Publications

TitleAbstractYear
Filter
PMID(sorted descending)
Filter
rocky mountain spotted fever in dogs, brazil.clinical illness caused by rickettsia rickettsii in dogs has been reported solely in the united states. we report 2 natural clinical cases of rocky mountain spotted fever in dogs in brazil. each case was confirmed by seroconversion and molecular analysis and resolved after doxycycline therapy.200919239764
evaluation of serological tests for the diagnosis of rickettsiosis in denmark.two commercially available immunofluorescence assays (ifa) were compared using historical sera evaluated for rickettsial antibodies by the weil-felix test. an ifa test produced by focus diagnostics prepared with rickettsia rickettsii and r. typhi antigens was compared with a custom made kit from fuller laboratories with r. rickettsii, r. typhi, r. conorii and r. helvetica as antigens. the serum panel used for the comparison included weil-felix-positive and -negative samples. cross-reactions were ...200919162092
prevalence of rickettsia species in canadian populations of dermacentor andersoni and d. variabilis.we determined the prevalence of rickettsiae in dermacentor adults at 15 localities in canada. rickettsia rickettsii was not detected in any tick, whereas rickettsia peacockii was present in 76% of dermacentor andersoni adults and rickettsia montanensis in 8% of dermacentor variabilis adults. this host specificity was maintained in localities where both tick species occurred in sympatry.200919151178
experimental infection of capybaras hydrochoerus hydrochaeris by rickettsia rickettsii and evaluation of the transmission of the infection to ticks amblyomma cajennense.the present study evaluated the infection of capybaras (hydrochoerus hydrochaeris) by rickettsia rickettsii and their role as amplifier hosts for horizontal transmission of r. rickettsii to amblyomma cajennense ticks. two groups of two capybaras each were evaluated: on day 0, group 1 (g1) was infested by r. rickettsii-infected ticks, and group 2 (g2) was inoculated intraperitoneally with r. rickettsii. two additional groups were control groups, not exposed to r. rickettsii, being cg1 group the c ...200919147293
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 ...200919094824
experimental infection of the rabbit tick, haemaphysalis leporispalustris, with the bacterium rickettsia rickettsii, and comparative biology of infected and uninfected tick lineages.the present study consisted of two experiments that evaluated experimental infections of haemaphysalis leporispalustris ticks by a brazilian strain of rickettsia rickettsii, and their effect on tick biology. in experiment i, ticks were exposed to r. rickettsii during the larval, nymphal or adult stages by feeding on rabbits (oryctolagus cuniculus) needle-inoculated with r. rickettsii, and thereafter reared on uninfected rabbits for the entire next tick generation. regardless of the tick stage th ...200919067185
comparative susceptibility of larval stages of amblyomma aureolatum, amblyomma cajennense, and rhipicephalus sanguineus to infection by rickettsia rickettsii.the current study compared the susceptibility of larval stages of amblyomma cajennense (f.), amblyomma aureolatum (pallas), and rhipicephalus sanguineus (latreille) to infection by a brazilian strain of rickettsia rickettsii. guinea pigs experimentally infected by r. rickettsii were simultaneously infested by larvae of the three tick species. recovered engorged larvae were allowed to molt to nymphs and held in an incubator at 23 degrees c and 85-90% rh. subsequent flat nymphs were tested for ric ...200819058642
experimental infection of dogs with a brazilian strain of rickettsia rickettsii: clinical and laboratory findings.the bacterium rickettsia rickettsii is the etiological agent of an acute, severe disease called rocky mountain spotted fever in the united states or brazilian spotted fever (bsf) in brazil. in addition to these two countries, the disease has also been reported to affect humans in mexico, costa rica, panama, colombia and argentina. like humans, dogs are also susceptible to r. rickettsii infection. however, despite the wide distribution of r. rickettsii in the western hemisphere, reports of r. ric ...200819057821
molecular characterization of rickettsia rickettsii isolated from human clinical samples and from the rabbit tick haemaphysalis leporispalustris collected at different geographic zones in costa rica.five strains of spotted fever group (sfg) rickettsiae previously isolated from human clinical cases and from the tick haemaphysalis leporispalustris were used for molecular characterization in this study to establish their genetic relationship compared with the prototype rickettsia rickettsii strain sheila smith. samples were tested by polymerase chain reaction (pcr) targeting the rickettsial genes gtla, ompa, and ompb. pcr products of the latter two genes were dna sequenced and compared with av ...200819052300
laboratory maintenance of rickettsia rickettsii.this unit includes protocols for the laboratory maintenance of the obligate intracellular bacterium rickettsia rickettsii, including propagation in mammalian cell cultures, as well as isolation, counting, and storage procedures. regulations for working with r. rickettsii in biosafety level 3 containment are also discussed.200819016440
warmer weather linked to tick attack and emergence of severe rickettsioses.the impact of climate on the vector behaviour of the worldwide dog tick rhipicephalus sanguineus is a cause of concern. this tick is a vector for life-threatening organisms including rickettsia rickettsii, the agent of rocky mountain spotted fever, r. conorii, the agent of mediterranean spotted fever, and the ubiquitous emerging pathogen r. massiliae. a focus of spotted fever was investigated in france in may 2007. blood and tissue samples from two patients were tested. an entomological survey w ...200819015724
rickettsial spotted fever in capoeirão village, itabira, minas gerais, brazil.the present study investigated the infection by spotted fever rickettsia in an endemic area for brazilian spotted fever (bsf; caused by rickettsia rickettsii) in minas gerais state, brazil. human, canine and equine sera samples, and amblyomma cajennense adult ticks collected in a rural area of itabira city, minas gerais state were tested for rickettsial infection. through immunofluorescence assay (ifa) we demonstrated the presence of antibodies anti-r. rickettsii in 8.2%, 81.3% and 100% of the h ...200818949349
