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Didier Raoult - One of the best experts on this subject based on the ideXlab platform.
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ISOLATION OF Rickettsia africae FROM AMBLYOMMA VARIEGATUM TICKS AND SEROSURVEY IN HUMANS, CATTLE, AND GOATS
2015Co-Authors: Philippe Parola, Veronique Roux, Guy Vestris, Dominique Martinez, Bernard Brochier, Didier RaoultAbstract:Abstract. 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 described as an agent of African tick-bite fever occurring in sub-Sahelian Africa. A high seroprevalence of antibodies to R. africae was demonstrated among mammals, particularly humans, cattle, and goats. These results and a recently reported case of an infection due to R. africae on Guadeloupe dem-onstrate that R. africae is present on this island. Although this disease has been underdiagnosed there, it may be frequent and may exist on other Caribbean islands where A. variegatum has propagated dramatically over recent years. Bacteria of the genus Rickettsia are gram-negative intra-cellular bacilli associated with arthropods.1 Ticks are the main reservoir of these Rickettsiae in which they are main-tained by transtadial and transovarial transmission.2 Ticks may also act as vectors that infect humans or animals whil
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Rickettsia africae infection complicated with painful sacral syndrome in an italian traveller returning from zimbabwe
International Journal of Infectious Diseases, 2014Co-Authors: Lorenzo Zammarchi, Didier Raoult, Alberto Farese, Michele Trotta, Aldo Amantini, Alessandro BartoloniAbstract:We report a case of Rickettsia africae infection complicated with painful sacral syndrome in an Italian traveller returning from Zimbabwe. The patient presented with fever, a tache noire on the left leg, and a neurological syndrome characterized by severe pain of the left leg, predominantly located in the left dorsal thigh and radiating to the calf; she had urinary retention and faecal incontinence. The diagnosis of R. africae was confirmed by polymerase chain reaction on a skin biopsy. The severe left leg pain persisted despite a complete course of doxycycline. A 4-month course of corticosteroids and the addition of carbamazepine was needed to achieve the control of pain. This case highlights the possibility of severe manifestations of R. africae infection and the possibility of a complex pathogenesis of the neurological syndrome, due perhaps to both the direct damage induced by R. africae and an immune-mediated mechanism.
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pathogenic spotted fever group Rickettsia
2013Co-Authors: Dorothea Stephany, Didier Raoult, Paul H. Consigny, Beati L, Raoult D. A NewAbstract:M, Prioe T, de Pina JJ, et al. Rickettsia africae, a tick-borne pathogen in travelers to sub-Saharan Africa. N Engl J Med. 2001;344:1504–10. DOI: 10.1056
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Cell Extract-Containing Medium for Culture of Intracellular Fastidious Bacteria
Journal of clinical microbiology, 2013Co-Authors: Sudhir Singh, Sophie Edouard, Malgorzata Kowalczewska, Carole Eldin, Céline Perreal, Pascal Weber, Saïd Azza, Didier RaoultAbstract:ABSTRACT 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 hydrophilic molecules and short peptides were critical for facilitating growth. Moreover, bacterial antigenicity was conserved, revealing the potential for this culture medium to be used in diagnostic tests and in the elaboration of vaccines against C. burnetii. We were also able to grow the majority of previously tested intracellular and fastidious bacterial species, including Tropheryma whipplei, Mycobacterium bovis, Leptospira spp., Borrelia spp., and most putative bioterrorism agents. However, we were unable to culture Rickettsia africae and Legionella spp. in this medium. The versatility of this medium should encourage its use as a replacement for the cell-based culture systems currently used for growing several facultative and putative intracellular bacterial species.
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RESEARCH Histologic Features and Immunodetection of African Tick-bite Fever Eschar
2013Co-Authors: Hubert Lepidi, Pierre-edouard Fournier, Didier RaoultAbstract: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 immunohistochemical techniques by using a monoclonal antibody to R. africae. ATBF eschars were histologically characterized by inflammation of vessels composed mainly of significantly more polymorphonuclear leukocytes than are found in cases of Mediterranean spotted fever (p<0.05). Small amounts R. africae antigens were demonstrated by immunohistochemica
Philippe Parola - One of the best experts on this subject based on the ideXlab platform.
