ABSTRACT. Background. Adenovirus (ADV) infections were difficult to diagnose in the past, and many infections were unrecognized. Direct fluorescent assay (DFA) for the rapid diagnosis of ADV infection, as part of a viral respiratory panel, became available at Primary Children's Medical Center (Salt Lake City, UT) in December 2000.Objective. To describe children with ADV infection diagnosed by DFA and viral culture and document the impact of rapid ADV testing on patient care.Methods. DFA testing for respiratory viruses including ADV was performed on nasal wash specimens with parallel viral culture. Chart review was performed for all ADV-positive patients identified from microbiology records between December 2000 and May 2002.Results. Of 1901 patients positive for respiratory viruses, 143 (7.5%) were ADV-positive by DFA or culture. The mean age of ADV-positive children was 23 months; 90% were <60 months old. Eighty percent were previously healthy, and 56% required admission with a mean length of stay of 3.4 days. The most common diagnoses included fever (31%), bronchiolitis (24%), and pneumonia (14%). Other conditions included suspected Kawasaki disease (KD) and hepatitis. Forty-six percent of ADV-positive children were given antibiotics at presentation, but only 2 (1.4%) had documented bacterial infection (one had Escherichia coli urinary tract infection and one had Moraxella catarrhalis bacteremia). Thirty-six percent of children had a change in management based on positive ADV DFA. In children with suspected KD (n ؍ 5), 100% had positive ADV DFA, and immune globulin was withheld in 4. One immunocompetent patient with fulminant liver failure received cidofovir treatment after a positive ADV DFA and recovered before liver transplant.Conclusions. ADV is a common infection in young children and often results in admission and unnecessary antibiotic therapy. Identifying ADV as the cause of illness can favorably impact care and in some instances may be life-saving. DFA testing for ADV should be considered for infants and children requiring admission for fever, respiratory illness, suspected KD, and hepatitis. Pediatrics 2004;113:e51-e56. URL: http://www.pediatrics. org/cgi/content/full/113/1/e51; adenovirus, rapid diagnosis, Kawasaki disease.ABBREVIATIONS. ADV, adenovirus; PCMC, Primary Children's Medical Center; DFA, direct fluorescent assay; ED, emergency department; RSV, respiratory syncytial virus; KD, Kawasaki disease; ESR, erythrocyte sedimentation rate; CRP, C-reactive protein; IVIG, intravenous immune globulin.A denovirus (ADV) is a well-known cause of respiratory illness in children. [1][2][3][4] It may produce upper or lower respiratory infection including bronchiolitis and pneumonia. 5 In addition, ADV infection is frequently associated with entities such as pharyngoconjunctival fever and epidemic conjunctivitis that are often diagnosed based on clinical examination alone. 6 Although most infections are self-limited, ADV can be associated with severe or lethal infection in both immunocompromised and healt...