Lee De Cola

Mention the profession "geographer" and most people think of mapmakers…or of explorers who study exotic cultures. But the scope of geography has expanded, forming hybrids with some very different fields…including medicine.

When medical geographer Lee De Cola teaches a class, he often brings along a projector filled with the images of dozens of colorful maps, showing how Lyme Disease, West Nile Virus, or some other malady has spread across the United States. Mr. De Cola is one of just a few hundred medical geographers in America, so it is not surprising that he draws puzzled looks from those who ask about his work.

"When I meet people on an airplane," Mr. De Cola explains, "they say, 'Medical geography, that sounds interesting…what's that all about?' All I have to do is tell them, 'Have you seen a map about AIDS recently?' They say, 'Sure.' That's medical geography:" Picking up a phrase from fellow geographer Tim Beach, he calls his field "the Why of Where."

Lee De Cola illustrates a lecture with a medical map predicting the spread of lyme disease in the U.S.

"Everything happens somewhere," notes Mr. De Cola, who is a research scientist at the U.S. Geological Survey. "So when we map it, it becomes much more illuminating to see a map of something, instead of talking about it in the abstract."

Although medical geography became an official specialty area just a few decades ago, its roots may actually be traced to ancient times. Mr. De Cola says it all started with the Greek doctor Hippocrates, known for his Hippocratic Oath, which emphasizes "above all, do no harm."

"Many of the phenomena we now call geography influenced people's health," Mr. De Cola says. "The quality of the water, the atmosphere, what lifestyles people had, what they ate, what health they had was determined by geographic phenomena. Here was a scholar writing 2,000 years ago about the very same issues we're talking about today."

In the mid-19th century, British doctor John Snow used principles of medical geography to locate the source of a cholera epidemic in London. "He showed a map of cases of cholera clustered around a pump that led him to suspect that it was the pump itself that was the source of polluted water that was giving people cases of cholera," Mr. De Cola explains. "That was medical geography. He actually created what we now would call a 'geographic information system.'"

In the 1930s, a group of dental geographers in Colorado found the connection between children drinking naturally fluoridated water and having fewer dental cavities. The crossover has spurred more cooperation between geographers and such health organizations as the U.S. government's Centers for Disease Control and Prevention (CDC). "The collaboration is really growing and it's in its very early stages," says Mr. De Cola. "I was down at CDC last year and realized that not only could we take information about diseases and make maps of it, but we can turn that process around and start asking spatial questions and use spatial information to help organize the information itself."

Spatial forecasting of Lyme Disease in 2005 showing incidence on a blue-red hue spectrum and probability on a saturation gradient

Thus, Lee De Cola and other medical geographers are combining a variety of social, economic and environmental data with the source and spread of disease. "You're collecting information on certain kinds of reports to doctors, pharmaceutical purchases, certain kinds of environmental measurements that are unusual," he says. "Putting all these things together, we [ask], 'Is there something unusual going on here? Is it an outbreak of a mosquito-borne disease? A bio-terrorism event? An oil spill?'"