WASHINGTON, April 25 (Xinhua) -- The U.S. Centers for Disease Control and Prevention (CDC) has determined that this virus is contagious and is spreading from human to human. However, at this time, it is not known how easily the virus spreads between people.

    How long can an infected person spread swine flu to others?

    People with swine influenza virus infection should be considered potentially contagious as long as they are symptomatic and possible for up to seven days following illness onset. Children, especially younger children, might potentially be contagious for longer periods.