H7N9 is the designation for one subtype of influenza viruses that is sometimes found in birds, but that does not normally infect humans. Like all influenza A viruses, there also are different strains of H7N9.
Beginning at the end of March 2013, China reported human and bird (poultry) infections with a new strain of H7N9 that is very different from previously seen H7N9 viruses.
5-6-13 Human Infections with Novel Influenza A (H7N9) Viruses
Avian Influenza A (H7N9) Virus CDCKCHD Healthcare Providers Flu Page
