Objective To understand the epidemiological, clinical and etiological characteristics of confirmed cases of human avian influenza A (H7N9) virus infections reported in Shanghai from 2013 to 2018, so as to evaluate the effectiveness of current prevention and control measures and to provide relative recommendations.
Methods Data of the laboratory confirmed human cases of influenza A (H7N9) virus infections in Shanghai from 2013 to 2018 were collected for epidemiological analysis.
Result Fifty-five laboratory confirmed cases were reported from 2013 to 2018 in Shanghai. Most of the cases occurred during winter and spring. Since 2014, the policy of seasonal closure of live poultry markets has been implemented in Shanghai. Only 2 cases were reported when the markets were closed, and both cases had and only had a history of exposure to live poultry in other provinces and cities. The cases of 60 years old and above accounted for 54.55% of all reported cases. Male cases accounted for 80% of all cases. In the occupational distribution, retiree was the main group (47.27%). For the geographical distribution, the cases were highly sporadic, with more cases in rural areas than urban areas. Of all cases, 90.91% had history of exposure to live poultry; 29.09% had unhealthy behaviors, including smoking and alcohol drinking; 74.55% had at least one underlying disease; and 81.82% developed severe pneumonia. The case fatality rate of 56.36%.
Conclusions The human cases of influenza A (H7N9) virus infections in Shanghai were highly sporadic. Most of the cases developed into the critical condition with poor prognosis. The main exposure factors for the infections were direct exposure to live poultry or in live poultry markets. Comprehensive prevention and control strategies, such as seasonal closure of live poultry markets, can effectively prevent and control human infections of avian influenza virus, including novel avian influenza viruses.