Infectious diseases threaten people everywhere. The disease may be AIDS or flu; the cause may be a parasite or fungus. Science and medicine have been engaged in the battle for centuries. Now, one of Washington's newest museums unveils a new exhibit on the science behind infectious diseases and the fight to conquer them.

Interactive display shows how bacteria develop resistance to antibiotic drugs

With a new, high-tech exhibit, the three-year-old Koshland Science Museum turns the focus on infectious diseases - the microbes that cause them and the challenges they present. The exhibit is full of sleek, user-friendly, interactive displays, but that doesn't mean there isn't a lot of serious science behind it.

"We really draw a lot upon research scientists," says Dr. Erika Shugart, curator of the new exhibit. "So for our exhibits we start with a committee of scientists, and we bring them together with museum designers, and they work together to come up with the ideas."

Shugart stresses the rigorous fact-checking behind the displays, which you would expect at a museum that's run by the National Academy of Sciences. But she also says that, when they choose their exhibits, they respond to popular interest.

"And we did poll our visitors, and infectious disease was one of those issues that people were interested about. They hear about bird flu and salmonella and e-coli in the news, and they're curious and they want to know more. And then we also pick areas of ongoing scientific research. We really want there to be cutting edge, interesting research that we can pull upon for the exhibits."

The infectious diseases exhibit includes conventional static displays with informational text and videos on large-format screens, such as one about the challenge of developing an AIDS vaccine.

But perhaps more interesting are the interactive presentations, where museum visitors can try different ways to prevent an epidemic and see how effective they are.

For example, a member of the scientific steering committee, Diane Griffin of Johns

Visitors learn how different control measures effect the spread of malaria.

Hopkins University, stands at an interactive console and explains how different approaches can be used to curtail the spread of malaria in Namawala, Tanzania.

"You can choose one or more of these interventions," Griffin explains, "so we've just chosen bed nets, and you punch another button, and it'll show you how malaria will spread in a situation where there are only bed nets that are used."

The results, which appear house-by-house on an animated video display, follow a sophisticated mathematical model of how different approaches work in controlling the disease. In this case, it takes me some trial and error to learn that it's only when drugs and spraying are used, in addition to bed nets, that this malaria outbreak can be controlled.

Sophisticated mathematical models project the course of an influenza epidemic as museum visitors choose different immunization strategies

Over at another interactive display, visitors can see how different vaccination programs can affect the progression of influenza, again using computer models that project the course of an epidemic, this time in Chicago. It turns out that by vaccinating less than two-thirds of the population, the epidemic is virtually halted.

Bryan Grenfell of Penn State University, another scientist on the steering committee, says it's an illustration of herd immunity, the idea that if you are surrounded by vaccinated people, you are less likely to become infected, even if you are not yourself vaccinated. The display has two graphs. The one on the right shows that almost a million people would become infected if no one got vaccinated.

"If you keep an eye on the left-hand graph now, it actually plateaus" at just 76 infected people, said Grenfell. "And that's because there's enough direct and indirect protection here to mean that the infection isn't going to spread in the population. So that's achieved herd immunity in the population. And this is just talking about infections at the moment, but it's an illustration of the indirect plus the direct effects of vaccination."

There's much more - for example, how bacteria develop resistance to drugs. If you can't get to Washington, there's an online version of the exhibit at the museum's website: www.Koshland-science.org