Climatic and environmental patterns associated with hantavirus pulmonary syndrome, Four Corners region, United States

To investigate climatic, spatial, temporal, and environmental patterns asso ciated with hantavirus pulmonary syndrome (HPS) cases in the Four Corners r egion, we collected exposure site data for HPS cases that occurred in 1993 to 1995. Cases clustered seasonally and temporally by biome type and geogra phic location, and exposure sites were most often found in pinyon-juniper w oodlands, grasslands, and Great Basin desert scrub lands, at elevations of 1,800 m to 2,500 m. Environmental factors (e.g., the dramatic increase in p recipitation associated with the 1992 to 1993 El Nino) may indirectly incre ase the risk for Sin Nombre virus exposure and therefore may be of value in designing disease prevention campaigns.