In mid-2003, a particularly severe avian influenza began to affect birds raised for poultry in parts of Southeast Asia. Within months, it spread to eight countries—an outbreak that was unprecedented in its geographical extent.

The disease remained confined to Southeast Asia until mid-2005, when the virus spread through parts of Central Asia to Europe, Africa, and the Middle East, affecting more than 60 countries in all and leading to the loss of more than 100 million birds.

The outbreaks are largely caused by a novel strain of influenza A. Unfortunately, people are not immune to it. As of March 2007, there were 278 confirmed cases of bird flu in humans, with more than half (168) resulting in death.

For updated information, see the World Health Organization’s website.