Epidemiological investigation on the first case of human infection with H7N9 avian influenza in Henan Province

Objective To investigate and analyze the first case of human infection with highly pathogenic avian influenza virus (H7N9) so as to provide scientific basis for control of avian influenza infection in humans. Methods Epidemiological survey was carried out including the process of morbidity, possible infection source, transmission route and risk factors, etc. Strict observation was made on close contacts of the patient. Meanwhile the patient underwent clinical diagnosis, treatment and laboratory tests. Results The patient was confirmed to be infected with highly pathogenic human avian influenza H7N9 virus as ascertained by expert group of ministry of health,and was cured and discharged. The patient had definate contact with live poultry, and using H7N9 pharyngeal swab through laboratory tests, avian influenza virus nucleic acid showed positivity results. No abnormalities were found in clinical manifestations in close contacts of the patient. By expanding surveillance on 160 cases of influenza-likeillness(ILI) and 858 cases of professional groups, the samples were not found to be H7N9 positive. However, on local live poultry market, two chicken pharyngeal swab specimens were detected to be H7N9 positive. Positive chickens were from other provinces. Conclusion History of live poultry exposure is believed to be the key risk factors in infection with H7N9 virus. So far there has been no evidence of human-to-human transmission. There has not been subclinical infection or mild cases found in crowd. However,there is the need to expand monitoring and epidemiological investigation so as to improve the understanding of the disease.