Human Immunodeficiency Virus - HIV

Human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome (AIDS). While therapy has become available to treat HIV infections, HIV remains a major public health problem, emphasizing the importance of continued diagnostic testing.

• HIV clinical symptoms by stage

  •  Acute retroviral syndrome – fever, fatigue, rash, headache, lymphadenopathy, pharyngitis, myalgias, nausea, vomiting, diarrhea, and night sweats
    • Develops 1-4 wks after exposure
    • Symptoms are too vague to distinguish acute HIV from other viral illnesses
  • Latency period without symptoms
    • Lasts 2-8 yrs
  • Early chronic infection phase
    • Persistent fever
    • Diarrhea
    • Adenopathy
    • Chronic oral and cutaneous conditions
  • End stage disease (AIDS)
    • CD4+ <200 cells/µL
    • Opportunistic infections – viral, bacterial, fungal
    • Malignancies – Kaposi sarcoma, non-Hodgkin lymphoma (NHL), invasive cervical cancer, primary brain lymphoma
    • Chronic metabolic complications – dyslipidemia, impaired glucose tolerance, lipodystrophy, wasting
  Indications for laboratory testing

  • At-risk patients
    • Symptoms of infection
    • Recent exposure to HIV-infected individual
    • History of high-risk behaviors
    • Pregnancy
    • Infant born to HIV-positive mother
  • Guideline recommendations for HIV screening
    • CDC, 2006 (endorsed by ACOG, ACP, IDSA, AAFP [Moyer, 2013])
      • All patients ages 13-64 yrs - in all health care settings
      • Patients at high risk for HIV - annual screening
      • Pregnant women - routine prenatal screening
    • USPSTF, 2013
      • All adolescents and adults ages 15 to 65 yrs
      • At-risk younger adolescents and older adults
      • Pregnant women - including those who present in labor who are untested and whose HIV status is unknown
  Recommended laboratory testing

