| 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 |
| phylogenetic analysis of members of the genus rickettsia using the gene encoding the outer-membrane protein rompb (ompb). | to confirm the phylogenetic analysis previously inferred by comparison of the citrate synthase and rompa gene sequences (gita and ompa, respectively), the rompb gene (ompb) of 24 strains of the genus rickettsia was amplified and sequenced. rompb is an outer-membrane protein of high molecular mass, the presence of which can be demonstrated in most rickettsiae by immunological cross-reactivity in western blots. no pcr amplification was obtained with rickettsia bellii or rickettsia canadensis. for ... | 2000 | 10939649 |
| 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 |
| experimental infection of lone star ticks, amblyomma americanum (l.), with rickettsia parkeri and exposure of guinea pigs to the agent. | the maculatum agent, rickettsia parkeri (a member of the spotted fever group rickettsiae), was inoculated into a colony of the lone star tick, amblyomma americanum, and followed for two tick generations. in addition, guinea pigs were exposed to the agent by direct injection and by feeding infected ticks on them. eighty (53%) of 150 nymphal a. americanum that were inoculated with suspensions of r. parkeri were positive by hemolymph test and fluorescent antibody test for rickettsial infection when ... | 2003 | 14596284 |
| rickettsia species infecting amblyomma cooperi ticks from an area in the state of são paulo, brazil, where brazilian spotted fever is endemic. | owing to the potential role of the tick amblyomma cooperi in the enzootic cycle of rickettsia rickettsii, the etiologic agent of brazilian spotted fever (bsf), this study evaluated infection by rickettsia species in a. cooperi ticks collected from an area in brazil where bsf is endemic. among a total of 40 a. cooperi adult ticks collected in an area of bsf endemicity in the state of são paulo, pcr analysis detected dna of rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positiv ... | 2004 | 14715737 |
| rickettsia parkeri: a newly recognized cause of spotted fever rickettsiosis in the united states. | ticks, including many that bite humans, are hosts to several obligate intracellular bacteria in the spotted fever group (sfg) of the genus rickettsia. only rickettsia rickettsii, the agent of rocky mountain spotted fever, has been definitively associated with disease in humans in the united states. herein we describe disease in a human caused by rickettsia parkeri, an sfg rickettsia first identified >60 years ago in gulf coast ticks (amblyomma maculatum) collected from the southern united states ... | 2004 | 14999622 |
| rickettsial infections--a threat to travellers? | recent developments in cell-culture techniques and molecular methods have led to the description of several new rickettsial diseases. an update on these new infections should be of interest to health workers with patients who are international travellers. | 2004 | 15353963 |
| rickettsia parkeri in amblyomma triste from uruguay. | our goal was to detect whether spotted fever group rickettsia are found in the suspected vector of rickettsioses, amblyomma triste, in uruguay. rickettsia parkeri was detected in a. triste, which suggests that this species could be considered a pathogenic agent responsible for human rickettsioses in uruguay. | 2004 | 15496258 |
| tick- and flea-borne rickettsial emerging zoonoses. | between 1984 and 2004, nine more species or subspecies of spotted fever rickettsiae were identified as emerging agents of tick-borne rickettsioses throughout the world. six of these species had first been isolated from ticks and later found to be pathogenic to humans. the most recent example is rickettsia parkeri, recognized as a human pathogen more than 60 years after its initial isolation from ticks. a new spotted fever rickettsia, r. felis was also found to be associated with fleas and to be ... | 2005 | 15845235 |
| rickettsia parkeri infection and other spotted fevers in the united states. | | 2005 | 16093473 |
| rickettsia parkeri as a paradigm for multiple causes of tick-borne spotted fever in the western hemisphere. | among the many contributions made to rickettsiology by entomologist and rickettsiologist ralph r. parker was his discovery in 1937 of a novel rickettsia isolated from the gulf coast tick, amblyomma maculatum. this bacterium was subsequently characterized as a unique rickettsial species in 1965 and named rickettsia parkeri in honor of its discoverer. during the next several decades r. parkeri was generally considered as one of several "nonpathogenic" spotted fever group (sfg) rickettsiae that res ... | 2005 | 16481534 |
| detection of a typhus group rickettsia in amblyomma ticks in the state of nuevo leon, mexico. | the state of nuevo leon, mexico has had outbreaks of typhus group rickettsiosis, most recently recognized in 1997. evaluation of the sera of 345 patients with a dengue-like illness revealed that 25.5% had antibodies reactive with typhus group rickettsiae and 16% had antibodies to rickettsia parkeri. rickettsiae were detected by pcr and shell-vial isolations in the field-collected amblyomma ticks. molecular characterization by dna sequence analysis of the glta, ompb, and 17-kda gene identified th ... | 2005 | 16481535 |
| rickettsia parkeri in uruguay. | | 2006 | 17283648 |
| rickettsia parkeri infection after tick bite, virginia. | we describe a man with a febrile illness and an eschar that developed at the site of a tick bite. rickettsia parkeri was detected and isolated from the eschar. this report represents the second documented case of r. parkeri rickettsiosis in a us serviceman in eastern virginia. | 2007 | 17479907 |
| gulf coast ticks (amblyomma maculatum) and rickettsia parkeri, united states. | geographic distribution of rickettsia parkeri in its us tick vector, amblyomma maculatum, was evaluated by pcr. r. parkeri was detected in ticks from florida, georgia, kentucky, mississippi, oklahoma, and south carolina, which suggests that a. maculatum may be responsible for additional cases of r. parkeri rickettsiosis throughout much of its us range. | 2007 | 17553257 |
| 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 |
