Facebook follows in the footsteps of Twitter, Google and other prominent Web 2.0 sites by introducing an application for tracking swine flu, the much-publicized pathogen that has killed dozens of people in Mexico and potentially infected hundreds more worldwide.

Facebook is utilizing its Lexicon tool, which traces the occurrence of certain words and phrases on its users’ Walls over time, as a possible way to monitor the impact – or at least discussions about – the disease.

A chart on the site shows a spike in discussion of swine flu over the weekend, accompanied by maps of the United States, Canada and the United Kingdom showing the percentage of users utilizing flu-related terms in discussions. Perhaps unsurprisingly, three areas of the United States in which swine flu has been reported – Texas, California and New York – show particularly heavy amounts of activity.

Other sites have been using their collective activity to trace the pathogen, including Google Flu Trends, a service of Google.org that uses aggregated search queries to follow general flu spread across the United States. Given the overall nature of its monitoring, which Google claims is two weeks after than "traditional flu surveillance systems," and the small number of confirmed swine flu cases, Google Flu Trends rates the flu activity in the United States as "low."

On April 29, Google rolled out a Mexico-specific version of Google Flu Trends, mapping the possible pandemic across that country’s states. While the overall flu activity for Mexico is "low," certain areas such as Oaxaca have been displaying "moderate" amounts of flu-related search activity.

"In response to recent inquiries from public health officials, we've been attempting to use Google search activity in Mexico to help track human swine flu levels," Jeremy Ginsberg and Matt Mohebbi, software engineers for Google, wrote on the Google Blog on April 29. "Experimental Flu Trends for Mexico is, as you might have guessed, very experimental. But the system has detected increases in flu-related searches in Mexico City (Distrito Federal) and a few other Mexican states in recent days."

The system, the engineers caution, is somewhat rougher than the original, U.S.-based version of Google Flu Trends.

"In the United States, we were able to validate our estimates using data from a surveillance system managed by the U.S. Centers for Disease Control and Prevention (CDC)," Ginsberg and Mohebbi wrote. "We have not verified our data for Mexico in the same manner, but we've seen that Google users in Mexico (and around the world) also search for many flu-related topics when they have flu-like symptoms."

The Mexico model takes into account the searches for "swine flu" generated by the merely panicked or curious, and attempts to filter for those queries more likely to have been entered by users experiencing symptoms of the disease.

Google Maps has also been enlisted by individuals to follow the virus' spread, while Twitter's real-time feed has seen a surge in people commenting on the flu and its implications. Wikipedia and the CDC feature regularly updated posts, along with information about treatment and prevention.

Some pundits are debating whether social-networking tools such as Twitter help by informing people of the latest news, or aggravate the situation by presenting a real-time forum for spreading panic.

Technically known as swine influenza A (H1N1), the virus manifests itself in symptoms that range from fever, muscle aches, headaches and cough to diarrhea and vomiting. Regular strains of the flu kill between 250,000 to 500,000 a year, but the swine flu has drawn particular attention due to the fact that, unlike those seasonal viruses, its victims have tended to be healthy adults as opposed to infants or the aged.

While questions remain as to whether swine flu will cause widespread devastation, research firm Gartner estimates that an actual pandemic could cause absenteeism rates of 40 percent or higher for the enterprise and smaller businesses.

"IT managers should meet with senior executives, line-of-business managers and other high-level decision-makers to answer any questions should be made aware of the seriousness of this pandemic preparation," Roberta Witty, research vice president at Gartner, said in a statement. "IT managers should plan, test and add capacity to ensure the sustainability of what is likely to be a predominantly work-at-home environment."