CDC Travelers Handbook (Yellow Book)

[hawkeye]

Influenza section now includes information about avian and pandemic influenza

The public health threat of a pandemic arising from novel influenza subtypes, including influenza A (H5N1), becomes imminent only if the virus gains the ability to spread efficiently from one human to another. Such transmission has not yet been observed with the currently circulating A (H5N1) viruses. However, a few cases of limited person-to-person spread of H5N1 viruses have been reported as of 2006, and no instances of transmission continuing beyond one person are thought to have occurred (for current information see http://www.cdc.gov/flu/avian/ gen-info/avian-flu-humans.htm). Since human infections with avian H5N1 viruses were first documented in 1997, no sustained human-to-human transmission has been documented. However, because influenza A viruses have the ability to constantly undergo change and may gain the ability to spread easily between people, monitoring for human infection and person-to-person transmission is an important component of pandemic preparedness (2).

http://wwwn.cdc.gov/travel/yellowBookCh4-Flu.aspx