Definitions - this outbreak is a
strain of H1N1.
H1N1 is a subtype of influenzavirus A and the most common cause of influenza in humans. Some strains of H1N1 are endemic in humans, including the strain(s) responsible for the 1918 flu pandemic and the many strains that cause influenza worldwide each year. Other strains of H1N1 are endemic in pigs and in birds. The 1918 flu pandemic killed 50–100 million people worldwide from 1918 to 1919.[1]
Low pathogenic H1N1 strains still exist in the wild today, causing roughly half of all flu infections in 2006.[2]
In March and April 2009, an outbreak of influenza in Mexico has confirm 26 cases, and 7 fatalities with the new strain of H1N1 was detected.[3] As of April 28, the new strain was suspected to have infected more than 2,500 individuals worldwide, with 152 attributed deaths (see 2009 swine flu outbreak). The U.S. Centers for Disease Control warned that it was possible the outbreak could develop into a pandemic.[4]
On April 27, 2009, the World Health Organization raised alertness from level 3 to level 4 (max 6) worldwide[5], since (sustained) human-to-human transfer of the virus was confirmed.
http://en.wikipedia.org/wiki/Influen...s_subtype_H1N1