Relapsing Fever
Introduction.
Relapsing fever is caused by members of the genus Borrelia. There are 2 forms
of relapsing fever - epidemic, transmitted by the human body louse, and endemic,
spread by ticks. Endemic RF is a zoonotic disease. Relapses occur because
these spirochaetes alter their cell surface proteins through antigenic shift.
Summary
Epidemic (louse-borne) relapsing fever
- Cause: Borrelia recurrentis
- Microscopy: Gram-negative spirals
- Transmission: Human-to-human via body lice (vector)
- Symptoms: 1 week incubation, then shaking chills, fever, headache,
muscle ache; After 3 - 7 days symptoms resolve, then recur after 1 week.
After this, they resolve.
- Complications: enlarged liver & spleen; mortality up to 40% if
patient is in poor health
- Pathogenesis: Endotoxin release due to antibody-mediated lysis of
Borrelia
- Treatment: Tetracycline or erythromycin
Endemic (tick-borne) relapsing fever
- Cause: Borrelia spp.
- Microscopy: Gram-negative spirals
- Transmission: Ticks (vector); Reservoir = rodents; ticks (zoonotic)
- Symptoms: 1 week incubation, then shaking chills, fever, headache,
muscle ache; After 3 - 7 days symptoms resolve, then recur after 1 week. Can
recur again and again.
- Complications: enlarged liver & spleen; mortality up to
5%
- Pathogenesis: Endotoxin release due to antibody-mediated lysis of
Borrelia
- Treatment: Tetracycline or erythromycin