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ISOLATION OF Rickettsia africae FROM AMBLYOMMA VARIEGATUM TICKS AND SEROSURVEY IN HUMANS, CATTLE, AND GOATS
2015Co-Authors: Philippe Parola, Veronique Roux, Guy Vestris, Dominique Martinez, Bernard Brochier, Didier RaoultAbstract:Abstract. 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 described as an agent of African tick-bite fever occurring in sub-Sahelian Africa. A high seroprevalence of antibodies to R. africae was demonstrated among mammals, particularly humans, cattle, and goats. These results and a recently reported case of an infection due to R. africae on Guadeloupe dem-onstrate that R. africae is present on this island. Although this disease has been underdiagnosed there, it may be frequent and may exist on other Caribbean islands where A. variegatum has propagated dramatically over recent years. Bacteria of the genus Rickettsia are gram-negative intra-cellular bacilli associated with arthropods.1 Ticks are the main reservoir of these Rickettsiae in which they are main-tained by transtadial and transovarial transmission.2 Ticks may also act as vectors that infect humans or animals whil
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first molecular detection of Rickettsia africae in ticks from the union of the comoros
Parasites & Vectors, 2014Co-Authors: Amina Yssouf, Cristina Socolovschi, Tahar Kernif, Sarah Temmam, Erwan Lagadec, Pablo Tortosa, Philippe ParolaAbstract: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. To evaluate the possible circulation of Rickettsia spp. in Comorian cattle, genomic DNA was extracted from 512 ticks collected either in the Union of the Comoros or from animals imported from Tanzania and subsequently tested for Rickettsia infection by quantitative PCR. Rickettsia africae was detected in 90% (60/67) of Amblyomma variegatum, 1% (1/92) of Rhipicephalus appendiculatus and 2.7% (8/296) of Rhipicephalus (Boophilus) microplus ticks collected in the Union of the Comoros, as well as in 77.14% (27/35) of Amblyomma variegatum ticks collected from imported cattle. Partial sequences of both bacterial gltA and ompA genes were used in a phylogenetic analysis revealing the presence of several haplotypes, all included within the Rickettsia africae clade. Our study reports the first evidence of Rickettsia africae in ticks collected from the Union of the Comoros. The data show a significant difference of infection rate of Rickettsia africae infected ticks between the Islands, with maximum rates measured in Grande Comore Island, sheltering the main entry port for live animal importation from Tanzania. The high infection levels reported herein indicate the need for an in-depth assessment of the burden of rickettsioses in the Union of the Comoros, especially among those at risk of infection, such as cattle herders.
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Rickettsia africae in hyalomma dromedarii ticks from sub saharan algeria
Ticks and Tick-borne Diseases, 2012Co-Authors: Tahar Kernif, Oleg Mediannikov, Philippe Parola, Jean-marc Rolain, Didier Raoult, Amel Djerbouh, Bouhous Ayach, Idir BitamAbstract:Spotted fever group (SFG) rickettsioses are caused by obligate, intracellular Gram-negative bacteria of the genus Rickettsia. In recent years, several species and subspecies of Rickettsias have been identified as emerging pathogens throughout the world, including sub-Saharan Africa. We report here the detection of Rickettsia africae, the agent responsible for African tick-bite fever, by amplification of fragments of gltA and ompA genes and multi-spacer typing from Hyalomma dromedarii ticks collected from the camel Camelus dromedarius in the Adrar and Bechar region (sub-Saharan Algeria). To date, R. africae has been associated mainly with Amblyomma spp. The role of H. dromedarii in the epidemiology of R. africae requires further investigation.
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The use of eschar swabs for the diagnosis of African tick-bite fever.
Ticks and tick-borne diseases, 2012Co-Authors: Cristina Socolovschi, Philippe Brouqui, Aurelie Renvoise, Philippe ParolaAbstract:African tick-bite fever (ATBF) caused by Rickettsia africae is a frequent cause of fever in returned travelers. Here, we used eschar swabs and/or eschar crust samples for the molecular diagnosis of ATBF in returned travelers. In 4 of 5 patients returning from South Africa, including 3 with negative serology, R. africae was identified by molecular tools targeting 2 different genes. The findings of this study highlight the usefulness of eschar swabs and/or eschar crust samples for the diagnosis of R. africae infection.
