Publications

TitleAbstractYear
Filter
PMID(sorted descending)
Filter
serologic evidence of human rickettsia infection found in three locations in panamá.since the middle of last century, cases of rickettsiosis have been found in panamá when outbreaks of murine typhus and spotted fever were reported. since then, little information exists about its prevalence in this country, since it is most often is misdiagnosed as another disease.201324652247
surface protein adr2 of rickettsia rickettsii induced protective immunity against rocky mountain spotted fever in c3h/hen mice.rickettsia rickettsii is the pathogen of rocky mountain spotted fever (rmsf), a life-threatening tick-transmitted infection. adr2 was a surface-exposed adhesion protein of r. rickettsii and its immunoprotection against rmsf was investigated in mice.201424582636
rickettsial infection in amblyomma cajennense ticks and capybaras (hydrochoerus hydrochaeris) in a brazilian spotted fever-endemic area.brazilian spotted fever (bsf), caused by the bacterium rickettsia rickettsii, is the deadliest spotted fever of the world. in most of the bsf-endemic areas, capybaras (hydrochoerus hydrochaeris) are the principal host for the tick amblyomma cajennense, which is the main vector of bsf.201424387674
"rickettsia amblyommii" and r. montanensis infection in dogs following natural exposure to ticks.to determine the risk of canine infection with spotted fever group (sfg) rickettsia spp. following natural tick exposure, 10 dogs determined to be free of evidence of exposure to or infection with tick-borne disease agents were exposed to ticks via weekly walks in a wooded area in north-central oklahoma. after each walk, dogs were examined and the number and species of ticks present were recorded. the dogs were then returned to outdoor kennels to allow the infestations and subsequent transmissio ...201424359419
natural blood feeding and temperature shift modulate the global transcriptional profile of rickettsia rickettsii infecting its tick vector.rickettsia rickettsii is an obligate intracellular tick-borne bacterium that causes rocky mountain spotted fever (rmsf), the most lethal spotted fever rickettsiosis. when an infected starving tick begins blood feeding from a vertebrate host, r. rickettsii is exposed to a temperature elevation and to components in the blood meal. these two environmental stimuli have been previously associated with the reactivation of rickettsial virulence in ticks, but the factors responsible for this phenotype c ...201324155949
environmental infestation and rickettsial infection in ticks in an area endemic for brazilian spotted fever.brazilian spotted fever (bsf), caused by rickettsia rickettsii, is endemic in the municipality of americana, southeastern brazil, where the disease is transmitted by the tick amblyomma cajennense. this study evaluated the tick fauna and rickettsial infection in free-living ticks that were captured monthly using dry ice traps in areas endemic for bsf in americana, from july 2009 to june 2010. two tick species were captured: a. cajennense (6,122 larvae; 4,265 nymphs; 2,355 adults) and amblyomma du ...201324142167
rickettsia felis infection in cat fleas ctenocephalides felis felis.the present study evaluated the rickettsial infection in a laboratory colony of cat fleas, ctenocephalides felis felis (bouche) in brazil. all flea samples (30 eggs, 30 larvae, 30 cocoons, 30 males, and 30 females) tested by polymerase chain reaction (pcr) were shown to contain rickettsial dna. pcr products, corresponding to the rickettsial glta, htra, ompa and ompb gene partial sequences were sequenced and showed to correspond to rickettsia felis, indicating that the flea colony was 100% infect ...201024031560
crystal structure of the n-terminal domains of the surface cell antigen 4 of rickettsia.the obligate intracellular, gram-negative bacterium rickettsia is the causative agent of spotted fevers and typhus in humans. surface cell antigen (sca) proteins surround these bacteria. we recently reported the co-localization of one of these proteins, sca4, with vinculin in cells at sites of focal adhesions and demonstrated that two vinculin binding sites directed the sca4/vinculin interaction. here we report the 2.2 å crystal structure of the conserved n-terminal 38 kda domain of sca4 from ri ...201323904352
ecology, biology and distribution of spotted-fever tick vectors in brazil.spotted-fever-caused rickettsia rickettsii infection is in brazil the major tick-borne zoonotic disease. recently, a second and milder human rickettsiosis caused by an agent genetically related to r. parkeri was discovered in the country (atlantic rainforest strain). both diseases clearly have an ecological background linked to a few tick species and their environment. capybaras (hydrochoerus hydrochaeris) and amblyomma cajennense ticks in urban and rural areas close to water sources are the mai ...201323875178
rickettsial infections in the tropics and in the traveler.the purpose of this review is to describe recent advances in our understanding of the pathogenesis, epidemiology, and clinical features of rickettsial diseases with emphasis placed on those relating to travel and tropical medicine.201323842049
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 ...201323778619
[mortality from rickettsia rickettsii spotted fever in patients at a pediatric hospital in the state of sonora, 2004-2012]. 201323546404
chemical characterization and acaricide potential of essential oil from aerial parts of tagetes patula l. (asteraceae) against engorged adult females of rhipicephalus sanguineus (latreille, 1806).rhipicephalus sanguineus, commonly known as the brown dog tick, is one of the most widely distributed species of tick. in dogs, it can cause anemia and provide the transmission of pathogenic microorganisms such as babesia canis, ehrlichia canis, hepatozoon canis, anaplasma platys, and mycoplasma haemocanis. to man, it can transmit the intracellular parasites rickettsia rickettsii and rickettsia conorii, the causative agents of the rocky mountain spotted fever in the americas and mediterranean an ...201323508761
