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Latest revision as of 16:39, 25 September 2020

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Roghayeh Marandi

Overview

Relapsing fever is a bacterial infection caused by several species of spirochete bacteria in the Borrelia family. TBRF is caused by more the 15 Borrelia species: Borrelia hermsii, Borrelia turicatae, Borrelia parkeri, Borrelia duttonii, Borrelia johnsonii, Borrelia miyamotoi. LBRF is caused by borrelia recurrentis which has a genome so similar to B. duttonii and B. crocidurae (causes of East and West African tick-borne relapsing fever). Humans are the sole reservoirs of Borrelia recurrentis, while small mammals (eg, pets, ground and tree squirrels, chipmunks) and reptiles (lizards, snakes, gopher tortoises) may serve as a reservoir for tickborne Borrelia species.

Causes

Common causes

Borrelia recurrentis causes louse-borne (epidemic) relapsing fever.
More than 15 additional Borrelia species can cause tick-borne (endemic) relapsing fever.Tick-borne relapsing fever (TBRF) is transmitted by the Ornithodoros tick (soft body ticks) from a small mammal reservoir and occurs in Africa, Spain, Saudi Arabia, Asia, and certain areas in the western United States and Canada

Borrelia miyamotoi disease can cause tick-borne relapsing fever but is transmitted by hard ticks. (sometimes called hard tick relapsing fever)]

Borrelia are gram-negative, helical, 8-30 11m long, 0.2-0.5 11m wide, and have 3-10 loosely coiled spirals. They are visible with light microscopy.they are flagellated and highly motile, and they divide by binary fission, with doubling times. They have a unique process of DNA rearrangement in their linear DNA. Each time the DNA is read a different antigenic marker, also known as a variable major protein, is created, which allows the organism to evade the immune system and therefore cause recurrent patterns of fever and other symptoms.

They are difficult to cultivate on artificial media. Because of frequent antigenic variation, difficult to serotype, and also identifying of Borrelia species by standard bacteriologic methods is problematic, so the nomenclature has relied on the vector specificity of these organisms.

Humans are the sole reservoirs of Borrelia recurrentis, while small mammals (eg, pets, ground and tree squirrels, chipmunks) and reptiles (lizards, snakes, gopher tortoises) may serve as a reservoir for tick-borne Borrelia species.

Louse-borne relapsing fever

Borrelia recurrentis is the only agent of louse-borne disease. Pediculus humanus, is the specific vector.

Borrelia organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. B.recurrentis infects the person via mucous membranes and then invades the bloodstream.
No animal reservoir exists
A single louse can only infect one person, but nosocomial infections are possible from contamination by infected blood.

Tick-borne Relapsing Fever

More than 15 additional Borrelia species can cause tick-borne (endemic) relapsing fever, which is transmitted to humans through the bite of infected "soft ticks" of the genus Ornithodoros. Soft ticks (family Argasidae) differ in many ways from the so-called hard. Also, Borrelia species are usually associated with specific species of ticks. For example, B. hermsii is transmitted by O. hermsi ticks, B. parkerii by O. parkeri ticks, and B. turicatae by O. turicata ticks. Each tick species has a preferred habitat and preferred set of hosts. They live in the nests of squirrels, chipmunks, and other small animals like chicken & pigs. They feed very quickly(less than a half-hour) and painlessly.
When rodents or other natural hosts vacate a cabin, humans may become the only available host. Patients usually are unaware of a tick bite or exposure.

The bacteria species associated with TBRF are:

Borrelia duttoni
Borrelia hermsii
Borrelia parkerii.
Relapsing infections are acquired from "Borrelia hermsii" or "Borrelia parkeri" can be spread from rodents, and serve as a reservoir for the infection, via a tick vector. "Borrelia hermsii" and "Borrelia recurrentis" cause very similar diseases, although the condition associated with "Borrelia hermsii" has more relapses and is responsible for more fatalities. In contrast, the disease caused by "B. recurrentis" has longer febrile and afebrile intervals and a more extended incubation period.

