Johns Hopkins ABX Guide
Rickettsia species
Rickettsia species is a topic covered in the Johns Hopkins ABX Guide.
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MICROBIOLOGY
- Obligate intracellular, small Gram-negative rod; genus Rickettsia
- An expanding number of species cause human infection.
- Transmitted by a variety of hematophagous arthropods: ticks, mites, lice, chiggers, fleas.
- Most Rickettsia spp. have a geographic distribution.
- R. typhi (murine or endemic typhus), worldwide.
- Divided into the spotted fever group (SFG) and typhus group (TG).
- Organisms infect endothelial cells, whose dysfunction leads to severe manifestations of the disease.
- Rickettsial species and associated arthropod vectors: list continues to grow, >15 known species causing human infection (number below by no means complete).
- Spotted Fever Group Rickettsia (SPGR):
- North American species of interest:
- R. rickettsii (Rocky Mt spotted fever, RMSF): tick, Western hemisphere (Dermacentor spp., dog and wood ticks and others).
- See separate Rickettsia rickettsii module for details on this pathogen.
- R. parkeri (American Boutonneuse fever): Gulf Coast tick (Amblyomma maculatum) or Lone Star tick (A. americanum).
- Febrile illness often with an eschar at the site of the tick bite.
- R. philipiii (previously known as Rickettsial spp. 364D): transmitted by Dermacentor occidentalis (Pacific Coast tick)
- Cases to date only describe in California but tick vector ranges the West Coast.
- R. rickettsii (Rocky Mt spotted fever, RMSF): tick, Western hemisphere (Dermacentor spp., dog and wood ticks and others).
- Worldwide: list not comprehensive, consider in returning travelers to the U.S.
- R. akari (Rickettsialpox): mite (Lioponyssoides sanguineus, ectoparasite of house mice)
- Seen in the U.S. and former states of the USSR.
- Urban disease
- Closely related, but no longer considered part of the SFGR.
- R. australis (Australian tick typhus): I. holochyclus and I. tasmani host but only I. holochyclus aka the Australian paralysis tick, believed to frequently bite humans.
- R. felis: flea-borne spotted fever
- Increasingly common and described in the Americas, Europe, Africa, SE Asia and Australia.
- R. conorii (Mediterranean spotted fever, MSF): dog tick (Rhipicephalus and Haemaphysalis genera)
- Seen most commonly in the Mediterranean, India, Asia (Southwest) and Africa.
- Subspecies:
- R. conorii conorii: MSF
- R. conorii caspia: endemic in Astrakhan region near Caspian sea
- R. conorii indica: endemic in India, eschar rare
- R. conorii isrealensis: eschar less frequent than MSF.
- R. africae (African tick-bite fever): ticks (Amblyomma hebraeum, A. variegatum)
- Mostly Southern Africa.
- Most common rickettsial infection seen in travelers to Africa.
- R. japonica (oriental spotted fever): At least six tick species implicated.
- Japan
- R. raoulti: dog tick (Dermacentor reticulatus)
- Described in Europe, Eastern Europe.
- May cause SENLAT syndrome (scalp eschar, neck lymphadenopathy after tick bite)
- R. sibirica (Siberian tick typhus, North Asian tick typhus): multiple tick vectors
- Siberia, Northern China, Mongolia
- R. slovaca: transmitted by dog ticks, Dermacentor spp.
- Associated with tick-borne lymphadenopathy (TIBOLA)
- R. akari (Rickettsialpox): mite (Lioponyssoides sanguineus, ectoparasite of house mice)
- North American species of interest:
- Typhus Group:
- R. prowazekii (epidemic typhus): lice-transmitted.
- Body louse (Pediculus humanus var. corporis)
- Worldwide
- Also, occasionally transmitted in North America by flying squirrel (Glaucomys volans)
- Sporadic, 39 cases in the US (1976-2001)
- R. typhi (murine/endemic typhus): global distribution, transmitted by fleas.
- Rat flea (Xenopsylla cheopsis) and cat flea (Ctenocephalides felis).
- Usually tropical, subtropical in distribution.
- R. prowazekii (epidemic typhus): lice-transmitted.
- Scrub Typhus Group: reclassified from Rickettsia to Orientia.
- Orientia tsutsugamushi (formerly R. tsutsugamushi, Tsutsugamushi disease, aka scrub typhus): transmitted by chiggers
- Southeast Asia.
- Can be a severe illness, similar to RMSF.
- Orientia tsutsugamushi (formerly R. tsutsugamushi, Tsutsugamushi disease, aka scrub typhus): transmitted by chiggers
- Spotted Fever Group Rickettsia (SPGR):
- Rickettsial susceptibility testing not routinely performed given the difficulty of culture.
- The reference standard is the dilution method using a plaque assay system (cell culture).
-- To view the remaining sections of this topic, please log in or purchase a subscription --
MICROBIOLOGY
- Obligate intracellular, small Gram-negative rod; genus Rickettsia
- An expanding number of species cause human infection.
- Transmitted by a variety of hematophagous arthropods: ticks, mites, lice, chiggers, fleas.
- Most Rickettsia spp. have a geographic distribution.
- R. typhi (murine or endemic typhus), worldwide.
- Divided into the spotted fever group (SFG) and typhus group (TG).
