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Virulence Dec 2022Rickettsiae include diverse Gram-negative microbial species that exhibit obligatory intracellular lifecycles between mammalian hosts and arthropod vectors. Human... (Review)
Review
Rickettsiae include diverse Gram-negative microbial species that exhibit obligatory intracellular lifecycles between mammalian hosts and arthropod vectors. Human infections with arthropod-borne continue to cause significant morbidity and mortality as recent environmental changes foster the proliferation of arthropod vectors and increased exposure to humans. However, the technical difficulties in working with have delayed our progress in understanding the molecular mechanisms involved in rickettsial pathogenesis and disease transmission. Recent advances in developing genetic tools for have enabled investigators to identify virulence genes, uncover molecular functions, and characterize host responses to rickettsial determinants. Therefore, continued efforts to determine virulence genes and their biological functions will help us understand the underlying mechanisms associated with arthropod-borne rickettsioses.
Topics: Animals; Humans; Mammals; Rickettsia; Rickettsia Infections; Virulence
PubMed: 36208040
DOI: 10.1080/21505594.2022.2132047 -
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 -
Microbes and Infection 2015Bacteria of the genera Rickettsia and Orientia (family rickettsiaceae, order rickettsiales) cause rickettsioses worldwide, and are transmitted by lice, fleas, ticks and... (Review)
Review
Bacteria of the genera Rickettsia and Orientia (family rickettsiaceae, order rickettsiales) cause rickettsioses worldwide, and are transmitted by lice, fleas, ticks and mites. In Europe, only Rickettsia spp. cause rickettsioses. With improvement of hygiene, the risk of louse-borne rickettsiosis (epidemic typhus) is low in Europe. Nevertheless, recrudescent form of Rickettsia prowazekii infection persists. There could be an epidemic typhus outbreak if a body lice epidemic occurs under unfavorable sanitary conditions. In Europe, endemic typhus or Rickettsia typhi infection, transmitted by rats and fleas, causes febrile illness. At the beginning of this century, flea-borne spotted fever cases caused by Rickettsia felis were diagnosed. Flea-borne rickettsiosis should be suspected after flea bites if fever, with or without rash, is developed. Tick-borne rickettsioses are the main source of rickettsia infections in Europe. Apart from Rickettsia conorii, the Mediterranean Spotted Fever (MSF) agent, other Rickettsia spp. cause MSF-like: Rickettsia helvetica, Rickettsia monacensis, Rickettsia massiliae or Rickettsia aeschlimannii. In the 1990s, two 'new' rickettsioses were diagnosed: Lymphangitis Associated Rickettsiosis (LAR) caused by Rickettsia sibirica mongolitimonae, and Tick-Borne Lymphadenopathy/Dermacentor-Borne-Necrosis-Erythema-Lymphadenopathy/Scalp Eschar Neck Lymphadenopathy (TIBOLA/DEBONEL/SENLAT), caused by Rickettsia slovaca, Candidatus Rickettsia rioja and Rickettsia raoultii. Lastly, European reports about mite-borne rickettsiosis are scarce.
Topics: Animals; Arthropods; Europe; Humans; Orientia tsutsugamushi; Rickettsia; Rickettsia Infections; Scrub Typhus
PubMed: 26384814
DOI: 10.1016/j.micinf.2015.09.009 -
The American Journal of Tropical... Jan 2017Rickettsia typhi and Rickettsia felis are flea-borne rickettsiae that are distributed throughout the world. This mini-review outlines the ecology and epidemiology of... (Review)
Review
Rickettsia typhi and Rickettsia felis are flea-borne rickettsiae that are distributed throughout the world. This mini-review outlines the ecology and epidemiology of flea-borne rickettsioses; highlights important clinical, diagnostic, and therapeutic considerations; and discusses areas of uncertainty regarding Rickettsia felis and other rickettsiae harbored by fleas.
Topics: Animals; Ectoparasitic Infestations; Humans; Rickettsia Infections; Siphonaptera
PubMed: 27799640
DOI: 10.4269/ajtmh.16-0537 -
Frontiers in Cellular and Infection... 2023Rickettial agents are a diverse group of alpha-proteobacteria within the order Rickettsiales, which possesses two families with human pathogens, Rickettsiaceae and... (Review)
Review
Rickettial agents are a diverse group of alpha-proteobacteria within the order Rickettsiales, which possesses two families with human pathogens, Rickettsiaceae and Anaplasmataceae. These obligate intracellular bacteria are most frequently transmitted by arthropod vectors, a first step in the pathogens' avoidance of host cell defenses. Considerable study of the immune responses to infection and those that result in protective immunity have been conducted. Less study has focused on the initial events and mechanism by which these bacteria avoid the innate immune responses of the hosts to survive within and propagate from host cells. By evaluating the major mechanisms of evading innate immunity, a range of similarities among these bacteria become apparent, including mechanisms to escape initial destruction in phagolysosomes of professional phagocytes, those that dampen the responses of innate immune cells or subvert signaling and recognition pathways related to apoptosis, autophagy, proinflammatory responses, and mechanisms by which these microbes attach to and enter cells or those molecules that trigger the host responses. To illustrate these principles, this review will focus on two common rickettsial agents that occur globally, species and .
