An Unusual Rash in an Infant: Expanding the Differential Diagnosis for Sepsis in an Infant Younger than 3 Months

Introduction: We present a case of Lyme disease in an infant younger than 3 months. Although Maine is a Lyme disease endemic area, infants younger than 1 year rarely present with Lyme disease. Clinical Findings: The infant was evaluated due to rash and a history of fever and irritability, with a history of tick bite 1 week earlier. Laboratory findings were normal. Clinical Course: The infant was evaluated for sepsis as recommended for young infants with fever. Because of the presence of erythema migrans rash and negative bacterial cultures, the infant was treated with ceftriaxone parenterally for 7 days and amoxicillin for an additional 7 days. There were no complications after treatment. Conclusions: Lyme disease in young infants has been rarely reported, with limited evidence about duration and route of treatment. The medical literature describes 3 cases of infant Lyme disease, with treatment durations ranging from several days of parenteral therapy followed by oral therapy to 14 days of parenteral therapy. These infants must be evaluated for typical systemic bacterial infections as well. However, in Lyme disease endemic areas, Lyme disease should also be considered, even in very young infants.