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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 ?
Fiebre manchada por rickettsias en el Delta del Parana: una enfermedad emergente.
Rickettsia parkeri, a tick-borne bacterium discovered in 1937, was considered nonpathogenic until 2004.
Study of rickettsias harbored by ticks (acaria, ixodoidea) in south-eastern France [in French].
Advanced molecular tools have allowed Rickettsia conorii conorii to be classified as a subspecies of R.
Polymerase chain reaction (PCR) survey for rickettsias and bartonellas in ticks from New Zealand.
Dasch, Naval Medical Research Institute, Bethesda, MD, USA; UR, Unite des Rickettsias, CNRS UPRES A, Marseille, France; D.
I Reunion Nacional del Grupo de Rickettsias y Borrelias II National Meeting of the Rickettsia and Borrelia working group].
The primary hosts for Rickettsia species are arthropods that can also act as disease vectors for humans and other vertebrates.
Spotted fever group rickettsiae have been identified in 3 Amblyomma species in Argentina: Rickettsia amblyommii and R.
The first fatal Rickettsia rickettsii infection was diagnosed in the southwest of Mexico.
The etiologic agent, Rickettsia rickettsii, and the tick vector, Amblyomma cajenennse (the Cayenne tick), were subsequently identified.
A rickettsia named the ELB agent, or "Rickettsia felis," was identified by molecular biology techniques in American fleas in 1990 and later in four patients from Texas and Mexico.