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Infectious Disease Clinics of North... Mar 2019Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness... (Review)
Review
Rickettsia are small, obligately intracellular, gram-negative bacilli. They are distributed among a variety of hematophagous arthropod vectors and cause illness throughout the world. Rickettsioses present as an acute undifferentiated febrile illness and are often accompanied by headache, myalgias, and malaise. Cutaneous manifestations include rash and eschar, which both occur at varying incidence depending on the infecting species. Serology is the mainstay of diagnosis, and the indirect immunofluorescence assay is the test of choice. Reactive antibodies are seldom present during early illness, so testing should be performed on both acute-phase and convalescent-phase sera. Doxycycline is the treatment of choice.
Topics: Animals; Anti-Bacterial Agents; Arthropod Vectors; Doxycycline; Humans; Rickettsia Infections; Rocky Mountain Spotted Fever
PubMed: 30712763
DOI: 10.1016/j.idc.2018.10.010 -
Infection and Immunity Sep 2022Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical... (Review)
Review
Ticks are hematophagous ectoparasites capable of transmitting multiple human pathogens. Environmental changes have supported the expansion of ticks into new geographical areas that have become the epicenters of tick-borne diseases (TBDs). The spotted fever group (SFG) of frequently infects ticks and causes tick-transmitted rickettsioses in areas of endemicity where ixodid ticks support host transmission during blood feeding. Ticks also serve as a reservoir for SFG . Among the members of SFG , R. rickettsii causes Rocky Mountain spotted fever (RMSF), the most lethal TBD in the United States. Cases of RMSF have been reported for over a century in association with several species of ticks in the United States. However, the isolation of R. rickettsii from ticks has decreased, and recent serological and epidemiological studies suggest that novel species of SFG are responsible for the increased number of cases of RMSF-like rickettsioses in the United States. Recent analyses of rickettsial genomes and advances in genetic and molecular studies of provided insights into the biology of with the identification of conserved and unique putative virulence genes involved in the rickettsial life cycle. Thus, understanding -host-tick interactions mediating successful disease transmission and pathogenesis for SFG rickettsiae remains an active area of research. This review summarizes recent advances in understanding how SFG species coopt and manipulate ticks and mammalian hosts to cause rickettsioses, with a particular emphasis on newly described or emerging SFG species.
Topics: Animals; Humans; Ixodidae; Mammals; Rickettsia; Rickettsia Infections; Rocky Mountain Spotted Fever; Ticks
PubMed: 35993770
DOI: 10.1128/iai.00621-21 -
Journal of Vector Borne Diseases 2020Rocky Mountain spotted fever (RMSF) is a rapidly progressive and potentially fatal tickborne disease caused by Rickettsia rickettsii. Despite current recommendations and... (Review)
Review
BACKGROUND AND OBJECTIVES
Rocky Mountain spotted fever (RMSF) is a rapidly progressive and potentially fatal tickborne disease caused by Rickettsia rickettsii. Despite current recommendations and information on the severity of RMSF, studies show that delayed recognition and treatment continues to occur.
METHODS
A literature search was performed on cases published in English between 1990-2017. The frequencies for demographic, clinical, and treatment variables was calculated.
RESULTS
A total of 340 cases from 34 articles were included. Data on rash were available for 322 patients, and 261 (80%) noted rash. Mortality was 4% (2) in those who received doxycycline within the first five days of illness, and 35% (18) when treatment was delayed beyond Day five. Twenty-four (16%) reported chronic sequelae, including speech impairment (7, 5%) and ataxia (5, 3%).
INTERPRETATION AND CONCLUSION
These data highlight the importance of early treatment, and add to our understanding of long-term sequelae. Early recognition by providers will facilitate appropriate treatment and reduction in morbidity and mortality.
Topics: Anti-Bacterial Agents; Doxycycline; Early Medical Intervention; Exanthema; Humans; Rickettsia rickettsii; Rocky Mountain Spotted Fever; United States
PubMed: 34290155
DOI: 10.4103/0972-9062.310863 -
Current Rheumatology Reports Jul 2021This article presents a comprehensive narrative review of reactive arthritis (ReA) with focus on articles published between 2018 and 2020. We discuss the entire spectrum... (Review)
Review
PURPOSE OF REVIEW
This article presents a comprehensive narrative review of reactive arthritis (ReA) with focus on articles published between 2018 and 2020. We discuss the entire spectrum of microbial agents known to be the main causative agents of ReA, those reported to be rare infective agents, and those reported to be new candidates causing the disease. The discussion is set within the context of changing disease terminology, definition, and classification over time. Further, we include reports that present at least a hint of effective antimicrobial therapy for ReA as documented in case reports or in double-blind controlled studies. Additional information is included on microbial products detected in the joint, as well as on the positivity of HLA-B27.
