A study of over six million phone users is attempting to explain why we have yet to see a widespread mobile virus outbreak, despite most people in the West now owning at least one mobile phone.

Researchers at the wonderfully named Centre for Complex Network Research at Northeastern University in the US concluded that a 'highly fragmented' market share and the relative scarcity of smartphones has hindered the spread of mobile malware.

The study, published in Science, notes that the chances of a mobile epidemic are increasing as smartphones enjoy a 150 per cent annual growth rate. "We haven't had a problem so far because only phones with operating systems are susceptible to viral infection," explained Marta Gonzalez, one of the authors of the publication.

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"Once a single operating system becomes common, we could potentially see outbreaks of epidemic proportion because a mobile phone virus can spread by two mechanisms: a Bluetooth virus can infect all Bluetooth-activated phones in a 30 metre radius, while a Multimedia Messaging System (MMS) virus, like many computer viruses, spreads using the address book of the device. Not surprisingly, hybrid viruses, which can infect via both routes, pose the most significant danger."

This study uses mobile phone data to create a predictive model of human mobility patterns. It found that Bluetooth viruses will eventually infect all susceptible handsets, but the rate is slow, being limited by human behavioral patterns. This characteristic suggests there should be sufficient time to deploy countermeasures such as antiviral software to prevent major Bluetooth outbreaks.

In contrast, spread of MMS viruses is not restricted by human behavioral patterns, however spread of these types of viruses are constrained because the number of susceptible smartphones is currently much smaller.