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emergence of Rickettsia africae oceania
Emerging Infectious Diseases, 2011Co-Authors: Carole Eldin, Oleg Mediannikov, Didier Raoult, Bernard Davoust, Olivier Cabre, Nicolas Barre, Philippe ParolaAbstract: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.
Pierre-edouard Fournier - One of the best experts on this subject based on the ideXlab platform.
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RESEARCH Histologic Features and Immunodetection of African Tick-bite Fever Eschar
2013Co-Authors: Hubert Lepidi, Pierre-edouard Fournier, Didier RaoultAbstract: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 immunohistochemical techniques by using a monoclonal antibody to R. africae. ATBF eschars were histologically characterized by inflammation of vessels composed mainly of significantly more polymorphonuclear leukocytes than are found in cases of Mediterranean spotted fever (p<0.05). Small amounts R. africae antigens were demonstrated by immunohistochemica
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Rickettsia africae, Western Africa.
Emerging Infectious Diseases, 2010Co-Authors: Oleg Mediannikov, Jean-françois Trape, Philippe Parola, Georges Diatta, Pierre-edouard FournierAbstract:To the Editor: Rickettsia africae, the causative agent of African tick-bite fever, is transmitted by Amblyomma hebraeum and A. variegatum ticks (1,2). These ticks are common in western, central, and southern Africa. Adults rarely feed on humans, although nymphs attach more frequently and larvae are sometimes serious pests (abundant and aggressive) (3). African tick-bite fever is a neglected disease that has been mainly detected in tourists who were bitten by a tick while traveling in disease-endemic areas (2). A recent worldwide report showed Rickettsial infection incidence to be 5.6% in a group of travelers in whom acute febrile infection developed after they returned from sub-Saharan Africa. African tick-bite fever is the second most frequently identified cause for systemic febrile illness among travelers, following malaria (4). Seroprevalence for spotted fever group Rickettsiae is high in the Sahel regions of Africa (5), although there may be different emergent and classic rickettsioses in Africa. R. africae has been detected by PCR in many African countries, including Niger, Mali, Burundi, and Sudan (6), and in most countries of equatorial and southern Africa (Figure). Most strains and cases have been found in South Africa (2). R. africae and African tick-bite fever have not previously been reported in Senegal, and few positive human serum samples have been documented in western Africa. A. variegatum, the main vector of R. africae, was introduced by cattle into Guadeloupe, West Indies, from Senegal in the early 1800s. Spotted fever caused by R. africae has become endemic there in the past 30 years (7). In addition to R. africae, A. variegatum ticks may transmit other human and animal pathogens, including Crimean-Congo hemorrhagic fever virus, Dugbe virus, Thogoto virus, Bhanja virus, Ehrlichia ruminantium, Theileria spp., Anaplasma spp., and Dermatophilus congolensis (3,6). Figure Distribution of Rickettsia africae in the African continent and serologic evidence of spotted fevers in humans. Gray shading indicates location of Senegal. From November through December 2008, ticks were collected from domestic animals (cattle, goats, sheep, dogs, horses, donkeys) in the Sine-Saloum region of Senegal (villages Dielmo, Ndiop, Medina, and Passi). Among the collected ticks, 8 fully engorged nymphs were kept alive in flasks at 90%–95% relative humidity. Other ticks were stored in 70% ethanol. Flagging at ground level was used to collect ticks from pastures. Species were identified according to standard taxonomic keys for adult ticks. Nymphs were allowed to molt before identification and subsequent bacterial culture. Rickettsial DNA in other ticks was detected by semiquantitative PCR with Rickettsia-specific primers (8). All positive samples were subjected to PCR by using primers designed for the gltA and ompA genes (6). Three Rickettsial spacers were chosen for typing: dksA-xerC, rpmE-tRNAmet, and mppA-purC (9). Tick larvae were the only stage collected by flagging at ground level. Flagging for 30 minutes collected 495 larvae near the village of Passi and 325 in Dielmo. The larvae were aggressive, and several attached onto the collector’s ankles despite preventive measures. All larvae were morphologically identified as Amblyomma spp. Amplification and sequencing of the portion of mitochondrial cytochrome oxidase I gene of 3 adult A. variegatum ticks, 2 individual larvae, and 1 pool of 10 larvae detected a 659-bp sequence 100% identical among all larvae and adults