ATLANTA -- Officials at the Centers for Disease Control and Prevention are concerned about a different kind of virus: a computer one.

Hackers broke into the CDC's Web site last week and planted a virus that could have infected visitors' computers. CDC officials said the hacking was concentrated to the agency's podcast site -- which has audio and video clips on a variety of public health topics -- and they do not think any sensitive information was compromised.

The podcast site, www.cdc.gov/podcasts, will be down for a few days.

CDC officials encouraged visitors to the site to scan their computers for viruses. CDC spokesman Tom Skinner said the podcast site received several hundred visits in the few hours between when the virus entered the system on Thursday and when the site was deactivated.

The podcast site was launched in July and has received about 40,000 visits, he said.