Clinical features of sporadic cases with H7N9 avian influenza in Taizhou city of Zhejiang province and characteristics of viral gene

Abstract

Objective To examine the clinical features of sporadic patients with H7N9 avian influenzain Taizhou city of Zhejiang province and to characterize its viral genes. Methods Fifteen patients with H7N9 influenza infection confirmed by Zhejiang Provincial Centre for Disease Control and Prevention during January 2014 and January 2015 were included in the study.The basic diseases, poultry exposure history, clinical manifestation, laboratory examination, imaging features, treatment and outcome and viral gene sequencing were analyzed retrospectively. Results The first clinical symptoms were fever and cough in all patients, acuterespiratory distress syndrome(ARDS) occurred in 13 patients, the average time from onset to antiviral therapy was (7±2) d. Among 15 patients, 9 survived and 6 died, including 2 died of multiple organ failure (MOF). The phylogenetic tree showed that there was highly homologous in hemagglutinin(HA) and neuraminidase(NA) genes between human H7N9 virus strains and poultry reference strains. The result of genetic sequencing indicated that human H7N9 virus strains had mutations at 226 (Q226L) sites in HA protein. Conclusions ARDS is likely to occur in patients with H7N9 viral infection, and early antiviral treatment usually leads to a good prognosis. With the occurrence of adaptive mutation in avian influenza virus H7N9, spread from poultry to the human beings may take place. Key words: Influenza A virus, H7N9 subtype; Respiratory distress syndrome, adult; Oseltamivir; Genes; Sequence analysis; Phylogenetic trees