Viral and Rickettsial Zoonoses Branch, Special Pathogens Branch, Division of Viral and Rickettsial Diseases, and Division of Field Epidemiology, Epidemiology Program Office, Centers for Disease Control and Prevention, Medical Entomology/Ecology Branch and Bacterial Zoonoses Branch, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, Navajo Area Indian Health Service, Office of Environmental Health and Engineering, Epidemiology Branch, Indian Health Service Headquarters, Department of Immunology and Infectious Diseases, Johns Hopkins University School of Hygiene and Public Health, Atlanta, Georgia
During an outbreak of hantavirus pulmonary syndrome (HPS) in the southwestern United States, trained environmental assessment teams conducted surveys at 17 case-patient homes and matched controls from June through August 1993. Variables related to rodent abundance were quantified and standardized rodent trapping was conducted around and within households. The majority of households were located in pinon-juniper vegetation 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 higher small rodent densities (median trap success for case sites = 17.3%, 12.7% for near controls, and 8.3% for far controls). Frequency of hantaviral 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 were slightly higher in case houses. The data indicate that higher rodent densities were associated with households in which HPS cases occurred. Strategies that control rodent numbers and decrease rodent access to dwellings may reduce risk of human infection.