The CDC also updated its estimates of the percentage of individuals infected with HIV who were unaware of their infection [11
]. The number of undiagnosed HIV infections was calculated by subtracting diagnosed AIDS prevalence and diagnosed HIV prevalence from the estimated overall HIV prevalence. This new analysis indicates that ~1 in 5 people living with HIV in 2006 (21%, or 232,700 total persons) were unaware of their infection. Whites had the lowest percentage of undiagnosed infections (18.8%) compared with Hispanics/Latinos (21.6%), blacks/African Americans (22.2%), American Indians/Alaska Natives (25.8%), and Asians/Pacific Islanders (29.5%). Persons with a behavioral risk of IDU had the lowest percentage of undiagnosed infections (female, 13.7%; male, 14.5%) compared with a rate of 26.7% in men exposed through heterosexual contact and 23.5% in MSM.
A recent analysis of data from the North American AIDS Cohort Collaboration on Research and Design examined the CD4 cell level at first presentation for HIV care at >60 HIV/AIDS clinical care sites in the United States and Canada [12
]. This analysis showed that the median CD4 cell count at first presentation for care was only 235 cells/μL (interquartile range [IQR], 175–426 cells/μL) in 1996, with a relatively modest increase to 327 cells/μL (IQR, 142–528 cells/μL) by 2007. There was remarkable homogeneity geographically across the United States and Canada in the percentage of HIV-infected patients presenting late into care. In one of the participating cohorts where the data were available, the diagnosis of HIV infection itself occurred at a median of <200 days prior to the patients’ first presentation for care, suggesting that the actual diagnosis of HIV infection occurs almost as late as their initial presentation for care [13
In an attempt to diagnose and treat HIV infection earlier than is currently the case, the CDC has recommended universal testing for HIV during routine medical care to identify individuals with HIV/AIDS and link them to HIV-specific medical services [14
]. The recommendations specify routine testing for all Americans aged 13–64 years (persons aged ≥64 years should be counseled to receive HIV testing if they have risk factors for HIV infection). Routine testing is intended not only to identify persons who are unaware that they are HIV infected but also to remove the stigma of being tested.
Unfortunately, many persons who already know they are HIV positive are not sufficiently engaged in care or treatment. Research conducted in 2003 suggested that only slightly more than half of all people living with HIV/AIDS in the United States who were eligible for antiretroviral treatment were receiving it [15
]. A study of 16 sites funded through the Ryan White CARE Act to locate “hard-to-reach” people living with HIV/AIDS found that 42% of those individuals were not receiving antiretroviral treatment [16
]. This study also found that marginalized groups (including racial/ethnic minorities, nonprescription drug users, and those who are poor, uninsured, and/or homeless) were less likely to be receiving HIV care than the general population of people living with HIV/AIDS if they had low CD4 cell counts. In a recent study combining national prescription data with CDC HIV prevalence estimates, it was estimated that as many as 314,000 individuals who have been diagnosed as being HIV infected are not receiving HIV care [17
]. If correct, this number exceeds the number of individuals estimated by the CDC to be infected with HIV but unaware of their infection.
In summary, the HIV epidemic in the United States has not abated. Contemporary antiretroviral therapy does prolong life, and the prevalence of HIV-infected individuals in the United States is higher than ever before. The data indicate that at least 50,000 new HIV infections will continue to be added each year, one-fifth of persons with new infections may not know they are infected, and a substantial proportion of those who know they are infected may not engage in HIV care. The demography of HIV infection has changed over time, with the poor, minority racial/ethnic groups, and women accounting for a greater proportion of infections than ever before. MSM remains an important risk factor for transmission, and heterosexual contact is responsible for an increasing proportion of new infections. Although HIV infection remains predominantly an infection of young people, there are a growing number of men and women aged ≥50 years who are infected. This number will grow as the HIV-infected population ages on effective antiretroviral therapy.
The challenges of early diagnosis of HIV infection and early engagement in HIV care are multiple, and a number of barriers must be overcome. Systemic barriers can affect anyone and include resource constraints to conduct testing [18
], lack of primary care provider training in HIV testing and counseling [19
], linking newly diagnosed persons to HIV care [22
], and state legal barriers [25
Some barriers may be specific to a demographic group. Among blacks/African Americans in the United States, lack of medical insurance and limited access to health care, poverty, and drug use are particular barriers [27
]. In women, competing subsistence needs (ie, going without care because money is needed for food, clothing, or housing or postponing care because of lack of transportation) and unmet needs for basic necessities such as child care are particular barriers [28
]. In some women, HIV infection may be a less immediate and pressing problem than other problems attendant to depression, drug use, sex trading, and a lack of adequate familial or social support [29
Fear of stigma associated with a diagnosis of HIV infection also puts many African American communities at a high risk of HIV infection and prevents infected individuals from identifying and seeking HIV care [27
]. Many at risk for HIV infection have a fear of the stigma that is greater than their desire to know their status, choosing instead to hide their high-risk behavior rather than seek counseling and testing. Therefore, they continue to be at risk and may infect others [30
]. Many of the same barriers that affect blacks/African Americans also affect Latinos in the United States. In addition, some Latinos face additional unique challenges, including language barriers, cultural values that may impede acknowledgment of risk behaviors (eg, machismo), and migration among those born outside the United States [31
These challenges and the best practices to link HIV-infected individuals to care are explored in the remaining papers in this supplement.