IM26.21-25 | Viral Infections: Herpesviruses, Respiratory Viruses, Rabies, and Dengue — Summary & Reflection

KEY TAKEAWAYS

HSV-1: oral herpes, encephalitis (temporal lobe); treat: acyclovir (IV 10 mg/kg 8-hourly for encephalitis — start immediately); latency in trigeminal ganglion.

HSV-2: genital herpes; treat: valacyclovir or acyclovir orally; suppressive therapy for frequent recurrences.

VZV — varicella: polymorphic rash (all stages simultaneously); treat: acyclovir in adults, immunocompromised; avoid aspirin (Reye's).

VZV — zoster: unilateral dermatomal vesicular rash; PHN in elderly; treat: valacyclovir 1g TDS × 7 days within 72 hours; gabapentin/amitriptyline for PHN.

Dengue: Aedes mosquito; NS1 day 1–5; IgM day 5+; rising HCT = plasma leakage; NO NSAIDs; critical phase = defervescence day 3–6; IV fluids guided by HCT + urine output; platelet transfusion only for <10,000/µL or active bleeding.

Rabies: centripetal nerve travel → CNS = fatal; Category I = nothing; Category II = wound wash + vaccine; Category III = wound wash + vaccine + RIG; immediate wound washing = the most critical step.

Influenza: antigenic drift (epidemics) + shift (pandemics); oseltamivir × 5 days within 48h; annual vaccine for high-risk groups.

COVID-19: ACE2 entry; dexamethasone for O2-requiring; remdesivir adjunct; anticoagulation for coagulopathy; critical illness = ARDS management.

REFLECT

India bears the highest rabies mortality in the world — 20,000 deaths annually — despite rabies being almost entirely preventable with correct PEP. The deaths are not from lack of treatment availability but from delays in seeking care, incomplete PEP courses, and lack of awareness of the Category III bite protocol. Similarly, dengue deaths occur not from lack of knowledge but from clinical errors — missing the critical phase, prescribing NSAIDs, or discharging patients at defervescence. Both represent a gap between clinical knowledge and clinical practice. Reflect on the systems-level barriers: Why do patients delay seeking care after animal bites? What misinformation in communities contributes to inadequate dengue management? What role can you play — as a clinician, a communicator, and an advocate — in reducing the gap between what is known and what is done for these two preventable causes of death in India? What would a patient-centred explanation of dengue warning signs look like for a patient or family with limited health literacy?