To determine the incidence, clinical and laboratory characteristics, and utility of molecular diagnosis of human monocytotropic ehrlichiosis (HME) in the primary care setting, we conducted a prospective study in an outpatient primary care clinic in Cape Girardeau, Missouri. One hundred and two patients with a history of fever for 3 days (>37.7°C), tick bite or exposure, and no other infectious disease diagnosis were enrolled between March 1997 and December 1999. HME was diagnosed in 29 patients by indirect immunofluorescent antibody assay and polymerase chain reaction (PCR). Clinical and laboratory manifestations included fever (100%), headache (72%), myalgia or arthralgia (69%), chills (45%), weakness (38%), nausea (38%), leukopenia (60%), thrombocytopenia (56%), and elevated aspartate aminotransferase level (52%). Hospitalization occurred in 41% of case-patients. PCR sensitivity was 56%; specificity, 100%. HME is a prevalent, potentially severe disease in southeastern Missouri that often requires hospitalization. Because clinical presentation of HME is nonspecific, PCR is useful in the diagnosis of acute HME.

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Cases of EM-like skin lesion in patients from Missouri and New York have distinct clinical presentations.

Rocky Mountain spotted fever is still the most lethal tick-vectored illness in the United States. We examine the dilemmas facing the clinician who is evaluating the patient with possible Rocky Mountain spotted fever, with particular attention to the following 8 pitfalls in diagnosis and treatment: (1) waiting for a petechial rash to develop before diagnosis; (2) misdiagnosing as gastroenteritis; (3) discounting a diagnosis when there is no history of a tick bite; (4) using an inappropriate geographic exclusion; (5) using an inappropriate seasonal exclusion; (6) failing to treat on clinical suspicion; (7) failing to elicit an appropriate history; and (8) failing to treat with doxycycline. Early diagnosis and proper treatment save lives.

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