citrate synthase gene comparison, a new tool for phylogenetic analysis, and its application for the rickettsiae.using pcr and an automated laser fluorescent dna sequencer, we amplified and sequenced a 1,234-bp fragment of the citrate synthase-encoding gene (glta) of 28 bacteria belonging to the genus rickettsia. comparative sequence analysis showed that most of the spotted fever group (sfg) rickettsiae belonged to one of two subgroups. the first subgroup included rickettsia massiliae, strain bar 29, rickettsia rhipicephali, "rickettsia aeschlimanni," and rickettsia montana, which have been isolated only f ...19979103608
tick-borne infection caused by rickettsia africae in the west indies. 19989575061
severe encephalopathies in children with antibodies reactive with rickettsia africae. 19989861952
tick-transmitted infections in transvaal: consider rickettsia africae. 199910081692
tick-borne rickettiosis in guadeloupe, the french west indies: isolation of rickettsia africae from amblyomma variegatum ticks and serosurvey in humans, cattle, and goats.twenty-seven rickettsiae were isolated and/or detected from 100 amblyomma variegatum ticks collected on guadeloupe in the french west indies. in this study, the polymerase chain reaction procedure appeared to be more sensitive in detecting rickettsiae in ticks than the shell-vial technique. sequencing a portion of the outer membrane protein a-encoding gene showed that these rickettsiae appeared to be identical to rickettsia africae, a member of the spotted fever group rickettsiae recently descri ...199910403315
[african rickettsia infections].epidemiology: african rickettsiasis is transmitted by rickettsia africae, a cattle tick. amblyomma spp. is an emerging rickettsiasis in sub-sehalian afric described in 1992. seroepidemiology studies conducted in africa show that it is probably the most widespread rickettsiasis in the sorld. in addition, the development of tourist activities in southern african countries has led to an increase in the number of reported cases in subjects returning from endemic areas. a high serprevalence of anti r ...199910518970
in vitro activities of telithromycin (hmr 3647) against rickettsia rickettsii, rickettsia conorii, rickettsia africae, rickettsia typhi, rickettsia prowazekii, coxiella burnetii, bartonella henselae, bartonella quintana, bartonella bacilliformis, and ehrlichia vitro activities of telithromycin compared to those of erythromycin against rickettsia spp., bartonella spp., coxiella burnetii, and ehrlichia chaffeensis were determined. telithromycin was more active than erythromycin against rickettsia, bartonella, and coxiella burnetii, with mics of 0.5 microg/ml, 0.003 to 0.015 microg/ml, and 1 microg/ml, respectively, but was inactive against ehrlichia chaffeensis.200010770788
phylogenetic analysis of members of the genus rickettsia using the gene encoding the outer-membrane protein rompb (ompb).to confirm the phylogenetic analysis previously inferred by comparison of the citrate synthase and rompa gene sequences (gita and ompa, respectively), the rompb gene (ompb) of 24 strains of the genus rickettsia was amplified and sequenced. rompb is an outer-membrane protein of high molecular mass, the presence of which can be demonstrated in most rickettsiae by immunological cross-reactivity in western blots. no pcr amplification was obtained with rickettsia bellii or rickettsia canadensis. for ...200010939649
[molecular tools in the epidemiology of tick-borne bacterial diseases].molecular tools have been used to detect rickettsiae in ticks. in ixodes ricinus ticks collected in france, we detected for the first time there an emerging pathogen, rickettsia helvetica, and an ehrlichia sp, closely related to the agent of human granulocytic ehrlichiosis. in guadeloupe (french west indies), we described the occurrence of african tick-bite fever due to rickettsia africae, which had been previously reported in sub-saharan africa only. in africa, we completed our knowledge about ...200111282521
detection and identification of spotted fever group rickettsiae and ehrlichiae in african ticks.rickettsia africae, a recently identified pathogen, was detected for the first time in amblyomma ticks from niger, mali, burundi, and sudan, and "r. mongolotimonae" was identified for the first time in africa. rickettsiae of unknown pathogenicity and two new ehrlichiae of the ehrlichia canis group were identified in ticks from mali and niger.200111747731
kinetics of antibody responses in rickettsia africae and rickettsia conorii infections.african tick-bite fever, caused by rickettsia africae, is the most common tick-borne rickettsiosis in sub-saharan africa. mediterranean spotted fever due to rickettsia conorii also occurs in the region but is more prevalent in mediterranean countries. using microimmunofluorescence, we compared the development of immunoglobulin g (igg) and igm titers in 48 patients with african tick-bite fever and 48 patients with mediterranean spotted fever. doxycycline treatment within 7 days from the onset of ...200211874871
outbreak of african tick-bite fever in six italian tourists returning from south may 1999, a cluster of cases of african tick-bite fever was detected in six italian tourists who had returned from south africa. all of the patients had moderate fever and cutaneous eschars. regional lymphangitis was observed in three of the patients and skin rash in two. by comparing the number of eschars with the number of detectable bite sites it was suggested that at least two-thirds of the biting vectors were capable of transmitting rickettsia africae. the clinical course of disease was ...200211939395
spotted fever group rickettsiae in ticks from the masai mara region of kenya.we have identified for the first time rickettsia africae, and the ticks that harbored them, in kenya. a total of 5,325 ticks were collected from vegetation, livestock, and wild animals during two field trips to southwestern kenya. most were immature forms (85.2%) belonging to the genera amblyomma or rhipicephalus. the adults also included representatives from the genus boophilus. ticks were assessed for rickettsial dna by a polymerase chain reaction (pcr) using primers for the spotted fever grou ...200312812343