- Organisms infect endothelial cells, whose dysfunction leads to severe manifestations of the disease.
- Rickettsial species and associated arthropod vectors: list continues to grow, >15 known species causing human infection (number below by no means complete).
- Spotted Fever Group Rickettsia (SPGR):
- North American species of interest:
- R. rickettsii (Rocky Mt spotted fever, RMSF): tick, Western hemisphere (Dermacentor spp., dog and wood ticks and others).
- See separate Rickettsia rickettsii module for details on this pathogen.
- R. parkeri (American Boutonneuse fever): Gulf Coast tick (Amblyomma maculatum) or Lone Star tick (A. americanum).
- Febrile illness often with an eschar at the site of the tick bite.
- R. philipiii (previously known as Rickettsial spp. 364D): transmitted by Dermacentor occidentalis (Pacific Coast tick)
- Cases to date only describe in California but tick vector ranges the West Coast.
- R. rickettsii (Rocky Mt spotted fever, RMSF): tick, Western hemisphere (Dermacentor spp., dog and wood ticks and others).
- Worldwide: list not comprehensive, consider in returning travelers to the U.S.
- R. akari (Rickettsialpox): mite (Lioponyssoides sanguineus, ectoparasite of house mice)
- Seen in the U.S. and former states of the USSR.
- Urban disease
- Closely related, but no longer considered part of the SFGR.
- R. australis (Australian tick typhus): I. holochyclus and I. tasmani host but only I. holochyclus aka the Australian paralysis tick, believed to frequently bite humans.
- R. felis: flea-borne spotted fever
- Increasingly common and described in the Americas, Europe, Africa, SE Asia and Australia.
- R. conorii (Mediterranean spotted fever, MSF): dog tick (Rhipicephalus and Haemaphysalis genera)
- Seen most commonly in the Mediterranean, India, Asia (Southwest) and Africa.
- Subspecies:
- R. conorii conorii: MSF
- R. conorii caspia: endemic in Astrakhan region near Caspian sea
- R. conorii indica: endemic in India, eschar rare
- R. conorii isrealensis: eschar less frequent than MSF.
- R. africae (African tick-bite fever): ticks (Amblyomma hebraeum, A. variegatum)
- Mostly Southern Africa.
- Most common rickettsial infection seen in travelers to Africa.
- R. japonica (oriental spotted fever): At least six tick species implicated.
- Japan
- R. raoulti: dog tick (Dermacentor reticulatus)
- Described in Europe, Eastern Europe.
- May cause SENLAT syndrome (scalp eschar, neck lymphadenopathy after tick bite)
- R. sibirica (Siberian tick typhus, North Asian tick typhus): multiple tick vectors
- Siberia, Northern China, Mongolia
- R. slovaca: transmitted by dog ticks, Dermacentor spp.
- Associated with tick-borne lymphadenopathy (TIBOLA)
- R. akari (Rickettsialpox): mite (Lioponyssoides sanguineus, ectoparasite of house mice)
- North American species of interest:
- Typhus Group:
- R. prowazekii (epidemic typhus): lice-transmitted.
- Body louse (Pediculus humanus var. corporis)
- Worldwide
- Also, occasionally transmitted in North America by flying squirrel (Glaucomys volans)
- Sporadic, 39 cases in the US (1976-2001)
- R. typhi (murine/endemic typhus): global distribution, transmitted by fleas.
- Rat flea (Xenopsylla cheopsis) and cat flea (Ctenocephalides felis).
- Usually tropical, subtropical in distribution.
- R. prowazekii (epidemic typhus): lice-transmitted.
- Scrub Typhus Group: reclassified from Rickettsia to Orientia.
- Orientia tsutsugamushi (formerly R. tsutsugamushi, Tsutsugamushi disease, aka scrub typhus): transmitted by chiggers
- Southeast Asia.
- Can be a severe illness, similar to RMSF.
- Orientia tsutsugamushi (formerly R. tsutsugamushi, Tsutsugamushi disease, aka scrub typhus): transmitted by chiggers
- Spotted Fever Group Rickettsia (SPGR):
- Rickettsial susceptibility testing not routinely performed given the difficulty of culture.
- The reference standard is the dilution method using a plaque assay system (cell culture).
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Last updated: September 5, 2020
Citation
Auwaerter, Paul G. "Rickettsia Species." Johns Hopkins ABX Guide, The Johns Hopkins University, 2020. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540481/all/Rickettsia_species.
Auwaerter PG. Rickettsia species. Johns Hopkins ABX Guide. The Johns Hopkins University; 2020. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540481/all/Rickettsia_species. Accessed March 25, 2023.
Auwaerter, P. G. (2020). Rickettsia species. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540481/all/Rickettsia_species
Auwaerter PG. Rickettsia Species [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2020. [cited 2023 March 25]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540481/all/Rickettsia_species.
* Article titles in AMA citation format should be in sentence-case
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T1 - Rickettsia species
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A1 - Auwaerter,Paul,M.D.
Y1 - 2020/09/05/
BT - Johns Hopkins ABX Guide
UR - https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540481/all/Rickettsia_species
PB - The Johns Hopkins University
DB - Pediatrics Central
DP - Unbound Medicine
ER -
