Cryptococcal meningitis — DTM&H MCQ

Correct answer: B — Serum cryptococcal antigen and lumbar puncture

The correct answer is B, serum cryptococcal antigen and lumbar puncture. This man has advanced HIV disease (CD4 24 cells/mm3) with headache, fever and blurred vision but no focal neurology, the classic presentation of cryptococcal meningitis, the leading cause of adult meningitis in this setting and a major driver of mortality in sub-Saharan Africa at this CD4 stratum. Serum cryptococcal antigen (CrAg) is a rapid, highly sensitive point-of-care test that should be performed immediately in any patient with advanced HIV disease and neurological symptoms, and a positive result mandates lumbar puncture to exclude meningitis, measure opening pressure and obtain CSF CrAg or India ink to confirm diagnosis and guide induction therapy. Blurred vision without focal signs reflects raised intracranial pressure from cryptococcal disease rather than a mass lesion, so CT is not required before LP unless focal neurology, reduced consciousness or seizures are present. Guidance for advanced HIV disease specifically recommends this CrAg plus LP pathway as the initial investigation in this clinical scenario. Why the other options are wrong: A. CT colonography: This is a bowel imaging technique for colorectal pathology and has no role in the investigation of headache, fever and visual disturbance in HIV. D. Widal serology: This test for typhoid antibodies is unreliable and outdated, and enteric fever does not typically cause blurred vision or this meningitic picture. C. Blood film for malaria alone: Malaria must be excluded in any febrile patient in Malawi, but investigating for malaria alone ignores the far more likely and immediately life-threatening diagnosis of cryptococcal meningitis at this CD4 count, and would miss it entirely. E. Urine schistosoma microscopy: Urinary schistosomiasis causes haematuria and bladder pathology, not headache, fever or visual symptoms, and is irrelevant to this presentation. Key point: In advanced HIV disease (CD4 less than 200, especially under 100) presenting with headache and fever without focal neurology, cryptococcal meningitis must be actively excluded with CrAg testing and lumbar puncture before other causes are pursued.

Reference: WHO Guidelines for Diagnosing, Preventing and Managing Cryptococcal Disease Among Adults, Adolescents and Children Living with HIV, 2022 (incorporated into WHO Consolidated Guidelines on HIV, adopted in UK DTMH and BHIVA-aligned tropical medicine teaching): https://www.ncbi.nlm.nih.gov/books/NBK620076/