abdomen but still have an acral-predominant (arms, legs, palms, soles) distribution Initially, the lesions are erythematous macules that then become more confluent and purpuric and can be papular The severity of the rash is proportional to the severity of the disease All patients with RMSF have some degree of vasculitis that is the basis for many of the associated systemic symptoms The patients are usually toxic appearing Systemic signs and symptoms include fever, headache, myalgia, conjunctivitis, vomiting, seizures, myocarditis, heart failure, shock; periorbital, facial, or peripheral edema; and disseminated intravascular coagulation or purpura fulminans Most commonly, the diagnosis is based on clinical presentation with a history of potential tick exposure The causative organism is not routinely cultured because of the danger to laboratory personnel Diagnosis is best made by a serologic test such as indirect immunofluorescence antibody (IFA) assay Antibodies can be detected to 10 days after onset of illness Some reference laboratories are now offering polymerase chain reaction (PCR) testing Thrombocytopenia, hyponatremia, and increased serum aminotransferase levels can develop as the disease progresses Doxycycline is the drug of choice for therapy in patients of all ages (despite its risk for potentially staining developing teeth) at a dose of mg/kg/day in two divided doses (maximum of 100 mg bid), intravenously or orally Chloramphenicol is a less optimal alternative and is not effective against ehrlichiosis, which can present similarly to RMSF Therapy is continued until the patient is afebrile for at least to days (typically to 10 days of antibiotic therapy) Secondary Syphilis (See also Chapters 88 Dermatologic Urgencies and Emergencies and 94 Infectious Disease Emergencies ) Secondary syphilis is a widespread eruption that occurs due to dissemination of untreated primary syphilis Manifestations of secondary syphilis usually occur to weeks after the appearance of the primary lesion, which is typically painless and so may have gone unnoticed The rash of secondary syphilis is characterized by a generalized cutaneous eruption, usually composed of brownish, dull-red macules or papules that range in size from a few millimeters to cm in diameter They are generally