first detection of rickettsia africae on martinique, in the french west indies. 200312930619
repellent efficacy of deet and kbr 3023 against amblyomma hebraeum (acari: ixodidae).the bont tick, amblyomma hebraeum koch, is the principal vector of rickettsia africae, the agent of african tick bite fever, in southern africa. in contrast to most other hard ticks, members of the genus amblyomma exhibit a characteristic attack host-seeking behavior. the efficacy of topically applied 20% lotions of deet (diethyl-3-methylbenzamide), the currently considered reference repellent substance, and kbr 3023, a recently developed piperidine compound, was evaluated against laboratory-rea ...200312693855
tick-borne rickettsioses in international travellers.tick-borne rickettsioses are of emerging importance in today's travel medicine but have until recently received little attention. we describe the current knowledge of tick-borne rickettsioses as they relate to international travel, their microbiological diagnosis, treatment, possible prevention, and future prospects.200415109588
african tick bite fever: not a spotless rickettsiosis!african tick bite fever is caused by rickettsia africae, a newly recognized species from south africa. we report the case of a patient with an unusual site of a tick bite and discuss cutaneous differences from other spotted fevers that may help dermatologists with clinical diagnosis.200312582376
amblyomma hebraeum is a vector of rickettsia africae and not r. conorii. 200112219911
introduction of the exotic tick amblyomma hebraeum into florida on a human host.a resident of florida returned from a short visit to southern africa to find a male amblyomma hebraeum tick attached to the skin behind her knee. amblyomma hebraeum is a major vector of 2 pathogens that cause important diseases in southern africa, heartwater of ruminants and african tick-bite fever of humans. the tick was tested by polymerase chain reaction assay for evidence of infection with cowdria ruminantium and rickettsia africae (the causative agents of heart-water and african tick-bite f ...200212197136
seroepidemiology of rickettsia africae infection in norwegian travellers to rural africa.rickettsia africae is the causative agent of african tick bite fever (atbf), an acute febrile illness frequently accompanied by inoculation eschars, regional lymphadenitis, myalgia and severe headache. recently, atbf has been recognized as an emerging health problem for international travellers to rural sub-saharan africa. to estimate the incidence, risk factors for and proportion of symptomatic cases of travel-associated r. africae infection, we performed a seroepidemiological study of 152 firs ...200211928860
[rickettsia africae, the agent of african tick-bite fever: an emerging pathogen in the west indies and reunion island (indian ocean)].rickettsia africae is the agent of african tick bite fever, an emerging disease transmitted by amblyomma ticks in sub-saharan africa. in 1998, we reported the first documented case of r. africae in the new world, in a patient who had returned from guadeloupe. in order to confirm the presence of r. africae in the west indies, entomologic surveys were conducted from 1999 to 2003 to collect amblyomma, which are considered as potential vectors and reservoirs of the bacteria. ticks were used as epide ...200415462202
phylogeny of rickettsia spp. inferred by comparing sequences of 'gene d', which encodes an intracytoplasmic protein.'gene d' is the ps120-protein-encoding gene, first described in rickettsia conorii and rickettsia japonica. sequence analysis of a 3030 bp fragment of 'gene d' in 24 representatives of the genus rickettsia was carried out to complete phylogenetic analyses previously inferred by comparison of gene sequences encoding citrate synthase, 17 kda antigen and rompa and rompb. the phylogenetic relationships between rickettsiae were inferred from the comparison of both the gene and the derived protein seq ...200111491333
rickettsia africae, a tick-borne pathogen in travelers to sub-saharan africa.african tick-bite fever occurs after contact with ticks that carry rickettsia africae and that parasitize cattle and game. sporadic reports suggest that this infection has specific clinical and epidemiologic features.200111357153
concomitant or consecutive infection with coxiella burnetii and tickborne diseases.q fever is a worldwide zoonosis caused by coxiella burnetii, which can be isolated from ticks. reports of people with both q fever and other tickborne diseases are rare. in this study, we describe 6 patients with q fever who were infected with 1 of the following tickborne pathogens: rickettsia conorii (2 patients), rickettsia slovaca (2), rickettsia africae (1), and francisella tularensis (1).200415614696
[fever and vesiculopapular exanthema due to infection with rickettsia africae after a sojourn in south africa].a 26-year-old woman, who had visited the krugerpark in south africa 5 days before, presented with fever, a skin lesion with a black crust (eschar), lymphadenopathy and a vesiculo papular rash. the clinical diagnosis 'rickettsia africae infection' was confirmed by specific serological tests. a second patient aged 43 years, whose vesicular rash did not respond to flucloxacillin had been in the krugerpark one week before and on examination was found with 2 eschars. based on epidemiological and clin ...200111206126
[three swedish cases of african tick-bite fever. can our native rickettsia species cause disease in humans?].the article consists in a report of three cases of african tick-bite fever in swedish tourists returning from brief visits to south africa. the clinical course included eschar, regional lymphadenopathy, fever and, in two cases, maculopapular rash. two cases were characterised by significant increases in anti-rickettsia conorii igg and igm antibody titres. however, the aetiological agent was assumed to be rickettsia africae, based on reports by others and the widespread serological cross-reactivi ...199910522094
african tick-bite fever imported into norway: presentation of 8 cases.we report on 8 norwegian travellers to southern africa with african tick-bite fever (atbf), a recently described spotted fever group rickettsiosis. all patients had acute flu-like symptoms and developed i or multiple inoculation eschars. the patients were treated with either doxycycline or ciprofloxacin, and all recovered. the diagnosis of atbf was confirmed by the detection of specific igm antibodies to rickettsia africae by microimmunofluoroscence in convalescent-phase serum samples.199910447320
