Surge in human H7N9 cases caused by poultry, not people.

Surge in human H7N9 cases caused by poultry, not people. New study findings indicate that the recent surge in human influenza A(H7N9) cases in China is probably due to increased spread from poultry to people and not because of a swell in human-to-human transmission. With a case fatality rate of around 40%, experts consider H7N9 to be one of the most troubling infectious disease threats in the world because of its potential to cause a deadly pandemic. So far, most of the more than 1,500 human cases since 2013 have been transmitted from poultry, not people. Since 2013, China has been struck by five epidemics of H7N9, the most recent one being by far the largest and most widespread. In addition to a record number of human cases, the fifth epidemic produced evidence that the virus had split into two strains, including one that was no longer susceptible to the old vaccine and was becoming harder to treat. The CDC developed a new vaccine, replacing the old one that was based on viruses taken after H7N9 emerged in 2013.