a 6-year-old girl with fever, rash, and increased intracranial pressure.rocky mountain spotted fever (rmsf) is a well-described, potentially lethal, tick-borne zoonotic infection and has very effective therapy. however, the diagnosis might not be made early enough, often leading to worse outcomes.201323485263
hitch-hiker taken for a ride: an unusual cause of myocarditis, septic shock and adult respiratory distress syndrome.rocky mountain spotted fever (rmsf) is a serious tick-borne illness caused by rickettsia rickettsii that is endemic in southeastern usa. although rmsf has been described as causing the classic clinical triad of fever, headache and a characteristic rash, serious and potentially life-threatening manifestations can occur. cardiopulmonary involvement, although infrequent, may occur with severe cases of rmsf. rickettsial myocarditis is an uncommon occurrence. we present a case of a previously healthy ...201323314875
investigation of an outbreak of rickettsial febrile illness in guatemala, 2007.we describe an outbreak of spotted fever group (sfg) rickettsiosis that occurred in 2007 in a farming community in southeastern guatemala. we identified 17 cases of an acute febrile illness, among which 10, including two fatalities, were confirmed or probable cases of rickettsial disease (case-fatality proportion 12%).201223266334
modelling spatial concordance between rocky mountain spotted fever disease incidence and habitat probability of its vector dermacentor variabilis (american dog tick).the spatial distribution of dermacentor variabilis, the most commonly identified vector of the bacterium rickettsia rickettsii which causes rocky mountain spotted fever (rmsf) in humans, and the spatial distribution of rmsf, have not been previously studied in the south central united states of america, particularly in texas. from an epidemiological perspective, one would tend to hypothesise that there would be a high degree of spatial concordance between the habitat suitability for the tick and ...201223242684
ixodid fauna and zoonotic agents in ticks from dogs: first report of rickettsia rickettsii in rhipicephalus sanguineus in the state of mato grosso do sul, mid-western brazil.ticks from 148 dogs from the urban area of the municipality of campo grande, state of mato grosso do sul, brazil, were collected, classified and analyzed using polymerase chain reaction (pcr) for the identification of rickettsia spp., trypanosoma cruzi and leishmania spp. a total of 2015 ticks were collected. the species rhipicephalus sanguineus (98.9 %) and amblyomma cajennense (1.1 %) were identified. molecular analysis revealed that no tick samples were infected by t. cruzi. regarding leishma ...201323229491
comparative genomics and transcriptomics of trait-gene association.the order rickettsiales includes important tick-borne pathogens, from rickettsia rickettsii, which causes rocky mountain spotted fever, to anaplasma marginale, the most prevalent vector-borne pathogen of cattle. although most pathogens in this order are transmitted by arthropod vectors, little is known about the microbial determinants of transmission. a. marginale provides unique tools for studying the determinants of transmission, with multiple strain sequences available that display distinct a ...201223181781
features of brazilian spotted fever in two different endemic areas in brazil.brazilian spotted fever (bsf) caused by rickettsia rickettsii is the most important rickettsiosis and the only reportable tick-borne disease in brazil. in brazil, the hard tick amblyomma cajennense is the most important bsf vector; however, in são paulo state, a. aureolatum was also recognized as a vector species in remaining atlantic forest areas near the metropolitan area of são paulo city. we analyzed clinical and epidemiological features of bsf cases from two distinct areas where a. cajennen ...201223168052
seroprevalence of tick-borne infections in military working dogs in the republic of korea.in this study we endeavored to determine the seroprevalence of tick-borne infections in the military working dog (mwd) population in the republic of korea (rok). our sample population consisted of 182 serum samples from mwds for 3 different years (1996, 2002, and 2007). in addition, 63 whole blood samples from 2007 were available for polymerase chain reaction (pcr). serum samples were evaluated by a commercially available enzyme-linked immunosorbent assay (elisa) and immunofluorescence assay (if ...201223167501
solution structure of the cold-shock-like protein from rickettsia rickettsii.rocky mountain spotted fever is caused by rickettsia rickettsii infection. r. rickettsii can be transmitted to mammals, including humans, through the bite of an infected hard-bodied tick of the family ixodidae. since the r. rickettsii genome contains only one cold-shock-like protein and given the essential nature of cold-shock proteins in other bacteria, the structure of the cold-shock-like protein from r. rickettsii was investigated. with the exception of a short α-helix found between β-strands ...201223143233
assessment of real-time pcr assay for detection of rickettsia spp. and rickettsia rickettsii in banked clinical samples.two novel real-time pcr assays were developed for the detection of rickettsia spp. one assay detects all tested rickettsia spp.; the other is specific for rickettsia rickettsii. evaluation using dna from human blood and tissue samples showed both assays to be more sensitive than nested pcr assays currently in use at the cdc.201323135935
unusual bacterial infections and the pleura.rickettsiosis, q fever, tularemia, and anthrax are all bacterial diseases that can affect the pleura. rocky mountain spotted fever (rmsf) and mediterranean spotted fever (msf) are caused by rickettsia rickettsii and rickettsia conorii, respectively. pleural fluid from a patient with msf had a neutrophil-predominant exudate. coxiellaburnetii is the causative agent of q fever. of the two cases described in the literature, one was an exudate with a marked eosinophilia while the other case was a tra ...201222977649
