Hand, Foot, and Mouth Disease

Etiology & Epidemiology - Tiny Viral Attackers

• Causative Agents: Picornaviridae family.
  • Coxsackievirus A16 (CVA16): Most common.
  • Enterovirus 71 (EV-A71): Linked to severe neurological issues.
  • Other Coxsackie A/B, Echoviruses.
• Epidemiology:
  • Age: Primarily children < 5-10 years.
  • Transmission: Faecal-oral (main), respiratory droplets, direct contact (vesicles, fomites).
  • Incubation: 3-6 days.
  • Seasonality (India): Summer & monsoon peak.
  • Communicability: Highest in 1st week; stool shedding for weeks.

⭐ EV-A71 is linked to severe outbreaks with neurological complications, particularly in Asia-Pacific_region_

Clinical Features - Spotting the Spots

• Incubation Period: 3-6 days.
• Prodrome (1-2 days prior to rash):
  • Low-grade fever
  • Malaise, anorexia
  • Sore throat/mouth, abdominal pain
• Enanthem (Oral Lesions): Often first sign.
  • Painful vesicles → erosions/ulcers (aphthae-like).
  • Location: Tongue, buccal mucosa, hard palate, gums, lips.
  • May cause drooling, refusal to eat.
• Exanthem (Skin Rash): Appears 1-2 days after enanthem.
  • Vesicles (oval, greyish, thin-walled) on an erythematous base.
  • Characteristic distribution:
    • Hands (palms > dorsa)
    • Feet (soles > dorsa)
    • Buttocks (common, especially in diaper area)
  • Less common: Knees, elbows, perineum.
  • Typically non-pruritic, but can be tender.
  • Heals in 7-10 days without scarring.

⭐ Atypical HFMD (often Coxsackievirus A6): More widespread/severe rash, can be vesiculobullous, petechial, or purpuric. May involve trunk, limbs, face. Onychomadesis (nail shedding) can occur 1-2 months later.

Complications - Danger Zones

• Usually mild; severe forms rare (esp. EV-A71).
• Severe (EV-A71 associated):
  • Aseptic meningitis
  • Encephalitis (brainstem)
  • Acute flaccid paralysis (AFP)
  • Myocarditis, pulmonary edema
• Common:
  • Dehydration (painful oral ulcers)
  • Onychomadesis (nail shedding 1-2 months post-infection)
  • Secondary skin infection

⭐ Enterovirus A71 (EV-A71) is notorious for causing severe neurological complications (e.g., brainstem encephalitis) and fatalities in HFMD outbreaks.

Diagnosis & DDx - Detective Work

• Clinical Diagnosis: Primarily by typical rash:
  • Oral: Painful vesicles/ulcers (tongue, buccal mucosa).
  • Skin: Vesicles on palms, soles, buttocks.
  • Prodrome: Mild fever.
• Lab (Usually not required): Viral culture, PCR, serology.
• Differential Diagnosis (DDx):

Management & Prevention - Care & Shield

• Supportive Care:
  • Analgesics & antipyretics (paracetamol, ibuprofen) for pain/fever.
  • Topical anesthetics (e.g., benzydamine, lidocaine gel) for oral ulcers.
  • Adequate hydration; soft, non-irritating foods.
• Prevention:
  • Good hygiene: frequent handwashing.
  • Disinfect contaminated surfaces.
  • Avoid close contact with infected individuals.
  • Isolate infected children from school/daycare until fever resolves and lesions heal.

⭐ Complication Watch: Neurological complications (e.g., aseptic meningitis, encephalitis), though rare, are more associated with Enterovirus 71 (EV-A71) infections. Monitor for severe headache, stiff neck, or altered sensorium.

High‑Yield Points - ⚡ Biggest Takeaways

• Caused by Coxsackievirus A16 (common) and Enterovirus 71 (severe, neuro complications).
• Features painful oral vesicles (enanthem) and maculopapular/vesicular rash on hands, feet, buttocks.
• Spreads via fecal-oral and respiratory routes; highly contagious.
• Predominantly affects children under 5 years.
• Diagnosis is clinical. Dehydration is a common complication.
• EV-A71 strains can lead to aseptic meningitis or encephalitis.
• Management is symptomatic and supportive (hydration, analgesics).