scholarly journals Rickettsia parkeri: a Rickettsial pathogen transmitted by ticks in endemic areas for spotted fever rickettsiosis in southern Uruguay

2012 ◽  
Vol 54 (3) ◽  
pp. 131-134 ◽  
Author(s):  
José M. Venzal ◽  
Agustín Estrada-Peña ◽  
Aránzazu Portillo ◽  
Atilio J. Mangold ◽  
Oscar Castro ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Rickettsia Parkeri ◽  
Molecular Tests ◽  
Glta Gene ◽  
Dna Pools ◽  
Human Infections

At first Rickettsia conorii was implicated as the causative agent of spotted fever in Uruguay diagnosed by serological assays. Later Rickettsia parkeri was detected in human-biting Amblyomma triste ticks using molecular tests. The natural vector of R. conorii, Rhipicephalus sanguineus, has not been studied for the presence of rickettsial organisms in Uruguay. To address this question, 180 R. sanguineus from dogs and 245 A. triste from vegetation (flagging) collected in three endemic localities were screened for spotted fever group (SFG) rickettsiosis in southern Uruguay. Tick extracted DNA pools were subjected to PCR using primers which amplify a fragment of the rickettsial gltA gene. Positive tick DNA pools with these primers were subjected to a second PCR round with primers targeting a fragment of the ompA gene, which is only present in SFG rickettsiae. No rickettsial DNA was detected in R. sanguineus. However, DNA pools of A. triste were found to be positive for a rickettsial organism in two of the three localities, with prevalences of 11.8% to 37.5% positive pools. DNA sequences generated from these PCR-positive ticks corresponded to R. parkeri. These findings, joint with the aggressiveness shown by A. triste towards humans, support previous data on the involvement of A. triste as vector of human infections caused by R. parkeri in Uruguay.

scholarly journals Spotted fever group rickettsial infection in dogs and their ticks from domestic–wildlife interface areas in southeastern Brazil

2020 ◽  
Vol 29 (1) ◽  
Author(s):  
Sabrina Destri Emmerick Campos ◽  
Nathalie Costa da Cunha ◽  
Camila de Souza Cerqueira Machado ◽  
Niara Vanat Nadal ◽  
Eloy Silva Seabra Junior ◽  
...  
Keyword(s):  
Natural Infection ◽  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Southeastern Brazil ◽  
Spotted Fever Group ◽  
Forest Fragments ◽  
Rickettsia Parkeri ◽  
Chain Reactions ◽  
Glta Gene ◽  
Pcr Targeting

Abstract Rickettsia rickettsii is the causative agent of Brazilian spotted fever (BSF), for which humans and dogs are both susceptible. Dogs are sentinels in serological surveys, however, canine disease is rarely reported. Therefore, we aimed to evaluate natural infection by spotted fever group (SFG) Rickettsia spp. in dogs and ticks collected from domiciles close to forest fragments, featuring domestic–wildlife interface areas. Samples from 115 dogs and 135 ixodids were assessed by polymerase chain reactions (PCR) targeting the gltA gene for Rickettsia spp. and the ompA gene for the SFG rickettsial species. One dog (0.87%; 1/115) was positive for R. rickettsii. This dog presented nonspecific laboratory and clinical abnormalities (thrombocytopenia, hyperproteinemia, lymph node enlargement, emaciation, anorexia, and lethargy). Rickettsia parkeri was identified in 2.96% (4/135) of the ticks (Amblyomma sculptum, A. aureolatum, and Rhipicephalus sanguineus). This study confirmed the presence of SFG bacteria in non-endemic and preserved locations, where domestic and wild populations interact. We reinforce the fact that the dog is susceptible to natural R. rickettsii infection. Although this is a rare finding, preventive measures should be taken against BSF in the studied areas. Finally, R. parkeri infection is possibly being demonstrated in A. sculptum for the first time.

scholarly journals One Health Approach to Rickettsiosis: A Five-Year Study on Spotted Fever Group Rickettsiae in Ticks Collected from Humans, Animals and Environment