[two cases of spotted fever group rickettsiosis contracted in southern parts of africa].a 40-year-old japanese male stayed in zimbabwe and developed a fever above 38 degrees c during which he noted a typical eschar in the lumbar region and also regional inguinal lymphadenopathy. although not conspicuous, erythematous eruptions accompanied by itching were observed on the face, trunk and lower extremities. after returning to japan and visiting our hospital, he was suspected of rickettsiosis and put on minocycline which gradually led to the improvement of the symptoms. immunofluoresce ...19989916419
rickettsia africae in the west indies.rickettsia africae is the agent of african tick-bite fever, a mild but common disease of local persons and tourists in africa. the major vector of this spotted fever group rickettsia is most likely amblyomma variegatum, the tropical bont tick, which has become widely distributed through the west indies in the last 30 years. this report reviews all available information on r. africae in the west indies.200616494746
african tick-bite fever: a case report.mediterranean spotted fever, a disease caused by rickettsia conorii, is a well-described syndrome among travelers returning from africa.1 in the present issue of journal of travel medicine2 a case of rickettsia conorii disease is presented and discussed in context with recently described african tick-bite fever caused by rickettsia africae. we report the clinical presentation and successful treatment of a traveler who likely had african tick-bite fever.19979815517
phylogenetic analysis of spotted fever group rickettsiae by study of the outer surface protein rompa.rickettsiae are classified in the order rickettsiales and have been included in the alpha subclass of the class proteobacteria on the basis of 16s rrna gene sequence comparison. to estimate the evolutionary forces that have shaped the members of the spotted fever group (sfg) rickettsiae, the ompa gene (apart from the tandem repeat units), encoding an antigenic high-molecular-mass membrane protein specific for the group, was amplified and sequenced from 21 isolates. the phylogenetic relationship ...19989734038
outbreak of rickettsia africae infections in participants of an adventure race in south africa.african tick-bite fever, caused by rickettsia africae and transmitted by amblyomma ticks, is an emerging rickettsiosis in southern africa. because of increased tourism to this area, several cases in tourists have been reported recently. we report 13 cases of r. africae infection diagnosed in france that occurred in competitors returning from an adventure race in south africa and compare our data with previously reported findings. most of our patients presented with fever, headache, multiple inoc ...19989709882
detection of rickettsia africae in rhipicephalus (boophilus) decoloratus ticks from the republic of botswana, south africa.a total of 53 engorged adult ticks belonging to the species rhipicephalus (boophilus) decoloratus (n = 9), rhipicephalus evertsi evertsi (n = 27), rhipicephalus appendiculatus (n = 9), amblyomma hebraeum (n = 5), and hyalomma marginatum turanicum (n = 3), were removed from oryx in botswana (south africa). they were tested for the presence of spotted fever group (sfg) rickettsia and anaplasma phagocytophilum using polymerase chain reaction (pcr). seventy-seven percent of r. decoloratus as well as ...200717690416
taxonomic relationships among spotted fever group rickettsiae as revealed by antigenic analysis with monoclonal antibodies.the spotted fever group (sfg) is made up of more than 20 different rickettsial species and strains. study of the taxonomic relationships among the group has been attempted by phenotypic, genotypic, and phylogenetic analyses. in this study, we determined taxonomic relationships among the sfg rickettsiae by comparative analysis of immunogenic epitopes reactive against a panel of monoclonal antibodies. a total of 98 monoclonal antibodies, which were directed against epitopes on the major immunodomi ...19989542904
[serological study of rickettsia infections in niamey, niger].rickettsioses is a possible alternative to presumptive diagnosis of malaria. a serologic study was carried out in 1994 to determine the prevalence of rickettsioses in children under 5 years of age from three different areas of niamey, niger. indirect immunofluorescent assays using the micromethod were performed with antigens for rickettsia conori, rickettsia mooseri, and coxiella burneti. results were read from a positive threshold of 1/160 up to 1/640. out of a randomized population of 177 chil ...19979304008
african tick-bite fever. an imported spotless characterize the clinical presentation and course of african tick-bite fever, a recently rediscovered rickettsiosis caused by rickettsia africae (a new species within the spotted fever group of rickettsiae), to establish its relationship with amblyomma tick species, and to discuss its role in the etiology of fever in patients who are returning from the tropics.19978996049
african tick bite fever in elderly patients: 8 cases in french tourists returning from south africa.african tick-bite fever, a tickborne disease caused by rickettsia africae, is endemic in rural areas of sub-saharan africa and in the french west indies. most cases reported in the literature occurred in middle-aged, otherwise-healthy persons and corresponded to benign diseases. the course of african tick bite fever in elderly people is less well documented.200818558881
characterization of and application of monoclonal antibodies against rickettsia africae, a newly recognized species of spotted fever group rickettsia.rickettsia africae is a newly described species which causes african tick bite fever. mediterranean spotted fever caused by r. conorii is endemic in the same regions of africa as tick bite fever, and differentiation of the two syndromes by characterization of their etiological agents is important for epidemiological studies. r. africae and r. conorii are, however, difficult to distinguish, and therefore, our aim was to produce monoclonal antibodies to address this problem. monoclonal antibodies ...19978968882
