With all the strange things going viral on the web, it's time to talk about real viruses. These primitive bits of DNA or RNA need a host to survive. They can cause something as simple and annoying as a common cold or as serious as AIDS.
Soundprint, an organization producing educational radio programs has a series called World of Viruses available at http://www.soundprint.org/virus/
The broadcasts cover a wide range of topics including foot and mouth disease, HIV, mosquito-borne viruses, HPV, and the viruses that live in sea water. You can also learn how the epidemiologists of the world track influenza so that they can figure out which strains will cause the next outbreak and prepare appropriate vaccines. So tune in and learn about your microscopic visitors. You know that they are always nearby.