  Recommended Laboratory Testing*
  Refer to testing algorithms Human Immunodeficiency Virus in Adults Testing algorithm (based on the CDC Updated Recommendations: Laboratory Testing for the Diagnosis of HIV Infection, June 27, 2014) Human Immunodeficiency Virus in Infants Testing algorithm
  Rapid Screening Test (Point-of-Care)
  Point-of-care test	Test Description Can be performed in point-of-care settings Provides results within minutes Limitation Not positive until 3-5 weeks after exposure Follow-up Refer to Human Immunodeficiency Virus in Adults Testing algorithm Preliminary positive results must be followed up with 4th generation Ag/Ab laboratory-based assay (including preliminary positive results obtained with Alere Determine HIV-1/2 Ag/Ab Combo rapid test)
  4th Generation HIV-1 p24 Antigen and Antibodies to HIV-1 (groups M and O) and HIV-2 Screen
  Human Immunodeficiency Virus (HIV) Combo Antigen/Antibody (HIV-1/O/2) by ELISA, Reflexive Panel 2012674	Test Description 2014 CDC Recommended Algorithm for Laboratory Diagnosis of HIV infection 4th generation qualitative screen for HIV-1 p24 antigen and antibodies to HIV-1 (groups M and O) and HIV-2 Reflex portion of the test confirms and discriminates between HIV-1 and HIV-2 antibodies Reflex Pattern If HIV-1,2 combo antigen/antibodies screen is repeatedly reactive, confirmation by antibody differentiation test is added Negative or indeterminate results for HIV-1/2 antibody differentiation are confirmed with a quantitative PCR test Follow-up Refer to HIV in Adults Testing algorithm
  Human Immunodeficiency Virus (HIV) Combo Antigen/Antibody (HIV-1/O/2) by ELISA, with Reflex to HIV-1 Antibody Confirmation by Western Blot 2006526	Test Description 4th generation qualitative screen simultaneously detects HIV-1 p24 antigen and antibodies to HIV types 1 and 2 Antibody/antigen combination testing reduces diagnostic window by 5 to 7 days when compared to antibody only assay Reflex Pattern If HIV-1,2 combo antigen/antibody screen is repeatedly reactive, confirmation by western blot is added Limitation Does not distinguish between the presence of HIV-1 p24 antigen, HIV-1 antibody, and HIV-2 antibody Follow-up Refer to HIV in Adults Testing algorithm
  Human Immunodeficiency Virus (HIV) Combo Antigen/Antibody (HIV-1/O/2) by ELISA, with Reflex to HIV-1/HIV-2 Antibody Differentiation, Supplemental 2013333	Test Description 4th generation qualitative screen simultaneously detects HIV-1 p24 antigen and antibodies to HIV 1 (groups M and O) and HIV-2 Antibody/antigen combination testing reduces diagnostic window by 5 to 7 days when compared to antibody only assay Reflex Pattern Repeatedly reactive HIV-1,2 combo antigen/antibody screen will reflex to HIV-1/HIV-2 antibody differentiation Limitation Does not complete the 2014 CDC Recommended Algorithm for Laboratory Diagnosis of HIV Infections Preferred test is Human Immunodeficiency Virus (HIV) Combo Antigen/Antibody (HIV-1/O/2) by ELISA, Reflexive Panel 2012674 Follow-up Refer to HIV in Adults Testing algorithm
  3rd Generation HIV-1, HIV-2 Antibody Screen
  Human Immunodeficiency Virus Types 1 and 2 (HIV-1, HIV-2) Antibodies by CIA with Reflex to HIV-1 Antibody Confirmation by Western Blot 2005377 Also available – HIV-1 only antibody screen with Western blot confirmation Human Immunodeficiency Virus Type 1 (HIV-1) Antibody by CIA with Reflex to HIV-1 Antibody Confirmation by Western Blot 2005375	Test Description Qualitative test detects antibodies to HIV types 1 and 2 Reflex Pattern If HIV-1,2 antibodies screen is repeatedly reactive, confirmation by western blot is added Limitation Not positive until 3-5 weeks after exposure Follow-up Refer to HIV in Adults Testing algorithm
  Confirmation Tests Following Repeatedly Reactive 3rd or 4th Generation Test
  Human Immunodeficiency Virus Types 1 and 2 (HIV-1/2) Antibody Differentiation, Supplemental, with Reflex to HIV-1 Quantitative PCR 2012669	Test Description Useful as a supplemental assay for repeatedly reactive 3rd or 4th generation HIV screen tests when following the CDC Proposed HIV Diagnostic Algorithms Limitation Test cannot be used as a rapid screen Follow-up Refer to HIV in Adults Testing algorithm
  Human Immunodeficiency Virus Type 1 (HIV-1) Antibody Confirmation by Western Blot 0020284	Test Description Use only when a specimen is repeatedly reactive for HIV-1 or HIV 1-2 antibodies Limitation Test cannot be used as a rapid screen Follow-up Refer to HIV in Adults Testing algorithm
  Human Immunodeficiency Virus Types 1 and 2 (HIV-1/2) Antibody Differentiation, Supplemental 2013107	Test Description Discriminates between HIV-1 and HIV-2 antibodies Use only when patient has a repeatedly reactive 3rd- or 4th-generation HIV screen test result Limitation Test cannot be used as a rapid screen Follow-up Refer to HIV in Adults Testing algorithm
  Follow-Up Testing for Confirmed HIV
  HIV Quantitative PCR Human Immunodeficiency Virus 1 by Quantitative PCR 0055598	Test Description Quantitative test May be ordered to detect acute HIV infection Use to determine and monitor therapy in confirmed HIV cases
  HIV Qualitative PCR Human Immunodeficiency Virus 1 (HIV-1) by Qualitative PCR 0093061	Test Description Qualitative test detects HIV-1 DNA and RNA in infants For initially positive test, recommend repeat testing at 1-2 months and 3-6 months of age to confirm diagnosis
  CD4 Lymphocyte Counts Lymphocyte Subset Panel  1 – CD4 Absolute Count Only 0095854	Test Description Quantitative test Absolute CD4 count is sufficient for routine HIV monitoring Order concurrently with HIV viral load testing for monitoring treatment and disease
  * All linked tests are offered by ARUP Laboratories