perinuclear antineutrophil cytoplasmic autoantibodies in dogs infected with various vector-borne pathogens and in dogs with immune-mediated hemolytic anemia.to determine the prevalence of perinuclear antineutrophil cytoplasmic autoantibodies (panca) in dogs with confirmed or suspected immune-mediated hemolytic anemia (imha) or dogs infected with various vector-borne pathogens, including rickettsia rickettsii, bartonella henselae, bartonella vinsonii subsp berkhoffii, ehrlichia canis, borrelia burgdorferi, and leishmania infantum.201222924722
a fatal urban case of rocky mountain spotted fever presenting an eschar in san jose, costa rica.this study reports the first urban human case of rocky mountain spotted fever caused by rickettsia rickettsii, in costa rica. an 8-year-old female who died at the national children's hospital 4 days after her admission, and an important and significant observation was the presence of an "eschar" (tache noire), which is typical in some rickettsial infections but not frequent in rocky mountain spotted fever cases.201222855769
epidemiology of brazilian spotted fever in the atlantic forest, state of são paulo, brazil.the tick-borne bacterium rickettsia rickettsii is the aetiological agent of brazilian spotted fever (bsf). the present study evaluated tick infestations on wild and domestic animals, and the rickettsial infection in these animals and their ticks in 7 forest areas adjacent to human communities in the são paulo metropolitan area (spma). the results were compared to ecological traits of each sampled area. two main tick species, amblyomma aureolatum and rhipicephalus sanguineus, were collected from ...201222716923
saliva, salivary gland, and hemolymph collection from ixodes scapularis ticks.ticks are found worldwide and afflict humans with many tick-borne illnesses. ticks are vectors for pathogens that cause lyme disease and tick-borne relapsing fever (borrelia spp.), rocky mountain spotted fever (rickettsia rickettsii), ehrlichiosis (ehrlichia chaffeensis and e. equi), anaplasmosis (anaplasma phagocytophilum), encephalitis (tick-borne encephalitis virus), babesiosis (babesia spp.), colorado tick fever (coltivirus), and tularemia (francisella tularensis) (1-8). to be properly trans ...201222371172
rickettsia species infecting amblyomma ticks from an area endemic for brazilian spotted fever in brazil.this study reports rickettsial infection in amblyomma cajennense and amblyomma dubitatum ticks collected in an area of the state of minas gerais, brazil, where brazilian spotted fever is considered endemic. for this purpose, 400 adults of a. cajenennse and 200 adults of a. dubitatum, plus 2,000 larvae and 2,000 nymphs of amblyomma spp. were collected from horses and from the vegetation. the ticks were tested for rickettsial infection through polymerase chain reaction (pcr) protocols targeting po ...201122166385
introduction to the alpha-proteobacteria: wolbachia and bartonella, rickettsia, brucella, ehrlichia, and anaplasma.wolbachia is an obligate intracellular endosymbiont and likely mutualist living within the heartworm dirofilaria immitis and a number of other filarial nematodes in the family onchocercidae. the bacterial infection is passed from worm to worm transovarially; the organisms are in ovarian cells, the developing microfilariae, and multiply and persist in all later developmental stages through the mosquito and into the next host. besides being present in the ovaries of the adult worms, they also are ...201122152604
distribution of rickettsia rickettsii in ovary cells of rhipicephalus sanguineus (latreille1806) (acari: ixodidae).abstract:201122117572
Seroprevalence and risk factors to Ehrlichia spp. and Rickettsia spp. in dogs from the Pantanal Region of Mato Grosso State, Brazil.Sera of 320 dogs from urban and rural areas of a Pantanal region of Brazil were evaluated for rickettsial (Rickettsia rickettsii, R. parkeri, R. amblyommii, R. rhipicephali, R. felis, and R. bellii) and ehrlichial (Ehrlichia canis) infection by the immunofluorescence assay (IFA). Risk factors for ehrlichiosis or rickettsiosis were also evaluated. Positive reaction against Ehrlichia spp. was detected in 227 (70.9%) dogs, 119 (74.3%) from an urban area and 108 (67.5%) from rural areas (P>0.05). Fo ...201122108015
protein candidates for the serodiagnosis of rickettsioses.the laboratory diagnosis of rickettsioses is based on serology (reference method), cell culture and/or molecular tools. however, the main drawback of serology is its incapacity to provide identification of rickettsiae at the level of species. the aim of this study was to propose the versatile protein markers able to discriminate the patients with murine typhus from those with mediterranean spotted fever. we have cloned and expressed 20 proteins of rickettsia prowazekii and rickettsia rickettsii, ...201122098357
experimental infection of the tick amblyomma cajennense, cayenne tick, with rickettsia rickettsii, the agent of rocky mountain spotted fever.in the laboratory, amblyomma cajennense (acari: ixodidae) (fabricius) larvae, nymphs and adults were exposed to rickettsia rickettsii by feeding on needle-inoculated animals, and thereafter reared on uninfected guinea pigs or rabbits. regardless of the tick stage that acquired the infection, subsequent tick stages were shown to be infected (confirming transstadial and transovarial transmissions) and were able to transmit r. rickettsii to uninfected animals, as demonstrated by serological and mol ...201122007869
Rocky Mountain spotted fever in Panama: a cluster description.Rocky Mountain spotted fever (RMSF) is a tick-borne infection caused by Rickettsia rickettsii. We report a cluster of fatal cases of RMSF in 2007 in Panama, involving a pregnant woman and two children from the same family.  The woman presented with a fever followed by respiratory distress, maculopapular rash, and an eschar at the site from which a tick had been removed.  She died four days after disease onset.  This is the second published report of an eschar in a patient confirmed by PCR to be ...201121997944
etiologies of rash and fever illnesses in campinas, brazil.few population-based studies of infectious etiologies of fever-rash illnesses have been conducted. this study reports on enhanced febrile-rash illness surveillance in campinas, brazil, a setting of low measles and rubella virus transmission.201121954258