2021 ◽  
Vol 10 (1) ◽  
pp. 35
Author(s):  
Ilaria Pascucci ◽  
Elisa Antognini ◽  
Cristina Canonico ◽  
Marco Giuseppe Montalbano ◽  
Alessandro Necci ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Geographic Area ◽  
Molecular Diagnostic ◽  
Spotted Fever Group ◽  
Rickettsia Species ◽  
Glta Gene ◽  
Starting Point ◽  
Pcr Products ◽  
Sfg Rickettsia

The spotted fever group of Rickettsiae is a heterogeneous group of Rickettsiae transmitted by ticks, causing similar diseases in humans (spotted fever). Until recently, it was supposed that a single pathogenic tick-borne SFG Rickettsia circulated in each different geographic area and that R. conorii subsp. conorii was the SFG Rickettsiae circulating in Italy, but in the last decade, thanks to molecular diagnostic, several different Rickettsia species, previously not considered pathogenic for decades, have been isolated from ticks and definitively associated to human disease, also in Italy. The present survey was carried out with the aim of investigating the presence of different SFG Rickettsia species in a geographic area where no information was available. Ticks collected from animals submitted to necropsy, removed from humans in local hospitals and collected from the environment were identified and tested by PCR for Rickettsia spp. based on the gltA gene, and positive PCR products were sequenced. A total of 3286 ticks were collected. Fifteen tick species were recognized, the most represented (79.52%) species in the collection was Ixodes ricinus, followed by Rhipicephalus sanguineus (9.13%). The overall prevalence of Rickettsia infection was 7.58%. Eight species of Rickettsia were identified, the most frequent was R. monacensis (56%), followed by R. helvetica (25.50%). Noteworthy, is the detection in the present study of Rrhipicephali, detected only twice in Italy. These are the first data available on SFG Rickettsiae circulation in the study area and they can be considered as starting point to assess the possible risk for humans.

scholarly journals Mediterranean Spotted Fever: Current Knowledge and Recent Advances

2021 ◽  
Vol 6 (4) ◽  
pp. 172
Author(s):  
Nikolaos Spernovasilis ◽  
Ioulia Markaki ◽  
Michail Papadakis ◽  
Nikolaos Mazonakis ◽  
Despo Ierodiakonou
Keyword(s):  
Clinical Features ◽  
Current Knowledge ◽  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Molecular Techniques ◽  
Rickettsia Conorii ◽  
Mediterranean Spotted Fever ◽  
Spotted Fever Group ◽  
Serological Tests ◽  
True Nature

Mediterranean spotted fever (MSF) is an emerging tick-borne rickettsiosis of the spotted fever group (SFG), endemic in the Mediterranean basin. By virtue of technological innovations in molecular genetics, it has been determined that the causative agent of MSF is Rickettsia conorii subspecies conorii. The arthropod vector of this bacterium is the brown dog tick Rhipicephalus sanguineus. The true nature of the reservoir of R. conorii conorii has not been completely deciphered yet, although many authors theorize that the canine population, other mammals, and the ticks themselves could potentially contribute as reservoirs. Typical symptoms of MSF include fever, maculopapular rash, and a characteristic eschar (“tache noire”). Atypical clinical features and severe multi-organ complications may also be present. All of these manifestations arise from the disseminated infection of the endothelium by R. conorii conorii. Several methods exist for the diagnosis of MSF. Serological tests are widely used and molecular techniques have become increasingly available. Doxycycline remains the treatment of choice, while preventive measures are focused on modification of human behavior and vector control strategies. The purpose of this review is to summarize the current knowledge on the epidemiology, pathogenesis, clinical features, diagnosis, and treatment of MSF.

scholarly journals Genotypic evaluation of rickettsial isolates recovered from various species of ticks in Portugal

1995 ◽  
Vol 114 (1) ◽  
pp. 169-178 ◽  
Author(s):  
F. Bacellar ◽  
R. L. Regnery ◽  
M. S. Núncio ◽  
A. R. Filipe
Keyword(s):  
Restriction Endonuclease ◽  
Dna Sequences ◽  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Spotted Fever Group ◽  
Potential Vector ◽  
Genotypic Analysis ◽  
Restriction Endonuclease Cleavage Site ◽  
Spotted Fever Group Rickettsia ◽  
First Time

