Epidemiological survey of the first case of pregnant women infection with avian influenza A (H9N2) virus in Shenzhen

ObjectiveTo identify the possible infection source of the first case of pregnant woman infection with avian influenza A (H9N2) virus reported in Longgang district of Shenzhen and provide evidence for the prevention and control of human infection with H9N2 virus in the future.

MethodsEpidemiological data of the case were collected systematically using field epidemiology method and the samples of case, close contacts and exposure environments were collected from 2017 to 2018. Influenza A virus was detected by using antigen test. The detection and subtyping of avian influenza virus were conducted with fluorescence quantitative PCR. The data was analyzed by using software Excel 2019.

ResultsThe throat swabs of the case was detected to be H9N2 virus nucleic acid positive and the case was diagnosed as the first pregnant women infection with H9N2 virus in Shenzhen. Eight close contacts showed no influenza -like symptoms during the medical observation period, and the influenza antigen and avian influenza nucleic acid tests were all negative. In 2017, the daily environment surveillance results showed that the positive rate of H9 virus subtype was 14.49%, The H9 virus subtype positive samples accounted for 62.69% in total universal influenza A virus positive samples. A total of 103 environmental samples were collected in the epidemic, in which 15 were universal influenza A virus positive and 9 were influenza A virus subtype H9 positive.

ConclusionThe infection source might be a pigeon farm, but the exposure to poultry products in daily life could not be excluded. Avian influenza virus contamination still exists in the environment of poultry markets in Shenzhen, suggesting that the population at high risk still might be exposed in epidemic season. It is necessary to pay attention to this problem.