infectious diseases
Overview of Rickettsial and Related Infections
Key Points
Rickettsial diseases and related diseases (anaplasmosis, ehrlichiosis, Q fever, scrub typhus) are caused by a group of gram-negative, obligately intracellular coccobacilli; all, except forCoxiella burnetii, have an arthropod vector. Rickettsial diseases cause fever and, depending on the disease, sometimes a local lesion (eschar), petechial rash, regional lymphadenopathy, encephalitic signs, vasculitis, gangrene of skin and tissues, organ dysfunction, and vascular collapse. Distinguish rickettsial and related diseases from other acute infections and from each other based on history, typical examination findings, and results of tests (eg, biopsy with indirect immunofluorescence assay, serologic tests, PCR). Treat with antibiotics presumptively, without waiting for diagnostic test results, to prevent significant deterioration, death, and prolonged recovery. First-line treatment is withdoxycycline. 