# Healthbeat Report: Tracking a disease

April 30, 2009 One local professor is tracking the latest flu outbreak.

It's information that can help save lives and slow or even stop the spread of the disease. Experts with sophisticated computers and complex mathematical equations are right now tracking the movement of this illness. And the bills in your wallet could be playing a significant role.

Cash may be tight for many Americans but when currency is flowing, no matter how fast or slow, it tells a great deal about people and how they travel. And that information is crucial for researchers like Dirk Brockmann who are mapping out the spread of this new flu.

The Northwestern physicist says currency movement mirrors human movement and knowing where people are going can help predict the spread of disease.

"So in other words if you do cities like Los Angeles and New York and you compute how many dollars travel between these cities maybe this is an indicator of how many people travel," said Dirk Brockmann, Ph.D., physicist, Northwestern University.

So how did they track those dollars? With the help of an internet game called Where's George.com.

Maybe you've seen some bills stamped with the Web site. If you get one of those dollars you can go to the Web site and enter the serial number and zip code where you are located.

The 11-year-old site was started for fun and was not intended to gather scientific information. But the owner shared his vast storehouse of data with Brockmann. That, combined with other mathematical equations, helped in the creation of a map which predicts the worst case scenario for this flu outbreak.

"I'm surprised it's faster than I expected," said Brockmann.

The model is showing that within four weeks around 1700 Americans could be infected with the disease.

About 100 of those cases would be in Chicago. But a map predicts the spread of disease as if no one was doing anything to stop it.

The actual numbers are expected to be lower but public health experts can still use the model to plan strategies for containing the bug.

"I think in one to two weeks we will have an idea of how severe this whole situation is going to be," said Dr. Kenneth Alexander, pediatric infectious diseases, University of Chicago Medical Center. Watch an extended interview with Dr. Alexander

Dr. Alexander says this virus is a hybrid - part pig, bird and human - and the coating or outside of the virus has proteins that many humans have yet to encounter.

"That is why this virus is spreading because our own immune system doesn't recognize these proteins yet," said Dr. Alexander.

But of this infectious disease, specialists say, there is still no need to panic. While we may not know a lot about how this strain will act, Dr. Alexander reminds us that every year the common flu claims the lives of more than 30,000 people.

"Now influenza is a virus we all must respect because every year it does kill but the point is I don't think this new influenza is a tiger with more teeth than the tiger we are use to every winter," said Dr. Alexander.

Professor Brockmann and colleagues began creating models of pandemics in 2004 after the SARS scare in China. They say this flu virus is already showing a much different pattern than past diseases.

Dirk Brockmann
Associate Professor
Engineering Sciences and Applied & Mathematics
Northwestern Institute on Complex Systems
Northwestern University