Volume 4, Number 2—June 1998
Perspective
Rickettsial Pathogens and Their Arthropod Vectors
Abdu F. Azad*
and Charles B. Beard†
and Charles B. Beard†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 |
| Others: | ||||
| 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).
