Infection with avian influenza A(H7N9) virus and epidemic analysis / 中国人兽共患病学报

ABSTRACT

The situation of the ongoing fifth epidemic (beginning October,2016) of human infection with avian influenza A (H7N9) virus are more serious than the first four ones.As of March 8,2017,the fifth epidemic reported 40.00％ of the cumulative cases.Recently,the pathogenic study reported two new human infections in Guangdong with an influenza A(H7N9)virus strain for which gene sequencing analysis revealed mutations in the haemagglutinin (HA) gene that resulted in the insertion of basic amino acids at the cleavage site of this protein,known to confer increased pathogenicity in chickens.However,most strains show no obvious difference in pathogenic characteristics compared with those detected during the first four waves.Although epidemiological studies showed that 3 clusters with limited human-to-human transmission have been investigated during the current wave,there are no indications of sustained person-to-person spread.Based on epidemic analysis and risk assessment results,it's likely that human infections with H7N9 virus will continue to occur in China,but epidemiological and pathogenic analysis suggested that it's unlikely to have a continued transmission of this virus.Profound public health significance would be presented by strengthening etiology and epidemiology studies of avian influenza A(H7N9) virus.