Rickettsia

[rĭ-ket´se-ah]

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.

Rickettsia

(ri-ket'sē-ă),

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]

Farlex Partner Medical Dictionary © Farlex 2012

rickettsia

(rĭ-kĕt′sē-ə)

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.

rick·ett′si·al adj.

Rick·ett·si·a

(ri-ket'sē-ă)

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.

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

Rickettsia

A 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).

Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

Rickettsia

a 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.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

Rickettsia

A rod-shaped infectious microorganism that can reproduce only inside a living cell. Scrub typhus is a rickettsial disease.

Mentioned in: Scrub Typhus

Rick·ett·si·a

(ri-ket'sē-ă)

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.

Medical Dictionary for the Dental Professions © Farlex 2012

Mentioned in

References in periodicals archive

PUBLIC HEALTH workers have new tick-borne rickettsial diseases to keep on their radar screens, according to updated federal guidelines.

Guide shares advice on identifying, managing US tick-borne diseases

Nevertheless, insect localization and removal as soon as possible, preferably within 36 hours, remain recommended strategies to prevent ixodid tickborne rickettsial diseases. Ticks should always be removed with forceps (or tweezers), not fingers (as squishing ticks can transmit several tickborne diseases across dermal barriers or create infectious aerosols), and in contiguity with their feeding mouthparts, rather than burning ticks with spent matches or painting embedded ticks with adhesives or nail polishes.

Recognizing reemerging and recently described rickettsial infections in the United States

Of patients who had samples tested at the CDPH Viral and Rickettsial Disease Laboratory as described in this report, only two met the specifications for ruling out poliovirus infection as recommended by WHO or CDC guidelines * ([dagger]) ([section]); all others lacked two stool specimens collected [greater than or equal to] 24 hours apart and <14 days after symptom onset.

Acute flaccid paralysis with anterior myelitis--California, June 2012-June 2014

Suspected cases of tickborne rickettsial diseases should be reported promptly to the state or local health department, and suspected transfusion-associated transmission should be reported to the supplying blood center and appropriate public health authorities.

Anaplasma phagocytophilum transmitted through blood transfusion--Minnesota, 2007

Reported by: A Deckert, MD, Shasta County Public Health, Redding; C Glaser, MD, Viral and Rickettsial Disease Laboratory: B Sun, DVM, Div of Communicable Disease Control, California Dept of Health Svcs.

Human death associated with bat rabies--California, 2003

A microbiologic diagnosis of recent rickettsial disease was in most cases based on immunofluorescence antibody (IFA) tests and, occasionally, on PCR and Western blot.

Multicenter geosentinel analysis of rickettsial diseases in international travelers, 1996-2008

On March 27, rabies was suspected, and samples, including serum, corneal impressions, a nuchal biopsy, and saliva, were collected and sent to the CDHS Viral and Rickettsial Disease Laboratory (VRDL).

Human rabies--California, 2002

Although hemorrhages have not been described for rickettsialpox, dissimilarities in the clinical features of rickettsial disease among countries have been reported (13).

Human rickettsialpox, Southeastern Mexico

Local clinicians are asked to refer patients with evidence of WNV disease, including encephalitis, aseptic meningitis, acute flaccid paralysis, or illness compatible with West Nile fever, for testing which is performed by 33 local public health laboratories and the state Viral and Rickettsial Disease Laboratory (VRDL).

Risk factors for West Nile virus neuroinvasive disease, California, 2005

We describe 7 cases of a rickettsial disease similar to FISF, which occurred in the eastern half of Australia.

Flinders Island spotted fever rickettsioses caused by "marmionii" strain of rickettsia honei, eastern Australia

The aim of the present study was to retrospectively diagnose suspected rickettsial disease (scrub typhus) by using MIF assay and molecular methods in patients with acute febrile illness of unknown origin.

Scrub typhus in Himalayas

Subsequent damage to the endothelium is followed by endothelial-cell activation and perivascular infiltration of lymphocytes, macrophages, and polymorphonuclear leukocytes, resulting in inflammatory vasculitis of dermal vessels, the histopathologic hallmark of rickettsial disease, and possibly thrombosis (23).

Histologic features and immunodetection of African tick-bite fever eschar