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Characterization of a novel transitional group Rickettsia species (Rickettsia tillamookensis sp. nov.) from the western black-legged tick, Ixodes pacificus.

A previously unrecognized Rickettsia species was isolated in 1976 from a pool of Ixodes pacificus ticks collected in 1967 from Tillamook County, Oregon, USA. The isolate produced low fever and mild scrotal oedema following intraperitoneal injection into male guinea pigs (Cavia porcellus). Subsequent serotyping characterized this isolate as distinct from recognized typhus and spotted fever group Rickettsia species; nonetheless, the isolate remained unevaluated by molecular techniques and was not identified to species level for the subsequent 30 years. Ixodes pacificus is the most frequently ide…

Experimentally infected human body lice (pediculus humanus humanus) as vectors of Rickettsia rickettsii and Rickettsia conorii in a rabbit model.

The human body louse, the natural vector of Rickettsia prowazekii, is able to experimentally transmit the normally flea-borne rickettsia R. typhi, suggesting that the relationships between the body louse and rickettsiae are not specific. We used our experimental infection model to test the ability of body lice to transmit two prevalent tick-borne rickettsiae. Each of two rabbits was made bacteremic by injecting intravenously 2 x 10(6) plaque-forming units of either R. rickettsii or R. conorii. Four hundred body lice were infected by feeding on the bacteremic rabbit and were compared with 400 u…

Phylogenetic analysis of the rompB genes of Rickettsia felis and Rickettsia prowazekii European-human and North American flying-squirrel strains.

The rickettsial outer membrane protein B (rompB) gene encodes the major surface antigens of Rickettsia species. We undertook sequencing and molecular analysis of the rompB gene of Rickettsia felis and a comparison with its homologs in spotted fever group (SFG) and typhus group (TG) rickettsiae, including the complete sequences of two North American flying squirrel strains and two European human strains of Rickettsia prowazekii. We sequenced 5,226 base pairs (bp) of the R. felis rompB, encoding a protein of 1,654 amino acids. We also sequenced 5,015 bp of rompB of the flying squirrel strains, e…

Rickettsia Felis Case Cluster in a Military Family.

Cases of flea-borne spotted fever (FBSF) have been on a steady increase in the southern United States and produce the highest numbers of reported vector-borne disease cases in Texas. Historically, cases were largely murine typhus caused by Rickettsia typhi and characterized by exposure to rodent fleas. However, more recently, spotted fever rickettsiosis caused by R. felis and characterized by exposure to the cat flea, Ctenocephalides felis, may be the dominant disease. We describe the management of a child with a complex clinical picture, including sickle cell β-thalassemia, bullous pemphigoid…

Genomic evolution and adaptation of arthropod-associated Rickettsia.

Rickettsia species are endosymbionts hosted by arthropods and are known to cause mild to fatal diseases in humans. Here, we analyse the evolution and diversity of 34 Rickettsia species using a pangenomic meta-analysis (80 genomes/41 plasmids). Phylogenomic trees showed that Rickettsia spp. diverged into two Spotted Fever groups, a Typhus group, a Canadensis group and a Bellii group, and may have inherited their plasmids from an ancestral plasmid that persisted in some strains or may have been lost by others. The results suggested that the ancestors of Rickettsia spp. might have infected Acari …

Rickettsia japonica infections in Huanggang, China, in 2021.

Two patients from Huanggang, China, were diagnosed with spotted fever group (SFG) rickettsiosis-caused by spotted fever group rickettsiae (SFGR)-in 2021. This study aimed to investigate the clinical symptoms, laboratory examinations, epidemiological factors, and therapeutic responses in patients with SFG rickettsiosis-an emerging disease in this region. The patients showed a variety of clinical signs and symptoms, such as acute febrile illness with severe headache, myalgia, asthenia, anorexia, eschar, lymphadenopathy, and rash on the trunk and extremities. They exhibited increased neutrophil r…

Мобильность хостов и пространственное распространение Рикетсии Рикеттси.

Существует огромное число патогенов с многокомпонентными циклами передачи, включая приемные устройства усилителя, векторы или сложные патогенные жизненный циклы. Эти сложные системы создают проблемы с точки зрения моделирования и разработки политики. Одним из важных примеров этого является смертельное инфекционное заболевание, вызванное " клещами " , - бразильский " жар " (BSF). Текущее увеличение числа случаев применения БФС связано с присутствием и расширением гидрохера Капибары Гидрохера, усилителя для агента Рикетсии Рикеттсии и основного хоста для вектора Амблиоммы ску

Совпадение в аннотации оригинала
There are a huge number of pathogens with multi-component transmission cycles, involving amplifier hosts, vectors or complex pathogen life c … the presence and expansion of the capybara Hydrochoerus hydrochaeris, amplifier host for the agent Rickettsia rickettsii and primary host for the tick vector Amblyomma sculptum. We introduce a stochastic dynamical model that captures the spatial distribution of capybaras and ticks to gain a better understanding of the spatial spread of the R. rickettsii and …

Parinaud's oculoglandular syndrome revealing subclinical Rickettsia conorii infection.