detection of anaplasma phagocytophilum in brazilian dogs by real-time polymerase chain reaction.anaplasma phagocytophilum was detected in dogs from brazil in the municipalities of seropédica and itaguaí, rio de janeiro state, by real-time polymerase chain reaction (pcr) using sybr green to detect the amplification. of 253 samples, 18 (7.11%) were positive, with a threshold cycle (ct) ranging from 31 to 35 cycles. the pcr product from a positive sample was cloned and sequenced. the sequence obtained demonstrated 100% identity with other a. phagocytophilum sequences published in the genbank ...201121908321
Study of infection by Rickettsiae of the spotted fever group in humans and ticks in an urban park located in the City of Londrina, State of Paraná, Brazil.Spotted fevers are emerging zoonoses caused by Rickettsia species in the spotted fever group (SFG). Rickettsia rickettsii is the main etiologic agent of Brazilian spotted fever (BSF)and it is transmitted by Amblyomma spp. ticks.201121901874
asymptomatic macrothrombocytopenia in a young pure-bred beagle dog: a case report.during baseline evaluation prior to a preclinical safety study, a 10-month-old male pure-bred beagle dog was found to have marked thrombocytopenia (6 × 10(3) platelets [plt]/µl) associated with a mean platelet volume (mpv) of 17.9 fl. tests for rickettsia rickettsii, ehrlichia canis, and borrelia burgdorferi were negative. buccal bleeding time was normal. over 3 months, plt were 4 to 141 × 10(3) plt/µl, and mpv was 11.4 to 25.1 fl; however, plt were <50 × 10(3) plt/µl and mpv was >16 fl during m ...201121859886
tick infestation and spotted-fever group rickettsia in shelter dogs, california, 2009.in response to an outbreak of rocky mountain spotted fever (rmsf) in baja california in early 2009, dogs at two shelters in neighbouring imperial county, california, were evaluated for ectoparasites. brown dog ticks (rhipicephalus sanguineus), a recognized vector for rmsf, were found on 35 (30%) of 116 dogs but all ticks tested negative for rickettsia rickettsii by pcr.201121824367
infection by spotted fever rickettsiae in people, dogs, horses and ticks in londrina, parana state, brazil.spotted fever is a disease caused by bacteria from the genus rickettsia of the spotted fever group (sfg). rickettsia rickettsii is likely the main agent of brazilian spotted fever (bsf). with the objective of gathering information on the circulation of sfg rickettsiae in londrina, parana state, ticks from dogs and horses and also blood from dogs, horses and humans were collected in a neighbourhood of the city which presented potential for circulation of rickettsiae between hosts and vectors. amb ...201121824336
fatal brazilian spotless fever caused by rickettsia rickettsii in a dark-skinned patient.brazilian spotted fever (bsf) is the most important and frequent rickettsial disease in brazil. a fatal case of bsf is reported in a 32-year-old black man, who died of irreversible shock after five days of fever, severe headache and abdominal pain with no rash. spleen, kidney and heart samples collected at autopsy were positive for rickettsia rickettsii by pcr and sequencing. the authors emphasize the need for a high index of diagnostic suspicion for spotted fever in black patients. absence of a ...201121779682
transformation frequency of a mariner-based transposon in rickettsia rickettsii.transformation frequencies of a mariner-based transposon system in rickettsia rickettsii were determined using a plaque assay system for enumeration and isolation of mutants. sequence analysis of insertion sites from both r. rickettsii and r. prowazekii indicated that insertions were random. transposon mutagenesis provides a useful tool for rickettsial research.201121764933
adherence to and invasion of host cells by spotted fever group rickettsia species.the pathogenic lifecycle of obligate intracellular bacteria presents a superb opportunity to develop understanding of the interaction between the bacteria and host under the pretext that disruption of these processes will likely lead to death of the pathogen and prevention of associated disease. species of the genus rickettsia contain some of the most hazardous of the obligate intracellular bacteria, including rickettsia rickettsii and r. conorii the causative agents of rocky mountain and medite ...201021687751
rickettsia monteiroi sp. nov., infecting the tick amblyomma incisum in brazil.free-living adult amblyomma incisum ticks were collected in an atlantic rainforest area at intervales state park, state of s+úo paulo, brazil. from an a. incisum specimen, rickettsiae were successfully isolated in vero cell culture by the shell vial technique. rickettsial isolation was confirmed by optical microscopy, transmission electron microscopy, and pcrs targeting portions of the rickettsial genes glta, htra, rrs, and sca1 on infected cells. fragments of 1,089, 457, 1,362, and 443 nucleoti ...201121685169
myocarditis, pericarditis, and cardiac tamponade associated with rocky mountain spotted fever. 201121658567
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 ...201121612532
rickettsia rickettsii transmission by a lone star tick, north carolina.only indirect or circumstantial evidence has been published to support transmission of rickettsia rickettsii by amblyomma americanum (lone star) ticks in north america. this study provides molecular evidence that a. americanum ticks can function, although most likely infrequently, as vectors of rocky mountain spotted fever for humans.201121529399
experimental infection of amblyomma aureolatum ticks with rickettsia rickettsii.we experimentally infected amblyomma aureolatum ticks with the bacterium rickettsia rickettsii, the etiologic agent of rocky mountain spotted fever (rmsf). these ticks are a vector for rmsf in brazil. r. rickettsii was efficiently conserved by both transstadial maintenance and vertical (transovarial) transmission to 100% of the ticks through 4 laboratory generations. however, lower reproductive performance and survival of infected females was attributed to r. rickettsii infection. therefore, bec ...201121529391
