The HIV Epidemic: High-Income Countries

Abstract

The HIV epidemic in higher-income nations is driven by receptive anal intercourse, injection drug use through needle/syringe sharing, and, less efficiently, vaginal intercourse. Alcohol and noninjecting drug use increase sexual HIV vulnerability. Appropriate diagnostic screening has nearly eliminated blood/blood product-related transmissions and, with antiretroviral therapy, has reduced mother-to-child transmission radically. Affected subgroups have changed over time (e.g., increasing numbers of Black and minority ethnic men who have sex with men). Molecular phylogenetic approaches have established historical links between HIV strains from central Africa to those in the United States and thence to Europe. However, Europe did not just receive virus from the United States, as it was also imported from Africa directly. Initial introductions led to epidemics in different risk groups in Western Europe distinguished by viral clades/sequences, and likewise, more recent explosive epidemics linked to injection drug use in Eastern Europe are associated with specific strains. Recent developments in phylodynamic approaches have made it possible to obtain estimates of sequence evolution rates and network parameters for epidemics.

Figure 1.

Dates of likely introductions of HIV to various parts of the world since the 1960s.

Figure 2.

Proportion of men who have sex with men who had gonorrhea and chlamydia (top) and syphilis (bottom) in the STD (sexually transmitted disease) Surveillance Program of the Centers for Disease Control and Prevention (CDC), United States, 2009.

Figure 3.

Proportion of urethral Neisseria gonorrhoeae isolates obtained from men who have sex with men attending sexually transmitted disease clinics from the Gonococcal Isolate Surveillance Project (GISP), Centers for Disease Control and Prevention (CDC), United States, 1990–2009.

Figure 4.

Diagnoses of HIV infection among adolescents and adult males by transmission category (top; all ages) and race/ethnicity (bottom; ages 13–24 years), Centers for Disease Control and Prevention (CDC), 37 states and five dependent areas of the United States, 2005–2008.

Figure 5.

This is a model of how we estimate that only 26 of each 100 HIV-infected people in the United States are virally suppressed such that they would be expected to have a very slow disease progression and would be minimally infectious to others. Based on Centers for Disease Control and Prevention (CDC), United States, 2009 estimates of the proportion of HIV-infected persons in the United States who know their HIV-seropositive status (79%), the proportion of those persons who are linked to HIV care (60%), and the proportion of them who are virally suppressed (55%), this is a cascade model of the overall number of 100 HIV-infected persons who are currently immunologically suppressed (only 26). (From Burns et al. 2010.)