and corresponding to cytochrome oxidase I of other ticks. The sequence is deposited in GenBank, accession no. {"type":"entrez-nucleotide","attrs":{"text":"GU062743","term_id":"261854057","term_text":"GU062743"}}GU062743. Adult ticks (n = 492) were collected from domestic animals; 85 (17.3%) were A. variegatum, and 74 (87.1%) were positive for Rickettsial genes according to real-time PCR. No associations between animal host, place of collection, and presence of R. africae were found (data not shown). During the subsequent amplification and sequencing of the 632-bp fragment of the ompA gene, all amplicons were found to be 100% identical to the ompA sequence of R. africae published in GenBank ({"type":"entrez-nucleotide","attrs":{"text":"CP001612.1","term_id":"228021280","term_text":"CP001612.1"}}CP001612.1). Molted nymphs were the source of 3 strains of R. africae. Although dogs are rarely reported to be hosts of A. variegatum (3), a dog was the host of the tick that carried the first isolated strain. A 1,290-bp fragment of the Rickettsial gltA gene and a 632-bp fragment of the ompA gene from all 3 strains were identical to the published sequence of the R. africae genome ({"type":"entrez-nucleotide","attrs":{"text":"CP001612.1","term_id":"228021280","term_text":"CP001612.1"}}CP001612.1). Multispacer typing showed that all 3 R. africae strains exhibited a genotype identical to that of all previously genotyped R. africae strains (genotype 38). To the best of our knowledge, this is the northernmost reported isolation of this pathogen in western Africa. Taking into consideration data described in previous studies and the results of our work, we conclude that A. variegatum is an aggressive and abundant species of tick. The reported transovarial transmission rate of 100% for R. africae (10), the abundance of ticks, and the high percentage of ticks that are infected (3) increase the probability that humans will be bitten by infected ticks. R. africae is present in Senegal, and human infections (in tourists and indigenous populations) may be as common there as in southern Africa, but better availability of diagnostic assays is needed. Surveys of the distribution of vector ticks and Rickettsiae should be performed, and target groups should be screened.
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histologic features and immunodetection of african tick bite fever eschar
Emerging Infectious Diseases, 2006Co-Authors: Hubert Lepidi, Pierre-edouard Fournier, Didier RaoultAbstract: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 immunohistochemical techniques by using a monoclonal antibody to R. africae. ATBF eschars were histologically characterized by inflammation of vessels composed mainly of significantly more polymorphonuclear leukocytes than are found in cases of Mediterranean spotted fever (p<0.05). Small amounts R. africae antigens were demonstrated by immunohistochemical examination in 6 of 8 patients with ATBF. Neutrophils in ATBF are a notable component of the host reaction, perhaps because ATBF is a milder disease than the other rickettsioses. Immunohistochemical detection of Rickettsial antigens may be useful in diagnosing ATBF.
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sub acute neuropathy in patients with african tick bite fever
Scandinavian Journal of Infectious Diseases, 2006Co-Authors: Mogens Jensenius, Sirka Vene, Pierre-edouard Fournier, Didier Raoult, K B Hellum, Tormod Fladby, Tormod Hagen, Tine Prio, Merete Skovdal Christiansen, Bjørn MyrvangAbstract: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 onset, cerebrospinal fluid samples from 5 patients were negative for R. africae PCR and serology, but revealed elevated protein content in 3 and mild pleocytosis in 1 case. Despite extensive investigations, no plausible alternative causes of neuropathy could be identified. Treatment with doxycycline in 2 patients had no clinical effect. Given the current increase of international safari tourism to sub-Saharan Africa, more cases of sub-acute neuropathy following ATBF may well be encountered in Europe and elsewhere in the y to come.
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Histologic Features and Immunodetection of African Tick-bite Fever Eschar
Emerging Infectious Diseases, 2006Co-Authors: Hubert Lepidi, Pierre-edouard Fournier, Didier RaoultAbstract: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 immunohistochemical techniques by using a monoclonal antibody to R. africae. ATBF eschars were histologically characterized by inflammation of vessels composed mainly of significantly more polymorphonuclear leukocytes than are found in cases of Mediterranean spotted fever (p
Mogens Jensenius - One of the best experts on this subject based on the ideXlab platform.
