Yes clean your pc ,iam not talking about formatting it or cleaning it from viruses.Clean your computer physically.
Keyboard and mouse can spread diseases if you do not clean them regularly and in a proper manner.and even the mouse .You are at great risk if you eat while using computer. Flu , influenza and other diseases can be easily spread by touch.Dangerous bacteria can badly affect specially if you are using a shared computer .
Not only keyboard or mouse you should also clean the screen regularly .
The following can stuck in your keyboard by consistent use
Dead skin cells
Solid food particles
If you use a shared computer, other users may also spread contagious skin diseases on your keyboard.
Now its time to combat,i mean its time to clean the PC.
For internal cleaning of Central processing unit you should use blower and in small areas toothbrush is best.Please do not use vacuum cleaner it can damage the circuitry of system.For cleaning of monitor many products (sprays) are available but you can easily use wet towels.For keyboard and mouse use cotton buds to clean through spaces and if dust is hard to remove you can use wet cloth to soften it and then remove by toothbrush.