retrospective clinical and molecular analysis of conditioned laboratory dogs (canis familiaris) with serologic reactions to ehrlichia canis, borrelia burgdorferi, and rickettsia rickettsii.dogs are susceptible to different tickborne infections, including members of the anaplasmataceae (ehrlichia canis, e. ewingii, e. chaffeensis, anaplasma phagocytophilum, a. platys), borrelia burgdorferi, and rickettsia rickettsii. these diseases can manifest with clinical signs including fever, anorexia, malaise, lameness, rash, and bleeding episodes; however, these signs are nonpathognomonic, and infections can occur in the absence of clinical signs. hematologic abnormalities can include leukop ...200818947166
experimental infection of opossums didelphis aurita by rickettsia rickettsii and evaluation of the transmission of the infection to ticks amblyomma cajennense.the present study evaluated the infection of opossums (didelphis aurita) by rickettsia rickettsii and their role as amplifier hosts for horizontal transmission of r. rickettsii to amblyomma cajennense ticks. three groups of opossums were evaluated: on day 0, group 1 (g1) was inoculated intraperitoneally with r. rickettsii; group 2 (g2) was infested by r. rickettsii-infected ticks; and group 3 (g3) was the uninfected control group. opossum rectal temperature was measured daily. blood samples were ...200818945194
prevalence of rickettsia species antibodies and rickettsia species dna in the blood of cats with and without fever.rickettsia species antibodies have been detected in some cats but it is unknown whether infected cats develop clinical signs. the prevalence of rickettsia species deoxyribonucleic acid (dna) in blood from clinically ill cats has not been determined. the objective of this study was to determine if cats with fever (body temperature >or=102.5 degrees f [39.2 degrees c]) were more likely to have evidence of rickettsial infection than healthy, age-matched, control cats with a body temperature<102.5 d ...200918786845
what's new in rocky mountain spotted fever?rocky mountain spotted fever (rmsf) remains an important illness despite an effective therapy because it is difficult to diagnose and is capable of producing a fatal outcome. the pathogenesis of rmsf remains, in large part, an enigma. however, recent research has helped shed light on this mystery. importantly, the diagnosis of rmsf must be considered in all febrile patients who have known or possible exposure to ticks, especially if they live in or have traveled to endemic regions during warmer ...200818755382
activation of p38 mitogen-activated protein kinase module facilitates in vitro host cell invasion by rickettsia rickettsii. 200818719192
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 ...200818714878
molecular detection of spotted fever group rickettsia in dermacentor silvarum from a forest area of northeastern china.in total, 676 dermacentor silvarum olenev (acari: ixodidae) from a forest area of jilin province in northeastern china were examined by polymerase chain reaction for the presence of spotted fever group (sfg) rickettsia. the overall positive rate was 10.7%, with a 95% confidence interval from 8.3 to 13.0%. the sfg rickettsia infection was more prevalent in adults than in nymphs, and in fed ticks obtained from domestic animals than in those collected on vegetation. sequence analysis of the partial ...200818714877
evidence of multiple zoonotic agents in a wild rodent community in the eastern sierra nevada.this study aimed to describe the occurrence of yersinia pestis, rickettsia rickettsii, anaplasma phagocytophilum, and ectoparasites in a wild rodent community in the eastern sierra nevada. from may to september 2006, rodents were live-trapped, examined for ectoparasites, and blood was collected. all rodents were serologically tested for antibodies to y. pestis, r. rickettsii, and a. phagocytophilum; in addition, blood samples and ectoparasites were tested by pcr to detect the presence of these z ...200818689664
an autonomous polymerization motor powered by dna hybridization.we present a synthetic molecular motor capable of autonomous nanoscale transport in solution. inspired by bacterial pathogens such as rickettsia rickettsii, which locomote by inducing the polymerization of the protein actin at their surfaces to form 'comet tails', the motor operates by polymerizing a double-helical dna tail2. dna strands are propelled processively at the living end of the growing polymers, demonstrating autonomous locomotion powered by the free energy of dna hybridization.200718654346
characterization of rickettsia rickettsii in a case of fatal brazilian spotted fever in the city of rio de janeiro, brazil.a lethal case of brazilian spotted fever (bsf) is presented. clinical features were initially of gastrointestinal involvement and evolved with progression to septic shock, meningoencephalitis and death on the 6th day of illness. indirect immunofluorescence assay (ifa) for spotted fever group rickettsia (sfgr) was non-reactive. diagnosis was confirmed by the polymerase chain reaction (pcr) and the nucleotide sequencing of a fragment of the ompa gene showed 100% homology to rickettsia rickettsii. ...200818641853
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 ...200818606772
curvature and torsion in growing actin networks.intracellular pathogens such as listeria monocytogenes and rickettsia rickettsii move within a host cell by polymerizing a comet-tail of actin fibers that ultimately pushes the cell forward. this dense network of cross-linked actin polymers typically exhibits a striking curvature that causes bacteria to move in gently looping paths. theoretically, tail curvature has been linked to details of motility by considering force and torque balances from a finite number of polymerizing filaments. here we ...200818560043
a case of murine typhus associated with large vessel infarct of the spleen.we present a case of rickettsia typhi infection (the causative agent of endemic typhus) associated with an isolated splenic infarction. large vessel infarction is a rare complication of murine typhus, unlike infections caused by rickettsia rickettsii and rickettsia conorii (the spotted fever group rickettsias) which are known to cause hemostatic changes that lead to coagulopathies and thrombotic events. this case adds to the scarce data in the literature on the association between large vessels ...200818552585