SUMMARYTwelve rickettsial isolates, fromRhipicephalus sanguineus, R. turanicus, Dermacentor marginatusandHyalomma marginatus, were subjected to genotypic analysis. Amplification of specific DNA sequences, restriction endonuclease digestion of amplified DNA products, and gel electrophoresis were used to identify specific DNA fragment-banding patterns. Five patterns were resolved. Four were homologous with those of previously described rickettsial genotypes,R. conorii, R. slovaca, R. rhipicephaliandR. massiliae. The fifth pattern differed by only a single altered restriction endonuclease cleavage site. For the first time in Portugal a widely distributed spectrum of spotted fever group rickettsia was found among potential vector species stressing the need to determine their potential for human and domestic animals infection.

scholarly journals Seroepidemiologic Study of Human Infections with Spotted Fever Group Rickettsiae in North Carolina

2014 ◽  
Vol 52 (11) ◽  
pp. 3960-3966 ◽  
Author(s):  
M. F. Vaughn ◽  
J. Delisle ◽  
J. Johnson ◽  
G. Daves ◽  
C. Williams ◽  
...  
Keyword(s):  
North Carolina ◽  
Spotted Fever ◽  
Spotted Fever Group ◽  
Spotted Fever Group Rickettsiae ◽  
Human Infections ◽  
Seroepidemiologic Study

scholarly journals Significant Growth by Rickettsia Species within Human Macrophage-Like Cells Is a Phenotype Correlated with the Ability to Cause Disease in Mammals

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
M. Nathan Kristof ◽  
Paige E. Allen ◽  
Lane D. Yutzy ◽  
Brandon Thibodaux ◽  
Christopher D. Paddock ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Spotted Fever ◽  
Growth Characteristic ◽  
Human Macrophage ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Phagocytic Cells ◽  
Pathogenic Potential ◽  
Rickettsia Species

Rickettsia are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of Rickettsia have been conclusively associated with disease of humans: Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, and Rickettsia parkeri, the cause of R. parkeri rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG Rickettsia species, Rickettsia conorii, within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. In this work, we demonstrated that multiple other recognized human pathogenic species of Rickettsia, including R. rickettsii, R. parkeri, Rickettsia africae, and Rickettsiaakari can grow within target endothelial cells as well as within PMA-differentiated THP-1 cells. In contrast, Rickettsia bellii, a Rickettsia species not associated with disease of humans, and R. rickettsii strain Iowa, an avirulent derivative of pathogenic R. rickettsii, could invade both cell types but proliferate only within endothelial cells. Further analysis revealed that similar to previous studies on R. conorii, other recognized pathogenic Rickettsia species could grow within the cytosol of THP-1-derived macrophages and avoided localization with two different markers of lysosomal compartments; LAMP-2 and cathepsin D. R. bellii, on the other hand, demonstrated significant co-localization with lysosomal compartments. Collectively, these findings suggest that the ability of pathogenic rickettsial species to establish a niche within macrophage-like cells could be an important factor in their ability to cause disease in mammals. These findings also suggest that analysis of growth within mammalian phagocytic cells may be useful to predict the pathogenic potential of newly isolated and identified Rickettsia species.

scholarly journals A streamlined method for transposon mutagenesis ofRickettsia parkeriyields numerous mutations that impact infection

2018 ◽  
Author(s):  
Rebecca L. Lamason ◽  
Natasha M. Kafai ◽  
Matthew D. Welch
Keyword(s):  
Host Cell ◽  
Virulence Factors ◽  
Vascular Endothelial Cells ◽  
Spotted Fever ◽  
Transposon Mutagenesis ◽  
Host Cells ◽  
Spotted Fever Group ◽  
Loss Of Function ◽  
Rickettsia Parkeri ◽  
Obligate Intracellular

