Chapter 25 - HIV infection

Summary

The epidemic of human immunodeficiency virus (HIV) infection that began in the late twentieth century has become one of the dominant health issues worldwide for the early twenty-first century. Advances in the prevention of HIV infection have reduced the global incidence of infection and advances in treatment have dramatically extended the lifespan of infected patients. In the developed world a 20-year-old who begins antiretroviral therapy is estimated to have a life expectancy of an additional 43.1 years while a treated patient in the developing world has an additional life expectancy of 26.7 years [1,2]. In 2009 of the estimated 33.3 million people worldwide living with HIV approximately 5 million were on antiretroviral therapy [3]. Since an additional 1.8 million people become infected with HIV each year, the effect of increased longevity will produce increasing opportunities for internists and surgeons to collaborate in the management of HIV-infected patients.

The clinical course of HIV infection has been well described and should be familiar to most physicians. HIV infection is associated with abnormalities in the number and function of CD4-positive T-lymphocytes. Because the CD4-positive T-lymphocytes are essential to the regulation of the human immune system, progressive immune dysfunction is a natural consequence of HIV infection in most patients. This progressive immune dysregulation is associated with decreased cell-mediated immune function, alterations in the humoral immune response, chronic inflammation and depressed mucosal immunity. The late stages of HIV infection are associated with pathologic processes in many organ systems and eventual death due to opportunistic infections or tumors. This natural history of the disease has been dramatically altered by the widespread use in the developed world of highly active antiretroviral therapy (HAART). HAART is an acronym that refers to combinations of antiretroviral agents that have been shown in clinical trials to result in undetectable plasma HIV RNA levels in the majority of patients. These combinations may include two nucleoside analogs plus either a protease inhibitor, an integrase inhibitor or a non-nucleoside reverse transcriptase inhibitor. Guidelines for the use of these agents in HIV-infected adults and children have been developed, are frequently updated, and are available through the Internet [4].