detection and identification of spotted fever group rickettsiae in dermacentor species from southern california.dermacentor occidentalis marx and dermacentor variabilis (say) commonly bite humans in california. these dermacentor species may play a role in transmitting spotted fever group (sfg) rickettsiae to humans in many parts of the state where dermacentor andersoni stiles, a known vector for the etiologic agent of rocky mountain spotted fever, rickettsia rickettsii, is absent. however, the specific rickettsial agents present in these ticks and their current prevalence are poorly understood. in total, ...200818533446
adrenal gland hemorrhage in patients with fatal bacterial infections.a wide spectrum of adrenal gland pathology is seen during bacterial infections. hemorrhage is particularly associated with meningococcemia, while abscesses have been described with several neonatal infections. we studied adrenal gland histopathology of 65 patients with bacterial infections documented in a variety of tissues by using immunohistochemistry. the infections diagnosed included neisseria meningitidies, group a streptococcus, rickettsia rickettsii, streptococcus pneumoniae, staphylococc ...200818500257
tick-borne diseases in north carolina: is "rickettsia amblyommii" a possible cause of rickettsiosis reported as rocky mountain spotted fever?cases of rocky mountain spotted fever (rmsf) in north carolina have escalated markedly since 2000. in 2005, we identified a county in the piedmont region with high case numbers of rmsf. we collected ticks and examined them for bacterial pathogens using molecular methods to determine if a novel tick vector or spotted fever group rickettsiae (sfgr) might be emerging. amblyomma americanum, the lone star tick, comprised 99.6% of 6,502 specimens collected in suburban landscapes. in contrast, dermacen ...200818447622
molecular identification of rickettsia felis in ticks and fleas from an endemic area for brazilian spotted fever.rickettsioses are arthropod-borne diseases caused by parasites from the order rickettsiales. the most prevalent rickettsial disease in brazil is brazilian spotted fever (bsf). this work intends the molecular detection of those agents in ectoparasites from an endemic area of bsf in the state of espírito santo. a total of 502 ectoparasites, among them amblyomma cajennense, amblyomma dubitatum (a. cooperi), riphicephalus sanguineus, anocentor nitens and ctenocephalides felis, was collected from dom ...200818425272
rocky mountain spotted fever in argentina.we describe the first molecular confirmation of rickettsia rickettsii, the cause of rocky mountain spotted fever (rmsf), from a tick vector, amblyomma cajennense, and from a cluster of fatal spotted fever cases in argentina. questing a. cajennense ticks were collected at or near sites of presumed or confirmed cases of spotted fever rickettsiosis in jujuy province and evaluated by polymerase chain reaction assays for spotted fever group rickettsiae. dna of r. rickettsii was amplified from a pool ...200818385370
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.200718320102
[fever that should not kill]. 200718320097
expressed sequence tags (ests) from the salivary glands of the tick amblyomma cajennense (acari: ixodidae).the neotropical tick amblyomma cajennense is a significant pest to domestic animals, the most frequently human-biting tick in south america and the main vector of brazilian spotted fever (caused by rickettsia rickettsii), a deadly human disease. the purpose of this study is to characterize the adult a. cajennense salivary gland transcriptome by expressed sequence tags (ests). we report the analysis of 1754 clones obtained from a cdna library, which reveal mainly transcripts related to proteins i ...200818243270
evaluation of conventional and real-time pcr assays for detection and differentiation of spotted fever group rickettsia in dog blood.spotted fever group rickettsia is important cause of emerging and re-emerging infectious disease in people and dogs. importantly, dogs can serve as sentinels for disease in people. sensitive and specific diagnostic tests that differentiate among species of infecting rickettsia are needed. the objective of this study was to develop a sensitive and specific pcr that differentiates sfg rickettsia infecting dog blood. conventional and real-time pcr assays were developed using primers that targeted a ...200818226476
rocky mountain spotted fever, panama.we describe a fatal pediatric case of rocky mountain spotted fever in panama, the first, to our knowledge, since the 1950s. diagnosis was established by immunohistochemistry, pcr, and isolation of rickettsia rickettsii from postmortem tissues. molecular typing demonstrated strong relatedness of the isolate to strains of r. rickettsii from central and south america.200718217566
rocky mountain spotted fever, colombia.we investigated 2 fatal cases of rocky mountain spotted fever that occurred in 2003 and 2004 near the same locality in colombia where the disease was first reported in the 1930s. a retrospective serosurvey of febrile patients showed that > 21% of the serum samples had antibodies aaainst spotted fever group rickettsiae.200718214179
prevalence of seropositivity to spotted fever group rickettsiae and anaplasma phagocytophilum in a large, demographically diverse us sample.most epidemiologic studies of tick-borne rickettsial diseases in the united states are small and have limited demographic scope, making broader risk assessment difficult.200818171216
genomic comparison of virulent rickettsia rickettsii sheila smith and avirulent rickettsia rickettsii iowa.rickettsia rickettsii is an obligate intracellular pathogen that is the causative agent of rocky mountain spotted fever. to identify genes involved in the virulence of r. rickettsii, the genome of an avirulent strain, r. rickettsii iowa, was sequenced and compared to the genome of the virulent strain r. rickettsii sheila smith. r. rickettsii iowa is avirulent in a guinea pig model of infection and displays altered plaque morphology with decreased lysis of infected host cells. comparison of the t ...200818025092
surveillance for zoonotic vector-borne infections using sick dogs from southeastern brazil.for many vector-borne organisms, dogs can be used as sentinels to estimate the risk of human infection. the objective of this study was to use dogs as sentinels for multiple vector-borne organisms in order to evaluate the potential for human infection with these agents in southeastern brazil. blood from 198 sick dogs with clinicopathological abnormalities consistent with tick-borne infections were selected at the são paulo state university veterinary teaching hospital in botucatu and tested for ...200718021025
