Objective: This study examined whether incident cases of pertussis cluster in urban census tracts and identified community characteristics that predict high-incidence areas.
Methods: An ecological study design was used. The study population included all persons diagnosed with pertussis from January 1, 1986, through December 31, 1994. Maps of rates were constructed via a geographic information system and clustering was statistically confirmed. Associations between pertussis rates and community characteristics were tested.
Results: Mapping and statistical analysis revealed spatial clustering of pertussis. Higher age-adjusted rates of pertussis infection were associated with higher proportions of residents below poverty level.
Conclusions: In urban areas pertussis infection clusters in areas of poverty.