Table 2

Tick-borne spotted fever group rickettsiae of unknown pathogenicity and nonvalidated, incompletely described, or uncultivated species isolated or detected in ticks

Rickettsia species or strainAssociated tick(s)Comment(s)Geographical distributiona
Rickettsia aeschlimannii-like Amblyomma tigrinum Reported in Bolivia; very similar to Old Word R. aeschlimannii South America
Strain AL Amblyomma longirostre Reported in bird ticks in Brazil; could be R. amblyommii South America
Candidatus Rickettsia amblyommii” Amblyomma americanum, Amblyomma cajennense, Amblyomma oblongoguttatum, Amblyomma ovale, Rhipicephalus microplus, Rhipicephalus sanguineus, Dermacentor nitens, Amblyomma maculatum U.S., Costa Rica, and Panama; very common and widely distributed in A. americanum ticks in the U.S., with avg infection frequencies of40-70%; pathogenic potential unknownNorth and Central America
Amblyomma cajennense, Amblyomma coelebs, Amblyomma neumanni, Amblyomma longirostre, Amblyomma geayi, Amblyomma auricularium Possibly associated with animal infection in Brazil; also reported in Argentina and French GuyanaSouth America
Candidatus Rickettsia andeanae” Amblyomma maculatum Occurs in A. maculatum ticks in the southeastern U.S.; recently isolated in cell culture, but pathogenic potential is unknownNorth and Central America
Amblyomma maculatum, Amblyomma parvum, Amblyomma pseudoconcolor, Amblyomma triste, Ixodes boliviensis Reported in ticks from Peru and Chile; in Argentinean ticks, reported as Rickettsia sp. strain ArgentinaSouth America
Strain ApPR Amblyomma parkeri Reported in bird ticks in Brazil; genetically related to R. parkeri, R. africae, and R. sibirica South America
Rickettsia antechini Ixodes antechini AustraliaAustralia
Strain Aranha Amblyomma longirostre Reported in bird ticks in Brazil; could be R. amblyommii South America
Rickettsia argasii Argas dewae AustraliaAustralia
Rickettsia asiatica Ixodes ovatus, Ixodes pomerantzevi Found in the blood of sika deer in JapanAsia
Rickettsia sp. AvBat Argas vespertilionis Europe
Candidatus Rickettsia barbariae” Rhipicephalus turanicus Europe
Rickettsia bellii Amblyomma sabanerae, Dermacentor occidentalis, Dermacentor variabilis, Dermacentor parumapertus, Dermacentor albipictus, H. leporispalustris, Argas cooleyi, Ornithodoros concanensis Sporadically distributed throughout the U.S. and described recently in El Salvador; rabbits and guinea pigs develop eschars following subcutaneous inoculation; no known cases of illness in humansNorth and Central America
Various species of Amblyomma, Haemaphysalis juxtakochi, Ixodes loricatus Represents a distinct basal group within the rickettsiae; it is the rickettsia with the greatest variety of tick hosts in South America; reported in Argentina, Brazil, and PeruSouth America
Rickettsia canadensis Haemaphysalis leporispalustris Canada and U.S.; elicits a febrile response in guinea pigs and rickettsemias of several-days' duration in meadow mice and baby chicks; suspected to cause illness in humans, but there have been no confirmed casesNorth and Central America
Strain Colombianensi Amblyomma dissimile, Rhipicephalus microplus Reported in Colombia; genetically related to R. tamurae and R. monacensis South America
Candidatus Rickettsia cooleyi” I. scapularis Occurs at very high frequencies and broadly distributed in I. scapularis ticks across the eastern, upper Midwestern, and southern U.S.; may represent an endosymbiontNorth and Central America
Strain COOPERI Amblyomma dubitatum (reported as Amblyomma cooperi)Reported in capybara ticks in Brazil; genetically related to R. parkeri, R. africae, and R. sibirica South America
Rickettsia sp. strain Davousti Ixodes ricinus, Ixodes lividus Ticks from migratory birdsEurope
Rickettsia sp. strain Davousti Amblyomma tholloni Closely related to R. heilongjiangensis Sub-Saharan Africa
Rickettsia derrickii Bothriocroton hydrosauri Australia
Rickettsia sp. strain DmS1 Dermacentor Europe
Rickettsia gravesii sp. nov. Amblyomma triguttatum Australia
