
Avian influenza primarily affects wild birds and domesticated poultry. Humans acquire avian influenza viruses chiefly through direct contact of the mucous membranes with secretions or excreta from infected birds or contaminated poultry products. The upper respiratory tract and conjunctivae appear to be the main portals of entry. Influenza pandemics occur when new virus subtypes emerge and become readily transmissible among humans. On average, pandemics occur about 3 or 4 times per century. Avian influenza is not a pandemic influenza. It is not easily transmitted among humans, and it has not been found in the United States. Therefore, at present, the risk to persons in this country is considered low.














































































































































































































































































