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Parasites & Vectors Mar 2014Ixodes ricinus is a major vector for a range of microbial pathogens and the most prevalent and widely distributed tick species on the European continent, occurring in...
BACKGROUND
Ixodes ricinus is a major vector for a range of microbial pathogens and the most prevalent and widely distributed tick species on the European continent, occurring in both natural and urban habitats. Nevertheless, little is known about the relative density of ticks in these two ecologically distinct habitats and the diversity of tick-borne pathogens that they carry.
METHODS
We compared densities of questing I. ricinus nymphs and adults in urban and natural habitats in Central and Northeastern Poland, assessed the prevalence and rate of co-infection with A. phagocytophilum, Rickettsia, Ehrlichia and 'Ca. Neoehrlichia spp.' in ticks, and compared the diversity of tick-borne pathogens using molecular assays (PCR).
RESULTS
Of the 1325 adults and nymphs, 6.2% were infected with at least one pathogen, with 4.4%, 1.7% and less than 0.5% being positive for the DNA of Rickettsia spp., A. phagocytophilum, Ehrlichia spp. and Ca. N. mikurensis, respectively. Although tick abundance was higher in natural habitats, the prevalence of the majority of pathogens was higher in urban forested areas.
CONCLUSION
We conclude that: (i) zoonotic genetic variants of A. phagocytophilum are widely distributed in the Polish tick population, (ii) although the diversity of tick borne pathogens was higher in natural habitats, zoonotic species/strains were detected only in urban forests, (iii) and we provide the first description of Ca. N. mikurensis infections in ticks in Poland.
Topics: Anaplasmataceae; Anaplasmataceae Infections; Animals; Base Sequence; DNA, Bacterial; DNA, Ribosomal; Female; Forests; Humans; Ixodes; Male; Molecular Sequence Data; Nymph; Phylogeny; Poland; Polymorphism, Genetic; Prevalence; Rickettsiaceae; Rickettsiaceae Infections; Sequence Analysis, DNA; Tick Infestations
PubMed: 24661311
DOI: 10.1186/1756-3305-7-121 -
Ticks and Tick-borne Diseases Jan 2022All species of hard ticks associated with reptiles as hosts throughout their life cycle, are currently assigned to genera including Amblyomma and Africaniella. Among...
Rickettsiaceae in two reptile-associated tick species, Amblyomma exornatum and Africaniella transversale: First evidence of Occidentia massiliensis in hard ticks (Acari: Ixodidae).
All species of hard ticks associated with reptiles as hosts throughout their life cycle, are currently assigned to genera including Amblyomma and Africaniella. Among these species, based on literature data, Africaniella transversale has never been investigated for the presence of tick-borne pathogens. In this study, seven DNA extracts (two from A. transversale and five from Amblyomma exornatum) were screened for the presence of important tick-borne protozoa (piroplasms) and bacteria (Anaplasmataceae and Rickettsiaceae) with conventional PCRs and sequencing. A new heat shock protein chaperonin (groEL) gene-specific PCR was also developed to identify Occidentia spp. in these samples. In A. transversale, Occidentia massiliensis (previously detected in rodent-associated soft ticks) and Rickettsia hoogstraalii were present. While the latter was molecularly identical with formerly reported sequences of this rickettsia, the genotype of O. massiliensis was new based on sequence and phylogenetic analyses of its groEL gene. In A. exornatum, a Rickettsia genotype closely related to R. tamurae and R. monacensis, was detected. The ompA sequence of this genotype was identical to that of Rickettsia sp. Ae-8 reported from A. exornatum in a reptile breeding facility in the USA. These results show that A. transversale might carry O. massiliensis which (unless having a symbiotic nature in ticks) may originate either from the reptile host of this hard tick species or the rodent prey of reptiles. This is also the first detection of the reptile tick-associated Rickettsia sp. Ae-8 (phylogenetically aligning with R. tamurae, R. monacensis) in Africa, i.e. within the original geographical range of A. exornatum.
