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Web searches to help track disease patterns

Miguel Helft

Looks like an early-warning system for outbreaks is here

SAN FRANCISCO: There is a new common symptom of the flu, in addition to the usual aches, coughs, fevers and sore throats. It turns out that a lot of ailing people enter phrases like “flu symptoms” into Google and other search engines before they call their doctors.

That simple act, multiplied across millions of keyboards in homes around the country, has given rise to a new early-warning system for fast-spreading flu outbreaks, called Google Flu Trends.

Tests of the new Web tool from Google.org, the company’s philanthropic unit, suggest that it may be able to detect regional outbreaks of the flu a week to 10 days before they are reported by the U.S. Centres for Disease Control and Prevention.

In February, for example, the CDC reported that flu cases had spiked in the mid-Atlantic States. But Google says its search data showed a spike in queries about flu symptoms two weeks before that report was released.

New service

Its new service at google.org/flutrends analyses those searches as they come in, creating graphs and maps of the country that, ideally, will show where the flu is spreading.

The CDC reports are slower because they rely on data collected and compiled from thousands of health care providers, laboratories and other sources. Some public health experts say the Google data could help accelerate the response of doctors, hospitals and public health officials to a nasty flu season, reducing the spread of the disease and, potentially, saving lives.

“The earlier the warning, the earlier prevention and control measures can be put in place, and this could prevent cases of influenza,” said Dr. Lyn Finelli, lead for surveillance at the influenza division of the CDC Between 5 and 20 per cent of the U.S. population contracts the flu each year, she said, leading to 36,000 deaths on average.

Worldwide

For now, the service covers only the U.S., but Google is hoping to eventually use the same technique to help track influenza and other diseases worldwide. “From a technological perspective, it is the beginning,” said Eric E. Schmidt, Google’s chief executive.

The premise behind Google Flu Trends — what appears to be a fruitful marriage of mob behaviour and medicine — has been validated by an unrelated study indicating that the data collected by Yahoo, Google’s main rival in Internet search, can also help with early detection of the flu.

“In theory, we could use this stream of information to learn about other disease trends as well,” said Dr. Philip M. Polgreen, Assistant Professor of medicine and epidemiology at the University of Iowa and an author of the study based on Yahoo’s data.

Still, some public health officials say many health departments already use other approaches, like gathering data from visits to emergency rooms to keep tabs on disease trends in their communities.

“We don’t have any evidence that this is more timely than our emergency room data,” said Farzad Mostashari, Assistant Commissioner, Department of Health and Mental Hygiene in New York City.

If Google provided health officials with details of the system’s workings so that it could be validated scientifically, the data could serve as an additional, free way to detect influenza, said Dr. Mostashari, who is also chairman of the International Society for Disease Surveillance.

A paper on the methodology of Flu Trends is expected to be published in Nature.

“Collective intelligence”

Researchers have long said that the material published on the Web amounts to a form of “collective intelligence” that can be used to spot trends and make predictions. But the data collected by search engines is particularly powerful, because the keywords and phrases that people type into them represent their most immediate intentions. People may search for “Kauai hotel” when they are planning a vacation and for “foreclosure” when they have trouble with their mortgage. Those queries express the world’s collective desires and needs, its wants and likes.

Internal research at Yahoo suggests that increases in searches for certain terms can help forecast what technology products will be hits, for instance. Yahoo has begun using search traffic to help it decide what material to feature on its site.

Two years ago, Google began opening its search data trove through Google Trends, a tool that allows anyone to track the relative popularity of search terms.

Sophisticated tools

Google also offers more sophisticated search traffic tools that marketers can use to fine-tune ad campaigns. And internally, the company has tested the use of search data to reach conclusions about economic, marketing and entertainment trends.

“Most forecasting is basically trend extrapolation,” said Hal Varian, Google’s chief economist. “This works remarkably well, but tends to miss turning points, times when the data changes direction. Our hope is that Google data might help with this problem.”

Prabhakar Raghavan, who is in charge of Yahoo Labs and the company’s search strategy, also said search data could be valuable for forecasters and scientists, but privacy concerns had generally stopped it from sharing it with outside academics.

Keywords for search

Google Flu Trends avoids privacy pitfalls by relying only on aggregated data that cannot be traced to individual searchers. To develop the service, Google’s engineers devised a basket of keywords and phrases related to the flu, including thermometer, flu symptoms, muscle aches, chest congestion and others.

Google dug into its database, extracted five years of data on those queries and mapped them onto the CDC’s reports of influenza-like illness.

It found a strong correlation between the data and the reports from the agency, which advised it on the development of the new service.

“We know it matches very, very well in the way flu developed in the last year,” said Larry Brilliant, executive director of Google.org. Dr. Finelli of the CDC and Dr. Brilliant both cautioned that the data needed to be monitored to ensure that the correlation with flu activity remained valid. — New York Times News Service

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