What is hand, foot, and mouth disease (HFMD)?

Hand, Foot, and Mouth Disease (HFMD)

Hand, foot, and mouth disease is a common, highly contagious viral illness primarily affecting children under five years of age, characterized by vesicular lesions on the hands, feet, and oral mucosa, typically caused by enteroviruses, especially coxsackievirus A16 and enterovirus 71. 1, 2

Clinical Presentation

• HFMD typically presents with fever and sore throat as initial symptoms, followed by the development of characteristic skin lesions after a few days 3
• The classic presentation includes painful vesiculopapular lesions on:
  • Hands (palms)
  • Feet (soles)
  • Oral mucosa (painful ulcers) 1, 4
• Constitutional symptoms commonly include:
  • Fever
  • Painful swallowing (most common constitutional symptom)
  • Irritability
  • Malaise 2
• The incubation period ranges from 3 to 10 days 3

Causative Agents

• HFMD is primarily caused by enteroviruses, with the most common pathogens being:
  • Coxsackievirus A16 (CV-A16) - traditionally most common
  • Enterovirus 71 (EV-A71) - associated with more severe outbreaks, especially in Asia
  • Coxsackievirus A6 (CV-A6) - emerging as a major cause of outbreaks worldwide 5, 1
• CV-A6 has been increasingly identified in recent outbreaks and is associated with:
  • More severe disease
  • Broader demographic impact (including adults)
  • Atypical and more widespread rash distribution 5, 6

Atypical Presentations

• "Eczema coxsackium" - HFMD superinfection of eczematous skin in children with atopic dermatitis, which may resemble herpes infection 4
• Widespread exanthema beyond the classic distribution (hands, feet, mouth) may occur, involving:
  • Buttocks
  • Legs
  • Arms
  • Trunk 6
• Perioral rash is particularly associated with CV-A6 infection 6
• Nail changes, including shedding (onychomadesis), may occur 1-2 months after the initial infection 4, 3

Diagnosis

• Diagnosis is primarily clinical, based on the characteristic distribution of lesions 1
• Laboratory confirmation can be achieved through:
  • Reverse transcriptase PCR (RT-PCR) of vesicle fluid samples (highest viral load)
  • RT-PCR of respiratory samples or stool specimens
  • The 5′ non-coding region is the preferred target for PCR testing 1, 7

Complications

• Most cases of HFMD are mild and self-limiting, resolving within 7-10 days 5
• Severe complications are rare but can include:
  • Neurological complications (particularly with EV-71):
    • Encephalitis/meningitis
    • Acute flaccid myelitis (AFM)
    • Acute flaccid paralysis (AFP) 7, 3
  • Respiratory complications (e.g., pulmonary edema)
  • Cardiac complications 3
• Immunocompromised patients may experience more severe disease 1

Management

• Treatment is primarily supportive as HFMD is usually self-limiting 1, 4
• Supportive care measures include:
  • Oral analgesics (acetaminophen or NSAIDs) for pain relief and fever reduction 1
  • Adequate hydration, especially when oral lesions make drinking painful 1
  • Soft diet to minimize discomfort from oral lesions 1
• For oral lesions:
  • Mild toothpaste and gentle oral hygiene
  • Delaying normal activities until symptoms resolve for severe oral ulcers 1
• For skin manifestations:
  • Moisturizing creams (e.g., urea cream/ointment)
  • Avoiding friction and heat exposure to affected areas 1
• Treatment of any secondary bacterial infections that may develop 1

Prevention and Control

• Hand hygiene is the most important preventive measure:
  • Thorough handwashing with soap and water (more effective than alcohol-based sanitizers) 1
• Environmental cleaning, particularly of toys and objects that children may put in their mouths 1
• Children with HFMD should avoid close contact with others until:
  • Fever resolves
  • Mouth sores heal 1
• Standard precautions and good hand hygiene practices in healthcare settings 1
• No vaccine is currently widely available, although research is underway 3

Epidemiology

• HFMD primarily affects children under 5 years of age, with decreasing incidence as age increases 2
• Slight male predominance has been observed 2
• Seasonal patterns vary by region, with peaks often occurring in summer and early autumn months 2
• Family history of HFMD is present in approximately 25% of cases, indicating household transmission 2
• Large outbreaks have been reported in Asian countries, particularly with EV-71 3