Researchers at Tel Aviv University have developed a Facebook application called PiggyDemic that allows users to "infect" their friends with a simulated virus or become infected themselves. The resulting patterns will allow researchers to gather information on how a virus mutates, spreads through human interaction, and the number of people it infects.

Scientists use mathematical algorithms to determine which virus will spread and how, but this method has some flaws. It assumes that a virus has equal distribution across populations, but that is simply not the case, the researchers say. Patterns of social interaction must also be taken into account.

Once added to a user's Facebook account, PiggyDemic follows the user's newsfeed to determine the people they interact with. Users are deemed "susceptible," "immune" or "infected" with various simulated viruses, and can pass them on to their online contacts. Researchers then follow these interactions using network visualization software, and watch the links between users as the "viruses" are passed on.