Introduction
Key features
Rickettsiae are small, obligately intracellular, Gram-negative bacteria that reside within an arthropod host (tick, flea, louse, or mite) during part of their life cycle
The arthropod vector transmits the rickettsiae in its saliva or feces during feeding
The major vertebrate target cells of Rickettsia (endothelium),
Orientia (endothelium), Ehrlichia (monocytes or neutrophils), Anaplasma (neutrophils), and Coxiella (macrophages) determine to a large degree the pathogenesis of the disease
In most spotted fever rickettsioses and scrub typhus, an eschar at the site of the vector’s inoculation of organisms is an important physical sign
A rash is the diagnostically critical clinical manifestation of Rocky
Mountain spotted fever, other spotted fevers, murine typhus, and louse-borne typhus
One of the most common rickettsial diseases in travelers is African tick bite fever