HIV Infection, AIDS, and Opportunistic Pathogens — WACS Viva & Clinical Scenarios (Infectious and Tropical Diseases)

Exam-style hiv infection, aids, and opportunistic pathogens viva scenarios with examiner probes and model answers for Internal Medicine candidates.

Scenarios covered

• SCENARIO 1: A 34-year-old treatment-naive male with newly diagnosed HIV infection presents with a 2-week history of worsening global headache, low-grade fever, photophobia, and intermittent confusion. On examination, Glasgow Coma Scale is 14/15, neck stiffness is present, and fundoscopy reveals bilateral papilloedema. CD4+ count is 28 cells/microlitre. Outline your diagnostic strategy, immediate medical management including control of intracranial pressure, definitive antimicrobial induction therapy, and the specific timing and rationale for initiating combination antiretroviral therapy (ART).
• SCENARIO 2: A 29-year-old female living with HIV (CD4+ count 65 cells/microlitre, non-adherent to co-trimoxazole prophylaxis) presents with progressive non-productive cough, profound exertional dyspnoea, and fever over 3 weeks. Room air arterial blood gas reveals pH 7.45, PaO₂ 54 mmHg, PaCO₂ 32 mmHg, and oxygen saturation of 82%. Plain chest radiography demonstrates diffuse bilateral interstitial infiltrates extending from the perihilar regions. Detail the diagnostic evaluation, immediate oxygenation strategy, full pharmacological management of suspected Pneumocystis jirovecii pneumonia including criteria
• SCENARIO 3: A 42-year-old male established on a first-line fixed-dose ART regimen of tenofovir disoproxil fumarate, lamivudine, and dolutegravir (TLD) for 18 months presents for routine review. Routine plasma HIV-1 RNA viral load is 14,800 copies/mL. Outline the systematic approach to investigating and confirming virological treatment failure, the step-by-step enhanced adherence counselling protocol, indications for genotypic antiretroviral resistance testing, and the principles governing the design of a virologically suppressive second-line regimen.
• SCENARIO 4: A 38-year-old female with advanced HIV disease (baseline CD4+ count 42 cells/microlitre) and microbiologically confirmed pulmonary tuberculosis commences anti-tuberculosis therapy. Four weeks later, ART is initiated. Three weeks after starting ART, she develops high spiking fevers, expanding cervical lymphadenopathy with overlying erythema, and worsening right middle-lobe consolidation on repeat chest radiography, despite verified compliance with all medications. Discuss the diagnostic criteria and clinical distinction between paradoxical and unmasking Immune Reconstitution Inflammatory Syndro
• SCENARIO 5: Explain the pharmacokinetics, molecular mechanisms of action, major metabolic and organ toxicities, and critical drug-drug interactions of antiretroviral drug classes (NRTIs, NNRTIs, INSTIs, and PIs). Specifically discuss dose modifications and regimen selection required in the setting of concurrent rifampicin-based tuberculosis therapy, chronic hepatitis B virus coinfection, and pre-existing renal impairment.