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Human immunodeficiency virus (HIV) infection and the immune impairments it can lead to (acquired immune deficiency syndrome or AIDS) continue to be leading causes of morbidity and mortality globally. As of 2015, AIDS continues to be a top-ten cause of death among many low-income countries,1 and HIV infection continues to be a major public health problem worldwide, particularly among certain risk groups. Significant advancements have been made in our understanding of HIV prevention and treatment in recent years; however, the HIV/AIDS epidemic continues to present numerous unique behavioral, medical, and societal challenges that have made control of the epidemic difficult.


The June 5, 1981 issue of the Centers for Disease Control and Prevention’s (CDC’s) Morbidity and Mortality Weekly Report included a description of five cases of Pneumocystis carinii pneumonia (PCP) among previously healthy men who have sex with men in Los Angeles, California.2 These would become the first reports of AIDS. HIV was identified as the cause of AIDS in 1983.3,4 In the United States, incidence and prevalence of HIV and AIDS have been disproportionately high among men who have sex with men (MSM) since the beginning of the epidemic.5 Other groups have also experienced greater risk compared to the general population including injection drug users6,7 and, initially, persons with hemophilia and other blood transfusion recipients.8 The clustering of the epidemic among marginalized and minority populations, along with early fears and misunderstanding of how HIV is transmitted, has led to persistent stigma associated with HIV infection. Stigma continues to exacerbate disparities in HIV prevention and treatment outcomes.9

In addition to stigma, several other factors specific to HIV/AIDS led to the rapid propagation of the epidemic. Because of the long incubation period from HIV infection until the onset of AIDS, HIV was able to circulate extensively before the clinical manifestations of AIDS led to its recognition as a public health problem. Factors that increased the spread of HIV included increases in the numbers of sexual partners and sexually transmitted diseases among substantial numbers of men who have sex with men, high rates of injection drug use with sharing of contaminated needles and syringes, and the utilization of clotting factor concentrates made from unheated plasma pooled from thousands of donors to treat hemophilia. These factors represented amplification systems that, in combination with the long incubation period for AIDS, allowed extensive transmission of HIV to occur even before the first clinical cases were discovered. The first antiretroviral drug (zidovudine) to treat HIV infection was not available until 1987,10 by which time the epidemic was widespread. Highly active antiretroviral therapy (HAART), which involves treating HIV-infected patients with a combination of antiretroviral drugs, became common practice for management of HIV in 1996.11,12 A cure continues to remain elusive.

Two strains of HIV have been identified: HIV-1 and HIV-2. HIV-1 is ...

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