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BASICS

Description

  • HIV is a retrovirus (lentivirus subgroup) integrating into CD4+ T cells, causing immunodeficiency.
  • Natural history: transmission → acute retroviral syndrome → seroconversion → asymptomatic chronic infection → symptomatic HIV/AIDS.
  • Untreated progression: AIDS in ~10 years; survival ~3 years after AIDS onset.

Epidemiology

  • ~30,500 diagnosed in US (>13 years) in 2020; incidence declined 8% from 2016–2019.
  • Worldwide: ~1.5 million new HIV cases in 2020.
  • US prevalence (2019): ~1.2 million people; 13% unaware of infection.
  • Global prevalence (2020): ~38 million people living with HIV; 45% of new diagnoses in Eastern/Southern Africa.
  • AIDS-related deaths (2020): ~680,000.

Etiology and Pathophysiology

  • Single-stranded, positive-sense enveloped RNA virus.
  • Viral RNA → DNA via reverse transcription → integrates into host genome.
  • Two types: HIV-1 (most common), HIV-2 (less infectious, West Africa).
  • Infects and depletes CD4+ T cells, causing immunosuppression.

Risk Factors

  • Sexual activity (receptive anal sex highest risk).
  • Injection drug use.
  • Maternal transmission (during pregnancy, delivery, breastmilk).
  • Blood product recipients before 1985.
  • Occupational exposure in healthcare.

GENERAL PREVENTION

  • Behavioral counseling for high-risk sexual activity and drug use.
  • Consistent condom use reduces transmission by ~77-80%.
  • Preexposure prophylaxis (PrEP) recommended for high-risk individuals with routine HIV and renal monitoring.
  • Postexposure prophylaxis (PEP) initiated within 72 hours for 28 days.
  • ART in HIV+ individuals maintaining viral load <200 copies/mL prevents transmission (treatment as prevention).
  • Routine HIV screening recommended for all 13–64 years; repeated in high-risk groups.
  • Pregnant women tested initially and again in third trimester.

COMMONLY ASSOCIATED CONDITIONS

  • Coinfections: syphilis, tuberculosis, hepatitis B/C.
  • Increased risk of cervical cancer, lymphoma, skin malignancies.

DIAGNOSIS

Clinical Features

  • Acute retroviral syndrome: influenza-like symptoms 1-4 weeks post exposure.
  • Clinical latency: asymptomatic, gradual CD4 decline over 8-10 years.
  • AIDS: CD4 <200 cells/µL or AIDS-defining infections (Pneumocystis pneumonia, cryptococcal meningitis, etc.)
  • Advanced HIV: CD4 <50 cells/µL, high mortality risk.

History

  • Risk exposures: sexual, social, occupational, drug use, blood transfusions, PrEP/PEP use.
  • Review immunizations.

Physical Exam

  • No pathognomonic signs; evaluate for weight loss, lymphadenopathy, neurologic and skin findings.

Differential Diagnosis

  • Opportunistic infections and malignancies including Burkitt lymphoma, CMV, EBV, tuberculosis.

Diagnostic Tests

  • HIV antibody/antigen immunoassay.
  • HIV RNA PCR for acute infection.
  • CD4 count and percentage.
  • CBC, chemistry panel, liver function tests.
  • Screening for hepatitis A/B/C, syphilis, gonorrhea, chlamydia, HPV.
  • Tuberculosis screening: PPD or IGRA and chest X-ray.
  • HLA-B*5701 testing for abacavir hypersensitivity.
  • Resistance genotyping if indicated.

FOLLOW-UP TESTS & SPECIAL CONSIDERATIONS

  • PEP: nPEP within 72 hours, 28 days triple therapy.
  • HIV, hepatitis, and STI testing at baseline, 4-6 weeks, 3 months, 6 months post-exposure.
  • Monitor viral load and CD4 after ART initiation.

TREATMENT

ART Goals

  • Suppress viral load (<200 copies/mL).
  • Preserve immune function.
  • Prevent opportunistic infections and malignancies.

Medication Regimens

  • First line: Integrase strand transfer inhibitor + 2 nucleoside reverse transcriptase inhibitors.
  • Examples: Bictegravir/TAF/emtricitabine; Dolutegravir/abacavir/lamivudine (HLA-B*5701 negative only).
  • Dolutegravir-based dual therapy for select patients.
  • Considerations: resistance testing, comorbidities, pregnancy status, drug interactions.

Additional Therapies

  • Opportunistic infection prophylaxis based on CD4 count:
  • TMP-SMX for Pneumocystis jiroveci if CD4 <200.
  • TB treatment for latent infection.
  • TMP-SMX for Toxoplasma gondii if CD4 <100.
  • Azithromycin for Mycobacterium avium complex if CD4 <50.
  • Vaccinations: Influenza, Hepatitis A/B, HPV, Pneumococcus, Tdap.

ONGOING CARE

Monitoring

  • Viral load every 2–8 weeks after starting ART until suppressed.
  • CD4 and labs every 3–4 months initially; less frequent once stable.
  • Annual lipid panel, metabolic labs.
  • Cervical cytology as per guidelines.

Diet

  • Balanced nutrition; avoid raw/unpasteurized foods.

PATIENT EDUCATION

  • Nonjudgmental, sex-positive counseling on risk reduction and transmission.
  • Emphasize importance of ART adherence and medical follow-up.
  • Encourage disclosure to sexual partners.

PROGNOSIS

  • Untreated AIDS life expectancy ~3 years.
  • Opportunistic infection presence reduces survival to ~1 year.
  • Adherence failure is primary cause of treatment failure.

REFERENCES

  1. Centers for Disease Control and Prevention. HIV statistics overview. https://www.cdc.gov/hiv/statistics/overview/index.html. Accessed May 25, 2023.

  2. CDC. Sexually transmitted infections treatment guidelines, 2021. https://www.cdc.gov/std/treatment-guidelines/STI-Guidelines-2021.pdf. Accessed May 25, 2023.

  3. U.S. Department of Health and Human Services. Guidelines for the use of antiretroviral agents in adults and adolescents living with HIV. https://clinicalinfo.hiv.gov/sites/default/files/guidelines/archive/AdultandAdolescentGL_2021_08_16.pdf. Accessed October 9, 2023.

Clinical Pearls

  • Routine HIV screening recommended for all adults and adolescents.
  • PrEP is effective prevention for high-risk individuals.
  • Acute HIV infection resembles mononucleosis or influenza.
  • Monitor for HIV in patients with unexplained weight loss, fatigue, night sweats, rash.
  • Vaccinate HIV+ patients and provide prophylaxis based on CD4 count.