Most people turn to Google to search for news on Justin Bieber, baseball scores, and who got kicked off Top Chef last night. But users of the search engine also turn to Google for medical advice, typing in symptoms and conditions as a sort of pre-screening tool before making the call to the doctor’s office. These health-related searches inspired the creation of Google Flu Trends, an official tool of the website that estimates influenza incidence and spread via the dynamics of searches for flu symptoms, medications, and other related terms. With some complicated mathematics, Google developed a formula predicting flu activity that closely matched actual surveillance data, an achievement deemed worthy of publication in Nature.
The success of Google Flu Trends have prompted scientists to wonder if other diseases can be similarly watched by tracking search engine data. But while everyone knows about the flu (even if it is often mistakenly blamed for illnesses caused by other bugs), more obscure diseases might not be as easily captured by such a strategy. Take the case of methicillin-resistant Staphylococcus aureus, the medical mouthful better known as MRSA. Though MRSA is the most common cause of human infections, with 94,000 cases in 2005, it isn’t usually part of the layperson’s medical vocabulary. But because the CDC surveillance system for MRSA only covers 9 sites, a team of researchers from the University of Chicago and the University of Colorado set out to see if Google searches would suffice as a higher resolution alarm system for public health observers.
“If we had a comprehensive, linked electronic-health-records system that researchers had access to, we wouldn’t need it,” senior author Diane Lauderdale, professor of epidemiology, told Wired. “There are systems like that in Scandinavian countries, where you can analyze disease factors in all kinds of ways. But you can’t do that in the U.S.”
As reported in Emerging Infectious Diseases, Lauderdale, Vanja Dukic and Michael David measured the frequency of Google searches for “MRSA” and “staph” (because many news stories refer to the bacteria as drug-resistant or antibiotic-resistant staph) between 2004 and 2008. The group also charted appearances by MRSA in the media, to control for the influence of the news upon searches, and used data from a consortium of hospitals to serve as a measure for MRSA hospitalizations over the time period. Other challenges, such as the frequent mis-spelling of “mersa” and the infrequent correct spelling of “methicillin” were also taken into account.
The data showed a steady rise in the number of searches for MRSA, staph, and even “mersa” that mirrored the increase in hospitalizations for MRSA over that same time period. Surprisingly, media reports about the drug-resistant bacteria were not very influential on the number of searches, except for the coverage of a 2007 CDC report that MRSA caused nearly 19,000 deaths in the year 2005 – which prompted a spike of Googling. As such, the team was able to create a model using the Google queries that predicted the rate of MRSA hospitalization with considerable accuracy, as reflected by the red and pink lines in the graph above.
Interestingly, Google searches for MRSA steadily increased at the same time as one group of MRSA infections declined. A study published last year examining the rates of hospital-acquired or health care-associated MRSA cases found a reduction from 2005 to 2008 as medical facilities stepped up preventative measures against the bacteria. The Google trend may thus reflect increases in the more alarming community-acquired form of MRSA, as spotlighted in Maryn McKenna’s Superbug. With a new prediction model, public health experts can keep an eye on the search engine trends to try to pinpoint outbreaks, even on a local level, before patients begin arriving in hospital emergency rooms with severe infections.
“If we knew the rate was two or three times higher in one city than another, that could be an influence on public health campaigns,” said Lauderdale in Wired.
Dukic VM, David MZ, Lauderdale DS. Internet queries and methicillin-resistant Staphylococcus aureus surveillance. Emerg Infect Dis. 2011 Jun