Germs can spread through the inhalation of infected airborne sneeze droplets or through direct contact, such as by shaking hands. But some 80 percent of flu cases are contracted by touching an infected object.

Most germs, including the influenza virus, can survive for only about five minutes on your hands, but they can live for up to two days on phones, keyboards, mice and other surfaces.

Most people fear germs from shaking hands, flying in airplanes or touching bathroom doorknobs. But the dirtiest objects for office workers are phones, desks, keyboards and mice, which have orders of magnitude more germs than anything else you're likely to come in contact with at work.

Several studies conducted in the past few years at the University of Arizona found that telephones are the most germ-infected objects in our lives, followed by desktops, water fountain handles, microwave door handles, keyboards and mice. (Famously, these studies, headed by microbiologist Charles Gerba, revealed that keyboards have 400 times more bacteria than an average toilet seat.) Here are the relative germ densities of frequently touched office equipment:

- Phone: 25,127 germs per square inch