| detection of alpha and gamma-proteobacteria in amblyomma triste (acari: ixodidae) from uruguay. | amblyomma triste is the most prevalent tick species reported in human tick bites in uruguay and has been found to be infected with rickettsia parkeri, but no other microorganisms have been reported from this tick. a sample of 254 adults of a. triste was collected by flagging on vegetation in suburban areas in southern uruguay. pools of five ticks were assembled and a screening for the dna from the resulting 51 pools was realized by pcr assays using primers for amplifying a fragment of 16s rrna g ... | 2008 | 18071910 |
| rickettsia parkeri in brazil. | we report finding rickettsia parkeri in brazil in 9.7% of amblyomma triste ticks examined. an r. parkeri isolate was successfully established in vero cell culture. molecular characterization of the agent was performed by dna sequencing of portions of the rickettsial genes glta, htra, ompa, and ompb. | 2007 | 18214195 |
| rickettsial infection in capybaras (hydrochoerus hydrochaeris) from são paulo, brazil: serological evidence for infection by rickettsia bellii and rickettsia parkeri. | in brazil, capybaras (hydrochoerus hydrochaeris) are important hosts for amblyomma ticks, which in turn can transmit rickettsiae to humans and animals. therefore, capybaras are potential sentinels for rickettsial infection. | 2007 | 18320102 |
| [rickettsial spotted fever in the paraná delta. an emerging disease]. | we describe a case of rickettsial spotted fever in the paraná delta region of buenos aires province in argentina. the patient developed an acute febrile syndrome characterized by myalgias, headache, asthenia and moderate odynophagia, followed by a diffuse macular, papular, and purpuric exanthema. the patient had been bitten recently by a tick on the left preauricular region and an erosive papular lesion was evident at the bite site. an indirect immunofluorescence antibody assay identified antibo ... | 2007 | 18422067 |
| amblyomma triste koch, 1844 (acari: ixodidae): hosts and seasonality of the vector of rickettsia parkeri in uruguay. | amblyomma triste koch, 1844, the tick species most frequently involved in human bites in uruguay, has been implicated as a vector of human rickettsiosis. seasonal abundance of adult a. triste was examined by standard flagging at three sites where human tick bites and cases of the disease have been reported. adult tick activity occurred from august to february (end of winter to mid summer in the southern hemisphere) with a peak in spring. activity declined in step with decreasing temperatures and ... | 2008 | 18565680 |
| 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 |
| rickettsia parkeri rickettsiosis and its clinical distinction from rocky mountain spotted fever. | rickettsia parkeri rickettsiosis, a recently identified spotted fever transmitted by the gulf coast tick (amblyomma maculatum), was first described in 2004. we summarize the clinical and epidemiological features of 12 patients in the united states with confirmed or probable disease attributable to r. parkeri and comment on distinctions between r. parkeri rickettsiosis and other united states rickettsioses. | 2008 | 18808353 |
| rickettsia parkeri in argentina. | clinical reports of an eschar-associated rickettsiosis in the paraná river delta of argentina prompted an evaluation of amblyomma triste ticks in this region. when evaluated by pcr, 17 (7.6%) of 223 questing adult a. triste ticks, collected from 2 sites in the lower paraná river delta, contained dna of rickettsia parkeri. | 2008 | 19046514 |
| tick-borne rickettsioses in america: unanswered questions and emerging diseases. | during most of the 20th century, rickettsia rickettsii, the agent of rocky mountain spotted fever, was considered the only tick-borne rickettsia associated with human diseases in the americas. this dogma suggested that the other characterized and noncharacterized rickettsiae isolated from ticks were not pathogenic to humans. this concept has been modified extensively in the past 10 years with the identification of at least three additional rickettsial species that cause human tick-borne ricketts ... | 2009 | 19094824 |
| ticks and tick-borne pathogens and putative symbionts of black bears (ursus americanus floridanus) from georgia and florida. | ticks were collected from 38 black bears (ursus americanus floridanus) from northwestern florida (n = 18) from 2003 to 2005 and southern georgia (n = 20) in 2006. five species (amblyomma americanum, a. maculatum, dermacentor variabilis, ixodes scapularis, and i. affinis) were collected from florida bears, and 4 species (a. americanum, a. maculatum, d. variabilis, i. scapularis) were collected from bears in georgia. ixodes scapularis was the most frequently collected tick, followed by d. variabil ... | 2009 | 19413369 |
| 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 parkeri in amblyomma americanum ticks, tennessee and georgia, usa. | to determine the geographic distribution of the newly recognized human pathogen rickettsia parkeri, we looked for this organism in ticks from tennessee and georgia, usa. using pcr and sequence analysis, we identified r. parkeri in 2 amblyomma americanum ticks. this rickettsiosis may be underdiagnosed in the eastern united states. | 2009 | 19788817 |
| proteomic analysis of rickettsia parkeri strain portsmouth. | rickettsia parkeri, a recently recognized pathogen of human, is one of several rickettsia spp. in the united states that causes a spotted fever rickettsiosis. to gain insights into its biology and pathogenesis, we applied the proteomics approach to establish a two-dimensional gel proteome reference map and combined this technique with cell surface biotinylation to identify surface-exposed proteins of a low-passage isolate of r. parkeri obtained from a patient. we identified 91 proteins by matrix ... | 2009 | 19797064 |
| tick bites and skin rashes. | fever and a rash following a tick bite can signify a true medical emergency. ticks are important vectors of disease worldwide, including rocky mountain spotted fever, lyme disease, and congo-crimean hemorrhagic fever. this paper will review the major ticks of medical importance and the diseases they transmit, including important emerging pathogens. | 2010 | 20071986 |