rocky mountain spotted fever.rocky mountain spotted fever (rmsf) is a life-threatening disease caused by rickettsia rickettsii, an obligately intracellular bacterium that is spread to human beings by ticks. more than a century after its first clinical description, this disease is still among the most virulent human infections identified, being potentially fatal even in previously healthy young people. the diagnosis of rmsf is based on the patient's history and a physical examination, and often presents a dilemma for clinici ...200717961858
host defenses to rickettsia rickettsii infection contribute to increased microvascular permeability in human cerebral endothelial cells.rickettsiae are arthropod-borne intracellular bacterial pathogens that primarily infect the microvascular endothelium leading to systemic spread of the organisms and the major pathophysiological effect, increased microvascular permeability, and edema in vital organs such as the lung and brain. much work has been done on mechanisms of immunity to rickettsiae, as well as the responses of endothelial cells to rickettsial invasion. however, to date, no one has described the mechanisms of increased m ...200817957455
tick-borne zoonotic bacteria in wild and domestic small mammals in northern spain.the prevalence and diversity of tick-borne zoonotic bacteria (borrelia spp., anaplasma phagocytophilum, coxiella burnetii, and spotted fever group rickettsiae) infecting 253 small mammals captured in the basque country (spain) were assessed using pcr and reverse line blot hybridization. trapping sites were selected around sheep farms (study 1, 2000 to 2002) and recreational parks (study 2, 2003 to 2005). the majority of the studied mammals (162) were wood mice (apodemus sylvaticus), but six othe ...200717693556
prevalence of antibodies against spotted fever group rickettsiae in a rural area of colombia.we recently rediscovered rocky mountain spotted fever in villeta, colombia, near the same locality (tobia) where it was first recognized in 1937. to have a better idea of the magnitude of this problem, sera from 392 randomly recruited healthy adults from villeta were analyzed by indirect immunofluorescent antibody assay to detect igg against rickettsia rickettsii as antigen. the seropositivity rate for spotted fever group rickettsiae was 40.3%. we did not find any association between the presenc ...200717690417
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 ...200717627445
molecular typing of isolates of rickettsia rickettsii by use of dna sequencing of variable intergenic regions.rickettsia rickettsii, the causative agent of rocky mountain spotted fever, is found throughout the americas, where it is associated with different animal reservoirs and tick vectors. no molecular typing system currently exists to allow for the robust differentiation of isolates of r. rickettsii. analysis of eight completed genome sequences of rickettsial species revealed a high degree of sequence conservation within the coding regions of chromosomes in the genus. intergenic regions between codi ...200717553977
murine typhus in children, south texas.children from south texas were evaluated for immunoglobulin g to rickettsia typhi, the causative agent of murine typhus. of 513 children, 8.6% of those 1-5 years of age, 13.3% of those 6-11 years of age, and 13.8% of those 12-17 years of age had positive results.200717553239
a case of rocky mountain spotted fever.rocky mountain spotted fever is a serious, generalized infection that is spread to humans through the bite of infected ticks. it can be lethal but it is curable. the disease gets its name from the rocky mountain region where it was first identified in 1896. the fever is caused by the bacterium rickettsia rickettsii and is maintained in nature in a complex life cycle involving ticks and mammals. humans are considered to be accidental hosts and are not involved in the natural transmission cycle of ...200717511369
the ticks (acari: ixodida: argasidae, ixodidae) of paraguay.the ticks reported in paraguay, which are here reviewed, can be categorized as 'endemic or established' (argas persicus or a sibling species, ornithodoros hasei, o. rostratus, o. rudis, o. talaje/o. puertoricensis, amblyomma aureolatum, am. auricularium, am. brasiliense, am. cajennense, am. calcaratum, am. coelebs, am. dissimile, am. dubitatum, am. incisum, am. longirostre, am. nodosum, am. ovale, am. pacae, am. parvum, am. pseudoconcolor, am. rotundatum, am. scutatum, am. tigrinum, am. triste, ...200717362600
detection of rickettsia rickettsii and bartonella henselae in rhipicephalus sanguineus ticks from california.sixty-two questing adult rhipicephalus sanguineus (latreille) ticks were collected by direct removal from blades of turfgrass and adjacent concrete walkways at a suburban home in riverside county, ca, and tested for the presence of rickettsia, bartonella, and ehrlichia dna. polymerase chain reaction (pcr) was used to amplify fragments of the 17-kda antigen gene and the rompa gene of the spotted fever group rickettsiae. one male tick contained r. rickettsii dna; its genotype differed from r. rick ...200717294935
association between polyarthritis and thrombocytopenia and increased prevalence of vectorborne pathogens in californian dogs. 200717277299
serologic survey of eptesicus fuscus from georgia, u.s.a. for rickettsia and borrelia and laboratory transmission of a rickettsia by bat ticks.bats and their ectoparasites are associated with bacterial agents of unknown pathogenicity. we tested sera from 56 eptesicus fuscus from georgia against borrelia hermsii, orientia tsutsugamushi, rickettsia conorii, and rickettsia rickettsii. we detected antibodies reactive against a relapsing fever borrelia and spotted fever group rickettsia in 3/56 and 1/56 bats, respectively. we attempted to culture bartonella from the blood of these bats but were unsuccessful. in addition, we fed bat ticks, c ...200617249357
clinical and laboratory features, hospital course, and outcome of rocky mountain spotted fever in children.to describe the clinical characteristics and course of children with laboratory-diagnosed rocky mountain spotted fever (rmsf) and to identify clinical findings independently associated with adverse outcomes of death or discharge with neurologic deficits.200717236897
