- Related Topics:
- tick
- Ornithodoros
- Pediculus
- Borrelia
- Borrelia recurrentis
relapsing fever
-
What is relapsing fever?
Relapsing fever is an infectious disease caused by spirochetes (spiral-shaped bacteria) of the genus Borrelia. It is characterized by recurring episodes of fever separated by periods of well-being. Spirochetes are transmitted by lice or ticks.
Symptoms of both tick and louse-borne relapsing fever are similar. After about a week of incubation, the infected person experiences a sudden onset of high fever, chills, headache, and muscle aches. These symptoms last about a week in louse-contracted cases, and less in tick-borne instances. The attack ends with sweating, low blood pressure, low temperature, and malaise, until febrile symptoms return about a week later. Additional relapses may follow.
Relapsing fever can be diagnosed through blood tests and is treatable with antibiotics such as penicillin, doxycycline, erythromycin, and tetracycline.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Which germs cause relapsing fever?
Relapsing fever is an infectious disease caused by spiral-shaped bacteria called spirochetes of the genus Borrelia. These bacteria are transmitted to humans through lice (Pediculus) and soft-bodied ticks (Ornithodoros) or hard-bodied ticks (Ixodes scapularis).
The disease presents with recurring episodes of fever, chills, headache, and muscle aches, which can persist for about a week. Additional relapses may follow, but are usually decreasing in severity, in cases contracted from ticks.
Relapsing fever can be diagnosed through blood tests and is treatable with antibiotics such as penicillin, doxycycline, erythromycin, and tetracycline.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How is relapsing fever usually spread to humans?
Relapsing fever spreads to humans through different vectors, depending on the type of the disease. Louse-borne relapsing fever transmits from person to person through lice (genus Pediculus) under conditions of crowding, cold weather, and poor hygiene, which favor the spread of lice. Tick-borne relapsing fever transmits from animals to humans through soft-bodied ticks of the genus Ornithodoros or by the hard-bodied tick Ixodes scapularis. This often occurs when people visit wooded campsites or cabins infested with rodents.
Both types of relapsing fever share similar symptoms, such as fever, chills, headache, and muscle aches.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are the main symptoms of relapsing fever?
Relapsing fever, caused by Borrelia spirochetes, presents similar symptoms whether transmitted by ticks or lice. After about a week of incubation, the disease manifests with a sudden high fever, chills, headache, and muscle aches. These symptoms typically last for about a week in louse-borne cases, and for a shorter duration in tick-borne cases.
The initial attack concludes with profuse sweating, low blood pressure, low temperature, and malaise, followed by a period of relative wellness. Febrile symptoms then return about a week later, with additional relapses possible. In louse-borne cases, relapses are rare, but in tick-borne cases, there can be as many as 12 relapses, usually decreasing in severity.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Why do the symptoms of relapsing fever come and go in cycles?
The symptoms of relapsing fever come and go in cycles because, after about a week of the spirochete living in its host, the infected person experiences a sudden onset of symptoms such as fever, chills, headache, and muscle aches. These symptoms persist for about a week in cases contracted from lice, and usually for a shorter period in the tick-borne disease. The attack ends in a crisis of profuse sweating, low blood pressure, low temperature, and malaise, after which the patient is fairly well until, about a week later, febrile symptoms return. Additional relapses may follow.
Inadequate therapy commonly results in relapse after treatment, probably because of the persistence of live spirochetes in the brain, where the drug concentration does not reach curative levels. After treatment, these protected spirochetes may reinvade the bloodstream.
1 Britannica SourceCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does relapsing fever affect the body’s organs and tissues?
Relapsing fever is an infectious disease caused by spirochetes, bacteria of the genus Borrelia, transmitted by lice and ticks. After about a week of incubation, the infected person experiences a sudden onset of high fever, chills, headache, and muscle aches. These symptoms typically last for about a week in louse-borne cases, and for a shorter period in tick-borne cases.
The attack ends with profuse sweating, low blood pressure, low temperature, and malaise, followed by a period of wellness until the return of febrile symptoms about a week later. The spirochetes may invade the central nervous system and cause neurological symptoms, such as meningitis. An enlarged liver or spleen, rashes, and inflammation of the eye and heart may also occur.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
relapsing fever, infectious disease characterized by recurring episodes of fever separated by periods of relative well-being and caused by spirochetes, or spiral-shaped bacteria, of the genus Borrelia. The spirochetes are transmitted from one person to another by lice (genus Pediculus) and from animals to humans by soft-bodied ticks of the genus Ornithodoros or by the hard-bodied tick Ixodes scapularis. Epidemics of the disease have occurred during wars, earthquakes, famines, and floods.
Tick-borne relapsing fever occurs in Africa, the Americas, Asia, and Europe and frequently is contracted by persons visiting wooded campsites or cabins that have been infested with rodents. The louse-borne disease is endemic to northeast Africa, and cases rarely occur outside the region. Louse-borne relapsing fever spreads under conditions of crowding, cold weather, and poor hygiene, all of which favour the spread of the lice that transmit the infectious organism from person to person.
Clinical course, diagnosis, and treatment
Disease onset, symptoms, and the clinical course of tick-borne and louse-borne relapsing fever are similar. After the spirochete has lived about one week in its newly infected host, the person experiences a sudden onset of high fever, chills, headache, and muscle aches. The symptoms persist for about a week in cases contracted from lice and usually for a shorter period in the tick-borne disease. The attack ends in a crisis of profuse sweating, low blood pressure, low temperature, and malaise, after which the patient is fairly well until, about a week later, febrile symptoms return. Additional relapses may follow—rarely more than one or two in the louse-borne disease but up to 12 (usually decreasing in severity) in cases contracted from ticks.
" height="20" alt="HEW Logo">
Mortality from relapsing fever is variable, ranging from nil in some tick-transmitted varieties to 6 percent or as high as 30 percent in some louse-borne epidemics associated with famine conditions. The spirochetes may invade the central nervous system and cause a variety of usually mild neurological symptoms, including meningitis. Neurological complications are more likely to occur in patients with the tick-borne disease. An enlarged liver or spleen, rashes, and inflammation of the eye and heart also may be noted in patients with relapsing fever.
A diagnosis of relapsing fever can be made by specific serological tests or by identification of the loosely coiled organism in the patient’s blood. Penicillin and other antibiotics, including doxycycline, erythromycin, and tetracycline, have proved effective against the disease. Often patients also are administered fluids parenterally to combat dehydration and electrolyte imbalance.
Inadequate therapy commonly results in relapse after treatment, probably because of the persistence of live spirochetes in the brain, where the drug concentration does not reach curative levels. After treatment these protected spirochetes may reinvade the bloodstream. Prevention by the elimination of the vectors that transmit the disease is of utmost importance.
History
Borrelia spirochetes were the first microbes to be associated clearly with serious human disease. German bacteriologist Otto Obermeier observed the organisms in the blood of relapsing fever patients in 1867–68 and published his observations in 1873. They are easily seen in dark-field microscopic preparations of the patient’s blood collected during the height of the febrile attack, but they disappear from the blood during the intervals between attacks. These observations, as well as the relapsing symptoms, have been related to changes in the antigenic characteristics of the spirochetes. As the patient develops immunity to the prevailing type and recovers from the attack, a new (mutant) type of the spirochete develops and produces the relapse. Because neither the bite nor the excreta of the louse is infectious, human infections usually result from crushing the louse on the skin while scratching.
The trusted destination for professionals, college students, and lifelong learners.
SUBSCRIBE
