Rickettsia are bacteriums. which are obligate intracellular parasites many disease-causing. that live in craniates and are transmitted by bloodsucking parasitic arthropods such as fleas. lice and ticks. Rickettsias are named after their inventor. the American diagnostician Harold Taylor Ricketts. who died of typhus in Mexico after corroborating the infective agent of that rickettsial disease.
Rickettsias unlike other bacteriums. but like viruses. they require a life host ( a life cell ) to last. Rickettsias from infected craniates. normally mammals. unrecorded and multiply in the GI piece of land of an arthropod bearer but do non do disease at that place ; they are transmitted to another craniate. perchance one of another species. by the arthropod’s mouthparts or fecal matters.
The cells are highly little ( 0. 25 um in diameter ) rod-shaped. coccus and frequently pleomorphic micro-organisms which have typical bacterial cell walls. no scourge ( except for Rickettsiae prowazekii ) . are Gram-negative and multiply via binary fission merely indoors host cells. They occur singly. in brace. or in strands.
Rickettsia and its Diseases
Organism and diseases
Rickettsia species Disease Natural cycleb Geographic distribution
Rickettsia prowazekii Epidemic typhus Human organic structure liceHumans Worldwide
Recrudescent typhus None Humans Worldwide
Lice. fleas Flying squirrels Eastern USA
R. typhi Murine typhus Fleas Rodents Worldwide
Fleas Opossums USA
R. felis Murine typhus like Fleas Opossums USA
Spotted Fever group:
R. rickettsiae Rocky Mountain spotted febrility Ticks Small mammals. Canis familiariss. coneies. birdsNorth & A ; South America
R. conorii Boutonneuse febrility Ticks Rodents. Canis familiariss Africa. Southern Europe. India
R. sibirica North Asia tick typhusTicks Rodents Eurasia. Asia
R. japonica Nipponese spotted fever TicksRodents. Canis familiariss Japan
R. australis Queensland tick typhus Ticks Rodents Australia
R. akari Rickettsialpox Mites House mice. rats Worldwide
Ehrlichia chaffeensis Human monocytic ehrlichiosis TicksHumans. deer USA. Europe
Ehrlichia Sp Human granulocytic ehrlichiosis Ticks Humans. cervid. rodentsUSA. Europe
Coxiella burnetiiQ feverTicksSmall mammals. sheep. caprine animals. cowss. Canis familiariss Worldwide
Orientia tsutsugamushiScrub typhusMitesRodentsAsia. Indian subcontinent. Australia
History and Facts
Most species are found merely in the cytol of host cells. but those which cause spotted febrilities multiply in karyon every bit good as in cytol. In the research lab. they may be cultivated in populating tissues such as embrocated poulet eggs or craniate cell civilizations.
Focus is usually put on the craniate host. while the arthropod vector is frequently more of import in the natural care of the pathogen. Consequently. co-evolution of rickettsiae with arthropods is responsible for many characteristics of the host-pathogen relationship that are alone among arthropod-borne diseases. including efficient pathogen reproduction. long-run care of infection. to call a few.
Rickettsial diseases. are widely distributed throughout the universe with sporadic and frequently seasonal eruptions. from clip to clip rickettsiae have re-emerged to organize epidemics in the human populations.
Throughout history. epidemics of louse-borne typhus have caused more deceases than all the wars combined. The on-going eruption of this disease in refugee cantonments in Burundi affecting more than 30. 000 human instances is a reminder that Rickettsial diseases can reappear in epidemic proportion as a consequence of the ruinous dislocation of societal conditions. In add-on to explosive epidemics. sporadic but limited eruptions of louse-borne typhus and other Rickettsial diseases have been reported throughout the universe. In the United States. a drastic addition of murine typhus in the 1940’s. Rocky Mountain spotted febrility in the late 1970’s. and the human ehrlichioses in the 1990’s attests to the potency of this deathly disease.
Rickettsia being in both mammalian and arthropod hosts serves as an first-class theoretical account for the survey of complex host-parasite interactions. Rickettsial associations with obligate blood-sucking arthropods represent the extremely altered end-product of biological development.
The ecologic separation and decreased selective force per unit area due to these associations may explicate rickettsial familial preservation. Their intimate relationships with vector hosts are characterized by efficient generation. long-run care. and transradial and transovarial transmittal.
Although rickettsiae have a symbiotic relationship with their arthropod hosts. in some cases. they act as true parasites for illustration. members of the Wolbachia and Orientia Tsutsugamushi alter reproduction and manipulate cellular procedures in their arthropod hosts. epidemic typhus. Rickettsia Prowazekii. kills its vector. the human organic structure louse
Treatment. Prevention and diagnosing
These diseases present as hectic unwellnesss after exposure to arthropods or carnal hosts or aerosols in endemic countries and are easy misdiagnosed. A hold in diagnosing may be partially responsible for the high mortality from Spotted febrility. The spread of the roseola is frequently characteristic: spread from the bole to the appendages is typical for typhus ; spread from the appendages to the bole is typical for patched febrility.
Lab: The usage of immunofluorescent antibodies to analyze a biopsy can be diagnostic. The being can be inoculated into tissue civilization and grown over 4-7 yearss but this is really risky to forces.
For the spread of this disease to be curved. proper sanitation is needed. An environment which doesn’t promote or sustained rats. arthropods. fleas. lice or anything that house or provides a dweller for the rickettsia.
Immunization against this disease is impossible. it is impossible because there isn’t any know vaccinum. So other preventative methods would look like the better option in this instance since still we can non be immunized.
Fortunately rickettsia can be treated with pharmaceuticals drugs illustration Tetracycline or Chloromycetins. Human unsusceptibility is of import because. following recovery from disease ; individuals become immune to farther infection.
Name of BookAuthor
Patients Care ( edition 4 ) Assorted Writers
Encarta Cadmium rom 2000Various Writers
hypertext transfer protocol: //www. genoscope. central nervous system. fr/externe/
English/Projets/Projet_BU/BU. hypertext markup language