the low seroprevalence of tick-transmitted agents of disease in dogs from southern ontario and quebec.infectious diseases caused by pathogens transmitted by ticks and other insect vectors are an important cause of morbidity and mortality in both dogs and humans throughout north america. the purpose of this study was to determine the seroprevalence of selected vector-transmitted pathogens in southern ontario and quebec. samples submitted to the vector borne disease diagnostic laboratory (vbddl) at the north carolina state university college of veterinary medicine were evaluated for antibodies to ...200617217089
rocky mountain spotted fever. 200617200577
serologic evidence for exposure to rickettsia rickettsii in eastern arizona and recent emergence of rocky mountain spotted fever in this region.during 2002 through 2004, 15 patients with rocky mountain spotted fever (rmsf) were identified in a rural community in arizona where the disease had not been previously reported. the outbreak was associated with rickettsia rickettsii in an unexpected tick vector, the brown dog tick (rhipicephalus sanguineus), which had not been previously associated with rmsf transmission in the united states. we investigated the extent of exposure to r. rickettsii in the local area through serologic evaluations ...200617187578
rickettsia rickettsii infection causes apoptotic death of cultured cerebellar granule neurons. 200717172530
[study on the development of a real-time quantitative polymerase chain reaction assay to detect rickettsia].to develop a real-time quantitative polymerase chain reaction(pcr) assay for detecting rickettsia rickettsii.200617152516
molecular typing of novel rickettsia rickettsii isolates from arizona.seven isolates of rickettsia rickettsii were obtained from a skin biopsy, two whole-blood specimens, and from rhipicephalus sanguineus ticks from eastern arizona. molecular typing of seven isolates of r. rickettsii and dna samples from two other rh. sanguineus ticks infected with r. rickettsii was conducted by pcr and dna sequencing of rompa and 12 variable-number tandem repeat regions (vntrs). all dna specimens from arizona were identical to each other and to reference human and dermacentor and ...200617114781
isolation of rickettsia rickettsii and rickettsia bellii in cell culture from the tick amblyomma aureolatum in brazil.brazilian spotted fever (bsf) is a highly lethal disease caused by rickettsia rickettsii. in the present study, rickettsial infection was evaluated in 669 amblyomma aureolatum adult ticks collected from naturally infested dogs in taiaçupeba, a bsf-endemic area in the state of são paulo. ten (1.49%) ticks were infected with rickettsia bellii, and 6 (0.89%) ticks were infected with r. rickettsii. both rickettsia species were isolated and established in vero cell cultures. the rickettsia isolates w ...200617114770
spotted fever group rickettsial infection in dogs from eastern arizona: how long has it been there?a serosurvey of free-roaming dogs for antibodies to spotted fever group rickettsiae was conducted using archival samples that had been collected in the white mountain region of eastern arizona during a plague study in 1996. immunoglobulin g antibodies to rickettsia rickettsii (5.1%) and to r. rhipicephali (3.6%) were demonstrated, and no cross-reactive samples were identified. this study indicates that r. rickettsii was likely present in the dog populations in this area prior to the recognition ...200617114769
molecular characterization of rickettsia rickettsii infecting dogs and people in north carolina.rocky mountain spotted fever (rmst) is an important cause of morbidity and mortality in people and dogs in the united states. disease manifestations are strikingly similar in both species, and illness in dogs can precede illness in people. r. rickettsii has been identified as a select agent by the cdc as a category c priority pathogen by the national institute of allergic and infectious diseases because it is amenable to use as a bioterror agent. the clinical and temporal relationship of natural ...200617114748
rocky mountain spotted fever in arizona: documentation of heavy environmental infestations of rhipicephalus sanguineus at an endemic site.a recent epidemiologic investigation identified 16 cases and 2 deaths from rocky mountain spotted fever (rmsf) in two eastern arizona communities. prevalence studies were conducted by collecting free-living ticks (acari: ixodidae) from the home sites of rmsf patients and from other home sites within the community. dry ice traps and flagging confirmed heavy infestations at many of the home sites. only rhipicephalus sanguineus ticks were identified and all developmental stages were detected. it is ...200617114735
a rickettsial mixed infection in a dermacentor variabilis tick from ohio.we present the first report of superinfection in a dermacentor variabilis tick from nature. the single tick, collected in ohio, was found infected with rickettsia belli, r. nontanensis, and r. rickettsii.200617114734
detection of rickettsia rickettsii and rickettsia sp. in blood clots in 24 patients from different municipalities of the state of sao paulo, brazil.the authors detected rickettsia genus organisms using shell vial and polymerase chain reaction (pcr)/sequencing analysis in blood clots in patients suspected of having brazilian spotted fever (bsf). dna was detected using pcr with three sets of primers to access the glta, ompa, and ompb genes. sequence analysis was carried out using an automatic sequencer with bioedit software. seventy-five percent of the culture samples were positive and all samples amplified rickettsial gene fragments. to date ...200617114719
fatal case of brazilian spotted fever confirmed by immunohistochemical staining and sequencing methods on fixed tissues.the authors describe the first characterization of rickettsia rickettsii in a fatal case occurring in rio de janeiro state, brazil.200617114718
brazilian spotted fever: a case series from an endemic area in southeastern brazil: epidemiological aspects.brazilian spotted fever (bsf) is the most important tick-borne disease in brazil and is caused by rickettsia rickettsii and transmitted by the ixodid tick amblyomma cajennense, its main vector. we present epidemiologic aspects of a case series of patients admitted to the hospital das clínicas da unicamp from 1985 to 2003 with a confirmed diagnosis of bsf either by a fourfold rise in indirect immunofluorescence (ifa) titers of igg antibodies reactive with r. rickettsii or isolation of r. ricketts ...200617114702
