11.02.2016

The New England Journal of Medicine

Human H7N9 infections appear to be acquired through zoonotic transmission, although clusters of human-to-human household transmission have occurred. A new study report a hospital cluster of H7N9 infections that took place from January to February 2015. A 28-year-old man (index patient), with repeated exposure to live poultry, presented with respiratory infection and was admitted to the respiratory department, where his condition worsened. Laboratory investigation showed that he was positive for H7N9 by serologic testing and polymerase-chain-reaction (PCR) assay. Seven days after admission of the index patient, influenza-like illness developed in a 33-year-old male physician (Doctor 1) who attended the index patient. The acute respiratory distress syndrome later developed in this  physician. Four days after the onset of symptoms in Doctor 1, influenza-like illness and bronchial pneumonia developed in a second attending physician (Doctor 2), a 35-year-old man, in the same department.  He too had close contact with the index patient. With the use of real-time reverse-transcriptase–PCR assay, seroconversion (hemagglutination-inhibition assay and microneutralization antibody assay), and viral isolation, H7N9 infection was confirmed in all three persons; they recovered from their illness and were discharged from the hospital. Even though the index patient appeared to be convalescent at the time of discharge, he continued to shed H7N9 virus 42 days after the initial onset of symptoms. The three viruses isolated from the index patient, Doctor 1, and Doctor 2 suggest direct human-to-human transmission; although a common community source cannot be ruled out, no such sources were identified.