| ultrastructure of rickettsia rhipicephali, a new member of the spotted fever group rickettsiae in tissues of the host vector rhipicephalus sanguineus. | rickettsia rhipicephali is similar in ultrastructure to r. rickettsii while differing from other rickettsiae of the typhus group and of q fever and others by its lack of a prominently reticulated cytoplasmic matrix and in the thickness of the inner osmophilic layer of the cell wall. in tissues of the tick vector rhipicephalus sanguineus, r. rhipicephali had a mean length and width of 1.2 and 0.46 micrometer, respectively. it possessed a trilaminar cell wall with an adhering capsule-like layer. t ... | 1979 | 570191 |
| demonstration and partial characterization of antigens of rickettsia rhipicephali that induce cross-reactive cellular and humoral immune responses to rickettsia rickettsii. | the relatively unrelated spotted fever group rickettsia rickettsia rhipicephali conferred on guinea pigs protective immunity against challenge with virulent r. rickettsii. immunity was conferred at all doses of r. rhipicephali used in the study. because of the serologic unrelatedness of these two rickettsiae, determined by the use of microimmunofluorescence and other serological assays, further studies were performed to define the nature of the immune response elicited by r. rhipicephali and the ... | 1992 | 1452343 |
| serotypes of tick-borne spotted fever group rickettsiae from western california. | a rickettsial survey of ixodid ticks known to bite man was conducted in 1979 in four coastal counties of california to obtain isolates from tick species that might be involved in the transmission of spotted fever-like illnesses, and to examine serologic characteristics of the rickettsiae relative to defined members of the spotted fever group (sfg). one hundred and seventy (19.4%) of 877 ticks comprising three species were shown by hemolymph test to harbor rickettsia-like organisms. a total of 85 ... | 1981 | 6789691 |
| citrate synthase gene comparison, a new tool for phylogenetic analysis, and its application for the rickettsiae. | using pcr and an automated laser fluorescent dna sequencer, we amplified and sequenced a 1,234-bp fragment of the citrate synthase-encoding gene (glta) of 28 bacteria belonging to the genus rickettsia. comparative sequence analysis showed that most of the spotted fever group (sfg) rickettsiae belonged to one of two subgroups. the first subgroup included rickettsia massiliae, strain bar 29, rickettsia rhipicephali, "rickettsia aeschlimanni," and rickettsia montana, which have been isolated only f ... | 1997 | 9103608 |
| phylogenetic analysis of spotted fever group rickettsiae by study of the outer surface protein rompa. | rickettsiae are classified in the order rickettsiales and have been included in the alpha subclass of the class proteobacteria on the basis of 16s rrna gene sequence comparison. to estimate the evolutionary forces that have shaped the members of the spotted fever group (sfg) rickettsiae, the ompa gene (apart from the tandem repeat units), encoding an antigenic high-molecular-mass membrane protein specific for the group, was amplified and sequenced from 21 isolates. the phylogenetic relationship ... | 1998 | 9734038 |
| molecular phylogeny and rearrangement of rrna genes in rickettsia species. | it has previously been observed that rickettsia prowazekii has an unusual arrangement of the rrna genes. in this species, the three rrna genes, 16s (rrs), 23s (rrl), and 5s (rrf), are not linked in the typical arrangements for bacteria. rather, the 16s rrna gene has been separated from the 23s and 5s rrna gene cluster, and the 23s rrna gene is preceded by a gene which codes for methionyl-trnaf(met) formyltransferase (fmt). in this study, we screened the genus rickettsia for the fmt-rrl motif in ... | 1999 | 10406115 |
| phylogeny of rickettsia spp. inferred by comparing sequences of 'gene d', which encodes an intracytoplasmic protein. | 'gene d' is the ps120-protein-encoding gene, first described in rickettsia conorii and rickettsia japonica. sequence analysis of a 3030 bp fragment of 'gene d' in 24 representatives of the genus rickettsia was carried out to complete phylogenetic analyses previously inferred by comparison of gene sequences encoding citrate synthase, 17 kda antigen and rompa and rompb. the phylogenetic relationships between rickettsiae were inferred from the comparison of both the gene and the derived protein seq ... | 2001 | 11491333 |
