ObjectiveTo investigate the detection rate, epidemiological status of mixed positive and gene mutations of avian influenza virus in live poultry markets in Foshan city from 2017 to 2018, so as to assess the potential risk of avian influenza in live poultry markets.
MethodsFrom April 2017 to March 2018, 1 440 environment surveillance samples in live poultry markets were collected and detected by fluorescence PCR. Complete gene of hemagglutinin (HA) were sequenced for some H9N2-positive samples, and the results were analyzed with collection time, collection site, type of samples and gene evolution.
ResultsAmong 1 440 samples, 422 were tested positive of influenza A virus. Two hundred and thirteen samples (213/422, 50.47%) were positive of H9N2 alone and 38 samples (38/422, 9.00%) were mixed positive. Forty-four samples (44/422, 10.43%) were positive of H5N6 alone and 26 samples (26/422, 6.16%) were mixed positive. Four samples (4/422, 0.95%) were positive for H7N9 alone and 16 samples (16/422, 3.79%) were mixed positive. Mixed positive rate of environmental samples were significantly higher than those from live poultry (14.7% vs 1.75%,x2=20.10, P<0.01). There was no statistically significant difference of mixed positive rates between the retailing markets and wholesaling markets (13.46% vs 8.18%,x2=1.97, P=0.1602). The HA sequences of the nine H9N2 virus strains and the domestic vaccine strain were clustered into h9.4.2 sub-clade.
ConclusionsThe H9N2 avian influenza virus was dominant in the live poultry markets in Foshan city and was the most common sub-type in the mixed positive samples. Surveillance of the sub-type should be focused in the future.