On April 25, the World Health Organization declared a "public health emergency of international concern" after evidence that a new strain of swine flu had begun spreading from Mexico to other countries.

'There's an information overload situation, where to decide which outbreak to respond to is very difficult.'— John Brownstein, HealthMap

A day later, Veratect Corp., a Kirkland, Wash.-based company announced in a news release that it first detected and started monitoring the outbreak of respiratory illness in Mexico on April 6. That was more than two weeks before WHO issued its first alert on the outbreak.

This week, WHO declared it was too late to contain the disease and stop its spread. As of Friday afternoon, WHO had confirmed 365 cases of the disease in 13 countries around the world.

Could the spread of the virus have been stopped if public health groups had paid better attention online earlier?

"That's the real question," said Dr. Kumanan Wilson, an associate professor of medicine at the University of Ottawa and Ottawa Health Research Institute, who co-authored a recent article about online disease detection tools. The article, published in the Canadian Medical Association Journal in March, showed that there may have been early warning signs on the internet of Canada's summer 2008 listeriosis outbreak.

Organizations like the World Health Organization have also been using electronic tools to monitor for outbreaks, Wilson said. They include the Global Public Health Intelligence Network, developed by Health Canada, which trolls the internet for news reports about diseases, as well as similar tools that are available to the public, such as:

• ProMed, which is run by the Federation of American Scientists.
• HealthMap, which is supported by Google.org, Google's charitable arm.

Wilson said ultimately, public health officials would like to use such tools be able to spot emerging pandemics early enough to isolate affected populations and curb the spread of diseases.

In the case of swine flu, Wilson said, "We weren't able to identify this early enough to effectively intervene."

At the moment, he said, it isn't clear if identification of potential pandemics at such an early stage will ever be possible, even with access to sophisticated online tools.

Earliest reports March 31, April 1

Wilson's co-author on the listeriosis paper was John Brownstein, an assistant professor of pediatrics at Harvard University and former Montrealer who co-created the non-profit Health Map service. The tool mines over 20,000 websites to find disease reports, extracts the text and organizes the information by disease and location.

'A lot of this needs validation … Are you going to get 900 reports for one that's accurate?'— Dr. Kumanan Wilson, University of Ottawa

In fact, Health Map had received its earliest report about the Mexican outbreak on April 1, Brownstein said.

Veratect, one of a few companies in North America that track diseases and civil unrest online for paying clients such as World Vision, claims it tracked the first case of the disease a day earlier.

Brownstein said his team obviously should have been paying closer attention to the mysterious respiratory illness that had affected 60 per cent of people in La Gloria, a town in the Mexican state of Vera Cruz, but similar outbreaks are common worldwide. It's hard to tell if such an outbreak will remain isolated or spread around the world, he added.

"There's an information overload situation, where to decide which outbreak to respond to is very difficult."

His organization does send daily emails to the Centres for Disease Control, the World Health Organization and other health organizations about disease outbreaks it detects, and the internet monitoring is improving, he said.

"The data we're getting is earlier and earlier," he said.

But it's easy to see that public health organizations may have trouble dealing with the flood of reports they receive.

Veratect sent 19,000 alerts in 2 years

Veratect told CBCNews.ca that it has issued 19,000 alerts on disease-related events to international development groups and other clients since it started two years ago. It estimates that it sends an average of two to five alerts per day to the U.S. Centres for Disease Control alone.

In the case of the swine flu outbreak, Veratect CEO Robert Hart said the company noticed and started monitoring the Mexican outbreak on Apr. 6. It warned both the WHO and the CDC on Apr. 16, he said. Four days later, the company decided that wasn't enough and phoned the CDC, Hart told CBC News.

"We became sufficiently concerned from our own experiences with … epidemiology that this is an event that they really needed to pay attention to."

Brownstein said it may be hard for groups such as the WHO and CDC to know what to pay attention to. One problem is that it's hard to tell how reliable the source data is that generated the alerts, Brownstein said.

"I think you need to know where that information is coming from and the user can decide whether to trust it or not," he said.

Veratect said its human analysts uses thousands of data sources and a custom-designed search engine, as well as a variety of search tools available publicly.

"For competitive reasons and their protection, Veratect is unable to share specific information about its sources," the company said in an email.

However, it said it uses information that is quite different than the data normally used by the WHO and CDC, which the company describes as "geared toward epidemiological data."

"While there is great value in their data, it is not geared to provide timely early warnings," the company said.

"In some cases we may have access to data that health organizations don't have the ability to tap into, but I think what is more important is that we are really analyzing the information we receive."

In order to determine whether to send an alert, Veratect uses a threshold that it developed in co-operation with the CDC that considers whether:

• A disease outbreak is severe enough to disrupt the local society, based on evaluation using a proprietary index.
• The outbreak has taken place within 50 kilometres of an international airport with direct non-stop connections to the U.S.

Google, Twitter are new data sources

Meanwhile, an increasing number of data sources have become available, such as Google Flu Trends and other tools that analyze the popularity of certain search terms, as well as social media sites such as Twitter.

Wilson said there's a lot of experimentation right now with those, but it's still not clear how much value they add to the data currently used to detect disease outbreaks.

"A lot of this needs validation," he said. "Are you going to get 900 reports for one that's accurate? It's hard to know."

Brownstein said HealthMap is studying such new data sources. But it doesn't yet release the information gleaned from them publicly, as it is unsure about the reliability. Veratect would not reveal whether it uses such data.

While there remain many issues to consider and work out when using online tools to watch for diseases, Brownstein said he believes the swine flu outbreak represents a "different era" in the world of information flow and communication.

"The speed at which we are receiving data of this outbreak and new reports in different countries, different provinces is just astonishing," he said. "And it's a testament to technology, but also people's openness to share information."