rickettsia rickettsii (rickettsiales: rickettsiaceae) in amblyomma americanum (acari: ixodidae) from kansas.the role of lone star ticks as vectors for rocky mountain spotted fever (rmsf) remains poorly described. we compared the entomological inoculation rates (eirs) for rickettsia spp. for representative sites in missouri and kansas, states that frequently report rmsf each year. host-seeking ticks were collected during 2006 and pooled tick homogenates analyzed by polymerase chain reaction to detect probable r. rickettsii, with confirmation for multiple gene targets performed on individual ticks from ...201121485390
rickettsia rickettsii in rhipicephalus ticks, mexicali, mexico.circulation of a unique genetic type of rickettsia rickettsii in ticks of the rhipicephalus sanguineus complex was detected in mexicali, baja california, mexico. the mexican r. rickettsii differed from all isolates previously characterized from the endemic regions of rocky mountain spotted fever in northern, central, and southern americas. rhipicephalus ticks in mexicali are genetically different from rh. sanguineus found in the united states.201121485383
dose-response model of rocky mountain spotted fever (rmsf) for human.rickettsia rickettsii is the causative agent of rocky mountain spotted fever (rmsf) and is the prototype bacterium in the spotted fever group of rickettsiae, which is found in north, central, and south america. the bacterium is gram negative and an obligate intracellular pathogen. the disease is transmitted to humans and vertebrate host through tick bites; however, some cases of aerosol transmission also have been reported. the disease can be difficult to diagnose in the early stages, and withou ...201121453373
medical microbiologyrickettsiae are small, gram-negative bacilli that have evolved in such close association with arthropod hosts that they are adapted to survive within the host cells. they represent a rather diverse collection of bacteria, and therefore listing characteristics that apply to the entire group is difficult. the common threads that hold the rickettsiae into a group are their epidemiology, their obligate intracellular life ...199621413251
outbreak of rocky mountain spotted fever in córdoba, colombia.rocky mountain spotted fever (rmsf) is a tick-borne disease caused by the obligate intracellular bacterium rickettsia rickettsii. although rmsf was first reported in colombia in 1937, it remains a neglected disease. herein, we describe the investigation of a large cluster of cases of spotted fever rickettsiosis in a new area of colombia.201121340366
complementation of rickettsia rickettsii rela/spot restores a nonlytic plaque phenotype.spotted fever group rickettsiae are known to produce distinct plaque phenotypes. strains that cause lytic infections in cell culture form clear plaques, while nonlytic strains form opaque plaques in which the cells remain intact. clear plaques have historically been associated with more-virulent species or strains of spotted fever group rickettsiae. we have selected spontaneous mutant pairs from two independent strains of rickettsia rickettsii, the virulent r strain and the avirulent iowa strain ...201121300770
clinical problem-solving. avoiding a rash diagnosis. 201121288099
serosurvey of antibodies against spotted fever group rickettsia spp. in horse farms in northern paraná, brazil.brazilian spotted fever (bsf) is an emerging disease most likely caused by rickettsia rickettsii. the objective of the present study was to estimate the seroprevalence of bsf rickettsia infections in equines from six horse farms located in londrina county, paraná, southern brazil. six owners of horse farms situated in cambé, santa fé, guaraci and londrina municipalities participated in the study. all farms were located in areas where bsf has not been reported. a total of 273 horses were sampled ...201021184706
seroprevalence of rickettsia bellii and rickettsia felis in dogs, são josé dos pinhais, state of paraná, brazil.brazilian spotted fever (bsf) is a vector-borne zoonosis caused by rickettsia rickettsii bacteria. dogs can be host sentinels for this bacterium. the aim of the study was to determine the presence of antibodies against rickettsia spp. in dogs from the city of são josé dos pinhais, state of paraná, southern brazil, where a human case of bsf was first reported in the state. between february 2006 and july 2007, serum samples from 364 dogs were collected and tested at 1:64 dilutions by indirect immu ...201021184698
serological survey of rickettsia sp. in horses and dogs in a non-endemic area in brazil.brazilian spotted fever (bsf) is a lethal rickettsiosis in humans caused by the bacteria rickettsia rickettsii, and is endemic in some areas of brazil. horses and dogs are part of the disease's life cycle and they may also serve as sentinel animals in epidemiological studies. the first human bsf case in the state of paraná was reported in 2005. the present study was conducted in the municipality of almirante tamandaré, where no previous case of bsf was reported. serum samples were collected from ...201021184695
rickettsia africae in amblyomma variegatum and domestic ruminants on eight caribbean islands.we used pcrs with omp a primers to determine if spotted fever group rickettsiae occurred in amblyomma variegatum from 6 caribbean islands. positive amplicons were obtained from ticks from the u.s. virgin islands (9/18; 50%), dominica (39/171; 30%), montserrat (2/5; 40%), nevis (17/34; 50%), st. kitts (46/227; 20%), and st. lucia (1/14; 7%). sequences for a convenience sample of reaction products obtained from a. variegatum on st. kitts (7), american virgin islands (4), montserrat (2), and st. lu ...201021158615
infrequency of rickettsia rickettsii in dermacentor variabilis removed from humans, with comments on the role of other human-biting ticks associated with spotted fever group rickettsiae in the united states.abstract from 1997 to 2009, the tick-borne disease laboratory of the u.s. army public health command (usaphc) (formerly the u.s. army center for health promotion and preventive medicine) screened 5286 dermacentor variabilis ticks removed from department of defense (dod) personnel, their dependents, and dod civilian personnel for spotted fever group rickettsiae using polymerase chain reaction and restriction fragment length polymorphism analysis. rickettsia montanensis (171/5286 = 3.2%) and ricke ...201021142953