Topics: Amblyomma; Animals; Ixodidae; Phylogeny; Reptiles; Rickettsia; Rickettsiaceae; Ticks
PubMed: 34624588
DOI: 10.1016/j.ttbdis.2021.101830 -
Seminars in Immunopathology May 2015Arthropod-borne obligately intracellular bacteria pose a difficult challenge to the immune system. The genera Rickettsia, Orientia, Ehrlichia, and Anaplasma evolved... (Review)
Review
Arthropod-borne obligately intracellular bacteria pose a difficult challenge to the immune system. The genera Rickettsia, Orientia, Ehrlichia, and Anaplasma evolved mechanisms of immune evasion, and each interacts differently with the immune system. The roles of CD8 T cells include protective immunity and immunopathology. In Rickettsia infections, CD8 T cells are protective mediated in part by cytotoxicity toward infected cells. In contrast, TNF-α overproduction by CD8 T cells is pathogenic in lethal ehrlichiosis by induction of apoptosis/necrosis in hepatocytes. Yet, CD8 T cells, along with CD4 T cells and antibodies, also contribute to protective immunity in ehrlichial infections. In granulocytic anaplasmosis, CD8 T cells impact pathogen control modestly but could contribute to immunopathology by virtue of their dysfunction. While preliminary evidence indicates that CD8 T cells are important in protection against Orientia tsutsugamushi, mechanistic studies have been neglected. Valid animal models will enable experiments to elucidate protective and pathologic immune mechanisms. The public health need for vaccines against these agents of human disease, most clearly O. tsutsugamushi, and the veterinary diseases, canine monocytotropic ehrlichiosis (Ehrlichia canis), heartwater (Ehrlichia ruminantium), and bovine anaplasmosis (A. marginale), requires detailed immunity and immunopathology investigations, including the roles of CD8 T lymphocytes.
Topics: Animals; CD8-Positive T-Lymphocytes; Host-Pathogen Interactions; Humans; Rickettsiaceae; Rickettsiaceae Infections; T-Lymphocyte Subsets
PubMed: 25823954
DOI: 10.1007/s00281-015-0480-x -
Schweizer Archiv Fur Tierheilkunde Oct 2016'Candidatus Neoehrlichia mikurensis' is an emerging tick-borne zoonotic agent that primarily affects immunocompromised human patients. Dogs and foxes are frequently...
'Candidatus Neoehrlichia mikurensis' is an emerging tick-borne zoonotic agent that primarily affects immunocompromised human patients. Dogs and foxes are frequently exposed to ticks, and both species are in close proximity to humans. This is the first study to systematically investigate the occurrence of 'Candidatus Neoehrlichia mikurensis' in Canidae in Europa. We analyzed 1'739 blood samples from dogs in Switzerland, Italy, Spain and Portugal and 162 blood samples from free-ranging red foxes (Vulpes vulpes) in Switzerland. All samples were tested using a previously described multiplex real-time PCR for the Anaplasmataceae family, the 'Candidatus Neoehrlichia' genus and the 'Candidatus Neoehrlichia mikurensis' species. All Anaplasmataceae positive samples were subsequently tested using specific real-time PCRs for Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis and Rickettsia helvetica. Among the tested animals, one dog from Zurich tested positive for 'Candidatus Neoehrlichia mikurensis'. The 12-year old West Highland white terrier had been splenectomized 3 months prior to the blood collection and presented with polyuria/polydipsia. Fanconi syndrome was diagnosed based on glucosuria with normoglycemia and hyperaminoaciduria. A. platys and E. canis were detected in 14/249 dogs from Sicily and Portugal; two of the dogs were coinfected with both agents. Four Swiss foxes tested positive for A. phagocytophilium. R. helvetica was detected for the first time in a red fox. In conclusion, 'Candidatus Neoehrlichia mikurensis' infection should be considered in sick dogs, particularly when immunocompromised. The pathogen seems not to be widespread in Canidae in the investigated countries. Conversely, other Anaplasmataceae were more readily detected in dogs and foxes.
