What Is Rickettsia.
What Is Rickettsia?
Rickettsia are bacteria, which are obligate intracellular parasites many disease-causing, that live in vertebrates and are transmitted by bloodsucking parasitic arthropods such as fleas , lice and ticks. Rickettsias are named after their discoverer, the American pathologist Harold Taylor Ricketts, who died of typhus in Mexico after confirming the infectious agent of that rickettsial disease.
Rickettsias unlike other bacteria, but like viruses, they require a living host (a living cell) to survive. Rickettsias from infected vertebrates, usually mammals, live and multiply in the gastrointestinal tract of an arthropod carrier but do not cause disease there; they are transmitted to another vertebrate, possibly one of another species, by the arthropod's mouthparts or faeces.
The cells are extremely small (0.25 um in diameter) rod-shaped, cocci and often pleomorphic microorganisms which have typical bacterial cell walls, no flagella (except for Rickettsiae prowazekii), are gram-negative and multiply via binary fission only inside host cells. They occur singly, in pairs, or in strands.
Rickettsia and its Diseases
Organism and diseases
Rickettsia
species Disease Natural cycleb Geographic distribution
Vectors Hosts
Typhus group:
Rickettsia prowazekii Epidemic typhus Human body 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 fever Ticks Small mammals, dogs, rabbits, birdsNorth & South America
R. conorii Boutonneuse fever Ticks Rodents, dogs Africa, Southern Europe, India
R. sibirica North Asia tick typhusTicks Rodents Eurasia, Asia
R. japonica Japanese spotted fever TicksRodents, dogs Japan
R. australis Queensland tick typhus Ticks Rodents Australia
R. akari Rickettsialpox Mites House mice, rats Worldwide
Rickettsia are bacteria, which are obligate intracellular parasites many disease-causing, that live in vertebrates and are transmitted by bloodsucking parasitic arthropods such as fleas , lice and ticks. Rickettsias are named after their discoverer, the American pathologist Harold Taylor Ricketts, who died of typhus in Mexico after confirming the infectious agent of that rickettsial disease.
Rickettsias unlike other bacteria, but like viruses, they require a living host (a living cell) to survive. Rickettsias from infected vertebrates, usually mammals, live and multiply in the gastrointestinal tract of an arthropod carrier but do not cause disease there; they are transmitted to another vertebrate, possibly one of another species, by the arthropod's mouthparts or faeces.
The cells are extremely small (0.25 um in diameter) rod-shaped, cocci and often pleomorphic microorganisms which have typical bacterial cell walls, no flagella (except for Rickettsiae prowazekii), are gram-negative and multiply via binary fission only inside host cells. They occur singly, in pairs, or in strands.
Rickettsia and its Diseases
Organism and diseases
Rickettsia
species Disease Natural cycleb Geographic distribution
Vectors Hosts
Typhus group:
Rickettsia prowazekii Epidemic typhus Human body 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 fever Ticks Small mammals, dogs, rabbits, birdsNorth & South America
R. conorii Boutonneuse fever Ticks Rodents, dogs Africa, Southern Europe, India
R. sibirica North Asia tick typhusTicks Rodents Eurasia, Asia
R. japonica Japanese spotted fever TicksRodents, dogs Japan
R. australis Queensland tick typhus Ticks Rodents Australia
R. akari Rickettsialpox Mites House mice, rats Worldwide