| isolation of rickettsia parkeri and identification of a novel spotted fever group rickettsia sp. from gulf coast ticks (amblyomma maculatum) in the united states. | until recently, amblyomma maculatum (the gulf coast tick) had garnered little attention compared to other species of human-biting ticks in the united states. a. maculatum is now recognized as the principal vector of rickettsia parkeri, a pathogenic spotted fever group rickettsia (sfgr) that causes an eschar-associated illness in humans that resembles rocky mountain spotted fever. a novel sfgr, distinct from other recognized rickettsia spp., has also been detected recently in a. maculatum specime ... | 2010 | 20208020 |
| serological evidence of rickettsia parkeri as the etiological agent of rickettsiosis in uruguay. | we report three new rickettsiosis human cases in uruguay. the three clinical cases presented clinical manifestations similar to previous reported cases of rickettsia parkeri in the united states; that is mild fever (< 40 degrees c), malaise, headache, rash, inoculation eschar at the tick bite site, regional lymphadenopathy, and no lethality. serological antibody-absorption tests with purified antigens of r. parkeri and rickettsia rickettsii, associated with immunofluorescence assay indicated tha ... | 2009 | 20209269 |
| the expanding spectrum of eschar-associated rickettsioses in the united states. | until recently, rickettsia rickettsii was the only substantiated cause of tick-borne spotted fever group (sfg) rickettsiosis in humans in the united states. rickettsia parkeri, originally thought to be nonpathogenic in humans, was recently proved to be another cause of tick-borne sfg rickettsiosis. | 2010 | 20404224 |
| rickettsiae in gulf coast ticks, arkansas, usa. | to determine the cause of spotted fever cases in the southern united states, we screened gulf coast ticks (amblyomma maculatum) collected in arkansas for rickettsiae. of the screened ticks, 30% had pcr amplicons consistent with rickettsia parkeri or candidatus rickettsia amblyommii. | 2010 | 20409375 |
| rickettsia infection in dogs and rickettsia parkeri in amblyomma tigrinum ticks, cochabamba department, bolivia. | only few published data are available on ticks and tick-borne zoonotic pathogens in bolivia. to evaluate rickettsial seroprevalence and infection in dogs and ticks, during february-april 2007, we collected whole blood, sera, and ticks from dogs living in the rural, peri-urban, and urban areas of cochabamba, bolivia. dog sera were subjected to enzyme-linked immunosorbent assay test to detect igg antibodies against rickettsia rickettsii and 68.2% of samples were found to be positive (n = 30; 95% c ... | 2010 | 20426684 |
| experimental infection of the opossum didelphis aurita by rickettsia felis, rickettsia bellii, and rickettsia parkeri and evaluation of the transmission of the infection to ticks amblyomma cajennense and amblyomma dubitatum. | this work evaluated the infection of opossums (didelphis aurita) by rickettsia felis, rickettsia bellii, and rickettsia parkeri and their role as amplifier hosts for horizontal transmission to amblyomma cajennense and/or amblyomma dubitatum ticks. infection in d. aurita was induced by intraperitoneal inoculation with r. felis (n = 4 opossums), r. bellii (n = 4), and r. parkeri (n = 2). another group of six opossums were inoculated intraperitoneally with leibovitz-15 sterile culture medium, repre ... | 2010 | 20455783 |
| defining a core set of actin cytoskeletal proteins critical for actin-based motility of rickettsia. | many rickettsia species are intracellular bacterial pathogens that use actin-based motility for spread during infection. however, while other bacteria assemble actin tails consisting of branched networks, rickettsia assemble long parallel actin bundles, suggesting the use of a distinct mechanism for exploiting actin. to identify the underlying mechanisms and host factors involved in rickettsia parkeri actin-based motility, we performed an rnai screen targeting 115 actin cytoskeletal genes in dro ... | 2010 | 20478540 |
| tickborne infections in the southern united states. | established and emerging tickborne infections are significant causes of human illness in the southern united states. rocky mountain spotted fever, human monocytic ehrlichiosis, human ewingii ehrlichiosis and tularemia are known pathogens in this geographic distribution. rickettsia parkeri and novel ehrlichioses are more recently described tickborne infections reviewed in this article. an understanding of the tick vectors, pathogenesis, epidemiology, clinical presentation, diagnosis and treatment ... | 2010 | 20697259 |
| historical and recent evidence for close relationships among rickettsia parkeri, r. conorii, r. africae, and r. sibirica: implications for rickettsial taxonomy. | rickettsia parkeri, a member of the spotted fever group rickettsias, was first described in 1939 and was thought to be non-pathogenic until recently, when it was found to cause a spotted fever-like illness in humans and areas of necrosis (eschars) at the sites of tick bites. accordingly, there is currently much interest in this emerging pathogen. in this study, all published articles concerning r. parkeri were reviewed and analyzed for evidence of relatedness among this agent and other spotted f ... | 2009 | 20836828 |
| cattle and the natural history of rickettsia parkeri in mississippi. | abstract cattle have been recognized as hosts for amblyomma maculatum, the gulf coast tick, for over 100 years. for nearly as long, a. maculatum have been known to harbor the spotted fever group rickettsia (sfgr), now known as rickettsia parkeri. however, human infection with r. parkeri was not documented until 2004. results presented herein describe a laboratory and a field study evaluating cattle and the natural history of a. maculatum and r. parkeri in mississippi. in the laboratory study, se ... | 2011 | 20846012 |
| tick-borne disease agents in various wildlife from mississippi. | because tick-borne diseases are becoming increasingly important throughout the world, monitoring their causative agents in wildlife may serve as a useful indicator of potential human exposure. we assessed the presence of known and putative zoonotic, tick-borne agents in four wildlife species in mississippi. animals were tested for exposure to or infection with ehrlichia chaffeensis, ehrlichia ewingii, borrelia lonestari, rickettsia spp., anaplasma phagocytophilum, and francisella tularensis. who ... | 2011 | 20846016 |
