The 'sero-type switching' phenomenon in dengue is clinically significant because:

• A Secondary infection with a different serotype triggers antibody-dependent enhancement (ADE), increasing risk of severe dengue ✓
• B It causes lifelong immunity to all four DENV serotypes after primary infection
• C It allows the virus to evade antiviral drug therapy
• D It reduces the effectiveness of the NS1 antigen test in secondary infections

Explanation

Primary dengue infection with one serotype confers lifelong immunity to that serotype but only short-lived cross-immunity (~3 months) to others. In secondary infection with a different DENV serotype, pre-existing heterotypic antibodies form cross-reactive but non-neutralizing immune complexes that bind Fc receptors on monocytes/macrophages, enhancing viral uptake — Antibody-Dependent Enhancement (ADE). This leads to higher viraemia and increased risk of Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). This is why secondary infections carry higher morbidity.

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.