These symptoms and the associated physical signs may suggest acute cholecystitis or appendicitis. Autopsy examinations demonstrate vascular lesions of the stomach, intestines, liver, gallbladder, and pancreas. The pulmonary findings in RMSF are well recognized. Nonproductive cough may be a prominent symptom in as many as one third of patients. Radiologic findings include interstitial and alveolar infiltrates.
Cardiovascular involvement is common.
The tachycardia is appropriate for the degree of fever. Progressive hypotension secondary to peripheral circulatory changes in severe RMSF may be complicated by myocardial dysfunction. The electrocardiogram shows nonspecific ST segment and T wave changes. Tissue examination reveals myocardial vasculitis. Acute renal insufficiency may occur, usually as a reflection of inadequate perfusion of the kidneys.