Borrelia burgdorferi

It is the causative agent of the famous Lyme disease. They are motile with endoflagella and are arranged in wide spiral forms. Cases are most commonly seen in Connecticut, Wisconsin, New York, New Jersey, etc. Lyme disease is acquired by the bite of Ixodes tick. It starts as a characteristic rash called erythema chronicum migrans or “bull’s eye” lesions, fever, headache followed by arthritis, meningitis, encephalitis, myocarditis, heart block and bilateral facial palsy in untreated cases. It evades immune attack by antigenic variations in the outer surface proteins.

Antibody detection by ELISA, immunofluorescence tests, and confirmed by Western Blot or PCR for nucleic acids is the mainstay of laboratory diagnosis. Culture is not preferred as it is difficult to grow. Giemsa stained smears of samples, dark field microscopy showing motile, coiled bacteria; phase contrast microscopy; silver impregnation staining for immunofluorescence can be done. Borrelia do not take the Gram stain.