rickettsial infections of dogs, horses and ticks in juiz de fora, southeastern brazil, and isolation of rickettsia rickettsii from rhipicephalus sanguineus ticks.the present study was performed in an area endemic for brazilian spotted fever (bsf) in juiz de fora, state of minas gerais, brazil, during the years 2007 and 2008, when fatal cases of bsf (caused by rickettsia rickettsii) were reported. adult ticks (acari: ixodidae) identified as rhipicephalus sanguineus (latreille) and amblyomma cajennense (fabricius) were collected from dogs and horses, respectively, and tested by polymerase chain reaction (pcr). overall, 13.1% of the rh. sanguineus ticks and ...201020950356
100th anniversary of the death of ricketts: howard taylor ricketts (1871-1910). the namesake of the rickettsiaceae family.the us american pathologist and microbiologist howard taylor ricketts died 100 years ago. he is renowned for discovering the causative organism and the transmission route of rocky mountain spotted fever and of tabardillo--an epidemic louse-borne typhus occurring especially in mexico. he also found that both diseases were caused by related infectious agents (rickettsia rickettsii and rickettsia prowazekii). the scientific community therefore named both a taxonomic family (rickettsiaceae) and an o ...201020888424
absence of rickettsia rickettsii and occurrence of other spotted fever group rickettsiae in ticks from tennessee.rocky mountain spotted fever (rmsf) is the most common tick-borne illness in tennessee. little is known about the occurrence of r. rickettsii, the causative agent, in ticks in tennessee. to better understand the prevalence and distribution of rickettsial agents in ticks, we tested 1,265 amblyomma, dermacentor, and ixodes adult and nymphal ticks. additionally, we tested 231 amblyomma americanum larvae. ticks were collected from 49 counties from humans, wild animals, domestic canines, and flannel ...201020810834
[rocky mountain spotted fever in brazil].although the number of confirmed cases of spotted fever has been declining in brazil since 2005, the mortality rate (20% to 30%) is still high in comparison to other countries. this high mortality rate is closely related to the difficulty in making the diagnosis and starting the correct treatment. only two groups of antibiotics have proven clinical effectiveness against spotted fever: chloramphenicol and tetracyclines. until recently, the use of tetracyclines was restricted to adults because of ...201020721447
secretory process of salivary glands of female amblyomma cajennense (acari: ixodidae) ticks fed on resistant rabbits.ticks have great economic and health importance since infested animals have reduced milk and meat production, and, besides that, they are expensive ectoparasites to control. while feeding, ticks can transmit to their hosts a large amount of pathogens, including rickettsia rickettsii responsible for the "spotted fever" or "fever of the mountains." it is known that animals infested with ticks or artificially immunized with their salivary gland extracts develop resistance, which is related to a dec ...201120711802
amblyomma imitator ticks as vectors of rickettsia rickettsii, mexico.real-time pcr of amblyomma imitator tick egg masses obtained in nuevo leon state, mexico, identified a rickettsia species. sequence analyses of 17-kd common antigen and outer membrane protein a and b gene fragments showed to it to be r. rickettsii, which suggested a potential new vector for this bacterium.201020678325
brazilian spotted fever in cart horses in a non-endemic area in southern brazil.brazilian spotted fever (bsf) is an often fatal zoonosis caused by the obligate intracellular bacterium rickettsia rickettsii. the disease is generally transmitted to humans by amblyomma spp. ticks. serological evidence of past infection by r. rickettsii has been reported in horses, but the pathogenicity of r. rickettsii in horses remains unknown. cart horses are still widely used in urban and urban fringe areas in brazil, and these animals may constitute suitable sentinels for bsf human in thes ...201020624353
rocky mountain spotted fever in the united states, 2000-2007: interpreting contemporary increases in incidence.rocky mountain spotted fever (rmsf), a potentially fatal tick-borne infection caused by rickettsia rickettsii, is considered a notifiable condition in the united states. during 2000 to 2007, the annual reported incidence of rmsf increased from 1.7 to 7 cases per million persons from 2000 to 2007, the highest rate ever recorded. american indians had a significantly higher incidence than other race groups. children 5-9 years of age appeared at highest risk for fatal outcome. enzyme-linked immunoso ...201020595498
experimental infection of rhipicephalus sanguineus ticks with the bacterium rickettsia rickettsii, using experimentally infected dogs.we evaluated if rickettsia rickettsii-experimentally infected dogs could serve as amplifier hosts for hipicephalus sanguineus ticks. in addition, we checked if rh. sanguineus ticks that acquired ri. rickettsii from dogs could transmit the bacterium to susceptible hosts (vector competence), and if these ticks could maintain the bacterium by transstadial and transovarial transmissions. uninfected larvae, nymphs, and adults of rh. sanguineus were allowed to feed upon three groups of dogs: groups 1 ...201120569011
innate immunity in wooless lamb to larvae of amblyomma cajennense tick (fabricius, 1787) (acari: ixodidae).the cayenne tick amblyomma cajennense infests preferably horses in its adult form but other mammal species in its immature stages and is the main vector of rickettsia rickettsii, the brazilian spotted fever pathogen. as wooless lambs are often raised on pasture together with horses, an experiment was performed to investigate their possible acquisition of resistance to a. cajennense after experimental infestations. seven naïve wooless lambs were infested thrice at 60 days interval with immature a ...201020537112
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 ...201020426684