AbstractThe rickettsiae are obligate intracellular alphaproteobacteria that exhibit a complex infectious life cycle in both arthropod and mammalian hosts. As obligate intracellular bacteria,Rickettsiaare highly adapted to living inside a variety of host cells, including vascular endothelial cells during mammalian infection. Although it is assumed that the rickettsiae produce numerous virulence factors that usurp or disrupt various host cell pathways, they have been challenging to genetically manipulate to identify the key bacterial factors that contribute to infection. Motivated to overcome this challenge, we sought to expand the repertoire of available rickettsial loss-of-function mutants, using an improvedmariner-based transposon mutagenesis scheme. Here, we present the isolation of over 100 transposon mutants in the spotted fever group speciesRickettsia parkeri. These mutants targeted genes implicated in a variety of pathways, including bacterial replication and metabolism, hypothetical proteins, the type IV secretion system, as well as factors with previously established roles in host cell interactions and pathogenesis. Given the need to identify critical virulence factors, forward genetic screens such as this will provide an excellent platform to more directly investigate rickettsial biology and pathogenesis.

scholarly journals Isolation and Identification of Rickettsia massiliae from Rhipicephalus sanguineus Ticks Collected in Arizona

2006 ◽  
Vol 72 (8) ◽  
pp. 5569-5577 ◽  
Author(s):  
Marina E. Eremeeva ◽  
Elizabeth A. Bosserman ◽  
Linda J. Demma ◽  
Maria L. Zambrano ◽  
Dianna M. Blau ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Vero Cells ◽  
The United States ◽  
Spotted Fever Group ◽  
Pcr Assay ◽  
Isolation And Identification ◽  
Cytotoxic Effects ◽  
Rickettsia Massiliae ◽  
Genotypic Characteristics

ABSTRACT Twenty Rhipicephalus sanguineus ticks collected in eastern Arizona were tested by PCR assay to establish their infection rate with spotted fever group rickettsiae. With a nested PCR assay which detects a fragment of the Rickettsia genus-specific 17-kDa antigen gene (htrA), five ticks (25%) were found to contain rickettsial DNA. One rickettsial isolate was obtained from these ticks by inoculating a suspension of a triturated tick into monolayers of Vero E6 monkey kidney cells and XTC-2 clawed toad cells, and its cell culture and genotypic characteristics were determined. Fragments of the 16S rRNA, GltA, rOmpA, rOmpB, and Sca4 genes had 100%, 100%, 99%, 99%, and 99%, respectively, nucleotide similarity to Rickettsia massiliae strain Bar29, previously isolated from R. sanguineus in Catalonia, Spain (L. Beati et al., J. Clin. Microbiol. 34:2688-2694, 1996). The new isolate, AZT80, does not elicit cytotoxic effects in Vero cells and causes a persistent infection in XTC-2 cells. The AZT80 strain is susceptible to doxycycline but resistant to rifampin and erythromycin. Whether R. massiliae AZT80 is pathogenic or infectious for dogs and humans or can cause seroconversion to spotted fever group antigens in the United States is unknown.

scholarly journals Characterization of Mutations in therpoB Gene in Naturally Rifampin-ResistantRickettsia Species

1999 ◽  
Vol 43 (10) ◽  
pp. 2400-2403 ◽  
Author(s):  
Michel Drancourt ◽  
Didier Raoult
Keyword(s):  
Spotted Fever ◽  
Single Point ◽  
Experimental Studies ◽  
Single Point Mutation ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Resistant Species ◽  
Encoding Gene ◽  
Group Species

ABSTRACT Rickettsiae are gram-negative, obligately intracellular bacteria responsible for arthropod-borne spotted fevers and typhus. Experimental studies have delineated a cluster of naturally rifampin-resistant spotted fever group species. We sequenced the 4,122- to 4,125-bp RNA polymerase β-subunit-encoding gene (rpoB) from typhus and spotted fever group representatives and obtained partial sequences for all naturally rifampin-resistant species. A single point mutation resulting in a phenylalanine-to-leucine change at position 973 of theRickettsia conorii rpoB sequence and present in all the rifampin-resistant species was absent in all the rifampin-susceptible species. rpoB-based phylogenetic relationships among these rickettsial species yielded topologies which were in accordance with previously published phylogenies.

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