ABSTRACT
Rickettsiaceae are obligate intracellular bacteria that have a reduced genome owing to their intracellular lifestyle. The infection cycle for these organisms involves a reservoir (dogs, rodents deer, squirrels) and vectors (ticks, fleas, lice, mites) The most clinically relevant categorization is into four groups: the Ancestral group (AG) which includes R. bellii (non-pathogenic in humans); the Typhus group (TG) that includes R. prowazekii, (Epidemic typhus-vector = lice) and R typhi (murine typhus-vector = flea); the Spotted Fever group (SFG) that includes R. rickettsia (Rocky Mountain Spotted Fever), R. conori (Mediterranean Spotted fever), R. africae (African Tick Bite Fever) and many other pathogenic rickettsiae-vectors = ticks; the Transitional group (TRG) including R felis (cat-flea typhus-vector = flea) and R akari (Rickettsial pox-vector = mite). Scrub Typhus has been transferred to a separate Genus as Orientia tsutsugamushi –vector = mite) The organisms affect vascular endothelial cells and inhibit the immune response. The main diagnostic approach is PCR and serology and the main antibiotic used to treat the infections is doxycycline.