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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
Journal of Immunology, 2006Co-Authors: Jan Kristian Damas, Bjørn Myrvang, Mogens Jensenius, Jean-marc Rolain, Didier Raoult, Thor Ueland, Kari Otterdal, Stig S Froland, Arne Yndestad, Pal AukrustAbstract: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 ligand (sCD40L), which decreased during follow-up. 2) These enhanced sCD40L levels seem to reflect both direct and indirect (through endothelial cell activation involving CX3CL1-related mechanisms) effects of R. africae on platelets. 3) In combination with sCD40L, R. africae promoted a procoagulant state in endothelial cells by up-regulating tissue factor and down-regulating thrombomodulin expression. 4) Although the R. africae-mediated activation of platelets involved TLR2, the combined procoagulant effects of R. africae and sCD40L on endothelial cells involved TLR4. 5) Doxycycline counteracted the combined procoagulant effects of R. africae and sCD40L on endothelial cells. Our findings suggest an inflammatory interaction between platelets and endothelial cells in ATBF, involving TLR-related mechanisms. This interaction, which includes additive effects between sCD40L and R. africae, may contribute to endothelial inflammation and hypercoagulation in this disorder.
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sub acute neuropathy in patients with african tick bite fever
Scandinavian Journal of Infectious Diseases, 2006Co-Authors: Mogens Jensenius, Sirka Vene, Pierre-edouard Fournier, Didier Raoult, K B Hellum, Tormod Fladby, Tormod Hagen, Tine Prio, Merete Skovdal Christiansen, Bjørn MyrvangAbstract: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 onset, cerebrospinal fluid samples from 5 patients were negative for R. africae PCR and serology, but revealed elevated protein content in 3 and mild pleocytosis in 1 case. Despite extensive investigations, no plausible alternative causes of neuropathy could be identified. Treatment with doxycycline in 2 patients had no clinical effect. Given the current increase of international safari tourism to sub-Saharan Africa, more cases of sub-acute neuropathy following ATBF may well be encountered in Europe and elsewhere in the y to come.
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Repellent efficacy of four commercial DEET lotions against Amblyomma hebraeum (Acari: Ixodidae), the principal vector of Rickettsia africae in southern Africa.
Transactions of the Royal Society of Tropical Medicine and Hygiene, 2005Co-Authors: Mogens Jensenius, Anne-marié Pretorius, Francoise Clarke, Bjørn MyrvangAbstract:Summary 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 4 h. Three lotions with 19.5, 31.6 and 80% DEET concentrations, respectively, had a repellent efficacy of ≥90% at 1 h post-application, of ≥77% at 2 h post-application and of A. hebraeum ticks.
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rickettsioses and the international traveler
Clinical Infectious Diseases, 2004Co-Authors: Charles D Ericsson, Mogens JenseniusAbstract: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 patients present with a benign febrile illness accompanied by headache, myalgia, and cutaneous eruptions, but severe complications and fatalities are occasionally seen. Current microbiological tests include culture, polymerase chain reaction, and serological analysis, of which only the latter method is widely available. Tetracyclines are the drugs of first choice and should be prescribed whenever a case of rickettsiosis is suspected. Preventive measures rely on minimizing the risk of arthropod bites when traveling in areas of endemicity.
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comparison of immunofluorescence western blotting and cross adsorption assays for diagnosis of african tick bite fever
Clinical and Vaccine Immunology, 2004Co-Authors: Mogens Jensenius, Sirka Vene, Pierre-edouard Fournier, Signe Holta Ringertz, Bjørn MyrvangAbstract:In 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). African tick bite fever (ATBF) is a flu-like illness frequently accompanied by inoculation eschars, headache, and neck myalgia (7). The disease is caused by Rickettsia africae, a recently identified spotted fever group (SFG) Rickettsia, and is transmitted by cattle ticks in large parts of rural sub-Saharan Africa (9). ATBF typically occurs in clusters and has recently emerged
Jean-marc Rolain - One of the best experts on this subject based on the ideXlab platform.
