ABSTRACT
This chapter traces the history of the AIDS pandemic in the United States, following the recognition of a new disease in 1981 characterized by outbreaks of bizarre opportunistic infections and unusual malignancies in multiple distinct populations – young homosexual men, IV drug users, recipients of blood/blood products, babies of HIV(+) mothers – linked by definitive evidence of immune dysfunction. Against formidable odds, five years after recognition of the first cases, the epidemiology of the disease had been described, the causative virus – the human immunodeficiency virus (HIV) – had been identified, the pathophysiology of the disease had been recognized and a test to diagnose infection had been developed. The chapter identifies the complex immuno-pathophysiologic features of the causative virus as they were recognized including identification as a retrovirus with an RNA genome, associated with fatal disease in mammals after a long incubation period; extremely high mutation and recombination rates resulting in multiple mutant versions of the virus in an infected individual; and a complex replication process involving attachment to host CD4+T cells – mediators of the adaptive immune system – which results in permanent integration of an HIV provirus into the host nucleus. Despite this scientific progress, a diagnosis of Acquired Immuno-Deficiency Syndrome (AIDS) was still, essentially, a death sentence until 1996, when combined treatment with antiretroviral agents (ART) proved to be effective for the treatment of AIDS and control of HIV infection. The advent of ART dramatically changed the course of the pandemic in industrialized countries, transforming HIV infection into a treatable chronic disease and saving millions of lives. This was followed by demonstration that if viral load is effectively suppressed in HIV(+) individuals, the virus is no longer transmissible. A final, critical factor in HIV infectivity was recognition that even well-treated HIV-infected individuals harbor hidden reservoirs of HIV-infected cells in a latent, non-replicating state. This reservoir is the reason HIV infection has never been completely eradicated. This first half of the chapter ends with summary statistics depicting the 2017 status of the HIV/AIDS pandemic in the United States when the cumulative number of individuals ever diagnosed with AIDS was 1,281,787; annual new HIV infections in the United States had decreased by more than two-thirds since the height of the epidemic in the mid-1980s to 38,700/year; and more than 700,000 people had died with AIDS since the beginning of the epidemic.
The second half of the chapter follows the global HIV/AIDS pandemic, beginning with the initial recognition of cases in the early 1980s in central Africa. The narrative follows recognition that a clinically identical syndrome of progressive immune dysfunction was occurring in a completely different population – heterosexual men and women, often with a history of multiple sexual partners but no history of homosexuality, drug use or transfusion. A series of molecular phylogenetic studies which led to the theory that HIV origin emerged in central Africa as early as the turn of the century is reviewed. The history of the pandemic in Africa is described including efforts to introduce ART beginning in the mid-1990s with increasing adoption over time. From 2018 statistics, only 19.5 million of the 36.7 million HIV-infected people in the world are receiving ART at all and viral suppression is reportedly achieved in less than half of these. The chapter ends with a summary of ongoing scientific strategies designed to combat HIV/AIDS, including current efforts to develop an effective vaccine.