The purpose of this study was to report a case of Parinaud's oculoglandular syndrome associated with subclinical Rickettsia conorii infection. We report a case of a 66-year-old male patient presented with unilateral persistent granulomatous conjunctivitis in the left eye and an ipsilateral preauricular lymphadenopathy without associated systemic features. Laboratory evaluation showed a positive indirect immunofluorescence antibody test for R. conorii. The patient received a 2-week course of oral doxycycline, with subsequent complete resolution of all his symptoms. Rickettsial disease should be…

Abducens nerve palsy and meningitis by Rickettsia typhi.

Patients with rickettsial infection may present with encephalitis or meningitis but neurologic involvement is rare in murine typhus. Here, we report two patients with Rickettsia typhi meningitis who presented with cranial neuropathy, presumably caused by two distinct disease processes. Recognition of the disease manifestations is important because rickettsial infections are potentially associated with significant morbidity. Simple effective treatments are available.

Outbreak of Rickettsia typhi infection - Austin, Texas, 2008.

Murine typhus is a fleaborne rickettsial disease caused by the organism Rickettsia typhi. Symptoms include fever, headache, chills, vomiting, nausea, myalgia, and rash. Although murine typhus is endemic in southern Texas, only two cases had been reported during the past 10 years from Austin, located in central Texas. On August 8, 2008, the Austin/Travis County Department of Health and Human Services (ATCDHHS) contacted the Texas Department of State Health Services (TDSHS) concerning a cluster of 14 illnesses with serologic findings indicative of murine typhus. On August 12, 2008, TDSHS initiat…

Смертельная человеческая инфекция Рикитсиа Рикеттсии, Юкатан, Мексика.

На юго-западе Мексики был диагностирован первый смертельный приступ рикетсии. У пациента была лихорадка, эритроматическая сыпь, боль в животе и сильная центральная нервная система, связанная с нервным кризисом. Диагностика инфекции Р. Ррикеттсии была установлена иммунохимией и специфической цепной реакцией полимеразы.

Совпадение в аннотации оригинала
The first fatal Rickettsia rickettsii infection was diagnosed in the southwest of Mexico. The patient had fever, erythematous rash, abdominal pain, and severe central nervous system involvement with convulsive crisis. The diagnosis of R. rickettsii infection was established by immunohistochemistry and specific polymerase chain reaction.

Expression of green fluorescent protein in Rickettsia conorii.

Rickettsiae are obligate intracellular class III pathogens for which genetic manipulation has only recently been shown to be feasible. Such experiments were restricted to the typhus group rickettsiae, namely R. typhi and R. prowazekii. Here we report the first genetic manipulation of Rickettsia conorii, the bacterial agent responsible for the Mediterranean spotted fever. A gene encoding a variant of the green fluorescent protein under the control of the sterically repressed promoter (srp) from E. coli was integrated into the genome of this bacteria and detected by FACS analysis.

Лицом к нервам, связанным с Рикиттсией conorii.

Паралич лицевых нервов иногда приписывался инфекционным агентам, но виды Рикитциалов не были задокументированы в качестве причинно-следственных агентов. Мы сообщали о двух девочках-подростках с параличом на лице и серологическими свидетельствами инфекции R conorii. Эти случаи указывают на то, что рикетсиосы должны быть включены в число причин возникновения паралича на лице, особенно в эндемических районах.

Совпадение в аннотации оригинала
Facial nerve palsy has been occasionally attributed to infectious agents, but Rickettsiae species have not been documented as causative agents. We report two adolescent girls with facial nerve palsy and serological evidence of R conorii infection. These cases indicate that rickettsioses should be included among the causes of facial nerve palsy, particularly …

Antibodies to Rickettsia conorii in dogs: seasonal differences.

Eight dogs, having showed positivity to Rickettsia conorii in serum samples obtained during the spring and summer, were studied again by means of a second determination during the next winter, 4-10 months later. Serum titer became negative in six dogs, persisted high in one, and fell from 1:640 to 1:40 in another dog. This seasonal difference suggests a short persistence of antibodies in dogs after contact with R. conorii in the Mediterranean area.

[Rickettsia conorii: a new cause of erythema nodosum].

A case of 26 year old male with an infection caused by Rickettsia conorii (RC) associated to erythema nodosum (EN) is presented. The patient had EN together with a high temperature and toxic symptoms 2 weeks after camping in the mountains. The diagnosis was made by ascertaining IgM titers positive to RC by indirect immunofluorescence (IIF). The disease disappeared 24 hours after the initiation of treatment with doxiciclin. Based on this observation, we consider RC to be an etiologic agent which should be taken into account in the differential diagnosis of EN.

Infection of genetically immunodeficient mice with Rickettsia conorii.

In order to determine the definitive importance of T- and B-lymphocytes in immunity to Rickettsia conorii, mice genetically deficient in T-cells, B-cells, or both T- and B-cells were infected experimentally. T-lymphocytes rather than humoral antibodies were crucial to rickettsial clearance and a reduced mortality rate. Mice incapable of an antibody response to polysaccharide capsular antigens effectively controlled rickettsial infection with no mortality. In contrast, nude mice produced antibody to thymus-independent antigens early in the course of infection, yet experienced severe rickettsial…