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
rickettsia africae sp. nov., the etiological agent of african tick bite fever.we propose the name rickettsia africae sp. nov. (with type strain z9-hu) for a distinct species of spotted fever group (sfg) rickettsiae that is the etiological agent of african tick bite fever in humans. this rickettsia has a distinct natural cycle and can be phenotypically distinguished from the other sfg rickettsiae by microimmunofluorescence serotyping, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and by western blotting (immunoblotting). genotypic differences between r. afr ...19968934912
serosurvey for cowdria ruminantium, coxiella burnetii, and spotted fever group rickettsiae in ostriches (struthio camelus) from zimbabwe.sera from 216 ostriches on nine farms around zimbabwe were examined by indirect fluorescent antibody (ifa) testing for the presence of antibodies reactive with cowdria ruminantium, coxiella burnetii, and rickettsia africae, a spotted fever group rickettsia. although no reactive antibodies could be detected to c. ruminantium or c. burnetii, 51/216 (35%) sera reacted with r. africae. the seroprevalence in ostriches from the south of zimbabwe was significantly higher than in birds from the north (p ...19968790897
prevalence of antibodies to coxiella burnetti, rickettsia conorii, and rickettsia typhi in seven african countries.the prevalences of antibodies reactive with coxiella burnetti, rickettsia conorii, and rickettsia typhi were determined by indirect fluorescent antibody testing of sera from seven african countries. the seroprevalences of antibodies reactive with c. burnetti and r. conorii in countries from north africa were similar to those reported from southern europe. in countries of sub-saharan africa, the seroprevalence of antibodies reactive with c. burnetti varied greatly; the generally higher figures fo ...19958589132
acute spotted fever rickettsiosis among febrile patients, cameroon.although potential arthropod vectors are abundant in cameroon, acute febrile illnesses are rarely evaluated for arboviral or rickettsial infections. serum samples from 234 acutely febrile patients at clinics in tiko and buea, cameroon, were examined for antibodies to rickettsia africae and african alphaviruses and flaviviruses. these serum samples did not contain antibodies against typhoid, and blood malarial parasites were not detected. serum samples of 32% contained immunoglobulin m antibodies ...200415109409
rickettsia species infecting amblyomma cooperi ticks from an area in the state of são paulo, brazil, where brazilian spotted fever is endemic.owing to the potential role of the tick amblyomma cooperi in the enzootic cycle of rickettsia rickettsii, the etiologic agent of brazilian spotted fever (bsf), this study evaluated infection by rickettsia species in a. cooperi ticks collected from an area in brazil where bsf is endemic. among a total of 40 a. cooperi adult ticks collected in an area of bsf endemicity in the state of são paulo, pcr analysis detected dna of rickettsia bellii in 16 ticks (40%), and 3 other ticks (7.5%) were positiv ...200414715737
novel spotted fever group rickettsiosis, brazil.we report a clinical case of spotted fever group rickettsiosis acquired in sao paulo, brazil. definitive diagnosis was supported by seroconversion between acute-phase and convalescent-phase serum samples. molecular analysis of skin samples indicated the agent was a novel spotted fever group strain closely related to rickettsia africae, r. parkeri, and r. sibirica.201020202436
rickettsia africae, western africa. 201020202453
african tick bite fever.african tick bite fever is an acute febrile illness that is frequently accompanied by headache, prominent neck muscle myalgia, inoculation eschars, and regional lymphadenitis. the disease is caused by rickettsia africae, a recently identified spotted fever group rickettsia, which is transmitted by ungulate ticks of the amblyomma genus in rural sub-saharan africa and the french west indies. whereas reports on african tick bite fever in indigenous populations are scarce, the number of reported cas ...200312954562
tick-borne rickettsioses, neglected emerging diseases in rural senegal.rickettsioses are one of the most important causes of systemic febrile illness among travelers from developed countries, but little is known about their incidence in indigenous populations, especially in west africa.201020856858
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
a survey for spotted fever group rickettsiae and ehrlichiae in amblyomma variegatum from st. kitts and nevis.eighty-nine amblyomma variegatum ticks were collected from the islands of st. kitts and nevis in the caribbean and preserved in 70% ethanol or local rum. after being washed in sterile water, their dna was extracted and analyzed by a polymerase chain reaction (pcr) for dna of spotted fever group rickettsiae and ehrlichiae. none of the tested ticks was positive in a pcr assay using the primers 16s ehrd and 16s ehrr for the 16s rrna gene of ehrlichia spp.. forty-one percent of the a. variegatum (36 ...200312932098
[rickettsia africae infection. three cases confirmed by pcr].african tick bite fever or rickettsia africae infection has been recognized as an emerging health problem in the last few years. the aim of this study was to describe 3 cases of spanish tourists who suffered from r. africae infection after visiting south africa.200415207109
spotted fever group rickettsiae from ticks captured in sudan.ticks were collected from ruminants in various areas of sudan in 1998 and 2000. primer pairs of rickettsial citrate synthase gene (glta) and a spotted fever group (sfg) rickettsial 190-kda surface antigen gene (rompa), respectively, were used for identification. polymerase chain reaction (pcr)-positive products were used for dna sequencing. the glta gene was detected in 55% of the ticks examined (57/104). among the 57 ticks studied, 19 were positive for the rompa gene. thus, 18% of the ticks exa ...200415218219
