosis, elevated protein), strongly support the diagnosis of Lyme neuroborreliosis.
Low or undetectable levels of IgG antibodies in CSF may indicate the absence of active neuroborreliosis or an early stage of infection before intrathecal antibody synthesis begins. However, false negatives may occur, particularly in immunocompromised individuals or those treated early with antibiotics.
