Human immunodeficiency virus infection

HIV infection is a chronic viral disease that, if untreated, leads to progressive T cell depletion with resultant infectious and oncological complications.

HIV-1 is responsible for the vast majority of infections, while human immunodeficiency type 2 is relatively uncommon and follows a more indolent course.

In the US, the incidence and prevalence of HIV are estimated at 18 cases per 100,000 person-years and 380.9 persons per 100,000 population, respectively.

Infection begins by invasion of the target cells in a mucosa, following which the infection spreads to the lymphoid system. In untreated patients, the destruction of HIV-infected CD4 T cells results in immunodeficiency and chronic inflammation. CD4 T cell counts of < 350 cells/mcL are associated with an increased risk of complications such as varicella-zoster, tuberculosis, and other severe bacterial infections. The risk of opportunistic infections, such as pneumocystis pneumonia and esophageal candidiasis, increases with CD4 T cell counts of < 250 cells/mcL. CD4 T cells count < 100 cells/mcL result in an increased risk of coccidioidomycosis, cryptococcosis, CMV infection, histoplasmosis, progressive multifocal leukoencephalopathy, disseminated M. avium complex, brain toxoplasmosis, HIV-associated wasting syndrome, and finally death.

The standardized mortality ratio for patients with HIV is estimated at 3.97 for those who have never received ART and 2.76 for those treated with ART. The 2-year and 10-year survival rates for patients diagnosed with AIDS are 82% and 26%, respectively. AIDS (including AIDS infection-related malignancies and opportunistic infections), non-AIDS-related infections, and non-AIDS infection-related malignancies are the most common causes of death. CVD is the leading cause of death in adeqately treated HIV patients.