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Update Summary

March 31, 2023

The following sections, tables, and figures were updated:


For the Chapter in the Schwinghammer Handbook, please go to Chapter 42, Human Immunodeficiency Virus Infection.



  • image Infection with human immunodeficiency virus (HIV) occurs through three primary routes: sexual, parenteral, and perinatal. Sexual intercourse, primarily receptive anal and vaginal intercourse, is the most common method for transmission.

  • image HIV infects cells expressing cluster of differentiation 4 (CD4) receptors, such as T-helper lymphocytes, monocytes, macrophages, dendritic cells, and brain microglia. Infection occurs via an interaction between glycoprotein 160 (gp160) on HIV with CD4 (primary interaction) and chemokine coreceptors (secondary interactions) present on the surfaces of these cells.

  • image The hallmark of untreated HIV infection is profound CD4 T-lymphocyte depletion and severe immunosuppression (Acquired Immunodeficiency Syndrome [AIDS]) that puts persons with HIV at significant risk for infectious diseases caused by opportunistic pathogens. Opportunistic infections (OIs) in settings without access to antiretroviral drugs are the chief cause of morbidity and mortality associated with HIV infection.

  • image The current goal of combination antiretroviral therapy (ART) is to achieve maximal and durable suppression of HIV replication, measured as the level of HIV-RNA in plasma (viral load) less than the lower limit of quantitation, usually 20 to 50 copies/mL (20 × 103–50 × 103/L). Another equally important outcome is an increase in CD4 lymphocytes because this closely correlates with the risk for developing OIs.

  • image General principles for the management of OIs include preventing or reversing immunosuppression with ART, preventing exposure to pathogens, vaccination, prospective immunologic monitoring, primary chemoprophylaxis, treatment of acute episodes, secondary chemoprophylaxis, and discontinuation of prophylaxes following ART and subsequent immune recovery.

  • image Clinical use of antiretroviral agents is complicated by drug-drug interactions. Some interactions are beneficial and used purposely; others may be harmful, leading to dangerously elevated or inadequate drug concentrations. For these reasons, clinicians involved in the pharmacotherapy of HIV infection must exercise constant vigilance and maintain a current knowledge of drug interactions.

  • image Recommendations for the initial treatment of HIV advocate a minimum of two or three active antiretroviral agents from at least two drug classes. The typical regimen consists of two nucleoside/nucleotide analogs with an integrase strand transfer inhibitor (InSTI).

  • image Inadequate suppression of viral replication allows HIV to select for antiretroviral-resistant HIV variants, a major factor limiting the ability of antiretroviral drugs to inhibit virus replication. Recommendations for treating drug-resistant HIV include choosing at least two drugs (preferably three) of different classes to which the patient’s virus is susceptible. Susceptibility can be assessed using either genotypic or phenotypic resistance testing.

  • image The reduction of viral load with ART lowers the risk of transmission to others. Additionally, pre- and post-exposure prophylaxis with antiretroviral agents in at-risk persons lowers HIV acquisition ...

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