Background:
As part of a strategy to reduce disease incidence and sequelae of undetected infections, Philadelphia screening and treatment efforts have expanded beyond traditional venues to include District Health Care Center clinics, Family Court, Adult Prisons, the Youth Study Center of the Philadelphia Corrections System, and Health Resource Centers in selected high schools. In 2003, a citywide screening program including all Public High Schools was also implemented.

Objective:
To examine the temporal association between increased screening efforts and changes in CT morbidity over time, and to identify screening venues with the highest positivity rates

Method:
For each screening venue supported by the Philadelphia Department of Public Health's STD Control Program, we determined positivity rates by venue for years 2000 thru 2005. We then evaluated associations between the temporal trends in positivity and site type, test type, and the age and sex of the site's target screening population.

Result:
While the total number of PDPH CT screening tests has consistently increased from 108,893 in 2002 to 154,612 in 2004, reported morbidity peaked in 2003 with 17,747 cases. In 2004, we first saw a significant decline in morbidity despite expanded testing; this decreasing trend continues through 2005. Data stratified by venue will also be presented.

Conclusion:
Expanded screening initially resulted in higher morbidity as previously undiagnosed infections were detected and treated, but CT morbidity is now decreasing substantially even though increased screening activities have been sustained. We expect to see a further decline in adolescent positivity as a result of the high school screening program and the continued participation of sites with large adolescent populations.

Implications:
By targeting populations with higher prevalence and identifying venues that yield the highest number of previously undetected cases, STD screening programs can better focus their efforts to achieve a greater impact on the prevalence of chlamydia.