Different versions of bird flu have been spreading around the world in recent years.<br /><br />The virus, officially known as H5N1, is believed to have killed millions of wild and domestic birds worldwide. Some other animals have also been infected.<br /><br />The virus infected a very small number of people as well. But, H5N1 largely has remained outside the human population. Most of the few human cases involved direct contact between people and infected birds.<br /><br />Reuters news agency recently explored areas of the world where versions of H5N1 have infected humans.
