Increased Risk for Hantavirus Forecasted for Southwestern U.S.

Scientists Use Satellite Images to Predict Risk of 2006 Outbreaks

Scientists from the Johns Hopkins Bloomberg School of Public Health and the University of New Mexico predict that the Four Corners region of the United States (where Arizona, New Mexico, Colorado and Utah meet) will be at greater risk for hantavirus infection this year than in 2005. In addition, they also warned that parts of southern Colorado and north-central New Mexico—previously at low-risk for hantavirus compared to the Four Corners region—will be at increased risk in 2006. The forecast is based on an analysis of satellite imagery and is published in the July 12, 2006, edition of the journal Occasional Papers of the Museum of Texas Tech University. The study is among the first to forecast the locations and extent of infectious disease outbreaks.

Hantavirus pulmonary syndrome is a rare but deadly respiratory disease caused by exposure to a variety of hantaviruses. People contract the virus through contact with rodents and rodent droppings. In 2005, the Four Corners region recorded four cases of hantavirus. The researchers forecast the hantavirus risk in 2006 to be “moderate,” similar in severity to the 6 and 8 cases recorded in the region in 1998 and 1999, respectively.

“The conditions in the Four Corners region tell us that there is a greater risk for hantavirus this year compared to last year,” said Gregory E. Glass, PhD, the study’s lead author and a professor in the W. Harry Feinstone Department of Molecular Microbiology and Immunology at the Bloomberg School of Public Health. “Our study demonstrates that satellite imagery can be used to identify the location and extent of infectious diseases spread by animals.”

To forecast the risk of hantavirus, Glass and his colleagues examined Landsat Thematic Mapper satellite images of the Four Corners region taken in 2005. The images provided information on vegetation growth, soil moisture and other ecological conditions, which Glass and his colleagues previously determined were where mice and hantavirus thrived. They then calculated the level of risk for the region and for specific areas within the region in 2006. Researchers verified the accuracy of their forecast model by comparing their forecasts with actual hantavirus outbreaks going back to 1993, when the disease was first identified in the United States. Their forecasts, based on data from 1993, 1997 and 1998, accurately predicted the actual disease outbreaks for 1994, 1998 and 1999, respectively. Mice were also collected and tested as an independent measure of hantavirus activity.

“We can use this prediction model to target risk reduction information, to inform local health care providers and to work with local and state health authorities on information campaigns,” said Diane Goade, co-author of the study and an associate professor of internal medicine at the University of New Mexico.

“Predicted Hantavirus Risk in 2006 for the Southwestern U.S.” was written by Gregory E. Glass, Timothy M. Shields, Robert R. Parmenter, Diane Goade, James N. Mills, James Cheek, Joseph Cook and Terry L. Yates. Glass and Shields are with the Johns Hopkins Bloomberg School of Public Health. Goade, Cook and Yates are with the University of New Mexico. Parmenter is with the Valles Caldera National Preserve in Los Alamos, N.M. Mills is with the Centers for Disease Control and Prevention and Cheek is with Indian Health Services.

The research was funded by grants from NASA, the National Science Foundation/National Institutes of Health Ecology of Infectious Disease Program and the Centers for Disease Control and Prevention.