What are the steps for diagnosing and treating HIV (Human Immunodeficiency Virus) infection?

HIV Diagnosis and Treatment Protocol

The diagnosis of HIV infection requires a systematic approach using serologic tests for antibody detection, followed by confirmatory testing, and then appropriate treatment initiation based on clinical staging. 1

Diagnostic Process

Initial HIV Testing

• Screening test: Begin with a sensitive screening test such as enzyme-linked immunosorbent assay (ELISA) or rapid assay 1
  • Fourth-generation assays that detect both HIV antibodies and p24 antigen are recommended as initial screening tests 1
  • These tests can detect infection earlier (4-7 days after infection) compared to antibody-only tests 1

Confirmation of Positive Results

• All reactive screening tests must be confirmed by:
  • Western blot or indirect immunofluorescence assay (IFA) 1
  • For fourth-generation assays, follow with an antibody immunoassay that distinguishes HIV-1 from HIV-2 antibodies 1

Special Testing Considerations

• For suspected acute infection (within 4 weeks of exposure):

  • Consider HIV RNA testing (viral load) as antibodies may not yet be detectable 1
  • HIV RNA becomes positive 3-5 days before p24 antigen 1

• For infants born to HIV-positive mothers:

  • Antibody tests are unreliable due to maternal antibody persistence
  • Use HIV DNA PCR or RNA PCR tests for diagnosis 1
  • Definitive determination for infants under 15 months requires laboratory evidence of HIV in blood or tissues 1

• For suspected HIV-2 infection:

  • Consider testing if patient is from West Africa or has epidemiological links to areas with HIV-2 prevalence 1
  • Use the Multispot rapid test which is FDA-approved for differentiating HIV-1 from HIV-2 1

Testing Frequency

• Persons with known high-risk behaviors should be tested at least annually 1
• For HIV PrEP users, testing should be repeated at least every 3 months 2
• After high-risk exposure, if initial test is negative, repeat testing at 6,12, and 24 weeks 1

Post-Diagnosis Assessment

Medical History

• Document date of diagnosis and approximate date of infection if possible 1
• Obtain thorough medication history, especially for patients with prior antiretroviral therapy 1
• Record lowest CD4 count and highest viral load ever documented 1

Laboratory Evaluation

1. CD4 cell count and viral load measurement
2. Complete blood count
3. Comprehensive metabolic panel
4. STI screening:
   • Serologic test for syphilis
   • Nucleic acid amplification tests for gonorrhea and chlamydia
   • Hepatitis B and C serologies 1

Additional Testing Based on Risk Factors

• For women: Examination for Trichomonas and cervical specimen for chlamydia
• For patients reporting receptive anal sex: Rectal cultures for gonorrhea and chlamydia
• For patients reporting receptive oral sex: Pharyngeal culture for gonorrhea 1

Treatment Approach

Antiretroviral Therapy (ART)

• Initiate ART promptly after diagnosis to:
  • Slow immune system decline
  • Reduce risk of opportunistic infections
  • Decrease risk of HIV transmission 1

Prophylaxis for Opportunistic Infections

• Based on CD4 count, provide prophylaxis for:
  • Pneumocystis pneumonia (PCP)
  • Tuberculosis
  • Other opportunistic infections 1

Monitoring

• Regular monitoring of CD4 count and viral load
• Screening for STIs at least annually, more frequently with high-risk behaviors 1
• Assessment for treatment adherence and potential drug interactions 1

Counseling and Support

Psychosocial Support

• Address emotional distress following diagnosis 1
• Provide counseling on:
  • Accepting potential health implications
  • Coping with stigma
  • Maintaining physical and emotional health
  • Preventing HIV transmission 1

Prevention Counseling

• Discuss risk reduction strategies
• Provide guidance on safer sex practices and condom use 2
• Address substance use if applicable 1

Common Pitfalls to Avoid

1. Window Period Misinterpretation: Remember that antibody tests cannot rule out infection that occurred less than 6 months before testing 1

2. False Positives with Viral Load: Low copy number viral load results (<5,000 copies/mL) outside the setting of acute infection may be false positives and should prompt retesting 1

3. Missing HIV-2: Consider HIV-2 in patients with atypical serologic results, especially those with epidemiological links to West Africa 1

4. Infant Diagnosis Errors: Don't rely on antibody tests for infants born to HIV-positive mothers; use virologic assays instead 1

5. Delayed Diagnosis: Don't wait for symptoms to develop; early diagnosis and treatment significantly improve outcomes and reduce transmission 1