RECENT FINDINGS
Recent reports of ReA cover several rare causative microorganism such as Neisseria meningitides, Clostridium difficile, Escherichia coli, Hafnia alvei, Blastocytosis, Giardia lamblia, Cryptosporidium, Cyclospora cayetanensis, Entamoeba histolytica/dispar, Strongyloides stercoralis, β-haemolytic Streptococci, Mycobacterium tuberculosis, Mycoplasma pneumoniae, Mycobacterium bovis bacillus Calmette-Guerin, and Rickettsia rickettsii. The most prominent new infectious agents implicated as causative in ReA are Staphylococcus lugdunensis, placenta- and umbilical cord-derived Wharton's jelly, Rothia mucilaginosa, and most importantly the SARS-CoV-2 virus. In view of the increasingly large spectrum of causative agents, diagnostic consideration for the disease must include the entire panel of post-infectious arthritides termed ReA. Diagnostic procedures cannot be restricted to the well-known HLA-B27-associated group of ReA, but must also cover the large number of rare forms of arthritis following infections and vaccinations, as well as those elicited by the newly identified members of the ReA group summarized herein. Inclusion of these newly identified etiologic agents must necessitate increased research into the pathogenic mechanisms variously involved, which will engender important insights for treatment and management of ReA.
Topics: Arthritis, Reactive; Blastocystis Infections; COVID-19; Clostridium Infections; Cryptosporidiosis; Cyclosporiasis; Entamoebiasis; Enterobacteriaceae Infections; Escherichia coli Infections; Giardiasis; HLA-B27 Antigen; Humans; Meningococcal Infections; Pneumonia, Mycoplasma; Prohibitins; Rocky Mountain Spotted Fever; SARS-CoV-2; Staphylococcal Infections; Streptococcal Infections; Strongyloidiasis; Tuberculosis
PubMed: 34196842
DOI: 10.1007/s11926-021-01018-6 -
Pathogens (Basel, Switzerland) Nov 2022In 2021, 273 Rocky Mountain spotted fever cases were reported nationwide in Mexico. In Chihuahua City, fourteen samples were obtained from children suspected of...
In 2021, 273 Rocky Mountain spotted fever cases were reported nationwide in Mexico. In Chihuahua City, fourteen samples were obtained from children suspected of rickettsial infection. The analysis of samples (January to December 2021) showed prevalence rates of 28.5%, 43%, and 28.5% for Rickettsia rickettsii, Ehrlichia canis, and both pathogens in coinfection, respectively. The analysis of clinical haematological and biochemistry analytes showed alterations; 100% of the children had elevated liver enzymes and coagulation times, 64% showed leukocytosis due to neutrophilia, 55% had thrombocytopenia, lymphopenia, and hypoalbuminemia, and 45% showed normocytic normochromic anaemia. Statistically significant differences were observed in the expression of the chemokines IL-8, RANTES, CXCL9/MIG, and CXCL10/IP-10 across the coinfected and control groups, and the difference in IP-10 expression was significant for patients infected by R. rickettsii compared to the control group. Additionally, significant differences were observed for expression levels of IL-1β, IL-6, IL-17, IFNγ, and TNFα among the R. rickettsii-positive group compared to the control group. On the other hand, the coinfected group exhibited modified levels of IL-6, IL-8, and IL-10 compared with the control group. Finally, significant differences were observed for CD8+ T lymphocyte subpopulations between individuals positive for R. rickettsii and those positive for E. canis.
PubMed: 36422602
DOI: 10.3390/pathogens11111351 -
International Journal of Molecular... Jun 2021Pathogenic intracellular bacteria, parasites and viruses have evolved sophisticated mechanisms to manipulate mammalian host cells to serve as niches for persistence and... (Review)
Review
Pathogenic intracellular bacteria, parasites and viruses have evolved sophisticated mechanisms to manipulate mammalian host cells to serve as niches for persistence and proliferation. The intracellular lifestyles of pathogens involve the manipulation of membrane-bound organellar compartments of host cells. In this review, we described how normal structural organization and cellular functions of endosomes, endoplasmic reticulum, Golgi apparatus, mitochondria, or lipid droplets are targeted by microbial virulence mechanisms. We focus on the specific interactions of , , , spp. and representing intracellular bacterial pathogens, and of spp. and representing intracellular parasites. The replication strategies of various viruses, i.e., Influenza A virus, Poliovirus, Brome mosaic virus, Epstein-Barr Virus, Hepatitis C virus, severe acute respiratory syndrome virus (SARS), Dengue virus, Zika virus, and others are presented with focus on the specific manipulation of the organelle compartments. We compare the specific features of intracellular lifestyle and replication cycles, and highlight the communalities in mechanisms of manipulation deployed.
