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Source: Anderson PL, Kakuda TN, Fletcher CV. Human Immunodeficiency Virus Infection. In: DiPiro, JT, Talbert RL, Yee GC, Matzke GR, Wells BG, Posey LM. Pharmacotherapy: A Pathophysiologic Approach. 8th ed. Accessed June 26, 2012.

  • Infection caused by HIV virus
    • Hallmark of HIV disease depletion of cluster of differentiation 4 (CD4) cells and associated development of opportunistic infections and malignancies.

  • HIV an RNA retrovirus, types HIV-1 and HIV-2.
    • HIV-1: North America and western Europe
    • HIV-2: western Africa

  • HIV infects cells expressing CD4 (T-helper cell) receptors, such as:
    • T-helper lymphocytes
    • Monocytes
    • Macrophages
    • Dendritic cells
    • Brain microglia
  • Unrelenting destruction of CD4 cells causes profound immunosuppression and AIDS.
  • RNA-dependent DNA polymerase (reverse transcriptase) transcribes RNA into DNA.
  • Double-stranded DNA migrates into nucleus and is integrated into host-cell chromosome.
    • HIV can establish persistent, latent infection, inhibiting cure.
  • HIV replicates in activated cells.
  • Three phases of viral replication and pathogenesis:
    • Acute (2–3 weeks)
    • Chronic (several years)
    • Terminal (acquired immunodeficiency syndrome [AIDS])

  • Infection occursthrough 3 primary modes:
    • Sexual: Most common method for transmission, primarily anal and vaginal intercourse
      • Highest risk from receptive anorectal intercourse at 0.5–3% per sexual act
      • Condom use reduces risk of transmission by ~20-fold.
      • Individuals with genital ulcers or sexually transmitted infections (STIs) at great risk.
    • Parenteral
      • Infected blood exposure from needle sticks, IV injection with used needles, receipt of blood products, and organ transplants
      • Risk of transmission from needle sharing: 0.67% per episode
    • Perinatal
      • Most infections occur during or near time of birth.
      • Frequency of breast milk transmission: 4–16%.
  • Revised classification systems for adult and child HIV found in Tables 1 and 2.

Table 1. Surveillance Case Definition for HIV Infection among Adults and Adolescents (13 Years) – United States, 2008

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