Relapsing fever is an infection caused by bacteria in the Borrelia family, and has two major forms. Tick-borne relapsing fever is transmitted by the Ornithodoros tick and occurs in Africa, Spain, Saudi Arabia, Asia and certain areas in the western US and Canada. Louse-borne relapsing fever (transmitted by body lice) is prevalent in the developing world (Asia, Africa, and Central and South America).
Within 2 weeks of infection, individuals develop the sudden onset of high fever. In louse-borne relapsing fever, the initial episode usually lasts 3 to 6 days and is usually followed by a single, milder episode. In tick-borne relapsing fever, multiple episodes of fever occur and each may last up 3 days. Individuals may be free of fever for up to 2 weeks prior to a repeated episode of fever.
In both forms, the fever episode may end by crisis which consists of shaking chills, followed by intense sweating, falling temperature and low blood pressure -- this stage may result in death in up to 10% of individuals.
Some individuals after several cycles of fever 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.
|