Bird flu is making a comeback, although no cases have been seen in the U.S.
The World Health Organization is warning that a mutant strain of avian flu, immune to current vaccines, has taken human lives in Asia. They're expecting it to spread to China, India, and Vietnam, among other places.
Those most at risk are people who work with poultry.
Bird flu has not been seen much since an outbreak in 2003 and now the W-H-O is asking nations to increase their surveillance and to take preventive steps where needed.
Find out more, including symptoms: