Emergence of a new strain of the avian influenza A (H7N9) virus

Abstract

The first 3 cases of infection with a novel avian-origin reassortant influenza A (H7N9) virus were identified in China between February and March 2013. The cases were characterized by rapidly progressive pneumonia, respiratory failure, and acute respiratory distress syndrome leading to fatal outcome. Up till April 30, 2013, a total of 128 cases of H7N9 infection in human have been confirmed, including 24 deaths. However, the accurate mortality rate remains unknown because many cases might be asymptomatic or exhibit mild symptoms and therefore go undetected. Although poultry seems to be the animal reservoir of the H7N9 virus, the transmission route to humans remains unclear because approximately 40% of patients were not in contact with poultry just before they were infected. Notably, the genetic changes in H7N9 viruses suggest that they are most capable of human adaptation than all other types of avian flu viruses, and further adaptations can be expected even without sustained human-to-human transmission, except during possible blood-related transmission in two family clusters. The poor outcome observed in the first 3 cases may be attributed to delayed treatment with antivirals; oseltamivir was administered only on day 7 or 8 of illness. Moreover the 2009 Japanese H1N1 pandemic has led us to infer that early treatment interventions (o48 h) with neuraminidase inhibitors treatment should be initiated for patients with suspected or confirmed H7N9 virus infection. Diagnostic tests and potential H7N9 vaccines should be rapidly developed for individuals of all ages worldwide who probably have had no protective immunity as further spread of infection is possible. In the past issue of Respiratory Investigation, you can find an original manuscript relating to the clinical management for severe pneumonia with highly pathogenic avian influenza A (H5N1) virus (Respiratory Investigation 50; 140–150, 2012). Respiratory Investigation welcomes to focus on the topics of pulmonary medicine in Asia relating to the avian influenza viruses.