"Despite prevention efforts, some groups of people are affected by HIV/AIDS, viral hepatitis, STIs, and TB more than other groups. The occurrence of these diseases at greater levels among certain population groups is often referred to as a health disparity. Differences may occur by gender, race or ethnicity, education, income, disability, geographic location, and sexual orientation. Social determinants of health like poverty, unequal access to health care, lack of education, stigma, and racism are linked to health disparities. Health in the United States is a complex and often contradictory issue. As one of the wealthiest nations, the United States fares well in health comparisons with the rest of the world. However, the United States also lags behind almost every industrialized country in terms of providing care to all its citizens."