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Related to rickettsiae: bacteria, viruses, Chlamydiæ, chlamydiae, Spirochetes


n. pl. rick·ett·si·ae (-sē-ē′)
Any of various bacteria of the genus Rickettsia, carried as parasites by many ticks, fleas, and lice, that cause diseases such as typhus and Rocky Mountain spotted fever in humans.

[New Latin Rickettsia, genus name, after Howard Taylor Ricketts (1871-1910), American pathologist.]

rick·ett′si·al adj.


n, pl -siae (-sɪˌiː) or -sias
(Microbiology) any of a group of parasitic bacteria that live in the tissues of ticks, mites, and other arthropods, and cause disease when transmitted to man and other animals
[C20: named after Howard T. Ricketts (1871–1910), US pathologist]
rickˈettsial adj


(rɪˈkɛt si ə)

n., pl. -si•as, -si•ae (-siˌi)
any of various rod-shaped infectious microorganisms of the heterogeneous group Rickettsieae, formerly classified with the bacteria but markedly smaller and reproducing only inside a living cell: parasitic in fleas, ticks, mites, or lice and transmitted by bite.
[< New Latin (1916), after Howard T. Ricketts (1871–1910), U.S. pathologist; see -ia]
rick•ett′si•al, adj.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.rickettsia - any of a group of very small rod-shaped bacteria that live in biting arthropods (as ticks and mites) and cause disease in vertebrate hosts; they cause typhus and other febrile diseases in human beings
eubacteria, eubacterium, true bacteria - a large group of bacteria having rigid cell walls; motile types have flagella
family Rickettsiaceae, Rickettsiaceae - microorganism resembling bacteria inhabiting arthropod tissues but capable of causing disease in vertebrates


n. ricketsia, rickettsia, uno de los organismos gram-negativos que se reproducen solamente en células huéspedes de pulgas, piojos, garrapatas y ratones, y que se transmiten a humanos a través de las mordidas de éstos.
References in periodicals archive ?
We did not identify any rickettsiae from the blood of the jackal by PCR.
Rickettsiae and related ehrlichial organisms are obligate intracellular bacteria carried by mites, fleas, ticks, and lice and are the agents of numerous tick-borne diseases found in Virginia, such as Rocky Mountain spotted fever (Rickettsia rickettsii), Tidewater spotted fever (Rickettsia parkeri), Human monotropic ehrlichiosis (Ehrlichia chaffeensis), and Ewingii ehrlichiosis (Ehrlichia ewingii).
We just want to encourage you to have a low threshold for considering rickettsiae when the symptoms are consistent and the exposure history for tick bites or tick exposures are consistent," said Naomi Drexler, MPH, an epidemiologist with CDC's Rickettsial Zoonoses Branch during a May 24 CDC Clinician Outreach and Communication Activity call.
prowazekii may kill its host cells prematurely--before large numbers of rickettsiae accumulate.
Other spotted fever group rickettsiae also have been linked to febrile rash illnesses.
2004a Characterization of spotted fever group rickettsiae in flea and tick specimens from Northern Peru.
The first proposed method of identification based on molecular biology was the PCR / RFLP method of the gene that encodes citrate synthase, which allowed differentiation of nine species of rickettsiae of SFG.
Role of T lymphocyte subsets in immunity to spotted fever group Rickettsiae.
The rickettsiae are very small, Gram-negative, obligate intracellular bacteria that require an association with arthropods for a part of their life cycle and are maintained in nature in mammalian reservoirs.
Traditionally, pathogenic rickettsiae were classified into two groups: the typhus group (TG), composed of Rickettsia prowazekii and Rickettsia typhi, vectored by lice (Pediculus humanus) and fleas, respectively; and the spotted fever group (SFG), composed of more than 20 species mostly vectored by ticks (3).
Louse-borne typhus is no longer the major public health problem it once was in South Africa, (1) and in southern Africa rickettsiae are now best known as agents of tick bite fever (TBF); although Coxiella burnetii, the cause of Q fever, is also widespread in the region, it is far less often identified as a cause of human disease.