Topics: Animals; Biological Transport; Biomarkers; Energy Metabolism; Host-Parasite Interactions; Host-Pathogen Interactions; Humans; Intracellular Space; Organelles; Phagocytosis
PubMed: 34204285
DOI: 10.3390/ijms22126484 -
Trends in Genetics : TIG Mar 2021
Topics: Animals; China; Genome, Insect; Humans; Ixodidae; Molecular Sequence Annotation; New Zealand; Phylogeography; Rickettsia rickettsii; Rocky Mountain Spotted Fever
PubMed: 33353761
DOI: 10.1016/j.tig.2020.11.008 -
Frontiers in Cellular and Infection... 2019There are 17 human-biting ticks known in Australia. The bites of , and can cause paralysis, inflammation, and severe local and systemic reactions in humans,... (Review)
Review
There are 17 human-biting ticks known in Australia. The bites of , and can cause paralysis, inflammation, and severe local and systemic reactions in humans, respectively. Six ticks, including , and may transmit , or subsp. . These bacterial pathogens cause Q fever, Queensland tick typhus (QTT), Flinders Island spotted fever (FISF), and Australian spotted fever (ASF). It is also believed that babesiosis can be transmitted by ticks to humans in Australia. In addition, , and ticks may play active roles in transmission of other pathogens that already exist or could potentially be introduced into Australia. These pathogens include spp., spp., spp., spp., Dera Ghazi Khan virus (DGKV), tick-borne encephalitis virus (TBEV), Lake Clarendon virus (LCV), Saumarez Reef virus (SREV), Upolu virus (UPOV), or Vinegar Hill virus (VINHV). It is important to regularly update clinicians' knowledge about tick-borne infections because these bacteria and arboviruses are pathogens of humans that may cause fatal illness. An increase in the incidence of tick-borne infections of human may be observed in the future due to changes in demography, climate change, and increase in travel and shipments and even migratory patterns of birds or other animals. Moreover, the geographical conditions of Australia are favorable for many exotic ticks, which may become endemic to Australia given an opportunity. There are some human pathogens, such as and that are not currently present in Australia, but can be transmitted by some human-biting ticks found in Australia, such as , if they enter and establish in this country. Despite these threats, our knowledge of Australian ticks and tick-borne diseases is in its infancy.
Topics: Animals; Australia; Bacterial Infections; Humans; Incidence; Protozoan Infections; Tick-Borne Diseases; Virus Diseases; Zoonoses
PubMed: 30746341
DOI: 10.3389/fcimb.2019.00003 -
Vector Borne and Zoonotic Diseases... Aug 2021is a pathogen that is known to cause spotted fever, a zoonosis that is endemic in several regions of the Americas. However, no systematic review and meta-analysis has... (Meta-Analysis)
Meta-Analysis
is a pathogen that is known to cause spotted fever, a zoonosis that is endemic in several regions of the Americas. However, no systematic review and meta-analysis has been conducted to estimate the prevalence of this rickettsial disease in the Americas. Therefore, the objective of this study was to estimate the prevalence of in ticks in the Americas. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed and data were retrieved from four electronic databases: MEDLINE/PubMed, SciELO, ScienceDirect, and Directory of Open Access Journals. The pooled prevalence and heterogeneity were determined using a random-effects model and using Cochran's test and index, respectively. Publication bias was assessed using a funnel plot and Egger's method. The pooled prevalence of in ticks was highest in Colombia (17.00%; confidence interval [95% CI]: 7.01-30.24), followed by Mexico (9.89%; 95% CI: 2.03-22.74), Panama (2.76%; 95% CI: 0.45-6.93), Brazil (2.03%; 95% CI: 0.66-4.14), and the United States (0.50%; 95% CI: 0.15-1.05). The tick species most frequently infected by were sensu lato (6.23%; 95% CI: 2.79-10.92) and (4.36%; 95% CI: 0.25-13.14). It can be suggested that studies aiming to identify the potential vectors of should be conducted more intensively to better understand the epidemiology of spotted fever in the Americas.
Topics: Animals; Prevalence; Rhipicephalus sanguineus; Rickettsia; Rickettsia rickettsii; Rocky Mountain Spotted Fever; Spotted Fever Group Rickettsiosis
PubMed: 34010063
DOI: 10.1089/vbz.2021.0004 -
Infection and Immunity Nov 2021Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, is an enzootic, obligate, intracellular bacterial pathogen. Nitric oxide (NO) synthesized by...
Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, is an enzootic, obligate, intracellular bacterial pathogen. Nitric oxide (NO) synthesized by the inducible NO synthase (iNOS) is a potent antimicrobial component of innate immunity and has been implicated in the control of virulent spp. in diverse cell types. In this study, we examined the antibacterial role of NO on R. rickettsii. Our results indicate that NO challenge dramatically reduces R. rickettsii adhesion through the disruption of bacterial energetics. Additionally, NO-treated R. rickettsii cells were unable to synthesize protein or replicate in permissive cells. Activated, NO-producing macrophages restricted R. rickettsii infections, but inhibition of iNOS ablated the inhibition of bacterial growth. These data indicate that NO is a potent antirickettsial effector of innate immunity that targets energy generation in these pathogenic bacteria to prevent growth and subversion of infected host cells.
Topics: Energy Metabolism; Host-Pathogen Interactions; Immunity, Innate; Macrophages; Nitric Oxide; Nitric Oxide Synthase Type II; Rickettsia rickettsii; Rocky Mountain Spotted Fever
PubMed: 34491789
DOI: 10.1128/IAI.00371-21