Avian influenza A H7 viruses normally circulate Dispersal amongst avian populations with some variants known Know to occasionally infect humans .

An H7N9 virus was first reported Reporting to have infected humans in March 2013 , in China .

The World Health Organization ( WHO ) has identified Check H7N9 as `` ... an unusually dangerous virus for humans . ''

Analysis of the storm and its impact on humans , engineering structures , and the landscape led to Causation better forecasting and faster responses to storm warnings , stronger construction ( especially of marine vessels ) , and improved Cause_to_make_progress preparedness .