References

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 __NOTOC__
 {{Relapsing fever}}
-{{CMG}}
+{{CMG}} [[Roghayeh Marandi]]
+==Overview==
+[[Relapsing fever]] is a bacterial infection caused by several species of [[spirochete]] bacteria in the [[Borrelia]] family. [[Tick-borne relapsing fever|TBRF]] is caused by more the 15 [[Borrelia]] species: [[Borrelia]] hermsii, [[Borrelia]] turicatae, [[Borrelia]] parkeri, [[Borrelia]] duttonii, [[Borrelia]] johnsonii, [[Borrelia]] miyamotoi. [[Louse-borne relapsing fever|LBRF]] is caused by [[borrelia recurrentis]] which has a genome so similar to B. duttonii and B. crocidurae (causes of East and West African tick-borne relapsing fever). Humans are the sole reservoirs of [[Borrelia recurrentis]], while small mammals (eg, pets, ground and tree squirrels, chipmunks) and reptiles (lizards, snakes, gopher tortoises) may serve as a reservoir for [[Tick-born illness|tickborne]] [[Borrelia]] species.
-==Overview==
 ==Causes==
-===Infection===
+===Common causes===
-In the United States, TBRF is caused by one of three Borrelia species: ''B. hermsii'', ''B. parkerii'', and ''B. turicatae''.  Most human illness is caused by ''B. hermsii''.
+*[[Borrelia recurrentis]] causes [[Louse-borne relapsing fever|louse-borne (epidemic) relapsing fever]].
+*More than 15 additional [[Borrelia]] species can cause [[Tick-borne relapsing fever|tick-borne (endemic) relapsing fever]].[[Tick-borne relapsing fever]] ([[Tick-borne relapsing fever|TBRF]]) is transmitted by the Ornithodoros tick (soft body ticks) from a small mammal reservoir and occurs in Africa, Spain, Saudi Arabia, Asia, and certain areas in the western United States and Canada
+[[Borrelia]] miyamotoi disease can cause [[tick-borne relapsing fever]] but is transmitted by hard ticks. (sometimes called hard tick relapsing fever)]
-The relapsing fever Borrelia spp are gram negative helical bacteria normally 0.2 to 0.5 microns in width and 5 to 20 microns in length.  They are visible with light microscopy and have the cork-screw shape typical of all spirochetes (see picture).  They have a unique process of DNA rearrangement in their linear DNA.  Each time the DNA is read a different antigenic marker, also known as a variable major protein, is created, which allows the organism to evade the immune system and therefore cause recurrent patterns of fever and other symptoms.
+*[[Borrelia]] are [[gram-negative]], helical, 8-30 11m long, 0.2-0.5 11m wide, and have 3-10 loosely coiled spirals. They are visible with light microscopy.they are [[Flagellate|flagellated]] and highly [[motile]], and they divide by [[binary fission]], with doubling times. They have a unique process of [[DNA]] rearrangement in their [[DNA|linear DNA]]. Each time the [[DNA]] is read a different [[antigenic]] marker, also known as a variable major protein, is created, which allows the organism to evade the [[immune system]] and therefore cause recurrent patterns of [[fever]] and other symptoms.
-Borrelia is transmitted to humans through the bite of infected soft ticks of the genus Ornithodoros.  Soft ticks (family Argasidae) differ in many ways from the so-called hard [[tick]]s (family [[Ixodidae]]), including the more familiar dog tick and deer tick.
+*They are difficult to cultivate on artificial media. Because of frequent [[antigenic variation]], difficult to [[serotype]], and also identifying of  [[Borrelia]] species by standard bacteriologic methods is problematic, so the nomenclature has relied on the [[vector]] specificity of these organisms.
-[[Image:Ornithodoros hermsi.jpg|left|frame|Ornithodoros hermsi]]
-In contrast to hard ticks, soft ticks take brief blood meals lasting less than a half hour, usually at night.  Between meals the ticks live in the nesting materials in their host burrows.  Individual ticks will take many such blood meal during each stage of their life cycles, including the development of eggs by adult females. The bites of soft ticks are usually painless and the persons who are bitten while asleep are usually unaware that they were bitten.
-The individual Borrelia species that cause TBRF are usually associated with specific tick vectors.  For instance, ''B. hermsii'' is transmitted to humans by ''O. hermsi'' ticks, while ''B. parkerii'' is transmitted by ''O. parkeri'' and ''B. turicatae'' is transmitted by ''O. turicata''.  Each tick has a preferred environment and preferred set of hosts.  ''O. hermsi'' tends to be found at higher altitudes (1500 – 8000 feet) where it is associated primarily with ground or tree squirrels and chipmunks.  ''O. parkeri'' occurs at lower altitudes, where they inhabit caves and the burrows of ground squirrels and prairie dogs, as well as those of burrowing owls.  ''O. turicata'' occurs in caves and ground squirrel or prairie dog burrows in the plains regions of the Southwest, feeding off these animals and occasionally burrowing owls or other burrow- or cave-dwelling animals.
+*Humans are the sole reservoirs of [[Borrelia recurrentis]], while small [[mammals]] (eg, pets, ground and tree squirrels, chipmunks) and [[reptile]]s (lizards, snakes, gopher tortoises) may serve as a reservoir for [[Tick-borne relapsing fever|tick-borne Borrelia species]].
