A 28-year-old HIV-negative man returns from Southeast Asia with high fever, severe headache, and myalgia for 5 days. Tourniquet test is positive. Platelet count is 48,000/µL, haematocrit 46% (baseline 40%). NS1 antigen is positive; dengue IgM antibody is negative. He develops early signs of plasma leakage. According to WHO 2009 dengue classification, this patient is categorised as:
- A Dengue without warning signs
- B Dengue with warning signs (haematocrit rise, thrombocytopenia, plasma leakage) ✓
- C Severe dengue with severe plasma leakage
- D Dengue haemorrhagic fever grade III (DHF grade III by old WHO classification)
Explanation
The WHO 2009 dengue classification replaces the old DHF/DSS grading system with three categories: dengue without warning signs, dengue with warning signs, and severe dengue. Warning signs include: abdominal pain, persistent vomiting, clinical fluid accumulation (pleural effusion/ascites), mucosal bleeding, lethargy, liver enlargement >2 cm, rapid rise in haematocrit with rapid platelet drop. This patient has haematocrit rise (HCT 46% from 40% = 15% rise, above the 20% threshold for plasma leakage criterion of old DHF), early plasma leakage, and thrombocytopenia — meeting 'dengue with warning signs.' Severe dengue requires severe plasma leakage with shock, severe bleeding, or severe organ impairment.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.