Surveillance of the first case of human avian influenza A (H7N9) virus in Beijing, China

PURPOSE: Human infections with avian influenza A (H7N9) virus manifested in China in March 2013. The first case infected with H7N9 virus in Beijing involved a family member of a chicken dealer and was reported in April 2013. The clinical and epidemiological characteristics of this case and her parents were examined to illustrate some key traits regarding this novel H7N9 virus. METHODS: The index case was subjected to intensive clinical examination in order to observed the clinical process. Real-time PCR was used to confirm cases infected with H7N9 virus. The index case was administered oseltamivir (45 mg, twice daily) at the early stage of the infection. Sera were collected from the index case and her parents from the onset of illness onwards. The subjects were followed for 4 weeks. RESULTS: The sera were confirmed by neutralizing antibody tests. The index case’s clinical manifestation progressed quickly. The pharyngeal swab tested positive for influenza A based on the detection of influenza A antigen (rapid influenza diagnostic test) 15 h after the onset of fever and was positive for H7N9 virus. The patient’s temperature dropped to 36.2 °C 18 h after treatment by oseltamivir (32 h after fever). Cough and other symptoms alleviated rapidly. A number of specimens from the environment of this cluster and from the feces specimens tested positive for viral RNA of the H7N9 virus on the fourth day following onset of the index case’s illness. Pharyngeal swabs of the mother tested positive for H7N9 virus twice, but she showed no clinical symptoms. Four weeks after disease onset, the family did not present any clinical symptoms, and the results of the physical examination and blood tests were normal. The mother and the case’s sera had a fourfold increased neutralizing antibody titer. CONCLUSION: Early diagnosis and early initiation of the treatment of confirmed infections is the most effective strategy for managing H7N9 virus infection. Human beings exposed to H7N9 virus may develop asymptomatic infection.