Topics: Anaplasmataceae; Anaplasmataceae Infections; Animals; Coinfection; Dog Diseases; Dogs; Foxes; Genes, Bacterial; Mediterranean Region; Polymerase Chain Reaction; Prevalence; Rickettsiaceae; Rickettsiaceae Infections; Switzerland; Zoonoses
PubMed: 27707682
DOI: 10.17236/sat00087 -
Journal of Clinical Microbiology Aug 2018Rickettsioses are globally distributed and caused by the family , which comprise a diverse and expanding list of organisms. These include two genera, and Serology has... (Review)
Review
Rickettsioses are globally distributed and caused by the family , which comprise a diverse and expanding list of organisms. These include two genera, and Serology has been traditionally the mainstay of diagnosis, although this has been limited by cross-reactions among closely related members and diminished sensitivity/utility in the acute phase of illness. Other techniques, such as nucleic acid amplification tests using blood specimens or tissue swabs/biopsy specimens, sequencing, and mass spectrometry, have emerged in recent years for both pathogen and vector identification. This paper provides a concise review of the rickettsioses and the traditional and newer technologies available for their diagnosis.
Topics: Animals; Arthropod Vectors; Humans; Microbiological Techniques; Molecular Diagnostic Techniques; Orientia tsutsugamushi; Rickettsia; Rickettsia Infections; Scrub Typhus; Serologic Tests
PubMed: 29769278
DOI: 10.1128/JCM.01728-17 -
PLoS Neglected Tropical Diseases May 2022Murine typhus, which is caused by Rickettsia typhi, has a wide range of clinical manifestations. It has a low mortality rate but may result in meningoencephalitis and...
Murine typhus, which is caused by Rickettsia typhi, has a wide range of clinical manifestations. It has a low mortality rate but may result in meningoencephalitis and interstitial pneumonia in severe cases. Comparisons of complete genome sequences of R. typhi isolates from North Carolina, USA (Wilmington), Myanmar (B9991PP), and Thailand (TH1527) identified only 26 single nucleotide polymorphism (SNP) and 7 insertion-deletion (INDEL) sites in these highly syntenic genomes. Assays were developed to further define the distribution of these variant sites among 15 additional isolates of R. typhi with different histories from Asia, the USA, and Africa. Mismatch amplification mutation assays (MAMA) were validated for 22 SNP sites, while the 7 INDEL sites were analyzed directly on agarose gels. Six SNP types, 9 INDEL types, 11 total types were identified among these 18 isolates. Replicate DNA samples as well as comparisons of isolates with different passage and source histories gave consistent genetic typing profiles. Comparison of the SNP and INDEL markers to R. typhi's nearest neighbor Rickettsia prowazekii demonstrated that the majority of the SNPs represent intra-species variation that arose post divergence of these two species while several INDEL sites also exhibited intraspecies variability among the R. prowazekii genomes that have been completely sequenced. The assays for the presence of these SNP and INDEL sites, particularly the latter, comprise a low technology gel method for consistently distinguishing R. typhi and R. prowazekii as well as for differentiating genetic types of R. typhi.
Topics: Animals; Mice; Rickettsia; Rickettsia prowazekii; Rickettsia typhi; Sequence Analysis, DNA; Thailand; Typhus, Endemic Flea-Borne
PubMed: 35639778
DOI: 10.1371/journal.pntd.0010354 -
Frontiers in Cellular and Infection... 2022We identified four flea-borne spotted fever cases caused by in a retrospective survey of 182 patients with fever of unknown origin (FUO) in China between 2021 and 2022....
We identified four flea-borne spotted fever cases caused by in a retrospective survey of 182 patients with fever of unknown origin (FUO) in China between 2021 and 2022. The clinical signs and symptoms of the patients were similar to those of other rickettsioses, including fever, rash, and liver and kidney dysfunction. All four patients in the present study developed pneumonia or lung lesions after infection. The cases of infection, a neglected infectious disease, were sporadic in multiple provinces of the country. The high prevalence (2.14%, 4/187) of among patients with FUO highlights the risk posed by this pathogen to public health in China.
