Rationale: Flu-like symptoms can be difficult to distinguish from routine viral illnesses. A variety of other blood stream infections may present with similar symptoms, and other factors, such as exposure or travel history, should be explored. The presence of serum markers for hepatitis is seen with many infections (e.g., EBV, CMV) and is not helpful, although it can narrow the differential diagnosis. Leptospirosis follows water exposure (swimming, boating), and brucellosis may be associated with exposure to animals or animal products. Adenovirus may be associated with conjunctivitis.