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Rickettsia africae in hyalomma dromedarii ticks from sub saharan algeria
Ticks and Tick-borne Diseases, 2012Co-Authors: Tahar Kernif, Oleg Mediannikov, Philippe Parola, Jean-marc Rolain, Didier Raoult, Amel Djerbouh, Bouhous Ayach, Idir BitamAbstract:Spotted fever group (SFG) rickettsioses are caused by obligate, intracellular Gram-negative bacteria of the genus Rickettsia. In recent years, several species and subspecies of Rickettsias have been identified as emerging pathogens throughout the world, including sub-Saharan Africa. We report here the detection of Rickettsia africae, the agent responsible for African tick-bite fever, by amplification of fragments of gltA and ompA genes and multi-spacer typing from Hyalomma dromedarii ticks collected from the camel Camelus dromedarius in the Adrar and Bechar region (sub-Saharan Algeria). To date, R. africae has been associated mainly with Amblyomma spp. The role of H. dromedarii in the epidemiology of R. africae requires further investigation.
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widespread use of real time pcr for Rickettsial diagnosis
Fems Immunology and Medical Microbiology, 2012Co-Authors: Aurelie Renvoise, Jean-marc RolainAbstract: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 of Rickettsial infections from clinical specimens. We retained sets of primers and probes to detect spotted fever group Rickettsia , typhus group Rickettsia , Rickettsia conorii , Rickettsia slovaca , Rickettsia africae and Rickettsia australis ; 643 clinical samples were screened for the presence of Rickettsia DNA. Overall, 45 positive samples were detected, including 15 Rickettsia africae , nine R.conorii , five Rickettsia sibirica mongolitimonae , four R.slovaca , two R.australis , four Rickettsia massiliae , one Rickettsia honei , one Rickettsia typhi and eight Rickettsia sp. Positive samples were detected mainly from cutaneous biopsies and swabs (31/45). Widespread use of real-time PCR is inexpensive and reduces delay in the diagnosis of Rickettsial infections. These real-time PCR assays could be implemented easily in laboratories that have molecular facilities and may be added to existing molecular tools as a point-of-care strategy.
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Rickettsia africae infection in man after travel to ethiopia
Emerging Infectious Diseases, 2009Co-Authors: Dorothea Stephany, Jean-marc Rolain, Didier Raoult, Pierre Buffet, Paul-henri ConsignyAbstract:To the Editor: The first human case of African tick-bite fever was described in 1992 as occurring in Zimbabwe. The causative agent was identified as a new serotype of the spotted fever group (SFG) Rickettsiae and named Rickettsia africae (1). These findings confirmed observations made by Pijper in the 1930s, which suggested that there were 2 different kinds of human SFG rickettsioses in sub-Saharan Africa: Mediterranean spotted fever caused by R. conorii and transmitted by Rhipicephalus species, ticks of dogs, and African tick-bite fever caused by R. africae and transmitted by Amblyomma species, ticks of cattle and wild ungulates. African tick-bite fever has subsequently been diagnosed in patients from several other sub-Saharan countries and also from the West Indies (2,3). In a recent analysis of the spectrum of diseases among returning travelers, tick-borne spotted fever was (after malaria) the second most frequent cause of systemic febrile illness among those returning from sub-Saharan Africa. It occurred more frequently than typhoid fever and dengue fever (4). The following case description reports an infection with R. africae in a man in France who recently returned from Ethiopia. On November 4, 2005, a 62-year-old French man sought care at the Medical Center of the Institut Pasteur in Paris for fever, along with chills, headache, neck and shoulder pain, and fatigue over the previous 4 days. At the onset of these symptoms he had noticed dark nodular lesions on his neck and his left groin followed 2 days later by a slightly painful eruption on his arms and his trunk. He had spent a month in southwest Ethiopia, north of Kelem near the Sudanese border, and returned to France on October 26, 2005. While in Ethiopia, he had assisted with a production of a documentary film about an Ethiopian tribe and had been in contact with cattle in the villages. He had not noticed any tick bites. On physical examination he had a fever of 38°C, a nodular lesion with a central dark crust on his neck, a