| 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 |
| eschar-associated spotted fever rickettsiosis, bahia, brazil. | in brazil, brazilian spotted fever was once considered the only tick-borne rickettsial disease. we report eschar-associated rickettsial disease that occurred after a tick bite. the etiologic agent is most related to rickettsia parkeri, r. africae, and r. sibirica and probably widely distributed from sao paulo to bahia in the atlantic forest. | 2011 | 21291605 |
| gotch ear in a goat: a case report. | abstract a 1-year-old castrated male saanen goat was observed to have drooping and edema of the left ear consistent with published accounts of gotch ear in cattle associated with a tick bite. the goat's left ear was edematous from the tip of the pinna to the base of the ear. no signs of trauma or infectious processes were observed. three engorged gulf coast ticks (amblyomma maculatum) were observed attached inside the ear. ticks were removed and the ear biopsied at tick attachment sites. the aff ... | 2011 | 21395411 |
| rickettsia parkeri in gulf coast ticks, southeastern virginia, usa. | we report evidence that amblyomma maculatum tick populations are well established in southeastern virginia. we found that 43.1% of the adult gulf coast ticks collected in the summer of 2010 carried rickettsia parkeri, suggesting that persons living in or visiting southeastern virginia are at risk for infection with this pathogen. | 2011 | 21529406 |
| 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 |
| distribution of spotted fever group rickettsiae in select tissues of experimentally infected and field-collected gulf coast ticks. | salivary glands, midgut, malpighian tubules, and ovaries were dissected from infected, colony-derived amblyomma maculatum (gulf coast ticks) injected as nymphs with either rickettsia parkeri (a spotted fever group rickettsia [sfgr]; treatment) or phosphate-buffered saline (negative control). for comparison, similar tissues were dissected from hemolymph-positive, field-collected ticks. tissues were analyzed by indirect fluorescent antibody (ifa) tests. all phosphate-buffered saline-injected ticks ... | 2011 | 21661331 |
| rickettsia parkeri rickettsiosis, argentina. | rickettsia parkeri, a recently identified cause of spotted fever rickettsiosis in the united states, has been found in amblyomma triste ticks in several countries of south america, including argentina, where it is believed to cause disease in humans. we describe the clinical and epidemiologic characteristics of 2 patients in argentina with confirmed r. parkeri infection and 7 additional patients with suspected r. parkeri rickettsiosis identified at 1 hospital during 2004-2009. the frequency and ... | 2011 | 21762568 |
| Effect of Forest Fragmentation on Tick Infestations of Birds and Tick Infection Rates by Rickettsia in the Atlantic Forest of Brazil. | Habitat loss and modifications affect biodiversity, potentially contributing to outbreaks of infectious diseases. We evaluated if the patch sizeinfragmented areas of Atlantic Forest in southeastern Brazil influences the diversity of forest birds and consequently the prevalence of ticks on birds and the rickettsial infection of these ticks. During 2 years, we collected ticks from birds in 12 sites: four small forest patches (80-140 ha), four large ones (480-1,850 ha), and four forest control area ... | 2011 | 22173291 |
| Detection of Rickettsia parkeri and Candidatus Rickettsia andeanae in Amblyomma maculatum Gulf Coast Ticks Collected from Humans in the United States. | Abstract Rickettsia parkeri, a spotted fever group (SFG) rickettsia recently found to be pathogenic to humans, causes an eschar-associated febrile illness. The R. parkeri rickettsiosis, Tidewater spotted fever, has been misdiagnosed as Rocky Mountain spotted fever due to serologic cross reactivity and the lack of specific diagnostic methods. Candidatus Rickettsia andeanae, also a SFG rickettsia, is a recently described agent of unknown pathogenicity originally identified in ticks collected fro ... | 2011 | 22022815 |
| high rates of rickettsia parkeri infection in gulf coast ticks (amblyomma maculatum) and identification of "candidatus rickettsia andeanae" from fairfax county, virginia. | the gulf coast tick, amblyomma maculatum, is a vector of rickettsia parkeri, a recently identified human pathogen that causes a disease with clinical symptoms that resemble a mild form of rocky mountain spotted fever. because the prevalence of r. parkeri infection in geographically distinct populations of a. maculatum is not fully understood, a. maculatum specimens collected as part of a tick and pathogen surveillance system in fairfax county, virginia, were screened to determine pathogen infect ... | 2011 | 21867421 |
| rickettsia parkeri in amblyomma maculatum ticks, north carolina, usa, 2009-2010. | we detected rickettsia parkeri in 20%-33% of amblyomma maculatum ticks sampled in north carolina. results highlight the high frequencies of r. parkeri-infected ticks in the state with the highest annual incidence of rocky mountain spotted fever. epidemiologic studies are needed to definitively link r. parkeri to cases of spotted fever rickettsiosis. | 2011 | 22172164 |
| Rickettsia parkeri invasion of diverse host cells involves an Arp2/3 complex, WAVE complex and Rho-family GTPase-dependent pathway. | Rickettsiae are obligate intracellular pathogens that are transmitted to humans by arthropod vectors and cause diseases such as spotted fever and typhus. Although rickettsiae require the host cell actin cytoskeleton for invasion, the cytoskeletal proteins that mediate this process have not been completely described. To identify the host factors important during cell invasion by Rickettsia parkeri, a member of the spotted fever group (SFG), we performed an RNAi screen targeting 105 proteins in Dr ... | 2011 | 22188208 |