comparison of immunofluorescence, western blotting, and cross-adsorption assays for diagnosis of african tick bite testing paired serum samples from 40 consecutive cases of african tick bite fever, we detected diagnostic antibodies against spotted fever group rickettsiae in 45% of the patients by immunofluorescence assay (ifa) and in 100% of the patients by western blotting (wb) (p < 0.01). a specific diagnosis of rickettsia africae infection could be established in 15% of the patients by ifa and in 73% of the patients by a combination of wb and cross-adsorption assays (p < 0.01).200415242958
detection of rickettsia africae in patients and ticks along the coastal region of cameroon.rickettsia africae was identified in seven (6%) of 118 patients with acute fevers of unknown etiology proven not to be malaria or typhoid fever from clinics along the coastal region of cameroon by polymerase chain reaction (pcr) amplification and sequencing of the citrate synthase (glta) and outer membrane protein a (ompa) genes of rickettsia. the majority (71%) of the patients were female. clinical manifestations included fever (100%), headache (71%), myalgia (71%), arthralgia (43%), pulmonary ...200415381820
widespread use of real-time pcr for rickettsial diagnosis.we report 2 years of experience with rickettsial molecular diagnosis using real-time pcr at the french national reference center. all rickettsia genomes available were compared to discover specific sequences to design new sets of primers and probes. the specificity was verified in silico and against a panel of 30 rickettsial species. sensitivity was determined using 10-fold serial dilutions. finally, primers and probes that were both specific and sensitive were routinely used for the diagnosis o ...201122092999
african tick-bite fever: four cases among swiss travelers returning from south africa.african tick-bite fever (atbf) is a recently described disease belonging to the spotted fever group. it is caused by rickettsia africae, and cases are mainly diagnosed in travelers returning from sub-saharan africa.200415541225
rickettsioses and the international traveler.the rickettsioses--zoonotic bacterial infections transmitted to humans by arthropods--were for many years considered to be oddities in travel medicine. during the previous 2 decades, however, reports of >450 travel-associated cases have been published worldwide, the vast majority being murine typhus caused by rickettsia typhi, mediterranean spotted fever caused by rickettsia conorii, african tick bite fever caused by rickettsia africae, and scrub typhus caused by orientia tsutsugamushi. most pat ...200415546086
update on spotted fever group rickettsiae in south africa.until very recently, mediterranean spotted fever caused by rickettsia conorii was the only spotted fever group (sfg) rickettsioses recognized in southern africa. however, increasing medical awareness of tick-borne infections, together with the introduction of improved isolation methods and the availability of molecular techniques, have led to the identification of several new sfg rickettsioses in the region. african tick bite fever, caused by rickettsia africae, is currently the most important o ...200415631070
repellent efficacy of four commercial deet lotions against amblyomma hebraeum (acari: ixodidae), the principal vector of rickettsia africae in southern africa.african tick bite fever, caused by rickettsia africae, is an emerging zoonotic infection in rural sub-saharan africa and the french west indies. we tested the repellent efficacy of four commercial diethyl-3-methylbenzamide (deet) lotions against amblyomma hebraeum koch, the principal vector of r. africae in southern africa, by using a human bioassay in which repellent-treated fingers were presented to questing tick nymphs hourly for 4h. three lotions with 19.5, 31.6 and 80% deet concentrations, ...200515993907
massive infection of seabird ticks with bacterial species related to coxiella burnetii.seabird ticks are known reservoirs of bacterial pathogens of medical importance; however, ticks parasitizing tropical seabirds have received less attention than their counterparts from temperate and subpolar regions. recently, rickettsia africae was described to infect seabird ticks of the western indian ocean and new caledonia, constituting the only available data on bacterial pathogens associated with tropical seabird tick species. here, we combined a pyrosequencing-based approach with a class ...201424657860
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
rickettsia africae and candidatus rickettsia barbariae in ticks in israel.dna of several spotted fever group rickettsiae was found in ticks in israel. the findings include evidence for the existence of rickettsia africae and candidatus rickettsia barbariae in ticks in israel. the dna of r. africae was detected in a hyalomma detritum tick from a wild boar and dna of c. rickettsia barbariae was detected in rhipicephalus turanicus and rhipicephalus sanguineus collected from vegetation. the dna of rickettsia massiliae was found in rh. sanguineus and haemaphysalis erinacei ...201424615133
sub-acute neuropathy in patients with african tick bite fever.african tick bite fever (atbf) caused by rickettsia africae is an emerging health problem in travellers to sub-saharan africa. we here present 6 patients with evidence of long-lasting sub-acute neuropathy following atbf contracted during safari trips to southern africa. three patients developed radiating pain, paresthaesia and/or motor weakness of extremities, 2 had hemi-facial pain and paresthaesia, and 1 developed unilateral sensorineural hearing loss. when evaluated 3-26 months after symptom ...200616449002
threats to international travellers posed by tick-borne date, 14 tick-borne diseases have been reported in international travellers, the majority of cases being lyme borreliosis caused by borrelia burgdorferi sensu lato in north america and eurasia, african tick bite fever caused by rickettsia africae in sub-saharan africa and eastern caribbean, and central european encephalitis caused by tick-borne encephalitis virus in europe. the clinical presentation is frequently non-specific, and tick-borne diseases should always, in the absence of other lik ...200616887719
