Infectious Disease · HIV/AIDS
The facts most likely to be tested
The standard initial antiretroviral therapy (ART) regimen consists of two nucleoside reverse transcriptase inhibitors (NRTIs) combined with an integrase strand transfer inhibitor (INSTI).
Abacavir requires HLA-B*57:01 testing prior to initiation to prevent a potentially fatal hypersensitivity reaction.
Tenofovir disoproxil fumarate (TDF) is associated with Fanconi syndrome and decreased bone mineral density, whereas tenofovir alafenamide (TAF) has a more favorable renal and bone profile.
Efavirenz, a non-nucleoside reverse transcriptase inhibitor (NNRTI), is frequently associated with vivid dreams, insomnia, and neuropsychiatric side effects.
Post-exposure prophylaxis (PEP) must be initiated within 72 hours of exposure and continued for 28 days to effectively reduce the risk of HIV transmission.
Pre-exposure prophylaxis (PrEP) using tenofovir/emtricitabine is indicated for individuals at high risk of HIV acquisition and requires baseline and periodic HIV testing to ensure the patient is not already infected.
Immune reconstitution inflammatory syndrome (IRIS) occurs when a patient with a low CD4 count experiences a paradoxical worsening of an underlying opportunistic infection shortly after starting ART.
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A 28-year-old male presents to the clinic to discuss HIV prevention after engaging in unprotected sexual intercourse with a partner of unknown HIV status 12 hours ago. He has no significant past medical history and is not currently taking any medications. Physical examination is unremarkable, and his HIV antigen/antibody combination immunoassay is negative. He is anxious about the risk of infection and requests the most appropriate preventative measure.
What is the most appropriate next step in management?
Initiate post-exposure prophylaxis (PEP) with a three-drug regimen (e.g., tenofovir/emtricitabine plus dolutegravir or raltegravir).
This tests the management of potential HIV exposure; PEP must be started within 72 hours, and a three-drug regimen is the standard of care to prevent seroconversion.
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Etiology / Epidemiology
Retrovirus transmitted via unprotected sexual contact, IV drug use, or vertical transmission. High-risk groups include MSM and individuals with multiple sexual partners.
Clinical Manifestations
Acute phase presents as mononucleosis-like syndrome. Advanced disease features opportunistic infections and AIDS-defining illnesses.
Diagnosis
Screening via 4th generation HIV-1/2 antigen/antibody immunoassay. Confirmatory testing via HIV-1/2 antibody differentiation immunoassay.
Treatment
Standard regimen: Bictegravir/Emtricitabine/Tenofovir alafenamide. Do not use Abacavir without HLA-B*5701 testing.
Prognosis
Goal is undetectable viral load. Monitor CD4 count; prophylaxis required if CD4 < 200.
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Epidemiology & Etiology
HIV is a lentivirus targeting CD4+ T-lymphocytes. Primary transmission routes are mucosal exposure to infected fluids and parenteral inoculation. Early detection is critical to prevent progression to Acquired Immunodeficiency Syndrome.
Pertinent Anatomy
The virus targets cells expressing the CD4 receptor and CCR5 or CXCR4 co-receptors. Lymphoid tissue serves as the primary reservoir for viral replication.
Pathophysiology
Viral RNA is converted to DNA via reverse transcriptase and integrated into the host genome. Chronic immune activation leads to progressive CD4 depletion. Clinical failure occurs when the immune system can no longer contain opportunistic pathogens.
Clinical Manifestations
Acute infection manifests as fever, lymphadenopathy, and pharyngitis. Late-stage disease presents with Pneumocystis jirovecii pneumonia, Kaposi sarcoma, and cryptococcal meningitis. Red flags include unexplained weight loss, chronic diarrhea, and persistent oral thrush.
Diagnosis
Initial screening uses the 4th generation HIV-1/2 antigen/antibody immunoassay. Positive results require a HIV-1/2 antibody differentiation immunoassay for confirmation. HIV-1 nucleic acid testing is used to resolve discordant results or detect acute infection.
Treatment
First-line therapy is a three-drug regimen consisting of an integrase strand transfer inhibitor (INSTI) plus two nucleoside reverse transcriptase inhibitors (NRTIs). Abacavir requires mandatory HLA-B*5701 screening to prevent hypersensitivity reaction. Adherence is the primary determinant of success.
Prognosis
Prognosis is excellent with early Antiretroviral Therapy (ART). Patients must be monitored for CD4 count and viral load every 3-6 months. Immune reconstitution inflammatory syndrome may occur shortly after starting therapy.
Differential Diagnosis
Mononucleosis: heterophile antibody positive
Cytomegalovirus: retinitis in immunocompromised
Toxoplasmosis: ring-enhancing brain lesions
Tuberculosis: apical cavitary lung disease
Lymphoma: B-symptoms with lymphadenopathy