Topics: Humans; Rickettsia Infections; Immunity, Innate; Rickettsia; Anaplasma phagocytophilum; Autophagy
PubMed: 37228668
DOI: 10.3389/fcimb.2023.1187267 -
International Journal of Infectious... Aug 2010Flea-borne infections are emerging or re-emerging throughout the world, and their incidence is on the rise. Furthermore, their distribution and that of their vectors is... (Review)
Review
Flea-borne infections are emerging or re-emerging throughout the world, and their incidence is on the rise. Furthermore, their distribution and that of their vectors is shifting and expanding. This publication reviews general flea biology and the distribution of the flea-borne diseases of public health importance throughout the world, their principal flea vectors, and the extent of their public health burden. Such an overall review is necessary to understand the importance of this group of infections and the resources that must be allocated to their control by public health authorities to ensure their timely diagnosis and treatment.
Topics: Animals; Bartonella Infections; Communicable Diseases, Emerging; Humans; Insect Vectors; Plague; Rickettsia Infections; Siphonaptera
PubMed: 20189862
DOI: 10.1016/j.ijid.2009.11.011 -
PLoS Neglected Tropical Diseases Aug 2019As a result of migrations and globalization, people may face a possible increase in the incidence of central nervous system rickettsial infections (CNS R). These... (Review)
Review
As a result of migrations and globalization, people may face a possible increase in the incidence of central nervous system rickettsial infections (CNS R). These diseases, caused by Rickettsia species and transmitted to humans by arthropod bites, are putatively lethal. However, the diagnosis of CNS R is challenging and often delayed due to their nonspecific clinical presentation and the strict intracellular nature of rickettsiae. Furthermore, transfer of rickettsiae to the brain parenchyma is not yet understood. The aim of this review is to analyze and summarize the features and correlated findings of CNS R in order to focus attention on these intriguing but frequently neglected illnesses. We also incorporated data on CNS infections caused by Rickettsia-related microorganisms.
Topics: Boutonneuse Fever; Brain; Central Nervous System; Humans; Parenchymal Tissue; Rickettsia; Rickettsia Infections; Rocky Mountain Spotted Fever; Scrub Typhus; Spotted Fever Group Rickettsiosis; Typhus, Endemic Flea-Borne
PubMed: 31465452
DOI: 10.1371/journal.pntd.0007469 -
Molecules (Basel, Switzerland) Sep 2020species are an important cause of emerging infectious diseases in people and animals, and rickettsiosis is one of the oldest known vector-borne diseases. Laboratory...
species are an important cause of emerging infectious diseases in people and animals, and rickettsiosis is one of the oldest known vector-borne diseases. Laboratory diagnosis of is complex and time-consuming. This study was aimed at developing two quantitative real-time PCRs targeting and genes for the detection, respectively, of spp. and DNA. Primers were designed following an analysis of gene sequences. The assays were optimized using SYBR Green and TaqMan methods and tested for sensitivity and specificity. This study allowed the development of powerful diagnostic methods, able to detect and quantify spp. DNA and differentiate species.
Topics: Animals; DNA, Bacterial; Humans; Real-Time Polymerase Chain Reaction; Rickettsia Infections; Rickettsia conorii
PubMed: 32992475
DOI: 10.3390/molecules25194431 -
EcoHealth Dec 2019Spotted fever group and related rickettsia (SFGR) are a neglected group of pathogens that belong to the genus Rickettsia. SFGR are zoonotic and are transmitted by... (Review)
Review
Spotted fever group and related rickettsia (SFGR) are a neglected group of pathogens that belong to the genus Rickettsia. SFGR are zoonotic and are transmitted by arthropod vectors, primarily ticks, fleas and mites to accidental hosts. These emerging and re-emerging infections are widely distributed throughout the world. Land-use change and increasing human-wildlife conflict compound the risk of SFGR infection to local people in endemic areas and travelers to these regions. In this article, we discuss the rickettsial organisms causing spotted fever and related diseases, their arthropod vectors in Asia and the impact of land-use change on their spread.
Topics: Animals; Arthropod Vectors; Asia; Ecosystem; Humans; Rickettsia; Rickettsia Infections; Siphonaptera; Spotted Fever Group Rickettsiosis; Zoonoses
PubMed: 30993545
DOI: 10.1007/s10393-019-01409-3 -
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