To avoid creating a complex map that looks like "spaghetti thrown on the screen," Janies and colleagues also simplified the map's design. Green lines represent transmission pathways most strongly supported by the research findings. Yellow lines indicate less certainty. Lines also are colored differently depending on whether they indicate an incoming or outgoing virus from a specific location. And users can search for specific transmission routes rather than seeing all transmission events on the map at once.
The maps represent scientists' best approximation of avian flu transmission based on the information available, Janies explained. Without access to every complete genome of every flu virus that ever infected a bird or human, researchers can never fully track evolutionary relationships, genetic histories and specific locations of each outgoing and incoming viral transmission.
"Collect and share as much data as possible and let the data tell the story," he said. "We're honest about the uncertainty our results may have - but even with partial data, we can infer much about a virus in an area based on its sources."
The method has already been applied to studies of the H1N1 flu currently infecting millions of people in the United States. International cooperation spearheaded by the NIH, GISAID and the Centers for Disease Control and Prevention has resulted in ready availability of H1N1 sequences for study.
"With what we have so far, we can see the spread of H1N1 out of the United States and all over the world. There is a different dynamic, in that this is a virus carried by humans, who are cosmopolitan and moving both ways," Janies said. "It's also a virus that has been transmitted all over the world in a matter of months, and it's still similar to its ancestors."
H5N1, on the other hand, has been creeping across Asia and into Europe and Africa for more than a decade and picked up mutations along the way, he noted. While H1N1 has spread more quickly, it is far less deadly to humans than H5N1 - meaning it is still useful for the world to keep an eye on avian flu, Janies said.
His group's visualizations will help make that possible.
The computing power used in this study was supplied by the Ohio Supercomputer Center and the Ohio State University Medical Center. The research is funded by the U.S. Army Research Laboratory and Office, Ohio State's Department of Biomedical Informatics and the Mathematical Biosciences Institute (MBI) at Ohio State.
Janies conducted the work with Rasmus Hovm-ller, Boyan Alexandrov and Jori Hardman of Ohio State's Department of Biomedical Informatics. Hovm-ller is also an investigator in the MBI.
Source: Ohio State University