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Volume 4, Number 2—June 1998


Rickettsial Pathogens and Their Arthropod Vectors

Abdu F. Azad*Comments to Author  and Charles B. Beard†
Author affiliations: *University of Maryland School of Medicine, Baltimore, Maryland, USA; †Centers for Disease Control and Prevention, Atlanta, Georgia, USA

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Table 1

Epidemiologic features of the pathogenic rickettsiaea

Rickettsia species Disease Natural cycleb
Geographic distribution
Vectors Hosts
Typhus group:
Rickettsia prowazekii Epidemic typhus Human body lice Humans 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 typhuslike Fleas Opossums USA
Spotted Fever group:
R. rickettsii Rocky Mountain spotted fever Ticks Small mammals, dogs, rabbits, birds North & South America
R. conorii Boutonneuse fever Ticks Rodents, dogs Africa, Southern Europe, India
R. sibirica North Asia tick typhus Ticks Rodents Eurasia, Asia
R. japonica Japanese spotted fever Ticks Rodents, dogs Japan
R. australis Queensland tick typhus Ticks Rodents Australia
R. akari Rickettsialpox Mites House mice, rats Worldwide
Ehrlichioses group:
Ehrlichia chaffeensis Human monocytic ehrlichiosis Ticks Humans, deer USA, Europe
Ehrlichia Sp Human granulocytic ehrlichiosis Ticks Humans, deer, rodents USA, Europe
Coxiella burnetii Q fever Ticks Small mammals, sheep, goats, cattle, dogs Worldwide
Orientia tsutsugamushi Scrub typhus Mites Rodents Asia, Indian subcontinent, Australia

aNot listed are R. helvetica, R. honei, and R. slovaca (6).
bEvidence for arthropod serving as a vector or vertebrate serving as a host is based on the rickettsial isolation from field-collected specimens, experimental studies, and indirect evidence for rickettsial presence or exposure to rickettsiae (hemolymph test and serosurveys).

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