Rickettsia sp. strains G021 and G022 Ixodes pacificus Northern California; possibly identical to Grants Pass or Tillamook strain isolated in Oregon and California in the late 1970s and early 1980s; pathogenic potential is unknownNorth and Central America
Candidatus Rickettsia goldwasserii” Haemaphysalis adleri, Haemaphysalis parva IsraelAsia
Rickettsia guntherii Haemaphysalis humerosa AustraliaAustralia
Rickettsia hoogstraalii Carios capensis JapanAsia
Haemaphysalis punctata, Haemaphysalis sulcata Europe
Argas persicus, Ornithodoros moubata Sub-Saharan Africa
Rickettsia sp. strain IG-1 Ixodes granulatus Taiwan, JapanAsia
Rickettsia sp. strain IXLI1 Ixodes lividus Closely related to R. japonica Europe
Koala rickettsia Bothriocroton concolor AustraliaAustralia
Candidatus Rickettsia kotlanii”Ixodid ticks Europe
Candidatus Rickettsia kulagini” Rhipicephalus sanguineus Europe
Rickettsia sp. clone KVH-02-3H7 Ixodes ricinus Europe
Candidatus Rickettsia liberiensis” Ixodes muniensis Closely related to R. raoultii Sub-Saharan Africa
Rickettsia montanensis Dermacentor andersoni U.S. and Canada; no known cases of illness in humansNorth and Central America
Dermacentor variabilis
Amblyomma americanum
Rickettsia monteiroi Amblyomma incisum Recently described in Brazil; joined to R. bellii and R. canadensis in the most basal group of tick-associated rickettsiaeSouth America
Candidatus Rickettsia moreli” Ixodes ricinus Europe
Strain NOD Amblyomma nodosum, Amblyomma calcaratum, Amblyomma longirostre Reported in bird ticks in Brazil; genetically related to R. parkeri, R. africae, and R. sibirica South America
Strain Pampulha Amblyomma dubitatum Reported in Brazil; genetically related to R. tamurae and R. monacensis South America
Rickettsia sp. strain Parumapertus Dermacentor parumapertus Western U.S.; causes mild to moderately severe disease in guinea pigsNorth and Central America
Rickettsia peacockii Dermacentor andersoni Western U.S. and Canada; closely related to R. rickettsii but considered a nonpathogenic endosymbiontNorth and Central America
Candidatus Rickettsia principis” Haemaphysalis japonica douglasi, Haemaphysalis danieli Russian Far East, northeastern ChinaAsia
Rickettsia sp. RDla440 Dermacentor auratus ThailandAsia
Rickettsia sp. RDla420 Dermacentor spp.ThailandAsia
Rickettsia rhipicephali Rhipicephalus haemaphysaloides TaiwanAsia
Rhipicephalus sanguineus
Rhipicephalus lunulatus, Rhipicephalus composites group Sub-Saharan Africa
Rhipicephalus sanguineus, Dermacentor occidentalis, Dermacentor variabilis, Dermacentor andersoni U.S.; causes moderately severe illness when inoculated into meadow voles; no known cases of illness in humansNorth and Central America
Haemaphysalis juxtakochi Infects ticks from the Brazilian Amazon and Atlantic rainforestsSouth America
Candidatus Rickettsia rioja” Dermacentor marginatus Europe
Rickettsia sauri Amblyomma hydrosauri AustraliaAustralia
Candidatus Rickettsia siciliensis” Rhipicephalus turanicus Europe
Candidatus Rickettsia tarasevichiae” Ixodes persulcatus Russia and JapanAsia
Rickettsia tasmanensis Ixodes tasmani AustraliaAustralia and Pacific
Rickettsia sp. strain Uilenbergi Amblyomma tholloni Closely related to the R. massiliae groupSub-Saharan Africa
Candidatus Rickettsia vini” Ixodes arboricola, Ixodes ricinus Europe
Rickettsia sp. Rhipicephalus (Boophilus) spp.LaosAsia
Rickettsia sp. Ixodes persulcatus Northern ChinaAsia
Rickettsia sp. Rhipicephalus turanicus Closely related to but distinct from the R. rhipicephali-R. massiliae lineageEurope
Rickettsia sp. Ixodes ricinus Sister taxon of R. bellii Europe
Rickettsia sp. Ixodes ricinus High homology with R. limoniae Europe
Rickettsia sp. Ixodes ricinus Sister taxon of R. bellii Europe
Rickettsia sp. Rhipicephalus evertsi Closely related to the R. rickettsii groupSub-Saharan Africa
Rickettsia sp. Rhipicephalus sanguineus, Haemaphysalis erinacei North Africa
Rickettsia sp. from A. tuberculatum (148) Amblyomma tuberculatum Southern U.S.; genetically similar to R. parkeri, R. africae, and R. sibirica; pathogenic potential unknownNorth and Central America
  • a See figures.