Borreliae Clinical Manifestations

Study Notes

Causes relapsing fever with an incubation period of 2 to 15 days.
Massive spirochetemia develops and remains high throughout the course of infection.
Sudden symptoms appear, including:
- High temperature
- Rigors
- Severe headache
- Muscle pain
- Weakness
Febrile period lasts about 3 to 7 days and ends abruptly with the development of an adequate immune response.
Disease recurs several days to weeks later, following a less severe but similar course.
Febrile periods worsen during spirochetemia and wane as the immune response clears the bacteria from circulation.

What is the incubation period of Borrelia recurrentis infection?
What is the duration of the febrile period in Borrelia recurrentis infection?
What are the sudden symptoms that appear in Borrelia recurrentis infection?
What happens to the febrile periods as the immune response clears the bacteria from circulation?

Two varieties of relapsing fever exist: tickborne (endemic relapsing fever) and louseborne (epidemic relapsing fever)
Tickborne relapsing fever is transmitted by the bite of soft ticks of the genus Ornithodoros
Louseborne relapsing fever is transmitted by crushed and scratched into the skin of the body louse, Pediculus humanus
Humans are the only reservoir for relapsing fever
Best prevention and control measure is to control exposure to the arthropod vectors

Microscopic examination involves direct examination of spirochetes in blood using thick and thin films of Giemsa or Wright-stained smears
Brightfield microscopy is used to visualize spirochetes, which are commonly seen among the red cells present
Culture can be done using Kelly medium, and animal inoculation is rarely used
Serology is difficult and impractical for diagnosis

Tetracyclines are the drugs of choice for treating relapsing fever
Death of spirochetes can cause sudden endotoxin release, leading to Jarisch-Herxheimer reaction
Symptoms of Jarisch-Herxheimer reaction include fever, chills, headache, and myalgia

Bacterial spread occurs through binding of plasminogen and urokinase-type plasminogen activator to its surface
This binding can act as a protease to promote tissue invasion
Complement evasion occurs through binding of factor H
Organisms can stimulate proinflammatory cytokines, including necrosis factor and interferons

Lyme disease is complex and consists of three stages: early infection (two stages) and late infection (one stage)
Stage 1 of Lyme disease is characterized by early infection, which includes erythema migrans (EM) in about 60% of patients
EM is a classic skin lesion that appears as a red macule at the site of the tick bite, expanding to form a larger annular erythema with a target appearance