SUMMARY: Local HIV/AIDS epidemics in some large U.S. cities have reached the status of "generalized epidemic," meaning there is significant HIV transmission outside defined risk groups such as gay/bisexual men and injection drug users, researchers from the Centers for Disease Control and Prevention (CDC) reported at the XVIII International AIDS Epidemic this week in Vienna. They also found that poverty, rather than race/ethnicity per se, is the major demographic factor influencing HIV prevalence among heterosexuals in economically disadvantaged urban areas.

These findings come from interviews with more than 9000 individuals living in "poverty areas" (census tracts where > 20% of residents had household income below the U.S. poverty level, or about $10,000) in 23 cities who took part in the U.S. National HIV Behavioral Surveillance system during 2006-2007. Men who have sex with men, injection drug users, and sex workers were excluded. Overall, about 2% were found to be HIV positive.

Below is a press release from the CDC describing the study and its findings.

New CDC Analysis Reveals Strong Link Between Poverty and HIV Infection

New Study in Low-Income Heterosexuals in America's Inner Cities Reveals High HIV Rates

Vienna, Austria -- July 19, 2010 -- The Centers for Disease Control and Prevention today released a first-of-its-kind analysis showing that 2.1 percent of heterosexuals living in high-poverty urban areas in the United States are infected with HIV. This analysis suggests that many low-income cities across the United States now have generalized HIV epidemics as defined by the United Nations Joint Program on HIV/AIDS (UNAIDS).

UNAIDS defines a generalized epidemic as one that is firmly established in the general population, with an overall HIV prevalence in the general population of more than 1 percent. While subpopulations with higher risk (such as men who have sex with men and injection drug users) may still contribute disproportionately to the spread of HIV in these areas, heterosexual transmission is also sufficient to sustain an epidemic independent of those groups.

The analysis also shows that poverty is the single most important demographic factor associated with HIV infection among inner-city heterosexuals. Contrary to severe racial disparities that characterize the overall U.S. epidemic, researchers found no differences in HIV prevalence by race/ethnicity in this population. The analysis will be presented at the XVIII International AIDS Conference in Vienna, Austria.

"This study reveals a powerful link between poverty and HIV risk, and a widespread HIV epidemic in America's inner cities," said Kevin Fenton, MD, PhD, director of CDC's National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention. "In this country, HIV clearly strikes the economically disadvantaged in a devastating way."

The analysis, led by Paul Denning, MD, a medical epidemiologist in CDC's Division of HIV/AIDS Prevention, included more than 9,000 heterosexual adults (aged 18-50) in high-poverty areas of 23 cities who participated in the 2006-2007 heterosexual cycle of the CDC's National HIV Behavioral Surveillance System. This system monitors HIV risk behaviors, HIV testing patterns, and use of HIV prevention services among U.S. populations at risk.

High-poverty areas were defined according to the U.S. Census Bureau, and included areas in which at least 20 percent of residents have household incomes below the poverty line.

Nationally, the United States is considered to have a concentrated HIV epidemic, meaning that it is confined mainly to individuals who engage in high-risk behaviors, which in the United States are primarily gay and bisexual men and injection drug users.

For this analysis, researchers followed UNAIDS criteria for determining a generalized epidemic, and excluded groups at highest risk for becoming HIV infected. Those groups not included in this analysis were gay and bisexual men -- who continue to represent the majority of new HIV infections in the United States -- injection drug users, and sex workers and their clients.

"These findings have significant implications for how we think about HIV prevention. We can't look at HIV in isolation from the environment in which people live," said Jonathan Mermin, MD, director of CDC's Division of HIV/AIDS Prevention. "This analysis points to an urgent need to prioritize HIV prevention efforts in disadvantaged communities. We are pleased that President Obama's new National HIV/AIDS Strategy reflects this type of approach, in terms of targeting HIV prevention resources to those in greatest need."

Prevalence was especially high in those with the lowest socioeconomic status. Within the low income urban areas included in the study, individuals living below the poverty line were at greater risk for HIV than those living above it (2.4 percent prevalence vs. 1.2 percent), though prevalence for both groups was far higher than the national average (0.45 percent). There were no significant differences in HIV prevalence by race or ethnicity in these low income urban areas: prevalence was 2.1 percent among blacks, 2.1 percent among Hispanics, and 1.7 percent among whites. By contrast, the U.S. epidemic overall is characterized by severe racial/ethnic disparities: the HIV prevalence rate for blacks is almost 8 times that of whites, and the HIV prevalence rate among Hispanics is nearly 3 times that of whites.

The absence of race-based differences in this analysis is likely due to existing high prevalence of HIV in poor urban areas, which -- regardless of race or ethnicity -- places individuals living in these areas at greater risk for exposure to HIV with each sexual encounter.

Authors note that other factors associated with poverty also likely contribute to high HIV prevalence in these settings. Some of these factors include limited health care access, which can reduce utilization of HIV testing and prevention services; substance abuse, which can increase sexual risk behavior; and high rates of incarceration, which can disrupt the stability of relationships.

This analysis provides greater insight into factors that may be driving heterosexual HIV transmission in the United States, which accounts for 31 percent of new infections each year. This study did not examine HIV prevalence among groups at higher risk for HIV in these areas, including MSM and IDU. Nationally, MSM account for 53 percent of new infections, IDU account for 12 percent, and those exposed through both MSM and IDU account for 4 percent.

Investigator affiliations: U.S. Centers for Disease Control and Prevention, Division of HIV/AIDS Prevention, Atlanta, GA.

7/23/10

Reference
P Denning and E DiNenno. Communities in crisis: is there a generalized HIV epidemic in impoverished urban areas of the United States. XVIII International AIDS Conference. Vienna, July 18-23, 2010. Abstract WEPDD101.

Other Source
Center for Disease Control and Prevention. New CDC Analysis Reveals Strong Link Between Poverty and HIV Infection. Press release. July 19, 2010.