myocardial involvement in rocky mountain spotted fever: a case report and review.rocky mountain spotted fever (rmsf), caused by rickettia rickettsii, is a serious tickborne illness that is endemic in the southeastern united states. although it is most commonly known as a cause of fever and rash, it can have systemic manifestations. the myocardium may rarely be involved, with symptoms that can mimic those of acute coronary syndromes. this report describes a case of serologically proven rmsf causing symptomatic myocarditis, manifested by chest pain, elevated cardiac enzyme lev ...200617031247
tick-borne rickettsial pathogens in ticks and small mammals in korea.in order to investigate the prevalence of tick-borne infectious agents among ticks, ticks comprising five species from two genera (hemaphysalis spp. and ixodes spp.) were screened using molecular techniques. ticks (3,135) were collected from small wild-caught mammals or by dragging/flagging in the republic of korea (rok) and were pooled into a total of 1,638 samples (1 to 27 ticks per pool). from the 1,638 tick samples, species-specific fragments of anaplasma phagocytophilum (1 sample), anaplasm ...200616957192
infection of human endothelial cells with spotted fever group rickettsiae stimulates cyclooxygenase 2 expression and release of vasoactive prostaglandins.rickettsiae, a diverse group of obligately intracellular gram-negative bacteria, include etiologic agents of the spotted fever and typhus groups of diseases. rocky mountain spotted fever and boutonneuse fever, due to rickettsia rickettsii and r. conorii, respectively, are characterized by widespread infection of the vascular endothelium, microvascular injury, and vasculitis. cultured human endothelial cells (ec) are highly susceptible to infection and respond by altering the expression of adhesi ...200616926398
lymph node hemophagocytosis in rickettsial diseases: a pathogenetic role for cd8 t lymphocytes in human monocytic ehrlichiosis (hme)?human monocytic ehrlichiosis (hme) and rocky mountain spotted fever (rmsf) are caused by ehrlichia chaffeensis and rickettsia rickettsii, respectively. the pathogenesis of rmsf relates to rickettsia-mediated vascular injury, but it is unclear in hme.200616859547
fatal human infection with rickettsia rickettsii, yucatán, mexico.the first fatal rickettsia rickettsii infection was diagnosed in the southwest of mexico. the patient had fever, erythematous rash, abdominal pain, and severe central nervous system involvement with convulsive crisis. the diagnosis of r. rickettsii infection was established by immunohistochemistry and specific polymerase chain reaction.200616704818
rocky mountain spotted fever.rocky mountain spotted fever (rmsf) is an unusual but important dermatological condition to identify without hesitation. the classic triad of headache, fever, and a rash that begins on the extremities and travels proximally to involve the trunk is found in a majority of patients. the cutaneous centripetal pattern is a result of cell to cell migration by the causative organism rickettsia rickettsii. such individuals should receive prompt antimicrobial therapy and supportive care to avoid serious ...200616643138
experimentally infected human body lice (pediculus humanus humanus) as vectors of rickettsia rickettsii and rickettsia conorii in a rabbit model.the human body louse, the natural vector of rickettsia prowazekii, is able to experimentally transmit the normally flea-borne rickettsia r. typhi, suggesting that the relationships between the body louse and rickettsiae are not specific. we used our experimental infection model to test the ability of body lice to transmit two prevalent tick-borne rickettsiae. each of two rabbits was made bacteremic by injecting intravenously 2 x 10(6) plaque-forming units of either r. rickettsii or r. conorii. f ...200616606977
virulent-avirulent conversions of rickettsia rickettsii in vitro. 195516589763
high-throughput molecular testing of ticks using a liquid-handling robot.to meet the need for high-throughput sample testing, dna extraction kits based on the 96-well plate format have been developed for use with blood and tissue samples. these methods have not been applied to dna extractions from ticks. to meet this need, we developed a high-throughput method for dna extraction and polymerase chain reaction (pcr) testing of tick samples. a liquid-handling robot was used to extract dna in a 96-well binding column plate with vacuum manifold. the quantity, purity, and ...200516465749
serologic survey of select infectious diseases in coyotes and raccoons in nebraska.to obtain data about select zoonotic and other infectious diseases in free-ranging predators in five ecoregions in nebraska, sera were collected from 67 coyotes (canis latrans) and 63 raccoons (procyon lotor) from november 2002 through january 2003. for coyotes, antibodies were detected against canine distemper virus (cdv, 61%), francisella tularensis (32%), rickettsia rickettsi (13%), and flaviviruses (48%). none of the coyote sera had antibodies to borrelia burgdorferi, brucella canis, or six ...200516456169
antibodies to rickettsia rickettsii, rickettsia typhi, coxiella burnetii, bartonella henselae, bartonella quintana, and ehrlichia chaffeensis among healthy population in minas gerais, brazil.rickettsial diseases except those belonging to spotted fever group rickettsioses are poorly studied in south america particularly in brazil where few epidemiological reports have been published. we describe a serosurvey for rickettsia rickettsii, r. typhi, coxiella burnetii, bartonella henselae, b. quintana, and ehrlichia chaffeensis in 437 healthy people from a brazilian rural community. the serum samples were tested by indirected micro-immunoflourescence technique and a cutoff titer of 1:64 wa ...200616444416
detection of rickettsia rickettsii in the tick amblyomma cajennense in a new brazilian spotted fever-endemic area in the state of minas gerais.the present study evaluated rickettsial infection in amblyomma spp. ticks collected in a farm in coronel pacheco, a brazilian spotted fever (bsf) endemic area. a total of 78 a. cajennense and 78 a. dubitatum free-living adult ticks were collected and tested by polymerase chain reaction (pcr) targeting a fragment of the rickettsial gene glta. only one pool of three a. cajennense ticks showed the expected product by pcr. this pool was further tested by pcr using sets of primers targeting the ricke ...200616444414
