Background: The United States has the highest rate of incarceration in the world. Some populations experience both high rates of incarceration and high rates of sexually transmitted infections (STIs).
Methods: To estimate the strength of this correlation, we calculated age-adjusted Pearson correlation coefficients between rates of incarceration and of reportable STIs in the 100 counties of North Carolina in 1999.
Results: Moderately strong correlations were found for chlamydia (r=0.577) and gonorrhea (r=0.521). The correlations between rates of incarceration and reported cases of acquired immunodeficiency syndrome and syphilis were weak (r=0.205 and 0.004, respectively).
Conclusions: Hypothetical causes of the stronger associations included incarceration increasing the number of infected prisoners or the infectiousness of released prisoners; an imbalance in the community sex ratio; and the negative influences of high rates of incarceration on social disorganization and collective efficacy. The magnitude of incarceration as a major force in American society, its association with some STIs, and our lack of empirical data on the potential causal connections argue for a new direction in STI research.