| rickettsial infection in dermacentor variabilis (acari: ixodidae) inhibits transovarial transmission of a second rickettsia. | this study examined the ability of ticks to maintain multiple species of spotted fever group rickettsiae via transovarial transmission. using a capillary feeding method, previously established ricketisia montana- and rickettsia rhipicephali-infected cohorts of dermacentor variabilis (say) were exposed to r. rhipicephali and r. montana, respectively, in two reciprocal challenge experiments. eggs collected from individual females, for two successive generations, of each cohort were assessed for ri ... | 2002 | 12495176 |
| infection and transovarial transmission of rickettsiae in dermacentor variabilis ticks acquired by artificial feeding. | in this study we examined the efficiency of an in vitro feeding technique using glass microcapillaries as a method of establishing rickettsiae-infected lines of ticks. to quantify the volume ingested by ticks during microcapillary feeding, the incorporation of radiolabeled amino acids in tick gut and hemolymph was calculated. fifteen of 18 ticks consumed between 0.06 and 6.77 microl. however, ingestion of fluid was not correlated to weight gain during capillary feeding. uninfected and partially ... | 2001 | 12653135 |
| detection of a spotted fever group rickettsia in the tick haemaphysalis juxtakochi in rondonia, brazil. | the tick genus haemaphysalis is represented by four species in the new world, of which only the species haemaphysalis leporispalustris has been associated with rickettsiae. the present study reports for the first time the presence of a rickettsia strain in the tick haemaphysalis juxtakochi. a free-living male of h. juxtakochi, collected in the state of rondonia, western amazon, brazil, was subjected to dna extraction and tested by pcr targeting the four rickettsial genes: glta, 17-kda, ompa and ... | 2004 | 15631911 |
| isolation of rickettsia rhipicephali and rickettsia bellii from haemaphysalis juxtakochi ticks in the state of são paulo, brazil. | in the present study, attempts to isolate rickettsia in cell culture were performed individually in seven specimens of haemaphysalis juxtakochi ticks collected in the state of são paulo (southeastern brazil). rickettsia was successfully isolated by the shell vial technique and established in vero cell culture from six ticks (six isolates). dna extracted from infected cells of these isolates was tested by pcr and dna sequencing, using genus-specific rickettsia primers targeting the genes glta, ht ... | 2007 | 17142361 |
| prevalence of rickettsia infection in dogs from the urban and rural areas of monte negro municipality, western amazon, brazil. | the present study evaluated the rickettsial infection among dogs living in the rural and urban areas of monte negro, state of rondônia, western brazilian amazon. canine sera were tested by the indirect immunofluorescence assay (ifa) using six rickettsial antigens: rickettsia bellii, rickettsia amblyommii, rickettsia rhipicephali, rickettsia rickettsii, rickettsia parkeri, and rickettsia felis. while the first three rickettsia species are known to occur in the study site, the latter three species ... | 2007 | 17627445 |
| canine infection by rickettsiae and ehrlichiae in southern brazil. | this study evaluated the infection caused by rickettsia and ehrlichia agents among dogs in southern brazil. a total of 389 dogs were tested by the indirect immunofluorescence assay (ifa) for rickettsia rickettsii, rickettsia parkeri, rickettsia amblyommii, rickettsia rhipicephali, rickettsia bellii, and ehrlichia canis. overall, 42.4% (165/389) of the dogs were seroreactive to at least one rickettsia species, but only 11 canine sera reacted with another rickettsia species without reacting with r ... | 2008 | 18606772 |
| detection of a spotted fever group rickettsia in the tick ixodes tasmani collected from koalas in port macquarie, australia. | four species of rickettsia are recognized as endemic to australia. this study reports the detection of a new spotted fever group rickettsia in the common marsupial tick ixodes tasmani neumann collected from koalas (phascolarctos cinereus) in port macquarie, nsw, australia. based on the results of polymerase chain reaction (pcr) amplification of extracted tick dna with primers targeting the citrate synthase gene (glta) and the outer membrane proteins a and b (ompa. ompb), rickettsiae were detecte ... | 2008 | 18714878 |