serological survey of vector-borne zoonotic pathogens in pet cats and cats from animal shelters and feral colonies.although cats and their arthropod parasites can sometimes be important sources of zoonotic diseases in humans, the extent of exposure among various cat populations to many potential zoonotic agents remains incompletely described. in this study, 170 domestic cats living in private homes, feral cat colonies, and animal shelters from california and wisconsin were evaluated by serology to determine the levels of exposure to a group of zoonotic vector-borne pathogens. serological positive test result ...200616434226
evaluation of a western blot method for the detection of yersinia antibodies: evidence of serological cross-reactivity between yersinia outer membrane proteins and borrelia burgdorferi.yersinia enterocolitica and yersinia pseudotuberculosis have been identified as causative organisms of reactive arthritis in humans. we evaluated a western blot assay which uses yersinia outer membrane proteins as antigens for the detection of yersinia antibodies as a replacement for the complement fixation (cf) assay. clinical agreement, sensitivity, and specificity were determined by testing 19 positive and 21 negative serum samples by the cf assay, western blot assay, and enzyme-linked immuno ...200516275939
cardiac involvement in a patient with clinical and serological evidence of african tick-bite fever.myocarditis and pericarditis are rare complications of rickettsiosis, usually associated with rickettsia rickettsii and r. conorii. african tick-bite fever (atbf) is generally considered as a benign disease and no cases of myocardial involvement due to rickettsia africae, the agent of atbf, have yet been described.200516242016
activation of p38 stress-activated protein kinase during rickettsia rickettsii infection of human endothelial cells: role in the induction of chemokine response.rickettsia rickettsii, a gram-negative and obligate intracellular bacterium, preferentially infects the vascular endothelium during human infections leading to inflammation and dysfunction. the aim of this study was to determine whether r. rickettsii infection of endothelial cells (ec) activates p38 and/or c-jun n-terminal kinases (jnk) mitogen-activated protein (map) kinase, key regulatory proteins that control the response to inflammatory stimuli. we show that infection of cultured human ec re ...200516153249
expression and secretion of chemotactic cytokines il-8 and mcp-1 by human endothelial cells after rickettsia rickettsii infection: regulation by nuclear transcription factor nf-kappab.infection of endothelial cells (ec) with rickettsia rickettsii results in rocky mountain spotted fever, an acute illness characterized by systemic inflammation. interleukin-8 (il-8) and monocyte chemoattractant protein-1 (mcp-1) are important chemokines for activating neutrophils and monocytes, respectively, and recruiting these circulating immune cells to the sites of inflammation. in this study, we have measured the expression and secretion of these chemokines during r. rickettsii infection of ...200516128401
detection of brazilian spotted fever infection by polymerase chain reaction in a patient from the state of são paulo.brazilian spotted fever (bsf) cases have been increasing in the state of são paulo but no genomic information about local rickettsia isolated from humans has been well documented. we recovered spotted-fever group rickettsiae from a sample of patient blood cultured in vero cells using the shell vial technique. rickettsial dna fragments (glta, ompa, and, ompb genes) were detected, and analysis of the ompb gene base sequences showed identity with the rickettsia rickettsii ompb sequence available in ...200516113868
rocky mountain spotted fever from an unexpected tick vector in arizona.rocky mountain spotted fever is a life-threatening, tick-borne disease caused by rickettsia rickettsii. this disease is rarely reported in arizona, and the principal vectors, dermacentor species ticks, are uncommon in the state. from 2002 through 2004, a focus of rocky mountain spotted fever was investigated in rural eastern arizona.200516093467
rocky mountain spotted fever--changing ecology and persisting virulence. 200516093463
central nervous system dysfunction associated with rocky mountain spotted fever infection in five dogs.five dogs from the northeastern united states were presented with clinical signs of neurological disease associated with rocky mountain spotted fever (rmsf) infection. four of the five dogs had vestibular system dysfunction. other neurological signs included paresis, tremors, and changes in mentation. all of the dogs had an elevated indirect fluorescent antibody titer or a positive semiquantitative enzyme screening immunoassay titer for rickettsia rickettsii at the time of presentation. although ...200515995164
[rocky mountain spotted fever in an american tourist].in a 28-year-old male american tourist who presented in the hospital with fever, cold shivers, headache, nausea, myalgia and arthralgia, rocky mountain spotted fever was suspected, partly because he came from an endemic region (the state of georgia). the patient was treated with doxycycline, 100 mg b.i.d.; 9 days after the first appearance of the symptoms, the diagnosis was confirmed by the report of a positive antibody titre against rickettsia rickettsii. the patient did not have exanthema. he ...200515835630
changes in the adherens junctions of human endothelial cells infected with spotted fever group rickettsiae.rickettsiae of the spotted fever group are obligately intracellular bacteria that primarily infect the vascular endothelium, invade adjacent cells propelled by actin polymerization, and cause severe systemic diseases. endothelial dysfunction and vascular leakage develop as a consequence; this effect is the pathophysiological mechanism that explains most clinical manifestations. here we report that rickettsial infection of cultured primary human endothelial cells is associated with the formation ...200515778845
rickettsial infection in animals and brazilian spotted fever endemicity.we compared the rickettsial infection status of amblyomma cajennense ticks, humans, dogs, and horses in both brazilian spotted fever (bsf)-endemic and -nonendemic areas in the state of sao paulo, brazil. most of the horses and few dogs from bsf-endemic areas had serologic titers against rickettsia rickettsii antigens. in contrast, no dogs or horses from bsf-nonendemic areas had serologic titers against r. rickettsii antigens, although they were continually exposed to a. cajennense ticks. all hum ...200515752445
