W.H.O.special adviser Keiji Fukuda said last week that the virus has continued to act in some ways like seasonal flu.

VOA: special.2009.11.11

Frank Ruhli says studies like this can prove useful in the fight against H1N1, another form of the influenza virus.

VOA: special.2010.06.29

The new study shows that happiness spreads through social networks like an emotional virus - a virus people would be happy to catch.

VOA: special.2009.01.21

These are areas like Afghanistan where more than one kind of polio virus exists.

VOA: special.2010.01.18

"My April results, like the three previous ones, registered a negative outcome for the HIV virus."

VOA: standard.2010.04.26

It's like a virus. It can be communicated to other people."

VOA: standard.2010.07.20