| development of shuttle vectors for transformation of diverse rickettsia species. | plasmids have been identified in most species of rickettsia examined, with some species maintaining multiple different plasmids. three distinct plasmids were demonstrated in rickettsia amblyommii aar/sc by southern analysis using plasmid specific probes. copy numbers of pram18, pram23 and pram32 per chromosome in aar/sc were estimated by real-time pcr to be 2.0, 1.9 and 1.3 respectively. cloning and sequencing of r. amblyommii aar/sc plasmids provided an opportunity to develop shuttle vectors fo ... | 2011 | 22216299 |
| spotted fever group rickettsia infecting ticks (acari: ixodidae) in the state of santa catarina, brazil. | during 2006-2008, a total of 260 adult ticks were collected from domestic and wild animals in different regions of the state of santa catarina (sc), brazil, including areas where human cases of brazilian spotted fever have been reported. collected ticks belonging to nine species (amblyomma aureolatum, amblyomma cajennense, amblyomma dubitatum, amblyomma longirostre, amblyomma ovale, amblyomma tigrinum, dermacentor nitens, rhipicephalus microplus and rhipicephalus sanguineus) were tested by polym ... | 2011 | 22241112 |
| expression of an epitope-tagged virulence protein in rickettsia parkeri using transposon insertion. | despite recent advances in our ability to genetically manipulate rickettsia, little has been done to employ genetic tools to study the expression and localization of rickettsia virulence proteins. using a mariner-based himar1 transposition system, we expressed an epitope-tagged variant of the actin polymerizing protein ricka under the control of its native promoter in rickettsia parkeri, allowing the detection of ricka using commercially-available antibodies. native ricka and epitope-tagged rick ... | 2012 | 22624012 |
| knockdown of selenocysteine-specific elongation factor in amblyomma maculatum alters the pathogen burden of rickettsia parkeri with epigenetic control by the sin3 histone deacetylase corepressor complex. | selenocysteine is the 21st naturally-occurring amino acid. selenoproteins have diverse functions and many remain uncharacterized, but they are typically associated with antioxidant activity. the incorporation of selenocysteine into the nascent polypeptide chain recodes the tga stop codon and this process depends upon a number of essential factors including the selenocysteine elongation factor (sef). the transcriptional expression of sef did not change significantly in tick midguts throughout the ... | 2013 | 24282621 |
| ticks and spotted fever group rickettsiae of southeastern virginia. | the incidence of tick-borne rickettsial disease in the southeastern united states has been rising steadily through the past decade, and the range expansions of tick species and tick-borne infectious agents, new and old, has resulted in an unprecedented mix of vectors and pathogens. the results of an ongoing 4-year surveillance project describe the relative abundance of questing tick populations in southeastern virginia. since 2009, more than 66,000 questing ticks of 7 species have been collected ... | 2013 | 24201057 |
| detection of human bacterial pathogens in ticks collected from louisiana black bears (ursus americanus luteolus). | there are 4 major human-biting tick species in the northeastern united states, which include: amblyomma americanum, amblyomma maculatum, dermacentor variabilis, and ixodes scapularis. the black bear is a large mammal that has been shown to be parasitized by all the aforementioned ticks. we investigated the bacterial infections in ticks collected from louisiana black bears (ursus americanus subspecies luteolus). eighty-six ticks were collected from 17 black bears in louisiana from june 2010 to ma ... | 2013 | 23415850 |
| feeding by amblyomma maculatum (acari: ixodidae) enhances rickettsia parkeri (rickettsiales: rickettsiaceae) infection in the skin. | rickettsia parkeri luckman (rickettsiales: rickettsiaceae), a member of the spotted fever group of rickettsia, is the tick-borne causative agent of a newly recognized, eschar-associated rickettsiosis. because of its relatively recent designation as a pathogen, few studies have examined the pathogenesis of transmission of r. parkeri to the vertebrate host. to further elucidate the role of tick feeding in rickettsial infection of vertebrates, nymphal amblyomma maculatum koch (acari: ixodidae) were ... | 2014 | 25118419 |
| avian migrants facilitate invasions of neotropical ticks and tick-borne pathogens into the united states. | migratory birds have the potential to transport exotic vectors and pathogens of human and animal health importance across vast distances. we systematically examined birds that recently migrated to the united states from the neotropics for ticks. we screened both ticks and birds for tick-borne pathogens, including rickettsia species and borrelia burgdorferi. over two spring seasons (2013 and 2014), 3.56% of birds (n = 3,844) representing 42.35% of the species examined (n = 85) were infested by ti ... | 2015 | 26431964 |
| rickettsia parkeri colonization in amblyomma maculatum: the role of superoxide dismutases. | the gulf coast tick (amblyomma maculatum) is an arthropod vector of rickettsia parkeri, the causative agent of american boutonneuse fever and an infectious agent of public health significance. in this study, we evaluated the biological significance of the superoxide dismutases (sods) of a. maculatum in hematophagy and r. parkeri colonization within the tick host. | 2016 | 27206371 |
| detection of rickettsia rickettsii, rickettsia parkeri, and rickettsia akari in skin biopsy specimens using a multiplex real-time polymerase chain reaction assay. | rickettsia rickettsii, rickettsia parkeri, and rickettsia akari are the most common causes of spotted fever group rickettsioses indigenous to the united states. infected patients characteristically present with a maculopapular rash, often accompanied by an inoculation eschar. skin biopsy specimens are often obtained from these lesions for diagnostic evaluation. however, a species-specific diagnosis is achieved infrequently from pathologic specimens because immunohistochemical stains do not diffe ... | 2014 | 24829214 |
