In human history, few things happen only once. Over millennia, even statistically rare events repeat. Yet despite huge efforts to replicate the feat, just once have we eradicated a human disease: smallpox, responsible for over 500 million deaths in the 20th century alone.

Eradicating smallpox was a technological and a human challenge, like many of our toughest global problems (see “Why We Can’t Solve Big Problems”). Technology made it possible to develop freeze-dried vaccine and the bifurcated needle. Hundreds of thousands of humans had to find every case of smallpox in the world, village by village, house by house, and vaccinate every single person exposed to the virus. I was on the smallpox team in India and Bangladesh in the 1970s, and we made over one billion house calls.

Today, we’re close to finally repeating that achievement: polio now circulates in only three countries. But new diseases keep surfacing. Over the last two decades, around 30 have crossed from animals to humans, including SARS and hantavirus. Modernity has increased the risk of a global pandemic. Growing populations and economies lead to deforestation and greater consumption of meat, including bush meat, which increase the likelihood of a virus jumping from animals to humans. Air travel gives viruses free transit across oceans in hours. 

Modernity is also the balm for this ailment. Since 1996, the median time it takes to detect a disease outbreak has fallen from 30 days to 14 days. Digital disease surveillance has greatly improved our ability to find diseases early enough to stop them from spreading.

The first systems to collect “cloud” data on emerging diseases used e-mail, like ProMed, or scoured the Web for evidence, like GPHIN. We can now gather data directly from people exposed to disease. Google’s Flu Trends experiment proved that analyzing how people search for information about flu online beats Centers for Disease Control reporting by up to two weeks. At the Skoll Global Threats Fund we are working on an initiative, Flu Near You, that asks people to answer questions about symptoms via Web or smartphone. That kind of participatory surveillance on mobile devices could help track and tackle diseases around the world.

We now have so much more technology than we did when smallpox was eradicated. We can solve this problem without making a billion house calls. All we need is creativity, commitment, and public will.

Larry Brilliant is president of the Skoll Global Threats Fund, a nonprofit identifying and addressing large-scale risks to humanity.