Regarding latent periods in post-streptococcal acute glomerulonephritis, nephritis characteristically appears:

• A 3 to 6 weeks after pharyngitis and 1 to 3 weeks after impetigo
• B 1 to 3 weeks after pharyngitis and 3 to 6 weeks after impetigo ✓
• C Within 48 hours of either pharyngitis or impetigo
• D Simultaneously with the onset of pharyngitis but never after impetigo

Explanation

Acute post-streptococcal glomerulonephritis follows pharyngitis by about 1 to 3 weeks and impetigo by a longer interval of about 3 to 6 weeks, reflecting the time needed for immune complex formation and deposition in glomeruli. Onset within 48 hours would suggest IgA nephropathy with synpharyngitic haematuria rather than post-streptococcal disease. Nephritogenic strains such as M type 12 cause post-pharyngitis disease while M49 is linked to impetigo, but both show a latent period.

Reference: Harrison's Principles of Internal Medicine, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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