| amblyomma maculatum feeding augments rickettsia parkeri infection in a rhesus macaque model: a pilot study. | rickettsia parkeri is an emerging eschar-causing human pathogen in the spotted fever group of rickettsia and is transmitted by the gulf coast tick, amblyomma maculatum. tick saliva has been shown to alter both the cellular and humoral components of the innate and adaptive immune systems. however, the effect of this immunomodulation on rickettsia transmission and pathology in an immunocompetent vertebrate host has not been fully examined. we hypothesize that, by modifying the host immune response ... | 2015 | 26244337 |
| immunoproteomic profiling of rickettsia parkeri and rickettsia amblyommii. | rickettsia parkeri is an amblyomma-associated, spotted fever group rickettsia species that causes an eschar-associated, febrile illness in multiple countries throughout the western hemisphere. many other rickettsial species of known or uncertain pathogenicity have been detected in amblyomma spp. ticks in the americas, including rickettsia amblyommii, "candidatus rickettsia andeanae" and rickettsia rickettsii. in this study, we utilized an immunoproteomic approach to compare antigenic profiles of ... | 2015 | 26234571 |
| comparative evaluation of infected and noninfected amblyomma triste ticks with rickettsia parkeri, the agent of an emerging rickettsiosis in the new world. | the distribution of rickettsia parkeri in south america has been associated with amblyomma triste ticks. the present study evaluated under laboratory conditions two colonies of a. triste: one started from engorged females that were naturally infected by r. parkeri (designated as infected group); the other started from noninfected females (designated as control group). both colonies were reared in parallel for five consecutive generations. tick-naïve domestic rabbits were used for feeding of each ... | 2013 | 23936795 |
| high prevalence of "candidatus rickettsia andeanae" and apparent exclusion of rickettsia parkeri in adult amblyomma maculatum (acari: ixodidae) from kansas and oklahoma. | amblyomma maculatum (the gulf coast tick), an aggressive, human-biting, nearctic and neotropical tick, is the principal vector of rickettsia parkeri in the united states. this pathogenic spotted fever group rickettsia species has been identified in 8-52% of questing adult gulf coast ticks in the southeastern united states. to our knowledge, r. parkeri has not been reported previously from adult specimens of a. maculatum collected in kansas or oklahoma. a total of 216 adult a. maculatum ticks wer ... | 2015 | 25773931 |
| rickettsia parkeri rickettsiosis in different ecological regions of argentina and its association with amblyomma tigrinum as a potential vector. | rickettsia parkeri, a newly recognized tick-borne pathogen of humans in the americas, is a confirmed cause of spotted fever group rickettsiosis in argentina. until recently, almost all cases of r. parkeri rickettsiosis in argentina have originated from the paraná river delta, where entomological surveys have identified populations of r. parkeri-infected amblyomma triste ticks. in this report, we describe confirmed cases of r. parkeri rickettsiosis from córdoba and la rioja provinces, which are l ... | 2014 | 25349376 |
| rickettsia parkeri rickettsiosis, arizona, usa. | in the united states, all previously reported cases of rickettsia parkeri rickettsiosis have been linked to transmission by the gulf coast tick (amblyomma maculatum). here we describe 1 confirmed and 1 probable case of r. parkeri rickettsiosis acquired in a mountainous region of southern arizona, well beyond the recognized geographic range of a. maculatum ticks. the likely vector for these 2 infections was identified as the amblyomma triste tick, a neotropical species only recently recognized in ... | 0 | 27089251 |
| molecular identification of rickettsia parkeri infecting amblyomma triste ticks in an area of argentina where cases of rickettsiosis were diagnosed. | specimens of the hard tick amblyomma triste were found infected with rickettsia parkeri in an area of argentina (general lavalle, buenos aires province) where cases of human illness attributed to this microorganism have been reported. molecular detection of r. parkeri was based on polymerase chain reactions that amplify a ca. 400-bp fragment of the 23s-5s intergenic spacer and a ca. 500-bp fragment of the gene encoding a 190-kda outer membrane protein. three (6.97%) of 43 a. triste ticks were de ... | 0 | 23440128 |
| 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 |
| detection of rickettsia parkeri from within piura, peru, and the first reported presence of candidatus rickettsia andeanae in the tick rhipicephalus sanguineus. | domestic farm animals (n=145) were sampled for the presence of ectoparasites in northwestern peru during march, 2008. ninety domestic animals (62%) were positive for the presence of an ectoparasite(s) and produced a total collection of the following: 728 ticks [amblyomma maculatum, anocentor nitens, rhipicephalus (boophilus) microplus, rhipicephalus sanguineus, and otobius megnini], 12 lice (haematopinus suis), and 3 fleas (ctenocephalides felis). a rickettsia genus-specific qpcr assay was perfo ... | 2013 | 23488453 |
| decreased small mammal and on-host tick abundance in association with invasive red imported fire ants (solenopsis invicta). | invasive species may impact pathogen transmission by altering the distributions and interactions among native vertebrate reservoir hosts and arthropod vectors. here, we examined the direct and indirect effects of the red imported fire ant (solenopsis invicta) on the native tick, small mammal and pathogen community in southeast texas. using a replicated large-scale field manipulation study, we show that small mammals were more abundant on treatment plots where s. invicta populations were experime ... | 0 | 27651533 |
| effect of amblyomma maculatum (acari: ixodidae) saliva on the acute cutaneous immune response to rickettsia parkeri infection in a murine model. | rickettsia parkeri luckman (rickettsiales: rickettsiaceae) is a pathogenic spotted fever group rickettsia transmitted by amblyomma maculatum koch (acari: ixodidae) in the united states. the acute innate immune response to this pathogen and the effect of tick feeding or salivary components on this response is largely unknown. we hypothesized that a. maculatum saliva enhances r. parkeri infection via downregulation of the acute cellular and cytokine immune response. c3h/hen mice were intradermally ... | 2016 | 27521760 |
