[Rickettsiales--modern findings]

The term rickettsiae has as a rule encompassed the intracellular bacteria. Molecular studies brought new data to rickettsial taxonomy. Many new data on rickettsia have been accumulated over recent years, and a comparison of the newly discovered diseases with previously known rickettsioses, as well as with their agents is of interest. The number of "new" agents that have been discovered in the last few years is remarkable. This review discusses the current knowledge of bacterial species that historically belonged to the order Rickettsiales, as well as the role of these agents as human and animal pathogens.