second lesion on his left inguinal fold (Figure, panel A), and a vesicular eruption on his arms and his trunk (Figure, panel B). Leukocyte count was 3,200, including 1,869 neutrophils and 867 lymphocytes. The platelet level was 174,000/mm3. The C-reactive protein level was 28.3 mg/L. The aspartate aminotransferase level was slightly elevated. The patient was treated with doxycycline 200 mg/day for 1 week for suspected African tick-bite fever. Follow-up showed a quick recovery from his symptoms except for fatigue that persisted for ≈1 month. Figure Inoculation eschar on left inguinal fold (A) and vesicular skin lesion (B) in a traveler recently returned to France from Ethiopia. A commercial immunofluorescence assay for R. conorii and R. typhi immunoglobulin G performed both on an initial blood sample and a second sample taken 1 week later were negative. A blood sample and a biopsy specimen of the inguinal eschar were sent to the National Reference Center of Rickettsiae in Marseille, France. Although cellular culture of both specimens and molecular testing of the blood sample were negative, PCR for the sequences of citrate synthase (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"RAU59733","term_id":"1389980"}}RAU59733, 93.1% homology) and Rickettsial OmpA (GenBank accession no. {"type":"entrez-nucleotide","attrs":{"text":"RAU83436","term_id":"62861416"}}RAU83436, 99.3% homology) applied on the skin biopsy detected R. africae and confirmed the diagnosis of African tick-bite fever. From 1969 to 1971, SFG Rickettsiae were isolated from Amblyomma spp. ticks collected in Ethiopia. They were regarded as R. conorii or as closely related bacteria (5). Later, more specific tests using western immunoblots with monoclonal antibodies showed that these Rickettsiae differed from R. conorii (6). In 1992 SFG Rickettsiae isolated from Amblyomma ticks collected in Zimbabwe and from the blood of a patient in Zimbabwe were compared to R. conorii, to other pathogenic SFG Rickettsiae, and to a SFG Rickettsia isolated from an Amblyomma spp. tick in Ethiopia 20 years before. The SFG Rickettsia isolates from Ethiopia were identical to isolates obtained in Zimbabwe from the Amblyomma ticks and the patient’s blood and were different from R. conorii and other pathogenic SFG Rickettsiae. This new serotype of SFG Rickettsiae was named R. africae (1,7). A recent study confirmed the presence of R. africae in ticks collected in Ethiopia, as well as R. aeschlimanii (8). Thus, evidence of R. africae in Ethiopia has been known for a long time. The geographic distribution of African tick-bite fever is related to the presence of Amblyomma spp. ticks, vectors and reservoirs of R. africae. Consequently African tick-bite fever should also be considered as a possible diagnosis in patients with febrile illness returning from countries where R. africae has been detected in Amblyomma ticks, even if a human infection has not yet been reported (9,10).
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molecular detection of spotted fever group Rickettsiae in ticks from ethiopia and chad
Transactions of The Royal Society of Tropical Medicine and Hygiene, 2008Co-Authors: Alessandra Mura, Jean-marc Rolain, Didier Raoult, Cristina Socolovschi, Bernard Davoust, Jacques Ginesta, Bertrand Lafrance, Stephan Magnan, Philippe ParolaAbstract: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, 2/12 Hyalomma marginatum rufipes collected in Ethiopia and one H. marginatum rufipes collected in Chad were positive for R. aeschlimannii. Our results confirm the previously reported presence of R. africae in Ethiopia and also show the first evidence of R. aeschlimannii in ticks collected in Ethiopia and Chad.
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two cases of cellulitis in the course of african tick bite fever a fortuitous association
Dermatology, 2008Co-Authors: Sophie Bouvresse, Jean-marc Rolain, Didier Raoult, Pascal Del Giudice, N Franck, Marc Buffet, Mariefrancoise Avril, Veronique Mondain, N DupinAbstract: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 Zimbabwe for a maculopapular exanthema and erysipelas-like rash of the leg. The diagnosis of cellulitis associated with ATBF was confirmed by PCR and serological methods. Both patients were treated for ATBF and cellulitis by a combination of doxycycline and beta-lactam antibiotics, and both had a good recovery. Inoculation eschar may be a risk factor for cellulitis; thus, we hypothesize a non-fortuitous association between ATBF and cellulitis.
