This year, Calisher is finding high numbers of antibody-carrying mice. Recently, examination of Western Slope mice showed that 40 percent were infected, while at Pinon Canon Maneuver Site in southeastern Colorado near Rocky Ford, where rates of infected mice usually hover near 1 percent, the 1999 level has been as high as 8 percent. A retired 27-year veteran of the Centers for Disease Control, Calisher was brought to CSU by microbiologist Barry Beaty and shortly afterward began the hantavirus project. He is assisted by mammalogist Jeff Root and by visiting scholars and graduate students. Their work, supported by the Centers for Disease Control, is the first long-term study of hantaviruses and their rodent carriers in Colorado.
Similar efforts are under way in New Mexico and Arizona.
Calisher spends about three days every six weeks at each site, passing on the Western Slope sites in winter. His sites consist of 12 lines of 12 traps each, the lines radiating from a center trap like wheel spokes. This arrangement helps track mouse movements. Calisher, Root and associates bait the traps and check them daily. Donning respirators, gloves and surgical gowns, the team examines all trapped animals before releasing them.