British scientists are hoping to use the location, or 'geo', information that is increasingly a part of mobile internet and phone usage, to track the spread of infectious diseases and so provide important clues about how quickly a pandemic might occur and also provide data with which epidemiologists can work.
They provide details in the current issue of the International Journal of Healthcare Technology and Management.
William John Knottenbelt of Imperial College London and colleagues there and at Edinburgh Napier University, explain that the precision of location tracking technology, such as that used by GPS, global positioning system, has improved greatly over the last few decades. They have now demonstrated that by tracking the locations of individuals in a closed environment, it is possible to record the nature and frequency of interactions between them. This information could be used to predict the way in which an infection will spread throughout such a population, given parameters such as transmission and recovery rates.
From the launch of GPS system in 1978, through wireless technologies such as Wi-Fi and Bluetooth, to mobile phone network assisted GPS and radio frequency identification tags (RFID tags), and ultrawideband the accuracy of real-time location tracking has increased to better than 10 metres and beyond. Location tracking systems are already being used to keep tabs on at-risk patients, who need constant monitoring to protect their safety and to monitor the whereabouts of employees working in extreme or dangerous environments.
As such the team has developed a software package that can record and playback location data with high-precision. The software then uses SIR modelling (S (for susceptible), I (for infectious) and R (for recovered)) and the epidemiological technique of contact tracing in order to predict the spread of a disease through a network of people.
Many diseases are transmitted through intimate personal and sexual contact, others through simply being in the same space as someone space as someone carrying an airborne infection. Sexually transmitted infections (STIs) are relatively easy to track and to trace partners who may have subsequently been infected but until recently its has been almost impossible to study the route an airborne infection might take from nose to hand to door handle to hand to another nose, for instance. With location-based services in handheld devices such as smart phones it is now possible to track the path of an infected person and their contacts with one metre accuracy.
The team points out that such a system would give emergency health providers a way to prioritise those who may have come into contact with an individual exposed to a serious illness, such as influenza or a currently unknown emergent disease. During an outbreak, information about contact between individuals could be used to produce a list ordered by probability for all people in a given location depending on contact with known cases of infection. Another application might be to trace the origin of an infection in a close environment, such as a hospital.
"As a proof of concept, the combination of the high precision location tracking hardware and the software that we have designed is a success. Our experiments show that, in a test environment at least, the hardware is capable of producing location readings that are sufficiently accurate to monitor the movement of individuals, to the extent that a contact tracing study that provides meaningful results can be performed," the team concludes.
- Andrew Michael Mason, Nicholas John Dingle, William John Knottenbelt. Modelling infection spread using location tracking. International Journal of Healthcare Technology and Management, 2010; 11 (6)
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