Neurologic Disease in HIV Infection

First described in 1981, acquired immunodeficiency syndrome (AIDS), presents as a constellation of signs, symptoms, and opportunistic diseases reflecting the human immunodeficiency virus’s (HIV) infection, dysregulation, and destruction of immune cells involved primarly in the cellular immune response such as CD4+ T lymphocytes but also including members of the monocyte/macrophage lineage such as central nervous system (CNS) microglia. The Centers for Disease Control and Prevention (CDC) defined AIDS as a CD4+ T-lymphocyte count below 200 cells/microliter and also identified a number of AIDS-defining conditions, both opportunistic diseases arising from a devastated cellular immune as well as conditions manifesting as a direct consequence of the immune dysregulation characteristic of HIV infection. The entire neuroaxis is susceptible to the HIV-related damage, and many AIDS-defining conditions manifest in the central nervous system (CNS).