Monday, May 07, 2007

Avian Flu: Seeing the Big Picture

Google Earth gives researchers a new perspective on how avian flu is spreading around the world.

By Rachel Ross

Mapping a malady: Researchers used Google Earth to build an interactive map showing how the H5N1 virus has traveled and mutated during the past 10 years. Lines on the map are color-coded to indicate the kind of host, be it waterfowl, raptor, shorebird, or human. Credit: Courtesy Andrew Hill, Daniel Janies, Robert Guralnick, CU-Boulder, Ohio State University, and Systematic Biology.

Multimedia •  View a video of the H5N1 map.

Researchers are using the online mapping program Google Earth to plot the course of H5N1, a troubling form of avian influenza. The 3-D computer graphics show how the virus has spread and changed, moving to new countries and infecting different kinds of creatures. Ultimately, the researchers hope that by looking at the data in new ways they will be able to predict where the next outbreak might occur.

"We're interested in seeing how the virus itself uses different hosts in different times and places, and watching how it mutates," says Daniel Janies, an assistant professor of biomedical informatics at Ohio State University. Janies is also the lead author of a paper on the virtual-mapping project that was published last week in the journal Systemic Biology.

The H5N1 virus is highly contagious in birds. First isolated in 1996, it can also infect other animals and humans. Transmission to and among humans is still rare. But the World Health Organization says that the virus has already killed 172 people worldwide, and researchers worry that H5N1 will mutate to become more infectious in humans, sparking a devastating pandemic. Since 1996, researchers have collected details about reported cases of the virus and created a catalogue listing the different genotypes, or strains. However, much about the virus, such as how different mutations affect its transmission, remains uncertain.

With the Google Earth data visualization project, Janies says, researchers can look at how the more dangerous variants of H5N1 have emerged so that they can develop biological control strategies. Resources to solve the problem are limited, Janies notes, and some potential solutions--such as stopping all migratory birds--are simply impossible. The virtual map could show researchers the best ways to focus their efforts.

"If a picture is worth a thousand words, then a virtual globe is worth a thousand pictures," says Robert Guralnick, an assistant professor at the University of Colorado at Boulder, who worked on the virtual-mapping project.

A web of lines superimposed on the Google Earth globe shows the various genotypes of H5N1. Each line is color-coded to correspond to a kind of host, such as waterfowl, shorebirds, mammals, or raptors. The researchers say that by looking at the timing and location of different known mutations, they were able to investigate different hypotheses about which animals are responsible for spreading the virus.

Andrew Hill, chief architect of the visualization project, says that one question he and his colleagues explored was whether the virus was being moved by migratory birds, such as waterfowl, or nonmigratory ones, such as chickens. "We found that's a really difficult question to answer," says Hill. "It depends on what [geographic] region you're talking about and what year."

The researchers also mapped mutations of two important proteins that are found on the surface of H5N1 and are believed to be involved in adapting the virus for human-to-human transmission. But the researchers were unable to identify a mutation of these two proteins that was associated with a particular bird or mammal.