Hand Foot and Mouth Disease

Hand foot and mouth disease is an acute viral illness of young children characterised by fever, painful oral ulcers and a vesicular rash on the hands and feet. Caused by enteroviruses of the Picornaviridae family: coxsackievirus A16 (commonest), A6, A10, A5, A7, A9, B1 to B3, B5, and enterovirus 71 (EV-A71), which is associated with neurological complications.

• Epidemiology: mainly children under 5 years (peak 1 to 3 years); outbreaks in nurseries and schools, summer and autumn peaks in temperate regions, year round in the tropics. Adults can be infected (usually milder). Incubation 3 to 6 days.
• Spread: faecal oral, respiratory droplets, contact with vesicle fluid and contaminated surfaces. Viral shedding in stool continues for weeks after recovery; infectious most in the first week.
• Typical course: self-limiting in 7 to 10 days. Coxsackie A6 causes more extensive rash (eczema coxsackium on pre-existing eczema, widespread vesiculobullous eruption) and nail shedding (onychomadesis) 2 to 8 weeks after illness.
• Complications: dehydration from painful swallowing (commonest reason for admission), febrile seizures, aseptic meningitis, brainstem encephalitis, acute flaccid paralysis, neurogenic pulmonary oedema, myocarditis (EV-A71 severe disease, mainly Asia-Pacific region); rare. Maternal infection near term can cause neonatal infection.

• Prodrome of low grade fever, malaise, sore throat, reduced appetite for 1 to 2 days.
• Oral lesions: painful 2 to 8 mm erythematous macules becoming grey vesicles and shallow ulcers on the tongue, buccal mucosa, palate and gums; drooling, refusal to eat or drink.
• Skin: non-itchy or mildly itchy 2 to 10 mm oval, grey vesicles on an erythematous base on the palms, soles, sides of fingers and toes, sometimes buttocks, knees, elbows and genitals; vesicles follow the skin lines and resolve without scarring over 7 to 10 days.
• Examination: hydration status (mucous membranes, capillary refill, urine output), temperature, neurological assessment, respiratory and cardiovascular status.
• Red flags (suggest EV-A71 or severe disease): fever for more than 3 days, high fever above 39 C, lethargy or irritability, myoclonic jerks, tremor, ataxia, limb weakness, neck stiffness, vomiting, rapid breathing, tachycardia, cold clammy skin, hypertension, hypotension, pulmonary oedema (frothy sputum), age under 3 years with persistent symptoms, seizures, signs of dehydration, immune deficiency, newborn.

• Clinical diagnosis based on typical oral and skin lesions with epidemiology.
• Laboratory confirmation is not required in uncomplicated disease. For severe, atypical or outbreak cases: enterovirus PCR from throat swab, vesicle fluid, stool or rectal swab, cerebrospinal fluid; viral culture.
• Severe illness: full blood count, glucose, electrolytes, blood gas, chest X-ray, ECG, echocardiography, lumbar puncture, brain MRI.
• Differentials: herpangina, herpetic gingivostomatitis, aphthous ulcers, varicella, measles, Kawasaki disease, drug eruption, insect bites, Stevens-Johnson syndrome.

• Supportive treatment for uncomplicated disease:
  • Fluids: frequent cool drinks (milk, water, diluted juices; avoid acidic, salty or spicy foods); ice pops; soft bland foods; oral rehydration solution if dehydrated (50 to 100 mL/kg over 4 hours).
  • Analgesia and antipyretic: paracetamol 15 mg/kg orally every 4 to 6 hours (maximum 4 doses in 24 hours); ibuprofen 5 to 10 mg/kg orally every 6 to 8 hours with food (over 3 months, avoid when dehydrated).
  • Do not use topical lidocaine gels or sprays in young children (seizure and methaemoglobinaemia risk); avoid choline salicylate gels (Reye syndrome risk).
  • Do not puncture blisters; keep skin clean; emollients; for secondary bacterial infection of lesions: mupirocin 2 percent ointment three times daily for 5 days.
• Hospital admission: dehydration, refusal to drink, red flags (neurological or cardiorespiratory), age under 3 months.
• Severe EV-A71 disease: intensive care; intravenous immunoglobulin 1 g/kg/day for 2 days for autonomic dysfunction or neurological complications; milrinone for cardiac failure and pulmonary oedema; mechanical ventilation as required.
• Antibiotics and antivirals are not indicated; no specific antiviral is licensed.
• Prevention: hand washing with soap and water (alcohol gel is less effective against enteroviruses), disinfect toys and surfaces with chlorine based cleaners, cover coughs, dispose of nappies carefully, avoid sharing cups and utensils. EV-A71 vaccine is available in some Asian countries.
• Exclusion: children can attend school once they are well enough and fever has settled; exclusion is not required for well children with the rash only (infectivity persists for weeks); inform nurseries during outbreaks.
• Pregnant contacts: usually mild; seek advice if near term.
• Safety netting: return urgently for persistent fever beyond 3 days, drowsiness, limb weakness, rapid breathing, vomiting, inability to drink, or fewer wet nappies.
• Review as needed; nail shedding resolves with regrowth.