A fish can catch virus from water or fish
A human can catch virus from
Water
Air
Food
Animals
Birds
Humans
A iPhone or computer can catch virus too
From another
Phone
Computer
Internet
Humans?
Birds- not likely yet
Keep yourself away from emails from strangers and downloading unnecessary stuff and unsecured hot spots or WiFi connection to avoid viruses.
For desktops use Microsoft Security Essential on regular basis which is free security program. Regular Windows updates also help protecting from viruses.
As a rule of thumb: Don't talk and share with strangers anything to remain safe....dame is true for your computers and iPhones.
Safe surfing....,,,
A Contagious Computer Virus That Spreads via Wi-Fi http://feeds.gawker.com/~r/gizmodo/excerpts/~3/vwcNXd6Mb1Q/a-contagious-computer-virus-that-spreads-via-wi-fi-1531496826