Epidemiological and clinical characteristics of human infections with H7N9 avian influenza virus in Hubei province, 2017

  Objective  To describe epidemiological characteristics and clinical features of human infection with H7N9 avian influenza virus in Hubei province in 2017.

  Methods  We extracted relevant data on all human infection cases (n = 30) with H7N9 avian influenza virus reported in Hubei province during 2017 from China Disease Prevention and Control Information System and Information Management System for Human H7N9 Avian Influenza Infection. Supplemental information were also collected by field study and from medical institutions involved in the diagnosis and treatment of the cases.

  Results  The cases distributed in 20 districts and counties in 9 municipalities across Hubei province. The history of exposure to poultry was confirmed in almost all the cases (96.67%, 29/30), including live poultry purchase, slaughter of live poultry, process of fresh poultry meat, poultry rearing, and passing by a site for live poultry sales which were ascertained in 12, 8, 7, 5, and 5 of the cases, respectively. There were no significant differences between the deaths and cured cases in gender (χ² = 0.443, P = 0.314), age (χ² = 5.812, P = 0.214), occupation (χ² = 3.529, P = 0.832), fever symptom (χ² = 2.402, P = 0.493), crucial time interval between diagnosis and treatment, location of infection (χ² = 0.524, P = 0.377), and previous disease history (χ² = 0.023, P = 0.59); but there was a significant difference in the type of medical institutions for the first time of seeking medical care. Of the cases, all had cough and phlegm; 66.67% had difficulty in breathing; and 60.00% had chest tightness. All the cases were treated with oseltamivir. The average interval between the onset of the disease and the time of first oseltamivir medication was 8.68 ± 5.73 days, and the average interval between the first medication of oseltamivir and negative conversion of virus nucleic acid was 8.72 ± 4.41 days.

  Conclusion  The epidemic of human infection with H7N9 avian influenza virus was highly sporadic as a whole but clustered in some regions in Hubei province in 2017. The type of medical institution providing first time medical care has certain impact on the prognosis of the human infection cases. The study results suggest that during epidemic seasons, antiviral therapy should be applied as early as possible to the infection cases with atypical clinical manifestations but confirmed history of exposure to poultry and pneumonia complicated by rapid progressive respiratory failure.