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.201020404224
rickettsia rickettsii infection of human macrovascular and microvascular endothelial cells reveals activation of both common and cell type-specific host response mechanisms.although inflammation and altered barrier functions of the vasculature, due predominantly to the infection of endothelial cell lining of small and medium-sized blood vessels, represent salient pathological features of human rickettsioses, the interactions between pathogenic rickettsiae and microvascular endothelial cells remain poorly understood. we have investigated the activation of nuclear transcription factor-kappa b (nf-kappab) and p38 mitogen-activated protein (map) kinase, expression of h ...201020385756
biology and ecology of the brown dog tick, rhipicephalus sanguineus.abstract: the brown dog tick (rhipicephalus sanguineus) is the most widespread tick in the world and a well-recognized vector of many pathogens affecting dogs and occasionally humans. this tick can be found on dogs living in both urban and rural areas, being highly adapted to live within human dwellings and being active throughout the year not only in tropical and subtropical regions, but also in some temperate areas. depending on factors such as climate and host availability, rh. sanguineus can ...201020377860
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 ...200920209269
the increasing recognition of rickettsial pathogens in dogs and people.dogs and people are exposed to and susceptible to infection by many of the same tick-borne bacterial pathogens in the order rickettsiales, including anaplasma phagocytophilum, ehrlichia canis, e. chaffeensis, e. ewingii, rickettsia rickettsii, r. conorii, and other spotted fever group rickettsiae. recent findings include descriptions of novel ehrlichia and rickettsia species, recognition of the occurrence and clinical significance of co-infection, and increasing awareness of rhipicephalus sangui ...201020207197
disruption of the rickettsia rickettsii sca2 autotransporter inhibits actin-based motility.rickettsii rickettsii, the etiologic agent of rocky mountain spotted fever, replicates within the cytosol of infected cells and uses actin-based motility to spread inter- and intracellularly. although the ultrastructure of the actin tail and host proteins associated with it are distinct from those of listeria or shigella, comparatively little is known regarding the rickettsial proteins involved in its organization. here, we have used random transposon mutagenesis of r. rickettsii to generate a s ...201020194597
review of microarray studies for host-intracellular pathogen interactions.obligate intracellular bacteria are privileged soldiers on the battlefield that represent host-pathogen interactions. microarrays are a powerful technology that can increase our knowledge about how bacteria respond to and interact with their hosts. this review summarizes the limitations inherent to host-pathogen interaction studies and essential strategies to improve microarray investigations of intracellular bacteria. we have compiled the comparative genomic and gene expression analyses of obli ...201020188126
serological prevalence study of exposure of cats and dogs in launceston, tasmania, australia to spotted fever group rickettsiae.a sero-epidemiological study of cats and dogs in the launceston area of tasmania, australia was undertaken to determine the prevalence of antibodies to spotted fever group (sfg) rickettsiae. results showed that 59% of cats and 57% of dogs were positive for antibodies, but there was no correlation between the animal's health and seropositivity at the time of testing, suggesting that rickettsial exposure is unrelated to ill-health in these two species of domestic animals.201020148824
rickettsial ompb promoter regulated expression of gfpuv in transformed rickettsia montanensis.rickettsia spp. (rickettsiales: rickettsiaceae) are gram-negative, obligate intracellular, alpha-proteobacteria that have historically been associated with blood-feeding arthropods. certain species cause typhus and spotted fevers in humans, but others are of uncertain pathogenicity or may be strict arthropod endosymbionts. genetic manipulation of rickettsiae should facilitate a better understanding of their interactions with hosts.201020126457
rickettsia 364d: a newly recognized cause of eschar-associated illness in california.four spotted fever group rickettsiae (sfgr) are known to infect humans in the united states. a member of the sfgr designated 364d and detected in dermacentor occidentalis ticks has not previously been identified as a human pathogen.201020073993
evidence of exposure to spotted fever group rickettsiae among arizona dogs outside a previously documented outbreak area.since 2003, two communities in eastern arizona have experienced a sustained outbreak of rocky mountain spotted fever (rmsf), caused by rickettsia rickettsii, associated with transmission by rhipicephalus sanguineus, the brown dog tick; 70 human cases, including eight deaths, were reported from these communities during 2003 through 2008. in both of the affected communities, antibodies to spotted fever group rickettsiae (sfgr) were present in dogs before the notice of the first human cases, sugges ...201120042069
genome sequence of the endosymbiont rickettsia peacockii and comparison with virulent rickettsia rickettsii: identification of virulence factors.rickettsia peacockii, also known as the east side agent, is a non-pathogenic obligate intracellular bacterium found as an endosymbiont in dermacentor andersoni ticks in the western usa and canada. its presence in ticks is correlated with reduced prevalence of rickettsia rickettsii, the agent of rocky mountain spotted fever. it has been proposed that a virulent sfg rickettsia underwent changes to become the east side agent. we determined the genome sequence of r. peacockii and provide a compariso ...200920027221
