BABCOCK UNIVERSITY COURSE: MLSM 505 TOPIC: SPIROCHAETES: BORRELIA

Characteristics: Borrelia organisms are weakly Gram negative, loosely coiled spiral organisms. They are larger than the other two genera of spirochaetes, measuring about 0.2 – 0.5 x 10 – 30 um. They are can be grown anaerobically in artificial medium in the laboratory.   Type species: B. recurrentis. Others of medical importance: B. duttoni, B. hermsii B. vincenti and B. burgdorferi.

 Pathogenicity B. recurrentis causes the European relapsing fever that is world wide. It is transmitted from person to person by the human body louse. B. duttoni causes the East African relapsing fever that is transmitted to humans by soft ticks. B. hermsii causes the American relapsing fever, transmitted by soft ticks. B. vincenti inhabit the oral cavity especially in persons with poor dental hygiene. It is associatd with gingivostomattis and Vincent’s angina.

B. burgdorferi causes Lyme disease, a severe condition of fever, headache, stiff neck and typical skin lesions that if untreated, leads to neurological and cardiac complications. It is transmitted by the species of hard tick Ixodes dammini. It is seen in the USA. Laboratory diagnosis  Specimen: Oral swab is required for B. vincenti. Perpheral blood is needed for other species.  

For B. burgdorferi, skin lesion, blood and even CSF may be cultured   Microscopy: B. vincenti is stained with Gram stain but a better stain is dilute ((1:10) carbol fuchsin. The other species stain well with Giemsa or Wright’s stain.   Culture: Borrelia organisms are grown with some difficulty in special media. B. burgdorferi will grow in BSK ( Barbour, Stoenner and Kelly ) medium incubated microaerophilically at 340C.

Mouse inoculation: 1 – 2ml of patient’s blood may be injected intraperitoneally into a young white mouse. The mouse blood examined after 48 hours under a DG microscope or after staining with Giemsa stain. Mid gut of tick may also be examined for the presence of the spirochaetes.

  Serology: Because of the difficulty in isolating borreliae, serological tests are useful for diagnosis. ELISA and indirect immuno fluorescent antibody tests are of value where a rise in titre of IgM antibody is diagnostic.   DNA amplification: PCR is a very useful diagnostic tool.   Treatment: Most borrelia infections are effectively treated with tetracycline.