In the epidemiology of dengue fever, 'secondary infection' by a heterologous dengue serotype is associated with severe dengue (dengue haemorrhagic fever/dengue shock syndrome) through which mechanism?
- A Direct viral cytopathic effect on platelets
- B Cross-reactive T-cell killing of endothelial cells
- C Antibody-dependent enhancement (ADE) of viral replication in monocytes/macrophages ✓
- D IgE-mediated type I hypersensitivity to dengue envelope protein
Explanation
Antibody-dependent enhancement (ADE) is the principal mechanism explaining why secondary dengue infection with a different serotype causes more severe disease. Pre-existing non-neutralizing antibodies from the primary infection bind the new serotype but instead of neutralizing it, facilitate its uptake by Fc-receptor-bearing monocytes/macrophages, dramatically amplifying viral replication and triggering a cytokine storm (tumour necrosis factor, IL-6, IL-8). This cascade increases vascular permeability, leading to plasma leakage, thrombocytopenia, and haemorrhage characterizing DHF/DSS.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.