ABSTRACT
This report compares rates of selected nationally notifiable diseases in the 100 most populated counties to overall U.S. rates. We analyzed data from the 2004 National Notifiable Diseases Surveillance System (NNDSS) maintained by CDC. Notifiable diseases reports, collected by the states and U.S. territories, are transmitted to CDC in an agreement with the Council of State and Territorial Epidemiologists. By using the Bureau of Census population estimates, we calculated and compared rates. Rates were higher in the most populated counties for six of the nine conditions examined in comparison with national rates: chlamydia (rate ratio:1.2), gonorrhea (rate ratio: 1.2), syphilis (rate ratio: 1.7), hepatitis A (rate ratio: 1.2), hepatitis B (rate ratio: 1.1), and shigellosis (rate ratio: 1.2). The incidence rate for Lyme disease was 40% lower among populated counties (rate ratio: 0.6). Incidence of infectious diseases is different in the most populated counties, and prevention programs should consider local occurrence.