-In the tick, Borrelia can be found in all the tissues including salivary glands and ovaries of certain subspecies of ticks (Schwan and Piesman 2002).  Infected Ornithodoros ticks can transmit relapsing fever spirochetes to humans through their saliva while feeding.  ''O. turicatae'' and ''O. parkeri'' ticks also can transmit spirochetes through secretion of infectious fluids from their coxal glands, which are excretory organs located at the base of the ticks' legs.  ''O. hermsi'' also secretes infectious coxal fluid but in such small amounts that it dries very quickly after being secreted and, therefore, poses little or no threat to its hosts.  Since the infection is also in the ovaries of certain ticks, such as O. hermsi, they can transmit their infections over many generations from female ticks to their offspring.  Soft ticks can live up to 10 years.  In certain parts of the Russia the same tick has been found to live almost 20 years.
 ====Louse-borne relapsing fever====
-''Borrelia recurrentis'' is the only agent of louse-borne disease. ''[[Pediculus humanus]]'', is the specific vector. Louse-borne relapsing fever is more severe than the tick-borne variety.
+[[Borrelia recurrentis]] is the only agent of louse-borne disease. [[Pediculus humanus]], is the specific vector.
+*[[Borrelia]] organisms that then multiply in the [[gut]] of the [[louse]]. When an infected [[louse]] feeds on an uninfected human, the organism gains access when the victim [[crushes]] the louse or scratches the area where the louse is feeding. [[Borrelia recurrentis|B.recurrentis]] infects the person via [[mucous membranes]] and then invades the [[bloodstream]].
-Louse-borne relapsing fever occurs in [[epidemics]] amid poor living conditions, famine and war in the developing world;<ref name=Cutler_2006>{{cite journal |author=Cutler S |title=Possibilities for relapsing fever reemergence |journal=Emerg Infect Dis |volume=12 |issue=3 |pages=369-74 |year=2006 |pmid=16704771}}</ref> it is currently prevalent in Ethiopia and Sudan.
+*No animal reservoir exists
+*A single louse can only infect one person, but [[nosocomial]] infections are possible from [[contamination]] by infected blood.
-Mortality rate is 1% with treatment; 30-70% without treatment. Poor prognostic signs include severe [[jaundice]], severe change in mental status, severe [[bleeding]], and prolonged [[QT interval]] on [[ECG]].
-''Borrelia'' species causing relapsing fever include ''Borrelia recurrentis'', caused by human body louse. No animal reservoir exists. Lice that feed on infected humans acquire the ''Borrelia'' organisms that then multiply in the gut of the louse. When an infected louse feeds on an uninfected human, the organism gains access when the victim crushes the louse or scratches the area where the louse is feeding. ''B. recurrentis'' infects the person via mucous membranes and then invades the bloodstream.
 ====Tick-borne Relapsing Fever====
+*More than 15 additional [[Borrelia]] species can cause [[Tick-borne relapsing fever|tick-borne (endemic) relapsing fever]], which is transmitted to humans through the bite of infected "soft ticks" of the genus Ornithodoros. Soft ticks (family Argasidae) differ in many ways from the so-called hard. Also, [[Borrelia]] species are usually associated with specific species of ticks. For example, B. hermsii is transmitted by O. hermsi [[ticks]], B. parkerii by O. parkeri [[ticks]], and B. turicatae by O. turicata [[ticks]]. Each tick species has a preferred habitat and preferred set of hosts. They live in the nests of squirrels, chipmunks, and other small animals like chicken & pigs. They feed very quickly(less than a half-hour) and [[painlessly]].
-Other relapsing infections are acquired from other ''Borrelia'' species, such as ''Borrelia hermsii'' or ''Borrelia parkeri'', which can be spread from rodents, and serve as a reservoir for the infection, via a [[tick]] vector. ''Borelia hermsii'' and ''Borrelia recurrentis'' cause very similar diseases although the disease associated with ''Borrelia hermsii'' has more relapses and is responsible for more fatalities, while the disease caused by ''B. recurrentis'' has longer febrile and afebrile intervals and a longer incubation period.
+*When rodents or other natural hosts vacate a cabin, humans may become the only available host. Patients usually are unaware of a [[tick bite]] or exposure.<br>
+The bacteria species associated with [[Tick-borne relapsing fever|TBRF]] are:
-Tick-borne relapsing fever is found primarily in Africa, Spain, Saudi Arabia, Asia, and certain areas in the Western U.S. and Canada. Most cases occur in the summer months and are associated in particular with sleeping in rustic cabins in mountainous areas of the Western United States.  There are approximately 25 cases of TBRF in the United States each year.
+*Borrelia duttoni
+*Borrelia hermsii
+*Borrelia parkerii.
+*Relapsing infections are acquired from "Borrelia hermsii" or "Borrelia parkeri" can be spread from [[Rodent|rodents]], and serve as a reservoir for the infection, via a [[tick]] [[vector]]. "Borrelia hermsii" and "Borrelia recurrentis" cause very similar diseases, although the condition associated with "Borrelia hermsii" has more [[relapse|relapses]] and is responsible for more fatalities. In contrast, the disease caused by "B. recurrentis" has longer [[febrile]] and [[afebrile]] intervals and a more extended [[incubation period]].
+[[Image:Ornithodoros hermsi.jpg|left|frame|Ornithodoros hermsi]][[File:Transmission of tick born.gif]]
 ==References==
 {{Reflist|2}}
-[[Category:Needs content]]
+[[Category:Needs overview]]
 [[Category:Bacterial diseases]]
 [[Category:Zoonoses]]
 [[Category:Infectious diseases]]