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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 -
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 -
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 -
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 -
Journal of the American Veterinary... Dec 2022To assess exposure to and infection with 3 pathogens (Rickettsia rickettsii, Anaplasma platys, and Ehrlichia canis) vectored by brown dog ticks (Rhipicephalus...
OBJECTIVE
To assess exposure to and infection with 3 pathogens (Rickettsia rickettsii, Anaplasma platys, and Ehrlichia canis) vectored by brown dog ticks (Rhipicephalus sanguineus) in sheltered dogs at the western US-Mexico border.
ANIMALS
239 dogs in shelters in San Diego and Imperial counties, US, and Mexicali and Tijuana, Mexico.
PROCEDURES
Each dog had blood drawn and basic demographic data collected. PCR was performed to determine active infection with Rickettsia spp, E canis, and A platys. Serology was performed to determine exposure to Rickettsia, Anaplasma, and Ehrlichia species.
RESULTS
2 of 78 (2.6%) dogs sampled in Tijuana were actively infected with R rickettsii. A single brown dog tick collected from a dog in Tijuana was PCR-positive for R rickettsii. Infection with E canis and A platys ranged across shelters from 0% to 27% and 0% to 33%, respectively. Dogs in all 4 locations demonstrated exposure to all 3 pathogens, though Rickettsia and Ehrlichia seropositivity was highest in Mexicali (81% and 49%, respectively) and Anaplasma seropositivity was highest in Tijuana (45%).
CLINICAL RELEVANCE
While infection and exposure were highest in sheltered dogs in the southern locations, dogs in all locations demonstrated exposure to all pathogens, demonstrating the potential for emergence and spread of zoonotic pathogens with significant public health consequences in southern California and northern Baja California. In addition, veterinarians and shelter staff should be aware that Ehrlichia or Anaplasma infection may co-occur with Rocky Mountain spotted fever, which is a human health risk.
Topics: Dogs; Humans; Animals; Rocky Mountain Spotted Fever; Mexico; One Health; Rhipicephalus sanguineus; Anaplasma; Anaplasmosis; Dog Diseases
PubMed: 36563069
DOI: 10.2460/javma.22.08.0388 -
Tropical Medicine and Infectious Disease Feb 2022The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (), human monocytic ehrlichiosis (), scrub typhus... (Review)
Review
The order Rickettsiales includes species that cause a range of human diseases such as human granulocytic anaplasmosis (), human monocytic ehrlichiosis (), scrub typhus (), epidemic typhus (), murine typhus (), Mediterranean spotted fever (), or Rocky Mountain spotted fever (). These diseases are gaining a new momentum given their resurgence patterns and geographical expansion due to the overall rise in temperature and other human-induced pressure, thereby remaining a major public health concern. As obligate intracellular bacteria, Rickettsiales are characterized by their small genome sizes due to reductive evolution. Many pathogens employ moonlighting/multitasking proteins as virulence factors to interfere with multiple cellular processes, in different compartments, at different times during infection, augmenting their virulence. The utilization of this multitasking phenomenon by Rickettsiales as a strategy to maximize the use of their reduced protein repertoire is an emerging theme. Here, we provide an overview of the role of various moonlighting proteins in the pathogenicity of these species. Despite the challenges that lie ahead to determine the multiple potential faces of every single protein in Rickettsiales, the available examples anticipate this multifunctionality as an essential and intrinsic feature of these obligates and should be integrated into available moonlighting repositories.
PubMed: 35202227
DOI: 10.3390/tropicalmed7020032