Epidemiological characteristics of human infection with avian influenza A (H7N9) in Guilin

Abstract

Objective To analyze the epidemiological characteristics of human infection with H7N9 avian influenza in Guilin in recent years and to provide on-site data and data support for scientific prevention and control of the epidemic of H7N9 avian influenza infection. Methods A descriptive epidemiological method was used to collect the data about human infection with H7N9 avian influenza form three aspects, which were human infection cases in 2017, environmental monitoring for H7N9 avian influenza virus and sentinel surveillance of influenza-like cases. The epidemiological characteristics of human infection with H7N9 avian influenza in Guilin in 2017 were analyzed. Chi-square test was used to compare the positive rates of H7N9 avian influenza virus in environmental specimens. Results A total of six cases of confirmed human H7N9 infection including three deaths were reported in Guilin city in 2017. These cases were from five counties and districts and all occurred in winter and spring. The patients were middle-aged and old men. Most of them were farmers and had a clear history of poultry exposure before the onset of infection. No human H7N9 infection was reported in close contacts or in influenza-like cases. Conclusions H7N9 avian influenza infection in Guilin was characterized by high sporadicity, high incidence in winter and spring, and predominantly middle-aged and elderly men. Avian exposure history was a high risk factor for human infection with H7N9 avian influenza virus. All of the studied cases were severe cases. No human-to-human transmission was reported. Farmers, having a history of poultry slaughter, and underlying diseases were potential risks causing death. Live poultry markets were the main sources of infection, hence closing market could reduce the detection rate of H7N9 avian influenza virus. Strengthen the management of live poultry market and poultry environmental monitoring, closing live poultry markets when viral detection was positive, and suspending live poultry trading were effective measures to control the epidemic of H7N9 avian influenza infection and prevent transmission. Key words: H7N9 avian influenza; Epidemiological characteristics; Prevention and control measures