Remember the old saying that “good artists borrow but great artists steal?” Well, British mathematicians Beggs and Shepherd are stealing a page from the Google powerhouse in hopes of cracking the mystery of how infections spread within hospitals.
Beggs’ colleague, mathematician Simon Shepherd, thinks the PageRank algorithm behind Google’s search engine can help, by ranking routes of infection in the same way it ranks search results.
“Something isn’t working,” Shepherd told New Scientist. “The hand-borne route is the major route, but there are others and we need to know what they are.”
“Our new model is based very much on the way Google has achieved number one status among search engines,” he explains. “When [Google’s] spiders crawl the web they build up a connectivity matrix of links between pages.”
Shepherd’s idea is to build a similar matrix describing all interactions between people and objects in a hospital ward, based on observing normal daily activity.
“Obviously nurses move among patients and that can spread infection, but they also touch light switches and lots of other surfaces too,” he says., “If you observe a network of all those interactions you can build a matrix of which nodes in the network are in contact with which other nodes.”
Shepherd has started testing the technique using data gathered for another study. “We sussed out in one ward that the chief node was a light switch,” he says. “It could potentially distribute infection to the rest of the ward very quickly.”
The PageRank technique will become most useful, however, after the completion of studies estimating the extent to which different interactions transfer bacteria.
Combining that information with the strength of different interactions within a ward makes it possible to calculate which ties to cut – by, perhaps, tougher cleaning – to maximally disrupt the network and cut infections.
“Ultimately, we would like to produce a software tool so managers of wards can carry out the analysis for themselves,” says Shepherd.