| correction: amblyomma maculatum feeding augments rickettsia parkeri infection in a rhesus macaque model: a pilot study. | | 2015 | 26322516 |
| seroepidemiologic study of human infections with spotted fever group rickettsiae in north carolina. | increasing entomologic and epidemiologic evidence suggests that spotted fever group rickettsiae (sfgr) other than rickettsia rickettsii are responsible for spotted fever rickettsioses in the united states. a retrospective seroepidemiologic study was conducted on stored acute- and convalescent-phase sera that had been submitted for rocky mountain spotted fever testing to the north carolina state laboratory of public health. we evaluated the serologic reactivity of the paired sera to r. rickettsii ... | 2014 | 25187639 |
| rickettsia parkeri and rickettsia montanensis, kentucky and tennessee, usa. | we found that 14.3% (15/105) of amblyomma maculatum and 3.3% (10/299) of dermacentor variabilis ticks collected at 3 high-use military training sites in west-central kentucky and northern tennessee, usa, were infected with rickettsia parkeri and rickettsia montanensis, respectively. these findings warrant regional increased public health awareness for rickettsial pathogens and disease. | 0 | 25271771 |
| spotted fever group rickettsiae in multiple hard tick species from fairfax county, virginia. | spotted fever group rickettsiosis (sfgr) is a potentially fatal disease that has displayed increasing incidence in the united states in recent years. the most well-known and severe type of this disease is rocky mountain spotted fever, but there are other mild forms that occur. recently, human infection with rickettsia parkeri has been reported and linked with the tick amblyomma maculatum. in 2010, a population of r. parkeri-infected a. maculatum was discovered in fairfax county, virginia, leadin ... | 2014 | 24978651 |
| an insight into the microbiome of the amblyomma maculatum (acari: ixodidae). | the aim of this study was to survey the bacterial diversity of amblyomma maculatum koch, 1844, and characterize its infection with rickettsia parkeri. pyrosequencing of the bacterial 16s rrna was used to determine the total bacterial population in a. maculatum. pyrosequencing analysis identified rickettsia in a. maculatum midguts, salivary glands, and saliva, which indicates successful trafficking in the arthropod vector. the identity of rickettsia spp. was determined based on sequencing the ric ... | 0 | 24605461 |
| a confirmed case of rickettsia parkeri infection in a traveler from uruguay. | the first confirmed case of rickettsia parkeri infection in uruguay is reported. to date, in south america, molecularly confirmed cases of human infection have been found in argentina and probably, brazil. our patient returned to spain after a 7-day trip to colonia suiza (southwestern uruguay). he presented fever (39°c), chills, and two eschars (tache noire-like) surrounded by an indurated, erythematous halo on the inner side of the left ankle besides a maculopapular rash on the legs. after trea ... | 2013 | 24166040 |
| detecting rickettsia parkeri infection from eschar swab specimens. | the typical clinical presentation of several spotted fever group rickettsia infections includes eschars. clinical diagnosis of the condition is usually made by analysis of blood samples. we describe a more sensitive, noninvasive means of obtaining a sample for diagnosis by using an eschar swab specimen from patients infected with rickettsia parkeri. | 0 | 23647926 |
| experimental infection of cotton rats and bobwhite quail with rickettsia parkeri. | amblyomma maculatum is the primary vector for rickettsia parkeri, a spotted fever group rickettsia (sfgr) and human pathogen. cotton rats and quail are known hosts for larval and nymphal a. maculatum; however, the role of these hosts in the ecology of r. parkeri is unknown. | 2013 | 23497681 |
| evidence of antibodies to spotted fever group rickettsiae in small mammals and quail from mississippi. | rickettsia parkeri is a recently recognized human pathogen primarily associated with the gulf coast tick amblyomma maculatum, with immature stages of this tick reported from wild vertebrates. to better understand the role of vertebrates in the natural history of this bacterium, we evaluated small mammals and ground-dwelling birds for evidence of infection with r. parkeri or exposure to the organism. we sampled small mammals (n=39) and passerines (n=47) in both north-central and southeast mississ ... | 2012 | 23199266 |
| rickettsia parkeri and candidatus rickettsia andeanae in gulf coast ticks, mississippi, usa. | | 0 | 23018026 |
| 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 |
| evaluation of gulf coast ticks (acari: ixodidae) for ehrlichia and anaplasma species. | amblyomma maculatum koch (the gulf coast tick) is an aggressive, human-biting ixodid tick distributed throughout much of the southeastern united states and is the primary vector for rickettsia parkeri, an emerging human pathogen. amblyomma maculatum has diverse host preferences that include white-tailed deer, a known reservoir for ehrlichia and anaplasma species, including the human pathogens e. ewingii and e. chaffeensis to examine more closely the potential role of a. maculatum in the maintena ... | 2016 | 28031351 |
| prevalence of antibodies to spotted fever group rickettsia spp. and ehrlichia spp. in coyotes (canis latrans) in oklahoma and texas, usa. | coyotes (canis latrans) are commonly infested with ticks, including amblyomma americanum, the predominant vector of ehrlichia chaffeensis and ehrlichia ewingii; dermacentor variabilis, an important vector of rickettsia rickettsii; and amblyomma maculatum, a major vector of rickettsia parkeri, a spotted fever group (sfg) rickettsia. to determine the degree to which coyotes are infected with or exposed to tick-borne bacterial disease agents, serum samples collected from coyotes in oklahoma and tex ... | 2013 | 23778619 |
