[Tropical animal and human rickettsial infections]

Advances in molecular biology have provided tools that have greatly clarified our knowledge of rickettsial diseases. Most rickettsias have been reclassified in the alpha subgroup of proteobacteria. Four groups of rickettsias have been identified: the spotted fever group, the typhus group, Ehrlichia, and Bartonella. Although still considered as a rickettsia, Coxiella burnetti, the agent causing Q fever, has been reclassified separately in the gamma subdivision of proteobacteria. Recognition of rickettsial disease is still based mainly on clinical manifestations (rash, eschar, and scratching sores). Little progress has been made in serologic testing. Indirect immunofluorescence is the most common technique. Diagnostic techniques based on molecular biology are currently available in only a small number of laboratories. Treatment with tetracyclines is indicated but prophylaxis through proper hygiene is the most effective approach.