| ecology of rickettsia in south america. | until the year 2000, only three rickettsia species were known in south america: (i) rickettsia rickettsii, transmitted by the ticks amblyomma cajennense, and amblyomma aureolatum, reported in colombia, argentina, and brazil, where it is the etiological agent of rocky mountain spotted fever; (ii) rickettsia prowazekii, transmitted by body lice and causing epidemic typhus in highland areas, mainly in peru; (iii) rickettsia typhi, transmitted by fleas and causing endemic typhus in many countries. d ... | 2009 | 19538276 |
| rickettsia 364d: a newly recognized cause of eschar-associated illness in california. | four spotted fever group rickettsiae (sfgr) are known to infect humans in the united states. a member of the sfgr designated 364d and detected in dermacentor occidentalis ticks has not previously been identified as a human pathogen. | 2010 | 20073993 |
| rickettsial infection in domestic mammals and their ectoparasites in el valle de antón, coclé, panamá. | the present research evaluated the presence of rickettsia spp. on ectoparasites of horses and dogs (using pcr techniques), and their sera (using immunofluorescence assay) in el valle de antón town in panama. a total of 20 horses and 20 dogs were sampled, finding four species of ectoparasites on dogs (the ticks rhipicephalus sanguineus, amblyomma ovale, amblyomma oblongoguttatum, and the flea ctenocephalides felis), and two tick species on horses (amblyomma cajennense and dermacentor nitens). dna ... | 2010 | 21144663 |
| tick-borne bacteria in free-living jaguars (panthera onca) in pantanal, brazil. | abstract tick-borne bacteria were investigated in 10 free-living jaguars and their ticks in the pantanal biome, brazil. jaguar sera were tested by indirect fluorescent antibody assays using rickettsia rickettsii, rickettsia parkeri, rickettsia amblyommii, rickettsia rhipicephali, rickettsia felis, rickettsia bellii, ehrlichia canis, and coxiella burnetii as crude antigens. all 10 jaguar sera reacted (titer ≥64) to at least one rickettsia species; 4 and 3 sera reacted with e. canis and c. burneti ... | 2011 | 21612532 |
| identification of rickettsia felis in fleas but not ticks on stray cats and dogs and the evidence of rickettsia rhipicephali only in adult stage of rhipicephalus sanguineus and rhipicephalus haemaphysaloides. | rickettsia spp. are zoonotic pathogens and mainly transmitted by various arthropod vectors, such as fleas, ticks, and lice. previous epidemiological studies indicated that ectoparasites infested on dogs or cats may be infected by rickettsia spp., and transmit them to human beings accidentally. in this study, the prevalence of rickettsia infection was evaluated using fleas and ticks from stray dogs and cats in taiwan. a total of 158 pools made by 451 cat fleas (ctenocephalides felis) from 37 dogs ... | 2011 | 22000945 |
| comparative growth of spotted fever group rickettsia spp. strains in vero cells. | in brazil, the spotted fever group (sfg) rickettsia rickettsii and rickettsia parkeri related species are the etiological agents of spotted fever rickettsiosis. however, the sfg, rickettsia rhipicephali, that infects humans, has never been reported. the study of growth dynamics can be useful for understanding the infective and invasive capacity of these pathogens. here, the growth rates of the brazilian isolates r. rickettsii str. taiaçu, r. parkeri str. at#24, and r. rhipicephali hj#5, were eva ... | 0 | 27508322 |
| rickettsia vini n. sp. (rickettsiaceae) infecting the tick ixodes arboricola (acari: ixodidae). | recently, a new rickettsia named 'candidatus rickettsia vini' belonging to the spotted fever group has been molecularly detected in ixodes arboricola ticks in spain, the czech republic, slovakia and turkey, with prevalence reaching up to 100 %. the aim of this study was to isolate this rickettsia in pure culture, and to describe it as a new rickettsia species. | 2016 | 27565956 |
| seroprevalence of rickettsia spp. in equids and molecular detection of 'candidatus rickettsia amblyommii' in amblyomma cajennense sensu lato ticks from the pantanal region of mato grosso, brazil. | the aim of the study was to evaluate exposure of equids to rickettsial agents (rickettsia rickettsii, rickettsia parkeri, 'candidatus rickettsia amblyommii', rickettsia rhipicephali, and rickettsia bellii) and rickettsial infection in ticks of a pantanal region of brazil. sera of 547 equids (500 horses and 47 donkeys) were evaluated by indirect immunofluorescence assay. in total, 665 adults and 106 nymphal pools of amblyomma cajennense f. sensu lato, 10 dermacentor nitens neumann ticks, and 88 l ... | 2014 | 26309313 |
