This is a multisystem disease caused by the spirochetes Borrelia (B.) hermsii, B. turicatae, and B. parkeri. Borrelia recurrentis is confined to the Horn of Africa and causes louse-borne, epidemic relapsing fever. Other species of Borrelia causing the endemic tick-borne variety occur in pockets in Africa, South America, and Asia. Relapsing fever does not occur in the UK.

Causes

Relapsing fever is caused by bacteria known as spirochetes, closely related to the organisms that cause Lyme disease. The bacteria may be transmitted to humans by either ticks or lice. Within two weeks of infection, affected people develop sudden-onset high fever. In louse-borne relapsing fever, the initial episode usually lasts three to six days and is usually followed by a single, milder episode.

After several cycles of fever, some people may develop dramatic central nervous system signs such as seizures, stupor, and coma. The Borrelia organism may also invade heart and liver tissues, causing inflammation of the heart muscle (myocarditis) and inflammation of the liver (hepatitis). Diffuse bleeding and pneumonia are other complications of this illness.

In the U.S., TBRF usually occurs west of the Mississippi River, particularly in the mountainous West and the high deserts and plains of the Southwest. In the mountains of California, Utah, Arizona, New Mexico, Colorado, Oregon, Washington, infections are usually caused by B. hermsii and are often acquired in cabins in forests. It is possible that the risk now extends into the southeastern United States.

Symptoms

Common symptoms are -

1. Repeating bouts of fever

2. Chills

3. Headache

4. Muscle and joint pain lasting 2 - 9 days

Treatment

The diagnosis can be confirmed by the presence of Borrelia in repeated thick and thin blood films of febrile patients stained with Giemsa or Wrights stain. More recently a quantitative buffy coat analysis has been shown to be both sensitive and specific in the diagnosis of relapsing fever.

TBRF is easily treated with one to two weeks of antibiotics. Most individuals will lose their fever within 24 hours of antibiotic treatment and return to normal within a week. Long-term complications and death due to TBRF are extremely rare.

The recommended treatment for patients is doxycycline at a dosage of 100 mg orally, twice daily for seven to 10 days, or tetracycline at a dosage of 500 mg, four times daily for seven to 10 days. When tetracycline is contraindicated a macrolide antibiotic may be prescribed. Penicillins are effective but should be given intravenously, especially when CNS involvement is suspected.