Environmental and life-style risk factors for Lyme disease in children.

Risk factors for Lyme disease and/or infection with Borrelia burgdorferi in children are not defined. A case-control study was performed using Lyme disease patients from our Lyme Clinic population. Age- and sex-matched controls from the same neighborhood were identified by the Lyme patients' families. A site visit was made to each case/control neighborhood. Twenty-four environmental variables, especially the ecologic characteristics of the home environment were examined. Forty-five items were surveyed by parent questionnaire, including certain "high-risk" activities and behaviors, whether ticks or certain animals were present on the property, and whether antitick measures were used. Control subjects had serologic assays for antibodies to B. burgdorferi. Forty-four Lyme disease patients and 44 well-matched control subjects participated; 2 controls were seropositive. Significant associations with Lyme disease were found for deer ticks in the home environment, ground cover containing moist humus, and leaf litter in the yard. Among the 45 items related to life-style, there was no correlation with Lyme disease for the use of any antitick measures or for any childhood activities; in fact, an inverse correlation was observed for camping and fishing. We conclude that conditions in the immediate home environment, including certain ecologic factors that favor the presence of Ixodes ticks, are associated with an increased risk for Lyme disease in children.