A 41-year-old man admitted for fever and respiratory failure had visited a local clinic 8 days earlier for fever and cough. Several days earlier, his 3 children had been diagnosed with influenza A by rapid influenza diagnostic test (RIDT) by nasopharyngeal swabs. At the clinic, RIDT done by nasopharyngeal swab two times on two consecutive days had negative results. On admission, chest computed tomography (CT) showed bilateral subpleural and peribronchovascular opacity, although RIDT by nasopharyngeal swab was negative. His respiratory distress worsened rapidly over the next several hours, necessitating intubation. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) with nasopharyngeal secretion was also negative. Despite test results, 2009 influenza A (H1N1) was strongly suspected due to chest CT and history. Oseltamivir was administered and respiratory distress gradually disappeared. He was extubated on hospital day 7. Bronchoalveolar-lavage collected on admission and sent to the laboratory for RT-PCR on hospital day 8, from which the result was positive for influenza A. He was discharged on hospital day 22.
