How are viruses spread?
Computer viruses are spread in ways similar to human viruses: through an exchange of germs via contact. Most people exchange computer information in time intervals on the order of minutes, hours or days. Furthermore, information is sent to a relatively small group of people. A user might send messages with attachments (usually documents) to an average of three people roughly every 33 minutes during business hours. While these figures may not be typical of most users, they’re plausible and are corroborated by the (relatively) slow spread of most computer viruses.
Viruses are easily spread through personal contact. When an infected person sneezes, coughs or even speaks, microscopic droplets containing a virus can be expelled. These droplets can infect others when transferred via contact (e.g., hands, doorknobs, etc.) and subsequently absorbed through the eyes, nose or mouth. Active viruses can remain living outside a body for up to 48 hours or more if moisture is present.