increased levels of soluble cd40l in african tick bite fever: possible involvement of tlrs in the pathogenic interaction between rickettsia africae, endothelial cells, and platelets.the pathophysiological hallmark of spotted fever group rickettsioses comprises infection of endothelial cells with subsequent infiltration of inflammatory cells. based on its ability to promote inflammation and endothelial cell activation, we investigated the role of cd40l in african tick bite fever (atbf), caused by rickettsia africae, using different experimental approaches. several significant findings were revealed. 1) patients with atbf (n = 15) had increased serum levels of soluble cd40 li ...200616888032
histologic features and immunodetection of african tick-bite fever eschar.african tick-bite fever (atbf) is a rickettsiosis caused by rickettsia africae. we describe histologic features and immunodetection of r. africae in cutaneous inoculation eschars from 8 patients with atbf, which was diagnosed by culture or association of positive pcr detection and positive serologic results. we used quantitative image analysis to compare the pattern of inflammation of these eschars with those from mediterranean spotted fever. we evaluated the diagnostic value of immunohistochemi ...200617073080
african tick bite fever--papulovesicular exanthem with fever after staying in south the wake of expanding international tourism, rickettsioses are increasingly observed also in central europe. african tick bite fever is a recently described, acute febrile illness with characteristic skin lesions. it is caused by rickettsia africae, which is transmitted to humans by ticks of the amblyomma genus. a 60-year-old woman presented with a papulovesic-ular exanthem, fever, and headache after returning from south africa. a purple nodule with central necrosis ("tache noire"or "inoculat ...200818021248
molecular detection of spotted fever group rickettsiae in ticks from ethiopia and chad.dna extracted from 363 ticks collected in ethiopia and 9 ticks collected in chad, africa were screened by pcr to detect dna from spotted fever group rickettsiae. fifteen ticks (4.1%) collected in ethiopia and one tick (11%) collected in chad tested positive when pcr targeting the glta and ompa rickettsial genes was performed. pcr-positive products of the glta and ompa genes were used for dna sequencing. rickettsia africae was detected in 12/118 amblyomma lepidum and in 1/2 a. variegatum. also, 2 ...200818440576
two cases of cellulitis in the course of african tick bite fever: a fortuitous association?in african tick bite fever (atbf), inoculation eschar - resulting from disruption of the cutaneous barrier - may be a risk factor for cellulitis. we report 2 cases of atbf associated with cellulitis. a 77-year-old woman was referred for severe leg cellulitis upon returning from sub-saharan africa. she developed erythematous macules. rickettsia africae was detected by pcr assay from a skin biopsy specimen, and atbf diagnosis was confirmed. a 75-year-old man was hospitalized after his return from ...200818503259
relative chemokine and adhesion molecule expression in mediterranean spotted fever and african tick bite fever.mediterranean spotted fever (msf) caused by rickettsia conorii (r. conorii) is a potential lethal disease while african tick bite fever (atbf) caused by rickettsia africae is a self-limiting flu-like illness. we hypothesized that different inflammatory potential in endothelial cells could contribute to the different clinical features in these rickettsioses.200919091423
molecular detection and identification of spotted fever group rickettsiae in ticks collected from the west bank, palestinian territories.tick-borne rickettsioses are caused by obligate intracellular bacteria belonging to the spotted fever group (sfg) rickettsiae. although spotted fever is prevalent in the middle east, no reports for the presence of tick-borne pathogens are available or any studies on the epidemiology of this disease in the west bank. we aimed to identify the circulating hard tick vectors and genetically characterize sfg rickettsia species in ixodid ticks from the west bank-palestinian territories.201626771654
pristinamycin for rickettsia africae infection.african tick bite fever is caused by rickettsia africae. the number of reported cases in international travelers has significantly increased recently. the gold standard treatment is doxycycline. here, we present a case of r africae infection associated with quick complete resolution following the initiation of pristinamycin therapy.200919335816
analysis of the rickettsia africae genome reveals that virulence acquisition in rickettsia species may be explained by genome reduction.the rickettsia genus includes 25 validated species, 17 of which are proven human pathogens. among these, the pathogenicity varies greatly, from the highly virulent r. prowazekii, which causes epidemic typhus and kills its arthropod host, to the mild pathogen r. africae, the agent of african tick-bite fever, which does not affect the fitness of its tick vector.200919379498
novel rickettsia and emergent tick-borne pathogens: a molecular survey of ticks and tick-borne pathogens in shimba hills national reserve, kenya.ticks are important vectors of emerging and re-emerging zoonoses, the majority of which originate from wildlife. in recent times, this has become a global public health concern that necessitates surveillance of both known and unknown tick-borne pathogens likely to be future disease threats, as well as their tick vectors. we carried out a survey of the diversity of ticks and tick-borne pathogens in kenya's shimba hills national reserve (shnr), an area with intensified human-livestock-wildlife int ...201728011185
rickettsia africae infection in man after travel to ethiopia. 200919891894
african tick-bite fever: a new entity in the differential diagnosis of multiple eschars in travelers. description of five cases imported from south africa to switzerland.african tick-bite fever (atbf) is a newly described spotted fever rickettsiosis that frequently presents with multiple eschars in travelers returning from sub-saharan africa and, to a lesser extent, from the west indies. it is caused by the bite of an infected amblyomma tick, whose hunting habits explain the typical presence of multiple inoculation skin lesions and the occurrence of clustered cases. the etiological agent of atbf is rickettsia africae, an emerging tick-borne pathogenic bacterium. ...201020233665
