HIV, and a Platelet Count of 18,000

Correct answer: D. The platelet count, because of the bleeding risk during and after surgery

• A. An UNDETECTABLE viral load means the infection is well suppressed, and it also means the patient is effectively non-infectious sexually. It reduces concern rather than raising it — and standard precautions apply to every patient regardless.
• B. A CD4 count of 410 is reasonably preserved — above 200 the risk of opportunistic infection is substantially reduced and routine dental care proceeds normally.
• C. Haemoglobin of 13.1 g/dL is within normal limits.
• D. CORRECT. A platelet count of 18,000/µL is SEVERE thrombocytopenia. The generally cited thresholds are: above 50,000 permits most routine dental surgery with local measures; 30,000–50,000 requires caution and consultation; and BELOW 30,000 carries a risk of spontaneous bleeding and mandates medical consultation, with platelet transfusion often needed before any surgical procedure. Immune thrombocytopenia is a well-recognised HIV-associated complication.

Note: Thresholds worth carrying: platelets above 50,000 for routine extraction; INR up to 3.5 for routine dental surgery without altering warfarin; absolute neutrophil count above 1,000 for elective care.

Correct answer: A. Pseudomembranous candidiasis

• A. CORRECT. PSEUDOMEMBRANOUS CANDIDIASIS (thrush) is the definitive answer and is the most common oral lesion in HIV. The diagnostic feature is exactly as described — the plaques are WIPEABLE and leave an erythematous, sometimes bleeding, base. The plaque is a mat of fungal hyphae, desquamated epithelium and debris.
• B. Oral hairy leukoplakia is EBV-driven, appears as vertical white corrugations on the LATERAL TONGUE, and does NOT wipe off. It is highly specific for HIV but is a different lesion.
• C. Leukoplakia is by definition a white patch that cannot be wiped away and cannot be attributed to any other condition. The wipeability excludes it.
• D. Lichen planus presents as fine white lace-like Wickham striae, usually bilateral on the buccal mucosa, and does not wipe off.

Note: Other HIV-associated oral lesions to recognise: linear gingival erythema, necrotizing ulcerative periodontitis, Kaposi sarcoma (HHV-8, purple macules on the palate), and aphthous-like major ulcers.

Correct answer: A. Reverse transcriptase

• A. CORRECT. HIV is a RETROVIRUS with a single-stranded RNA genome. Immediately after entry and uncoating, REVERSE TRANSCRIPTASE transcribes the viral RNA into double-stranded DNA — the step that must occur first, and the step that defines the retroviral family. It has no proofreading capacity, which is the source of HIV's extraordinary mutation rate and its capacity to develop resistance.
• B. Protease acts LAST, cleaving the gag-pol polyprotein into functional proteins during virion maturation. Protease inhibitors block the final step.
• C. Host DNA polymerase is used later, after integration, to transcribe from the integrated provirus — but it is a host enzyme and not the defining early viral step.
• D. Integrase acts AFTER reverse transcription, inserting the newly made viral DNA into the host genome. It is the second enzymatic step, not the first.

Note: The replication sequence maps directly onto the drug classes: entry (maraviroc, enfuvirtide) → reverse transcription (zidovudine, tenofovir, efavirenz) → integration (raltegravir, dolutegravir) → maturation (ritonavir, darunavir).

Correct answer: B. Hepatitis B

• A. HIV carries a transmission risk of roughly 0.3% after percutaneous exposure — real, but roughly a hundredfold lower than hepatitis B.
• B. CORRECT. HEPATITIS B is by far the greatest occupational bloodborne risk. Transmission after a percutaneous exposure from an HBeAg-positive source is roughly 22–31% — orders of magnitude higher than the others. HBV also survives on environmental surfaces in dried blood for at least seven days, so indirect transmission is possible. This is precisely why the hepatitis B vaccine is mandated and why OSHA requires employers to offer it free of charge.
• C. Hepatitis C carries a risk of roughly 1.8%. Higher than HIV, far lower than HBV, and there is no vaccine — but the occupational risk in dentistry remains well below HBV.
• D. Tuberculosis is a genuine occupational concern in dentistry but it is AIRBORNE, not bloodborne, and is not the answer to a bloodborne-pathogen question.

Note: Post-exposure priorities: wash immediately, report, source testing, and evaluate for prophylaxis. HIV PEP should begin as soon as possible, ideally within hours and no later than 72 hours.