From IDWiki
Species Disease Vector Geographic Area Eschar Rash Lymphadenopathy Other Symptoms Mortality
Rickettsiae: Spotted Fever Group (Tick-Borne)
Rickettsia rickettsii Rocky Mountain spotted fever Multiple Dermacentor, Amblyomma, and Rhipicephalus Americas rare yes; centripetal no fever >15%
Rickettsia conorii Boutonneuse fever, Mediterranean spotted fever Rhipicephalus sanguineus Southern Europe, Africa, and southern Asia frequent maculopapular no fever 2-7%
Rickettsia africae African tick-bite fever Amblyomma hebraeum and Amblyomma variegatum Africa and the West Indies frequent and often multiple papular or vesicular; may be absent yes fever ≤1%
Rickettsia parkeri maculatum disease Amblyomma maculatum Americas yes often yes fever ≤1%
Rickettsia japonica oriental spotted fever Dermacentor, Haemaphysalis, or Ixodes Asia yes yes
Rickettsia sibirica mongolitimonae Rhipicephalus sanguineus Europe, Africa and Asia yes yes
Rickettsia sibirica sibirica Dermacentor Asia or southern Russia yes yes
Rickettsia australis Ixodes Australia yes yes, vesicular
Rickettsia slovaca tick-borne lymphadenopathy Dermacentor marginatus Europe yes, often on scalp regional lymphadenopathy
Rickettsia honei Bothriocroton, Haemaphysalis, Ixodes, or Rhipicephalus Flinders Islands, eastern Australia, Thailand, or Nepal yes yes
Rickettsia aeschlimanii Hyalomma or Rhipicephalus Africa and Europe yes yes
Rickettsia helvetica ticks
Rickettsia heilongjianghensis Dermacentor or Haemaphysalis Asia yes yes
Rickettsia raoultii Dermacentor Europe yes, often on scalp regional lymphadenopathy
Rickettsia massiliae Rhipicephalus sanguineus Europe, Africa, and the Americas yes yes
Rickettsia amblyommii ticks
Rickettsia monacensis ticks
Rickettsia philipii strain 364D Dermcentor occidentalis California yes, often on scalp regional lymphadenopathy
Rickettsiae: Spotted Fever Group (Flea-, Louse, and Mite-Borne)
Rickettsia felis Flea flea exposure yes yes
Rickettsia akari rickettsialpox Liponyssoides sanguineus house mouse mites worldwide yes yes, vesicular yes fever ≤1%
Rickettsiae: Typhus Group
Rickettsia typhi endemic (murine) typhus Xenopsylla cheopis (rat flea) and Ctenocephalides felis (cat flea) tropics or subtropics, with flea exposure may or may not yes, centrifugal
Rickettsia prowazekii epidemic (louse-borne) typhus Pediculus humanus humanus (human body louse) and the fleas and live of flying squirrels United States, especially homeless shelters no yes, centrifugal no fever ≤1% to >15%
Rickettsiae: Scrub Typhus Group
Orientia tsutsugamushi scrub typhus Leptotrombidium mites (chiggers, trombiculid mites) Asian Pacific, Chile, and Dubai yes yes
Amblyomma phagocytophilum human granulocytotropic anaplasmosis ticks
Ehrlichia chaffeensis human monocytotropic ehrlichiosis Amblyomma americanum ticks (the Lone Star tick)
Ehrlichia ewingii human monocytotropic ehrlichiosis Amblyomma americanum and Dermacentor variabilis ticks
Ehrlichia canis ticks
Other Related Organisms
Neoehrlichia mikurensis ticks
Neorickettsia sennetsu raw fish
Wolbachia helminths


  • The mainstay of diagnosis is serology
    • Indirect immunofluorescence antibody assays of IgG antibodies
      • IgM do not appear any earlier in the course of disease and are less specific
    • Usually as acute and convalescent titres drawn 2 to 4 weeks apart showing a 4-fold increase in titres
    • Cross-reactivity is common within each group
  • PCR is becoming more widely available
    • Blood and tissue (e.g. eschar biopsy)
    • Done as PCR for the group followed by species-specific sequencing


Further Reading

  • Syndromic classification of rickettsioses: an approach for clinical practice. Int J Infect Dis. 2014;28:126-39. doi: 10.1016/j.ijid.2014.05.025