detection and identification of ehrlichia species in blood by use of pcr and electrospray ionization mass spectrometry.rapid detection and identification of ehrlichia species improves clinical outcome for patients suspected of ehrlichiosis. we describe an assay that employs multilocus pcr and electrospray ionization mass spectrometry (pcr/esi-ms) to detect and identify ehrlichia species directly from blood specimens. the results were compared to those of a colorimetric microtiter pcr enzyme immunoassay (pcr-eia) used as a diagnostic assay. among 213 whole-blood samples collected from patients who were clinically ...201019955274
managing rocky mountain spotted fever.rocky mountain spotted fever is caused by the tick-borne bacterium rickettsia rickettsii. symptoms range from moderate illness to severe illness, including cardiovascular compromise, coma and death. the disease is prevalent in most of the usa, especially during warmer months. the trademark presentation is fever and rash with a history of tick bite, although tick exposure is unappreciated in over a third of cases. other signature symptoms include headache and abdominal pain. the antibiotic therap ...200919883333
detection and identification of rickettsial agents in ticks from domestic mammals in eastern panama.several outbreaks of rocky mountain spotted fever have occurred in recent years in colombian communities close to the border with panama. however, little is known about rickettsiae and rickettsial diseases in eastern panamanian provinces, the darien province and the kuna yala, located north of the endemic area in colombia. in 2007, 289 ticks were collected in several towns from dogs, horses, mules, cows, and pigs. dna was extracted from 124 dermacentor nitens, 64 rhipicephalus sanguineus, 43 amb ...200919645289
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 ...200919538276
status of the "east side hypothesis" (transovarial interference) 25 years later.rocky mountain spotted fever (rmsf) cases in the notorious bitterroot valley outbreak of the early 20th century were peculiarly distributed, with virtually all reported from the west side of the valley. such a distribution remained unexplained until burgdorfer and colleagues (1981) reported that endosymbiotic rickettsiae were prevalent in wood ticks on the east side of the bitterroot river valley but not on the west side. the "east side agent" was said to prevent the transovarial transmission of ...200919538274
closing the gaps between genotype and phenotype in rickettsia rickettsii.rocky mountain spotted fever (rmsf) caused by rickettsia rickettsii is a severe rickettsiosis that occurs in nearly every state of the continental usa. rmsf is endemic in central and southern america, with recent well-documented cases in mexico, costa rica, panama, colombia, brazil, and argentina. rmsf is the most malignant among known rickettsioses causing severe multiorgan dysfunction and high case fatality rates, which can reach 73% in untreated cases. variations in pathogenic biotypes of r. ...200919538260
molecular detection of rickettsia bellii, rickettsia montanensis, and rickettsia rickettsii in a dermacentor variabilis tick from nature.rickettsial diseases, such as rocky mountain spotted fever, pose a public health threat because of humans' interrelationship with common arthropod species, such as ticks, mites, fleas, and lice. individuals may come in contact with these vectors of disease on a fairly regular basis either directly or indirectly through pets or wildlife species, at home or in recreational areas. therefore, it is of vital importance to know and understand the geographical distribution and prevalence of disease and ...201019485770
a survey of antibodies against rickettsia rickettsii and ehrlichia chafeensis in domestic animals from a rural area of colombia.in a rural area of colombia endemic for rocky mountain spotted fever, we performed indirect immunofluorescent antibody assays for rickettsia spp. and ehrlichia spp. using sera from randomly sampled dogs and horses to test the use of domestic animals as possible sentinels. antibodies against ehrlichia spp. were detected in 8 dogs (31.8%). antibody titers against rickettsia rickettsii antigen were positive in 4 dogs (18.2%) and 26 horses (16.3%). these values, albeit not directly comparable, are l ...200919478270
clusters of brazilian spotted fever in são paulo state, southeastern brazil. a review of official reports and the scientific literature. 200919456810
limited transcriptional responses of rickettsia rickettsii exposed to environmental stimuli.rickettsiae are strict obligate intracellular pathogens that alternate between arthropod and mammalian hosts in a zoonotic cycle. typically, pathogenic bacteria that cycle between environmental sources and mammalian hosts adapt to the respective environments by coordinately regulating gene expression such that genes essential for survival and virulence are expressed only upon infection of mammals. temperature is a common environmental signal for upregulation of virulence gene expression although ...200919440298
rickettsia rickettsii infection of human pulmonary microvascular endothelial cells: modulation of cyclooxygenase-2 expression. 200919438652
selective activation of signal transducer and activator of transcription (stat) proteins stat1 and stat3 in human endothelial cells infected with rickettsia rickettsii. 200919438651
brazilian spotted fever: two faces of a same disease? a comparative study of clinical aspects between an old and a new endemic area in brazil. 200919392896
brazilian spotted fever in the paediatric age-segment in the state of são paulo, southeastern brazil, 2003-2006. 200919374639
rickettsia rickettsii infection protects human microvascular endothelial cells against staurosporine-induced apoptosis by a ciap(2)-independent mechanism.manipulation of host cell death is an important determinant of the outcome of an infection. here, we investigate whether rickettsia rickettsii-infected host endothelial cells resist the effects of staurosporine, a potent inducer of apoptosis, and we explore the mechanisms underlying the anti-apoptotic effect of infection.200919358671
rickettsia rickettsii, rickettsia felis and rickettsia sp. twkm03 infecting rhipicephalus sanguineus and ctenocephalides felis collected from dogs in a brazilian spotted fever focus in the state of rio de janeiro/brazil. 200919298400
Refresh
firstprev
12345678910...
nextlast
Displaying items 101 - 200 of 1610