What are the diagnosis and management methods for Hand, Foot, and Mouth Disease (HFMD) in adults?

Diagnosis of Hand, Foot, and Mouth Disease in Adults

HFMD in adults is diagnosed clinically based on the characteristic vesicular rash on hands, feet, and oral mucosa, with RT-PCR of vesicle fluid being the preferred confirmatory test when laboratory confirmation is needed. 1

Clinical Diagnosis

The diagnosis relies primarily on recognizing the characteristic presentation, though adults often present atypically compared to children:

Classic Presentation

• Fever (typically low-grade but can exceed 39°C) usually appears first, followed 1-2 days later by the characteristic rash 2
• Oral lesions develop as small red spots progressing to painful vesicles and ulcers, particularly on the tongue, gums, and inside of the cheeks 2
• Vesicular rash on palms, soles, and sometimes buttocks 1
• Constitutional symptoms including malaise, sore throat, and irritability 2, 3

Atypical Presentations in Adults

Adults frequently present with atypical features that can complicate diagnosis:

• Extended purpuric lesions beyond the classic distribution, involving the trunk and limbs 4
• Bullous lesions rather than simple vesicles 4
• Cutaneous signs without mucosal involvement (occurs in up to 50% of adult cases) 4
• Eczema-like lesions, rosette-shaped pustular lesions, or Gianotti-Crosti-like eruptions 4, 5
• Petechial/purpuric eruptions that may mimic more serious conditions 5

Laboratory Confirmation

When laboratory confirmation is needed, RT-PCR targeting the 5' non-coding region of vesicle fluid is the gold standard due to its high sensitivity and specificity. 1

Alternative specimens include:

• Respiratory samples (throat swabs) 1, 6
• Stool specimens 1

Note that vesicle fluid has the highest viral loads and provides the most reliable results 1

Critical Differential Diagnoses

You must actively exclude these conditions, as they require different management:

Herpes Simplex Virus

• Key distinction: HSV has available antiviral treatment whereas HFMD does not 1
• Consider HSV testing if lesions are atypical or severe

Kawasaki Disease

• Key distinctions: Persistent high fever, diffuse erythema (not vesicular), conjunctival injection, strawberry tongue, cervical lymphadenopathy 2
• Critical to exclude due to cardiac complications requiring specific treatment 2

Drug Hypersensitivity Reactions

• Key distinction: Recent medication exposure, more diffuse maculopapular pattern rather than vesicular, timing correlates with drug initiation 2

Other Vesicular Conditions

• Varicella/disseminated zoster: More widely distributed lesions, different progression pattern 5
• Eczema herpeticum: Occurs on pre-existing eczematous skin 5
• Erythema multiforme: Target lesions with central clearing on extensor surfaces 2

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Management of Hand, Foot, and Mouth Disease in Adults

HFMD management is entirely supportive, focusing on pain control, maintaining hydration, and monitoring for rare complications, as no antiviral therapy exists for this condition. 1

Oral Lesion Management

For mild to moderate oral involvement:

• Oral analgesics: Acetaminophen or NSAIDs for limited duration to relieve pain and reduce fever 1
• White soft paraffin ointment to lips every 2 hours to prevent drying and cracking 1
• Warm saline mouthwashes or oral sponge for daily mouth cleaning 1
• Benzydamine hydrochloride oral rinse or spray every 3 hours, particularly before eating, to reduce inflammation and pain 1
• Chlorhexidine oral rinse twice daily as antiseptic measure 1

For severe oral involvement:

• Betamethasone sodium phosphate 0.5 mg dissolved in 10 mL water as 2-3 minute rinse-and-spit solution one to four times daily 1
• Barrier preparations such as Gengigel mouth rinse/gel or Gelclair for pain control 1
• Dilute mouthwashes by 50% if they cause excessive discomfort 1

Dietary Modifications for Oral Pain

• Eliminate: Tomatoes, citrus fruits, hot drinks, spicy/hot/raw/crusty foods 1
• Encourage: Ample fluid intake to keep mouth moist and prevent dehydration 1

Skin Lesion Management

Hand and Foot Care

• Intensive moisturization with urea-containing creams/ointments 1
• Avoid friction and heat exposure to affected areas 1
• Do not use chemical agents or plasters to remove corns/calluses 1

For Itchiness

• Zinc oxide 20% can be applied as a protective barrier, with studies showing 50% clearance rates 1
• Apply in thin layer after gentle cleansing, repeat as needed 1
• Avoid applying to open or weeping lesions 1
• For nighttime relief, apply zinc oxide followed by loose cotton gloves to create occlusive barrier 1

Open Sores on Feet

• Wash feet daily with careful drying, particularly between toes 1
• Avoid walking barefoot; wear appropriate cushioned footwear 1
• Do not soak feet in footbaths (induces maceration and worsens sores) 1
• Monitor for secondary infection: Increased redness, warmth, purulent drainage, or worsening pain 1

Infection Control and Return to Activities

Adults can return to work/normal activities once fever resolves and mouth sores heal, even if skin rash persists. 1

Key preventive measures:

• Hand hygiene is the most important preventive measure; thorough handwashing with soap and water is more effective than alcohol-based sanitizers 1
• Avoid sharing utensils, cups, or food 1
• Environmental cleaning of frequently touched surfaces 1

Monitoring for Complications

Warning signs requiring immediate medical attention:

• Persistent high fever beyond 3-4 days 2
• Severe headache, stiff neck, or unusual lethargy 2
• Respiratory distress 2
• Neurological symptoms (altered mental status, weakness, paralysis) 2

Neurological complications (meningitis, encephalitis, acute flaccid paralysis) are rare but more common with Enterovirus 71 infections 1, 2

Follow-Up and Re-Evaluation

• Oral ulcers typically persist 7-10 days 2
• Fever usually subsides within 3-4 days 2
• Reassess after 2 weeks if lesions not improving with standard care 1
• Re-evaluate after 4 weeks if evidence of infection has not resolved; consider alternative diagnoses 1

Late Manifestations

• Beau's lines (deep transverse nail grooves) may appear 1-2 months after fever onset as delayed sequela 1
• Periungual desquamation typically begins 2-3 weeks after fever onset 1

Special Populations

Immunocompromised patients may experience more severe disease and require closer monitoring 1

Common Pitfalls to Avoid

• Do not use topical antiseptic or antimicrobial dressings routinely for HFMD foot lesions 1
• Do not prescribe antivirals (none are effective for HFMD, unlike HSV) 1
• Do not exclude patients from work/activities based solely on healing skin lesions when fever has resolved and mouth sores healed 1
• Do not overlook the need to distinguish from Kawasaki disease, which requires urgent treatment 2