Answer
C — Airborne transmission is most likely. 1, 2
Rationale:
- A generalized vesicular rash involving trunk and mucosa (mouth) after a party is most consistent with varicella (chickenpox), which spreads via airborne small-particle aerosols and can transmit over distances; mucosal lesions are common, and trunk predominance is typical 1.
- Authoritative pediatric guidelines classify measles and varicella as airborne, in contrast to droplet-only pathogens (eg, influenza) and contact/fomite-dominant agents (eg, RSV) 2.
Why not A (contaminated surfaces) or B (contaminated food/drink)?
- Fomite transmission can occur for some pathogens but is not the primary/typical route for varicella; reported surface-linked chickenpox cases are rare outliers and not the basis for public health precautions 2, 3.
- Foodborne transmission does not explain a classic diffuse rash with oral involvement; food-related rashes are usually urticarial or localized reactions without mucocutaneous vesicles 4.
Actionable caveats to protect morbidity, mortality, and quality of life:
- If varicella or measles is suspected: implement airborne precautions immediately and assess vaccination status; early isolation reduces transmission and serious complications (pneumonia, encephalitis) 2, 1.
- Common pitfall: assuming droplet/contact only—guidelines specify airborne for varicella/measles; use respirators when indicated 2.