emergence of rickettsia africae, oceania.we detected rickettsia africae, the agent of african tick-bite fever (atbf), by amplification of fragments of glta, ompa, and ompb genes from 3 specimens of amblyomma loculosum ticks collected from humans and birds in new caledonia. clinicians who treat persons in this region should be on alert for atbf.201121192865
[rickettsia africae infection among participants in a women's safari to south africa].preface: in recent years infections with rickettsia africae (african tick bite fever) have become a common and important cause of febrile illness among travelers returning from sub-saharan africa, primarily from south africa.201021302470
risk factors for african tick-bite fever in rural central africa.african tick-bite fever is an emerging infectious disease caused by the spotted fever group rickettsia, rickettsia africae, and is transmitted by ticks of the genus amblyomma. to determine the seroprevalence of exposure to r. africae and risk factors associated with infection, we conducted a cross-sectional study of persons in seven rural villages in distinct ecological habitats of cameroon. we examined 903 plasma samples by using an indirect immunofluorescence assay for antibodies to r. africae ...201121460018
molecular diagnostics of rickettsia africae infection in travelers returning from south africa to the netherlands.abstract background: african tick-bite fever (atbf) is frequently diagnosed in the netherlands in travelers returning from south africa. it is caused by rickettsia africae and diagnosis is based on travel history and clinical presentation and usually confirmed by detecting serum antibodies against rickettsiae of the spotted fever group. however, these typically occur late in the course of the disease, and a mild clinical course or early antibiotic treatment can diminish antibody production. ...201121867422
molecular detection of rickettsia africae, rickettsia aeschlimannii, and rickettsia sibirica mongolitimonae in camels and hyalomma spp. ticks from this study, we aimed to identify and genetically characterize spotted fever group (sfg) rickettsiae in ticks, domestic one-humped camels, and horses from farms and bedouin communities in southern israel. a total of 618 ixodid ticks (hyalomma dromedarii, hyalomma turanicum, hyalomma excavatum, and hyalomma impeltatum) collected from camels and horses, as well as 152 blood samples from 148 camels and four horses were included in the study. initial screening for rickettsiae was carried out by ta ...201324107206
identification of rickettsia africae and wolbachia sp. in ceratophyllus garei fleas from passerine birds migrated from africa.the aim of the study was to reveal new aspects of the role of flea vector taken from migratory birds by screening of specimens with molecular biological methods. a field study was done in fishponds in slovakia. actually, 47 fleas were collected from reed warblers (acrocephalus scirpaceus) and their nests. dna was extracted and analyzed for representatives of the orders rickettsiales. a rickettsia that shares 99.7% of identity by glta gene with rickettsia africae was identified in ceratophyllus g ...201222448745
pathogen prevalence in ticks collected from the vegetation and livestock in nigeria.ticks are important disease vectors that can cause considerable economic losses by affecting animal health and productivity, especially in tropical and subtropical regions. in this study, we investigated the prevalence and diversity of bacterial and protozoan tick-borne pathogens in ticks collected from the vegetation and cattle in nigeria by pcr. the infection rates of questing ticks were 3.1% for rickettsia species, 0.1% for coxiella burnetii and 0.4% for borrelia species. other pathogens, suc ...201222327584
cell extract-containing medium for culture of intracellular fastidious bacteria.the culture of fastidious microorganisms is a critical step in infectious disease studies. as a proof-of-concept experiment, we evaluated an empirical medium containing eukaryotic cell extracts for its ability to support the growth of coxiella burnetii. here, we demonstrate the exponential growth of several bacterial strains, including the c. burnetii nine mile phase i and phase ii strains, and c. burnetii isolates from humans and animals. low-oxygen-tension conditions and the presence of small ...201323740722
spotted fever rickettsia species in hyalomma and ixodes ticks infesting migratory birds in the european mediterranean area.a few billion birds migrate annually between their breeding grounds in europe and their wintering grounds in africa. many bird species are tick-infested, and as a result of their innate migratory behavior, they contribute significantly to the geographic distribution of pathogens, including spotted fever rickettsiae. the aim of the present study was to characterize, in samples from two consecutive years, the potential role of migrant birds captured in europe as disseminators of rickettsia-infecte ...201425011617
detection of microbial agents in ticks collected from migratory birds in central italy.tick species characterization and molecular studies were performed within ornithological surveys conducted during 2010 and 2011 in the lazio region of central italy. a total of 137 ticks were collected from 41 migratory birds belonging to 17 species (four partial migrants and 13 long-distance migrants). most ticks were nymphs, with a predominance of hyalomma marginatum marginatum and h. m. rufipes, and a small portion of ixodes and amblyomma species. all tick species analyzed were infected, and ...201424576218
multiple pathogens including potential new species in tick vectors in côte d'ivoire.our study aimed to assess the presence of different pathogens in ticks collected in two regions in côte d'ivoire.201626771308
molecular detection of spotted fever group rickettsiae in amblyomma variegatum ticks from benin.spotted fever group (sfg) rickettsiae are obligate intracellular, gram-negative bacteria transmitted by ticks and causing febrile illness in humans. despite the presence of suitable tick vectors, the occurrence of sfg rickettsiae has never been investigated in the republic of benin (west africa). in the present study, 910 amblyomma variegatum ticks collected from 8 different locations in north eastern benin were tested for sfg rickettsiae. the samples were first screened for the presence of rick ...201627150592
