Rickettsia(redirected from rickettsiae)
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a genus of bacteria of the tribe Rickettsiae, made up of small, gram-negative, rod-shaped to coccoid, often pleomorphic microorganisms, which multiply only in host cells. Organisms occur in the cytoplasm of tissue cells or free in the gut lumen of lice, fleas, ticks, and mites and are transmitted by their bites. R. cono´rii is the etiologic agent of boutonneuse fever and is transmitted by the bite of ixodid ticks. R. prowaze´kii is the agent of scrub typhus and Brill-Zinsser disease; it is transmitted between humans by the human body louse and from flying squirrels to humans by fleas and lice. R. ty´phi is the cause of murine typhus, which is transmitted to humans chiefly by rat fleas. Rickettsial diseases are not common in communities with good sanitary standards, since prevention depends on controlling the rodent and insect populations. Major epidemics have occurred, especially in times of war when standards of sanitation drop.
rickettsia[rĭ-ket´se-ah] (pl. rickett´siae)
An individual organism of the family Rickettsiaceae.
A genus of bacteria (order Rickettsiales) containing small (that is, nonfilterable), often pleomorphic, coccoid to rod-shaped, gram-negative organisms that usually occur intracytoplasmically in lice, fleas, ticks, and mites but do not grow in cell-free media; pathogenic species infect humans and other animals, causing epidemic, murine, or endemic typhus, Rocky Mountain spotted fever, tsutsugamushi disease, rickettsialpox, and other diseases; type species is Rickettsia prowazekii.
[Howard T. Ricketts]
Rickettsia/Rick·ett·sia/ (rĭ-ket´se-ah) a genus of the tribe Rickettsieae, transmitted by lice, fleas, ticks, and mites to humans and other animals, causing various diseases.
Rickettsia a´kari the etiologic agent of rickettsialpox, transmitted by the mite Allodermanyssus sanguineus from the reservoir of infection in house mice.
Rickettsia austra´lis the etiologic agent of North Queensland tick typhus, possibly transmitted by Ixodes ticks.
Rickettsia cono´rii the etiologic agent of boutonneuse fever (Marseilles fever, Mediterranean fever) and possibly of Indian tick typhus, Kenya typhus, and South American tick-bite fever; transmitted by Rhipicephalus and Haemaphysalis ticks.
Rickettsia prowaze´kii the etiologic agent of epidemic typhus and the latent infection Brill's disease, which are transmitted between humans via Pediculus humanus.
Rickettsia rickett´sii the etiologic agent of Rocky Mountain spotted fever, transmitted by Dermacentor, Rhipicephalus, Haemaphysalis, Amblyomma, and Ixodes ticks.
Rickettsia tsutsugamu´shi the etiologic agent of scrub typhus, transmitted by larval mites of the genus Trombicula, including T. akamushi and T. deliensis, from rodent reservoirs of infection.
rickettsia/rick·ett·sia/ (rĭ-ket´se-ah) pl. rickett´siae an individual organism of the Rickettsiaceae.rickett´sial
n. pl. rickett·siae (-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.
[riket′sē·ə] pl. rickettsiae
Etymology: Howard T. Ricketts, American pathologist, 1871-1910
a genus of microorganisms that combines aspects of both bacteria and viruses. They can be observed with a light microscope, divide by fission, and may be controlled with antibiotics. They also exist as viruslike intracellular parasites, living in the intestinal tracts of insects such as lice. Thus a human infested with lice is also likely to be infected with a form of typhus transmitted by Rickettsia prowazeki. Rickettsial diseases have been responsible for many of history's worst epidemics. The various species are distinguished on the basis of similarities in the diseases they cause. The spotted fever group includes diseases such as Rocky Mountain spotted fever and rickettsialpox; the typhus group includes epidemic typhus and murine typhus; and a miscellaneous group includes Q fever and trench fever. Rickettsial diseases are uncommon in parts of the world where insect and rodent populations are well controlled. rickettsial, adj.
A genus of bacteria containing small (nonfilterable), often pleomorphic, coccoid to rod-shaped, gram-negative organisms that usually occur intracytoplasmically in lice, fleas, ticks, and mites; pathogenic species are parasitic in humans and other animals, causing epidemic typhus, murine or endemic typhus, Rocky Mountain spotted fever, tsutsugamushi disease, rickettsialpox, and other diseases; type species is Rickettsia prowazekii.
RickettsiaA micro-organism intermediate in size between the largest viruses and the smallest bacteria. Rickettsiae are spread by ticks and small insects, and cause TYPHUS, Q FEVER, and ROCKY MOUNTAIN SPOTTED fever. The eponymous discoverer of the genus died of typhus while investigating the cause. (Howard Taylor Ricketts, 1871–1910, American pathologist).
Rickettsiaa GENUS of bacteria within the phylum PURPLE BACTERIA. Rickettsias are INTRACELLULAR PATHOGENS of animals, including humans. They are smaller than some of the largest VIRUSES, and like viruses can only reproduce within a host CELL. They are rod-shaped, about 1–2 μ m in length and are generally transmitted to man by INSECTS and TICKS. For example, Rocky Mountain spotted fever is caused by Rickettsia rickettsii which is transmitted by ticks.
A rod-shaped infectious microorganism that can reproduce only inside a living cell. Scrub typhus is a rickettsial disease.
Mentioned in: Scrub Typhus
Genus of bacteria that usually occur intracytoplasmically in lice, fleas, ticks, and mites; pathogenic species infect humans and other animals, causing epidemic, murine, or endemic typhus, Rocky Mountain spotted fever other diseases.
a genus of small, rod-shaped, round to pleomorphic microorganisms in the order Rickettsiales. They are true bacteria, gram-negative, and cultivable only in living tissues. Transmitted by lice and ticks, they cause disease in humans and domestic animals but are also found in the cytoplasm of tissue cells of lice, fleas, ticks and mites, which may act as reservoirs and vectors. See also ehrlichia and coxiella.
causes rickettsial pox in humans, mice and rats.
causes queensland tick typhus in humans, small marsupials, rats.
causes new typhus in humans and rabbits.
see Chlamydophila pecorum.
causes boutonneuse fever in humans and dogs and small feral mammals.
see Ehrlichia ovina.
causes epidemic typhus in humans and possibly cattle, sheep and goats.
causes spotted fever in humans and many feral animals, especially rodents and in dogs and birds. See also rocky mountain spotted fever.
causes Siberian tick typhus in humans and many feral mammals, especially rodents.
causes murine typhus in humans and the brown rat.
pl. rickettsiae; an organism in the order Rickettsiales.