All of the following are recognized risk factors for dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) EXCEPT:

## Risk Factors for Dengue Hemorrhagic Fever and Dengue Shock Syndrome ### Pathophysiology of DHF/DSS **Key Point:** DHF/DSS results from a complex interplay of viral, host, and immunological factors. The **secondary infection hypothesis** (antibody-dependent enhancement) is the most widely accepted mechanism for severe dengue. ### Recognized Risk Factors | Risk Factor | Mechanism | Evidence | |-------------|-----------|----------| | **Secondary dengue infection** | Antibody-dependent enhancement (ADE); non-neutralizing antibodies from primary infection enhance viral replication | Well-established, primary risk factor | | **Viral load** | Higher viremia correlates with more severe disease | Documented in multiple studies | | **Host factors** | Age (infants, young children), female sex, comorbidities (DM, HTN, obesity) | Consistent epidemiological data | | **Serotype (primary)** | No single serotype is inherently more virulent in primary infection | Serotypes 1–4 cause similar primary disease | ### The Incorrect Statement **Warning:** The statement that "dengue serotype 2 is inherently more virulent during primary infection" is **misleading and not evidence-based**. **High-Yield:** All four dengue serotypes (DENV-1, DENV-2, DENV-3, DENV-4) cause similar disease severity in primary infection. Serotype differences in virulence are **NOT a recognized primary risk factor** for DHF/DSS in first-time dengue infections. - Serotype 2 has been associated with more severe epidemics in some populations, but this is confounded by secondary infection rates, not inherent virulence - The classic risk factor is **secondary infection** (reinfection with a different serotype), not primary infection with a specific serotype ### Mnemonic **ADE-VHFC** = Antibody-Dependent Enhancement, Viral load, Host factors, Female sex, Comorbidities ### Clinical Pearl In endemic areas like India, DHF/DSS is predominantly seen in secondary dengue infections due to ADE. Primary dengue is usually self-limited and non-hemorrhagic, regardless of serotype. [cite:Harrison 21e Ch 189; Park 26e Ch 15]