A HOUSEHOLD-BASED, CASE-CONTROL STUDY OF ENVIRONMENTAL-FACTORS ASSOCIATED WITH HANTAVIRUS PULMONARY SYNDROME IN THE SOUTHWESTERN UNITED-STATES

During an outbreak of hantavirus pulmonary syndrome (HPS) in the south western United States, trained environmental assessment teams conducte d surveys at 17 case-patient homes and matched controls from June thro ugh August 1993. Variables related to rodent abundance were quantified and standardized rodent trapping was conducted around and within hous eholds. The majority of households were located in pinon-juniper veget ation zones, and there were no significant differences in the type of house in which cases and controls lived. The only environmental factor that distinguished case households from controls was significantly hi gher small rodent densities (median trap success for case sites = 17.3 %, 12.7% for near controls, and 8.3% for far controls). Frequency of h antaviral infection in deer mice (Peromyscus maniculatus) did not vary significantly among households of cases and controls, with a range of 27.5-32.5% antibody-positive. Indices of rodent fecal contamination w ere slightly higher in case houses. The data indicate that higher rode nt densities were associated with households in which HPS cases occurr ed. Strategies that control rodent numbers and decrease rodent access to dwellings may reduce risk of human infection.