functional analysis of seca homologues from rickettsiae.the molecular basis of protein secretion that underlines rickettsial pathogenesis remains unknown. this paper reports the molecular and functional analysis of the putative seca gene, an essential component of the sec-dependent protein secretion pathway, from rickettsia rickettsii and rickettsia typhi, the aetiological agents of rocky mountain spotted fever and murine typhus, respectively. the sequence analysis of the cloned seca genes from r. rickettsii and r. typhi show orfs of 2721 and 2718 nt ...200515699207
nf-kappab activation during rickettsia rickettsii infection of endothelial cells involves the activation of catalytic ikappab kinases ikkalpha and ikkbeta and phosphorylation-proteolysis of the inhibitor protein ikappabalpha.rocky mountain spotted fever, a systemic tick-borne illness caused by the obligate intracellular bacterium rickettsia rickettsii, is associated with widespread infection of the vascular endothelium. r. rickettsii infection induces a biphasic pattern of the nuclear factor-kappab (nf-kappab) activation in cultured human endothelial cells (ecs), characterized by an early transient phase at 3 h and a late sustained phase evident at 18 to 24 h. to elucidate the underlying mechanisms, we investigated ...200515618150
sequence and expression analysis of the ompa gene of rickettsia peacockii, an endosymbiont of the rocky mountain wood tick, dermacentor andersoni.the transmission dynamics of rocky mountain spotted fever in montana appears to be regulated by rickettsia peacockii, a tick symbiotic rickettsia that interferes with transmission of virulent rickettsia rickettsii. to elucidate the molecular relationships between the two rickettsiae and glean information on how to possibly exploit this interference phenomenon, we studied a major rickettsial outer membrane protein gene, ompa, presumed to be involved in infection and pathogenesis of spotted fever ...200415528527
transfusion-transmitted tick-borne infections: a cornucopia of threats.over the past several decades, the frequency of contact between humans and ticks has increased dramatically. concomitantly, several newly recognized tick-borne pathogens have emerged joining those already known to be transmitted by ticks. together these factors have led to an enhanced public health awareness of ticks, tick-borne agents, and their associated diseases. reports that several of these agents are transmitted by blood transfusion have raised concerns about blood safety. the primary age ...200415497129
rickettsial vaccines: the old and the new.in the past century vaccine development for prevention of rickettsial diseases has been prolific. however, in the past 20 years no new rickettsial vaccine has been manufactured and there are currently no new or old rickettsial vaccines licensed. early rickettsial vaccines were difficult, expensive and very hazardous to produce. molecular biology techniques of today are currently being used to develop new rickettsial vaccines that are standardized, inexpensive, nonhazardous and efficacious.200415485334
bartonella henselae igg antibodies are prevalent in dogs from southeastern usa.in contrast to the large body of literature regarding bartonella henselae in humans and cats, there is little information about b. henselae as an infectious agent in dogs. due to the paucity of information regarding the b. henselae serology in dogs, we performed a cross-sectional serosurvey using b. henselae antigen in order to compare the seroprevalence between sick and healthy dogs from the south-eastern usa. ninety-nine sera were collected from clinically healthy dogs. three hundred and one s ...200415369661
prevalence of antibodies to spotted fever group rickettsiae in humans and domestic animals in a brazilian spotted fever-endemic area in the state of são paulo, brazil: serologic evidence for infection by rickettsia rickettsii and another spotted fever group rickettsia.in serum samples obtained from all the healthy humans, horses, dogs, and donkeys present on three farms in the pedreira municipality, an endemic area for brazilian spotted fever, an indirect immunofluorescence assay (ifa) detected antibodies against rickettsia rickettsii in 17 (77.3%) horses, 5 (31.3%) dogs (titers ranging from 64 to 4,048), and none of 4 donkeys or 50 humans. five canine and eight equine sera with high antibody titers to r. rickettsii were also tested by ifa against r. bellii, ...200415238696
a rickettsia wasp-like protein activates the arp2/3 complex and mediates actin-based motility.spotted fever group rickettsia are obligate intracellular pathogens that exploit the host cell actin cytoskeleton to promote motility and cell-to-cell spread. although other pathogens such as listeria monocytogenes use an arp2/3 complex-dependent nucleation mechanism to generate comet tails consisting of y-branched filament arrays, rickettsia polymerize tails consisting of unbranched filaments by a previously unknown mechanism. we identified genes in several rickettsia species encoding proteins ...200415236643
rocky mountain spotted fever at koair children's hospital, 1990-2002.the reported average annual incidence of rocky mountain spotted fever (rmsf) in kentucky is less than 5 per million population, although seroprevalence studies suggest that exposure to rickettsia riskettsii, the causative agent, is relatively common among children. the experience with rmsf at kosair children's hospital over a 12-year period was reviewed. fifteen cases were identified (5 boys and 10 girls). illness onset ranged from april to october, and 4 patients resided in jefferson county. th ...200415152446
fatal cases of rocky mountain spotted fever in family clusters--three states, 2003.rocky mountain spotted fever (rmsf), a tickborne infection caused by rickettsia rickettsii and characterized by a rash, has a case-fatality rate as high as 30% in certain untreated patients. even with treatment, hospitalization rates of 72% and case-fatality rates of 4% have been reported. this report summarizes the clinical course of three fatal cases of rmsf in children and related illness in family members during the summer of 2003. these cases underscore the importance of 1) prompt diagnosis ...200415152183
Refresh
firstprev
12345678910...
nextlast
Displaying items 201 - 300 of 1610