USMLE Guide: HIV/AIDS Management

Introduction

The management of HIV/AIDS is a crucial aspect of medical practice, requiring a comprehensive understanding of the virus, its pathophysiology, and available treatment options. This USMLE guide aims to provide a concise overview of HIV/AIDS management, including diagnosis, treatment, and preventive strategies.

I. Diagnosis

1. Screening

• HIV screening is recommended for all individuals aged 13-64 years, regardless of risk factors.
• Screening can be performed using either a fourth-generation antigen/antibody test or an HIV-1/2 antigen-antibody combination immunoassay.
• Positive screening results should be confirmed with a supplemental test, such as Western blot or HIV-1 RNA PCR.

2. CD4 T-Cell Count

• CD4 T-cell count is used to assess the immune status of individuals with HIV.
• It helps determine the need for prophylaxis against opportunistic infections and guides initiation of antiretroviral therapy (ART).
• A count <200 cells/μL indicates severe immunosuppression and increased risk for opportunistic infections.

3. Viral Load Measurement

• Quantification of HIV RNA viral load is essential for monitoring disease progression and assessing response to treatment.
• Suppression of viral replication is the primary goal of ART.
• A viral load <200 copies/mL is considered virologically suppressed.

II. Treatment

1. Antiretroviral Therapy (ART)

• ART is the cornerstone of HIV management, aiming to achieve and maintain viral suppression.
• Initial ART regimen typically consists of two nucleoside reverse transcriptase inhibitors (NRTIs) plus either an integrase strand transfer inhibitor (INSTI), non-nucleoside reverse transcriptase inhibitor (NNRTI), or a protease inhibitor (PI).
• Adherence to ART is crucial for optimal outcomes.

2. Prophylaxis against Opportunistic Infections

• Individuals with HIV should receive prophylaxis against opportunistic infections based on CD4 T-cell count and clinical factors.
• CD4 <50 cells/μL: Start prophylaxis for pneumocystis jirovecii pneumonia (TMP-SMX).
• CD4 <200 cells/μL: Add prophylaxis for Mycobacterium avium complex (azithromycin or clarithromycin).
• CD4 <100 cells/μL: Consider Toxoplasma gondii prophylaxis (TMP-SMX).

3. Vaccinations

• Immunizations are crucial for preventing infections in individuals with HIV.
• Recommended vaccinations include influenza, pneumococcal, hepatitis B, and human papillomavirus (HPV) vaccines.
• live vaccines (e.g., MMR, varicella, oral typhoid) are generally contraindicated in severely immunocompromised individuals.

III. Prevention

1. Pre-Exposure Prophylaxis (PrEP)

• PrEP involves the use of antiretroviral medications to prevent HIV acquisition in individuals at high risk.
• Combination therapy with tenofovir disoproxil fumarate and emtricitabine (TDF/FTC) is the preferred regimen.
• PrEP is recommended for individuals with ongoing high-risk behaviors, such as injection drug use or condomless sex with HIV-positive partners.

2. Post-Exposure Prophylaxis (PEP)

• PEP is the use of antiretroviral medications after potential HIV exposure to prevent infection.
• Initiation should occur as soon as possible, ideally within 72 hours of exposure.
• PEP consists of a 28-day regimen of two NRTIs plus a third agent (e.g., a boosted PI or an INSTI).

Conclusion

Effective management of HIV/AIDS requires a multidisciplinary approach, incorporating screening, accurate diagnosis, timely initiation of ART, prophylaxis against opportunistic infections, and preventive strategies. Understanding these essential aspects is crucial for medical professionals involved in the care of individuals living with HIV/AIDS.