Topics: China; Humans; Retrospective Studies; Rickettsia; Rickettsia Infections; Rickettsia felis
PubMed: 36211956
DOI: 10.3389/fcimb.2022.997315 -
Future Microbiology Jun 2020Infections caused by pathogenic species continue to scourge human health across the globe. From the point of entry at the site of transmission by arthropod vectors,... (Review)
Review
Infections caused by pathogenic species continue to scourge human health across the globe. From the point of entry at the site of transmission by arthropod vectors, hematogenous dissemination of rickettsiae occurs to diverse host tissues leading to 'rickettsial vasculitis' as the salient feature of pathogenesis. This perspective article accentuates recent breakthrough developments in the context of host-pathogen-vector interactions during rickettsial infections. The subtopics include potential exploitation of circulating macrophages for spread, identification of new entry mechanisms and regulators of actin-based motility, appreciation of metabolites acquired from and effectors delivered into the host, importance of the toxin-antitoxin module in host-cell interactions, effects of the vector microbiome on rickettsial transmission, and niche-specific riboregulation and adaptation. Further research on these aspects will advance our understanding of the biology of rickettsiae as intracellular pathogens and should enable design and development of new approaches to counter rickettsioses in humans and other hosts.
Topics: Animals; Disease Models, Animal; Disease Vectors; Host-Pathogen Interactions; Humans; Rickettsia; Rickettsia Infections; Symbiosis; Virulence Factors
PubMed: 32691620
DOI: 10.2217/fmb-2019-0266 -
Proceedings. Biological Sciences Sep 2006The best-known members of the bacterial genus Rickettsia are associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. These species... (Review)
Review
The best-known members of the bacterial genus Rickettsia are associates of blood-feeding arthropods that are pathogenic when transmitted to vertebrates. These species include the agents of acute human disease such as typhus and Rocky Mountain spotted fever. However, many other Rickettsia have been uncovered in recent surveys of bacteria associated with arthropods and other invertebrates; the hosts of these bacteria have no relationship with vertebrates. It is therefore perhaps more appropriate to consider Rickettsia as symbionts that are transmitted vertically in invertebrates, and secondarily as pathogens of vertebrates. In this review, we highlight the emerging diversity of Rickettsia species that are not associated with vertebrate pathogenicity. Phylogenetic analysis suggests multiple transitions between symbionts that are transmitted strictly vertically and those that exhibit mixed (horizontal and vertical) transmission. Rickettsia may thus be an excellent model system in which to study the evolution of transmission pathways. We also focus on the emergence of Rickettsia as a diverse reproductive manipulator of arthropods, similar to the closely related Wolbachia, including strains associated with male-killing, parthenogenesis, and effects on fertility. We emphasize some outstanding questions and potential research directions, and suggest ways in which the study of non-pathogenic Rickettsia can advance our understanding of their disease-causing relatives.
Topics: Animals; Biodiversity; Invertebrates; Phylogeny; Reproduction; Rickettsia
PubMed: 16901827
DOI: 10.1098/rspb.2006.3541 -
MicrobiologyOpen Oct 2023The life cycle of the mite-borne, obligate intracellular pathogen Orientia tsutsugamushi (Ot), the causative agent of human scrub typhus, differs in many aspects from...
The life cycle of the mite-borne, obligate intracellular pathogen Orientia tsutsugamushi (Ot), the causative agent of human scrub typhus, differs in many aspects from that of other members of the Rickettsiales order. Particularly, the nonlytic cellular exit of individual Ot bacteria at the plasma membrane closely resembles the budding of enveloped viruses but has only been rudimentarily studied at the molecular level. This brief article is focused on the current state of knowledge of escape events in the life cycle of Ot and highlights differences in strategies of other rickettsiae.
Topics: Animals; Humans; Orientia tsutsugamushi; Scrub Typhus; Mites; Cell Membrane; Rickettsia
PubMed: 37877457
DOI: 10.1002/mbo3.1380