Symptoms of RMSF usually appear approximately 7 days after tick exposure, although a history of tick bite is only elicited in 50% to 60% of patients. The initial phase of RMSF infection is characterized by sudden onset of fever, malaise, and severe headache, with accompanying nonspecific symptoms such as myalgias, nausea and vomiting, abdominal pain, anorexia, and photophobia (Fig. 65–1). Not surprisingly, RMSF may be misdiagnosed as a viral syndrome during this phase. The classic triad of RMSF (fever, rash, headache) is only seen in 3% of patients in the first 3 days, although it is usually seen in the majority of patients within the first 2 weeks.10 A rash usually appears between 2 and 5 days, although up to 10% of children may not develop a rash. The rash of RMSF usually begins as blanching, erythematous macules on the wrists and ankles, and spreads centripetally to the arms, legs, and trunks within hours (Fig. 65–6). Palms and soles are also involved. By the end of the first week, the characteristic petechial rash will develop in 35% to 60% of patients. Some patients may develop neurologic symptoms such as meningismus, altered mental status, amnesia, coma, seizures, cranial nerve palsies, central deafness, and cortical blindness. Other manifestations are less commonly reported but include conjunctivitis, periorbital and peripheral edema, congestive heart failure, arrhythmias, myocarditis, shock, hepatomegaly, and jaundice.