China says investigating human-to-human spread of bird flu

BEIJING (Reuters) - China is investigating the possibility of human-to-human transmission of a new strain of bird flu that has killed 17 people and is examining "family clusters" of people infected with the virus, a top health official was quoted as saying.

Authorities have slaughtered thousands of birds and closed some live poultry markets to slow the rate of human infection. But many aspects of this new variety of bird flu remain a mystery, particularly whether the H7N9 strain is being transmitted between people.