Human Immunodeficiency Virus - HIV
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Clinical Background
Algorithm(s)
PDF algorithm(s) available at www.arupconsult.com.
Human Immunodeficiency Virus in Adults Testing Algorithm

Human Immunodeficiency Virus in Infants Testing Algorithm

Immunodeficiency Evaluation for Chronic Infections in Adults and Older Children Testing Algorithm

Immunodeficiency Evaluation for Chronic Infections in Infants and Children Testing Algorithm

Human immunodeficiency virus 1 (HIV-1) is thought to have originated as a zoonotic transmission from simian immunodeficiency virus (SIV)-infected primates, while human immunodeficiency virus 2 (HIV-2) is thought to have originated as a zoonotic transmission from Sooty Mangabeys.

Epidemiology

  • Incidence - >5,000,000 annually infected worldwide
  • Age - 18-30 years (peak)
  • Sex - M>F
  • Transmission
    • Primarily via sexual contact (especially in men having sex with men)
    • Parenterally and perinatally
    • Tissue transplantation
    • Blood-borne; not transmitted via saliva, insect vectors or household contacts
    • Intravenous drug use

Organism

  • Retroviridae family - includes HIV-1 and -2, and HTLV-1 and -2
  • RNA single-stranded virus
  • HIV-1 and HIV-2 are etiologic agents of acquired immunodeficiency syndrome (AIDS)
  • HIV-1 accounts for the vast majority of all HIV infections in the U.S. 
    • Includes group M and at least 10 subtypes (A through J)
      • Group O (for outlier)
      • Group N (for non-M, non-O)
  • HIV-2 is endemic to West Africa and rarely seen in U.S. 
    • Includes groups A through E

Pathophysiology

  • HIV localizes to the lymphoid organs
    • Infects the CD4+ helper cells and  T-cell lymphocytes
  • Viremia ensues post infection
  • Viral spread from local inoculation occurs quickly
    • Approximately 30 billion virus particles produced in first weeks of infection

Clinical Presentation

  • Acute retroviral syndrome - fever, fatigue, rash, headache, lymphadenopathy, pharyngitis, myalgias, nausea, vomiting, diarrhea and night sweats
    • Resolves in a few days to a few weeks
  • Clinical latency - absence of clinical symptoms; viremia symptoms have cleared
  • AIDS - progression of HIV in treated or untreated patients
    • CD4+ <2,000 cells/µL
    • Opportunistic infections - viral, bacterial, fungal
    • Malignancies - Kaposi sarcoma, non-Hodgkin lymphoma (NHL), invasive cervical cancer, primary brain NHL
    • Chronic metabolic complications - dyslipidemia, impaired glucose tolerance, lipodystrophy

Prevention

  • Can be prevented in 98% of infants of infected mothers by drug therapy during pregnancy, elective caesarian section and refraining from breastfeeding
  • Use of condoms and needle exchange programs also reduce risk
See Also
Human Immunodeficiency Virus 1, Antiretroviral Drug Resistance Testing - HIV Drug Resistance
Lymphoma Phenotyping
Lymphomas, B-Cell - B-Cell Lymphomas
Lymphomas, T/NK-Cell - T/NK-Cell Lymphomas
Pneumocystis jiroveci
Sexually Transmitted Infections
Treponema pallidum - Syphilis

Refer to Human Immunodeficiency Virus at http://www.arupconsult.com for list of references


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