Borrelia Recurrentis

Question 1

Classification

Answer 1

Family: spirochaetaceae

Genus: Borrelia

Species: recurrentis

Question 2

Morphology

Answer 2

Irregular spirals

One or both ends pointed

Highly flexible:
Move both by rotation and twisting

Question 3

Growth characteristics

Answer 3

Microaerophilic

Grows well on CAM (chorioallantoic membrane) of chick embryos

Can survive for several months in infected blood or in culture

Question 4

Antigenic structure

Answer 4

Antigenic variation: changes in the course of a single infection

Evade host immune recognition

Causes “relapses” of fever episodes

Host immune reaction responsible for clinical disease

Question 5

Disease

Answer 5

Relapsing fever

Transmitted by louse bite

Clinical finding:

• sudden onset with chills, fever and headache
• lasts for 3 to 5 days and is followed by an afebrile period
• there are 3 to 10 of such recurrences
• during the febrile stages, organisms are present in the blood
• during the afebrile period; they are absent

Question 6

Microbiological diagnosis

Answer 6

Specimen:

Peripheral blood is obtained during the rise in fever, for smear

DME:
- dark field microscopy:
Moving rapidly among the erythrocytes (large, loosely coiled spirals)
- Wright’s or Giemsa stains

Cultures:
- it can be cultured in rich media, but the procedure is unreliable

Question 7

Treatment and prevention

Answer 7

Tetracycline, erythromycin and penicillin are recommended

PET