ABSTRACT
INTRODUCTION The pathogenesis of diseases caused by Rickettsia, Orientia, Ehrlichia, Anaplasma, Neorickettsia, and Coxiella differ greatly owing to differences in target cells, bacterial genomes, and cell wall structure, and bacteria-host cell interactions including subcellular location, immune responses stimulated during the infection, pathogenic mechanisms, and pathologic lesions (1,2). This chapter focuses on infections with Rickettsia. The concept pathogenesis comprises three components: the sequence of events from transmission until immune clearance of the agent, the host-pathogen interaction ranging from the whole patient to the cellular level, and the pathogenic mechanisms of cellular and tissue injury.