| molecular detection of rickettsia rhipicephali and other spotted fever group rickettsia species in amblyomma ticks infesting wild birds in the state of minas gerais, brazil. | the current study evaluated parasitism of wild birds by ticks in a fragment of atlantic forest in the state of minas gerais, brazil, and examined the ticks for rickettsial agents. birds were captured during 2014 and 2015 and ticks were identified by sequencing fragments of the 16s and 12s ribosomal dna. among 260 birds representing 19 families and 52 species, a total of 69 (26.5%) were found to be infested by larvae (ll) and/or nymphs (nn) of amblyomma longirostre (koch, 1844) (45 ll, 4 nn), amb ... | 2017 | 27745888 |
| molecular detection of tick-borne pathogen diversities in ticks from livestock and reptiles along the shores and adjacent islands of lake victoria and lake baringo, kenya. | although diverse tick-borne pathogens (tbps) are endemic to east africa, with recognized impact on human and livestock health, their diversity and specific interactions with tick and vertebrate host species remain poorly understood in the region. in particular, the role of reptiles in tbp epidemiology remains unknown, despite having been implicated with tbps of livestock among exported tortoises and lizards. understanding tbp ecologies, and the potential role of common reptiles, is critical for ... | 2017 | 28620610 |
| antibodies to ehrlichia canis, ehrlichia platys, and spotted fever group rickettsiae in louisiana dogs. | antibodies to ehrlichia canis, ehrlichia platys, and spotted fever group (sfg) rickettsiae were detected by indirect immunofluorescence in sera from 27 ill individually owned thrombocytopenic dogs (platelet concentrations less than 200,000 platelets/microliters) and 59 healthy kenneled dogs located in southern louisiana. platelet concentrations less than 100,000 platelets/microliters were detected in 63% of ill thrombocytopenic dogs and 6.8% of healthy kennel dogs. one ill thrombocytopenic dog h ... | 1988 | 3146636 |
| ticks and rickettsial infection in the wildlife of two regions of the brazilian amazon. | during 2009-2012, wild animals and their ticks were sampled in two areas within the amazon biome of brazil, in the states of mato grosso and pará. animal tissues, blood, and ticks were molecularly tested for rickettsia and coxiella dna. a total of 182 wild animals were sampled, comprising 28 mammalian, five avian, and three reptilian species. animal tissues or blood were all negative for rickettsia or coxiella dna. a total of 454 ticks (22 larvae, 226 nymphs, 127 males, 79 females) were collecte ... | 2015 | 25273064 |
| diversity of rickettsiae in a rural community in northern california. | far northern california forests are highly biodiverse in wildlife reservoirs and arthropod vectors that may propagate rickettsial pathogens in nature. the proximity of small rural communities to these forests puts people and domestic animals at risk of vector-borne infection due to spillover from wildlife. the current study was conducted to document exposure to rickettsial pathogens in people and domestic animals in a rural community, and identify which rickettsiae are present in sylvatic and pe ... | 2017 | 28274808 |
| the eco-epidemiology of pacific coast tick fever in california. | rickettsia philipii (type strain "rickettsia 364d"), the etiologic agent of pacific coast tick fever (pctf), is transmitted to people by the pacific coast tick, dermacentor occidentalis. following the first confirmed human case of pctf in 2008, 13 additional human cases have been reported in california, more than half of which were pediatric cases. the most common features of pctf are the presence of at least one necrotic lesion known as an eschar (100%), fever (85%), and headache (79%); four ca ... | 2016 | 27706171 |
| molecular detection and characterization of spotted fever group rickettsiae in taiwan. | rickettsioses are emerging infectious diseases caused by rickettsiae in association with arthropods. we report the detection of spotted fever group rickettsiae (sfgr) in taiwan using molecular methods. phylogenetic analyses of the 17-kd protein and citrate synthase (glta) genes showed that sfgr twkm01 detected in rhipicephalus haemaphysaloides ticks was most similar to rickettsia rhipicephali. three twkm01 isolates were obtained from three individual r. haemaphysaloides ticks. small, intracellul ... | 2007 | 17984347 |