| incident tick-borne infections in a cohort of north carolina outdoor workers. | tick-borne diseases cause substantial morbidity throughout the united states, and north carolina has a high incidence of spotted fever rickettsioses and ehrlichiosis, with sporadic cases of lyme disease. the occupational risk of tick-borne infections among outdoor workers is high, particularly those working on publicly managed lands. this study identified incident tick-borne infections and examined seroconversion risk factors among a cohort of north carolina outdoor workers. workers from the nor ... | 2016 | 27008102 |
| antibodies for rickettsia spp. in patients with negative serology for dengue virus, leptospirosis, and meningococcal disease in municipalities of são paulo state, brazil. | brazilian spotted fever is an infectious disease with a high mortality rate if not treated early. differential diagnosis is difficult, as the first clinical signs are non-specific and can be confused with other diseases. the aim of the study was to investigate evidence of infection with rickettsia rickettsii and rickettsia parkeri in negative sera samples, collected in 2014, from patients with suspected leptospirosis, dengue fever, and meningococcal disease in atibaia and bragança paulista munic ... | 2016 | 27812650 |
| specifying pathogen associations of amblyomma maculatum (acari: ixodidae) in western tennessee. | amblyomma maculatum koch (acari: ixodidae) is established in western tennessee, a region with increased risk for rocky mountain spotted fever and ehrlichiosis. this tick transmits rickettsia parkeri to humans, likely contributing to cases of rickettsiosis in the region. the objective was to determine pathogen associations within questing and host-collected a. maculatum, and identify ecological factors associated with pathogen infection that may increase the effectiveness of surveillance methods. ... | 2016 | 26744464 |
| diagnosis and management of tickborne rickettsial diseases: rocky mountain spotted fever and other spotted fever group rickettsioses, ehrlichioses, and anaplasmosis - united states. | tickborne rickettsial diseases continue to cause severe illness and death in otherwise healthy adults and children, despite the availability of low-cost, effective antibacterial therapy. recognition early in the clinical course is critical because this is the period when antibacterial therapy is most effective. early signs and symptoms of these illnesses are nonspecific or mimic other illnesses, which can make diagnosis challenging. previously undescribed tickborne rickettsial diseases continue ... | 2016 | 27172113 |
| the evolving medical and veterinary importance of the gulf coast tick (acari: ixodidae). | amblyomma maculatum koch (the gulf coast tick) is a three-host, ixodid tick that is distributed throughout much of the southeastern and south-central united states, as well as several countries throughout central and south america. a considerable amount of scientific literature followed the original description of a. maculatum in 1844; nonetheless, the gulf coast tick was not recognized as a vector of any known pathogen of animals or humans for >150 years. it is now identified as the principal v ... | 2015 | 26336308 |
| rickettsia sca4 reduces vinculin-mediated intercellular tension to promote spread. | spotted fever group (sfg) rickettsiae are human pathogens that infect cells in the vasculature. they disseminate through host tissues by a process of cell-to-cell spread that involves protrusion formation, engulfment, and vacuolar escape. other bacterial pathogens rely on actin-based motility to provide a physical force for spread. here, we show that sfg species rickettsia parkeri typically lack actin tails during spread and instead manipulate host intercellular tension and mechanotransduction t ... | 2016 | 27768890 |
| bacteria of the genera ehrlichia and rickettsia in ticks of the family ixodidae with medical importance in argentina. | the aim of this study was to get an overview about the occurrence of bacteria from the genus ehrlichia and rickettsia in ixodid ticks with medical importance in argentina. therefore, in 2013 and 2014, free-living ticks were collected in different provinces of northern argentina. these ticks were determined as amblyomma sculptum, amblyomma neumanni, amblyomma parvum, amblyomma triste, amblyomma ovale, amblyomma tonelliae and haemaphysalis juxtakochi. all samples were tested to determine the infec ... | 2017 | 27812828 |
| ecology of a tick-borne spotted fever in southern brazil. | rio grande do sul is the southernmost state of brazil, bordering uruguay. clinical cases of spotted fever group (sfg) rickettsiosis were recently reported in rio grande do sul. none of these cases was lethal, and all were confirmed by seroconversion to r. rickettsii antigens. because serological cross-reactions are well known to occur between different sfg agents, the sfg agent responsible for the clinical cases remains unknown in rio grande do sul, where no rickettsial agent is known to infect ... | 2016 | 27392739 |
| dynamics of exposure to rickettsia parkeri in cattle in the paraná river delta, argentina. | several cases of human rickettsiosis caused by rickettsia parkeri were recently documented in the paraná river delta of argentina, where the tick vector is amblyomma triste koch. as cattle suffer recurrent a. triste infestations, they are at risk of becoming infected with r. parkeri herein we investigated the dynamics of r. parkeri and its a. triste vector in a herd of beef cattle. cattle were followed for 18 mo and samples were analyzed for the presence of antibodies against four rickettsia spe ... | 2016 | 26794232 |
| 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 species within ticks (acari: ixodidae) collected from arkansas united states. | rocky mountain spotted fever (rmsf), caused by the etiological agent rickettsia rickettsii, is the most severe and frequently reported rickettsial illness in the united states, and is commonly diagnosed throughout the southeast. with the discoveries of rickettsia parkeri and other spotted fever group rickettsiae (sfgr) in ticks, it remains inconclusive if the cases reported as rmsf are truly caused by r. rickettsii or other sfgr. arkansas reports one of the highest incidence rates of rmsf in the ... | 2015 | 26334827 |