"Although the amount of social capital in a particular society previously has been correlated with violence and mortality, its relationship to infectious diseases has received little attention," said David Holtgrave, Ph.D., professor of behavioral science and health education in Emory's Rollins School of Public Health, and one of the study investigators. "In making that connection for the first time, we found that social capital is a very good predictor of infectious diseases including AIDS and sexually transmitted diseases, as well as a predictor of adolescent risk for these diseases."
In 1999, in 48 of 50 states (excluding Alaska and Hawaii), the investigators examined the relationship between social capital, poverty and income inequality, AIDS case rates and STD rates (syphilis, gonorrhea and chlamydia). They found that social capital was a significant predictor of all four diseases, explaining between 25% and 45% of the variance in the rate of each disease. They also found that social capital was a significant predictor of 10 out of 14 behavioral variables, including current sexual activities, early sexual debut, and greater number of partners. Poverty and income inequality were much less strong predictors of these disease and behavior outcomes.