rickettsia spp. in seabird ticks from western indian ocean islands, 2011-2012.we found a diversity of rickettsia spp. in seabird ticks from 6 tropical islands. the bacteria showed strong host specificity and sequence similarity with strains in other regions. seabird ticks may be key reservoirs for pathogenic rickettsia spp., and bird hosts may have a role in dispersing ticks and tick-associated infectious agents over large distances.024751287
molecular diagnosis of african tick bite fever using eschar swabs in a traveller returning from tanzania.african tick bite fever is an emerging infectious disease among travellers caused by the pathogen rickettsia africae. most travel-associated cases have been reported from countries in southern africa. so far it has rarely been reported among travellers to eastern africa and our patient is one of the first described cases imported from tanzania. a woman presented with fever, chills, headache, myalgia and a rickettsial eschar on her ankle after returning from tanzania. the diagnosis of african tic ...201627488618
first molecular detection of rickettsia africae in ticks from the union of the comoros.rickettsia africae is the agent of african tick bite fever, a disease transmitted by ticks in sub-saharan africa. in union of the comoros, a recent study reported the presence of a rickettsia africae vector but no information has been provided on the circulation of the pathogenic agent in this country.201425245895
molecular detection of rickettsia africae in amblyomma variegatum collected from sudan.despite the increasing awareness of the importance of emerging vector-borne diseases, human tick-borne diseases, particularly rickettsial infections, are overlooked, especially in the countries such as sudan with limited resources to perform molecular-based surveys. this study aimed at detection and genetic characterization of rickettsia spp. in ticks collected from sudan. the samples were first screened for the presence of rickettsial agents by glta real-time pcr and subsequently characterized ...025988442
spotted fever group rickettsiae in ixodid ticks in oromia, ethiopia, information on the transmission of human zoonotic pathogens through ixodid ticks remains scarce. to address the occurrence and molecular identity of spotted fever group rickettsiae using molecular tools, a total of 767 ixodid ticks belonging to thirteen different species were collected from domestic animals from september 2011 to march 2014. rickettsia africae dna was detected in 30.2% (16/53) amblyommma variegatum, 28.6% (12/42) am. gemma, 0.8% (1/119) am. cohaerens, 18.2% (4/22) a ...201525262832
case report of african tick-bite fever from poland.a confirmed case of rickettsiosis acquired in south africa and recognized in poland was described. the patient fulfilled clinical criteria highly suggestive of african tick bite fever, such as eschars, regional lymphadenitis, cutaneous rash within 10 days after his return from sub-saharan africa. infection with rickettsia africae was confirmed by polymerase chain reaction and sequencing.201324494003
high prevalence of rickettsia africae variants in amblyomma variegatum ticks from domestic mammals in rural western kenya: implications for human health.tick-borne spotted fever group (sfg) rickettsioses are emerging human diseases caused by obligate intracellular gram-negative bacteria of the genus rickettsia. despite being important causes of systemic febrile illnesses in travelers returning from sub-saharan africa, little is known about the reservoir hosts of these pathogens. we conducted surveys for rickettsiae in domestic animals and ticks in a rural setting in western kenya. of the 100 serum specimens tested from each species of domestic r ...025325312
rickettsia africae in amblyomma variegatum ticks, uganda and nigeria. 024050756
comparison of real-time quantitative pcr and culture for the diagnosis of emerging rickettsioses.isolation of rickettsia species from skin biopsies may be replaced by pcr. we evaluated culture sensitivity compared to pcr based on sampling delay and previous antibiotic treatment.201222413026
molecular identification of tick-borne pathogens in nigerian ticks.a molecular epidemiology investigation was undertaken in two nigerian states (plateau and nassarawa) to determine the prevalence of pathogens of veterinary and public health importance associated with ticks collected from cattle and dogs using pcr, cloning and sequencing or reverse line blot techniques. a total of 218 tick samples, amblyomma variegatum (n=153), rhipicephalus (boophilus) decoloratus (n=45), and rhipicephalus sanguineus (n=20) were sampled. pathogens identified in ticks included p ...201222326937
anaplasma, ehrlichia and rickettsial pathogens in ixodid ticks infesting cattle and sheep in western oromia, ethiopia.although ticks are widely distributed in all agro-ecological zones of ethiopia, information on tick-borne pathogens is scarce. this study was conducted to determine the presence of anaplasma spp., ehrlichia spp., and rickettsia spp. in rhipicephalus evertsi and rhipicephalus (boophilus) decoloratus collected from cattle and sheep at bako, western oromia, ethiopia, using polymerase chain reaction and sequencing. anaplasma ovis and anaplasma spp., ehrlichia ruminantium and ehrlichia spp. were dete ...201627411938
prediction of rickettsial skin eschars in humans using an experimental guinea pig model.until now, when a new rickettsia species was isolated in a tick, it was not possible to predict whether it was a human pathogen or if it would cause a skin eschar at the infection site. guinea pigs are injected intradermally with 25 different rickettsia species or subspecies: 16 induced an eschar, 5 induced inflammatory lesions and 4 have no effect. we observed that the occurrence of skin eschars in this model was significantly correlated (p <0.05) with observations of skin eschars in humans (14 ...200919527779
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