Hand foot and mouth disease

What is hand foot and mouth disease?

Hand foot and mouth disease (HFM) is a common mild and short-lasting viral infection most often affecting young children. It is characterised by blisters on the hands, feet and in the mouth. The infection may rarely affect adults.

Hand foot and mouth disease is also called enteroviral vesicular stomatitis.

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What is the cause of hand-foot-and-mouth disease?

Hand-foot-and-mouth is due to an enterovirus infection, usually Coxsackie virus (CV) A16. Other viruses causing HFM include:

• Enterovirus 71, linked with severe infections that may involve the nervous system
• CVA6, causing increasingly common and severe infection worldwide
• CV A5, A7, A9, A10, B2, and B5
• Echovirus
• Coxsackie virus 

Who gets hand foot and mouth disease?

HFM most often infects children under the age 10, and most are under 5 years of age (95%). It can uncommonly affect adults, and tends to be more severe in the elderly, immunocompromised, and pregnant women.

Hand foot and mouth disease is very infectious, so several members of the family or a school class may be affected. Epidemics are most common during the late summer or autumn months.

What are the clinical features of hand, foot and mouth disease?

Typical HFM causes:

• Lesions on the dorsal and palmar surfaces of the hands and feet. The progression is from flat pink patches to small, elongated greyish blisters, and, within a week, these peel off leaving no scars.
• Small vesicles and ulcers in and around the mouth, palate, and pharynx. These are sometimes painful, so the child eats little and frets.
• Red macules and papules on the buttocks and sometimes on the arms. Lesions can also occur on the genitalia.

Atypical hand foot and mouth disease results in a more widespread rash. Features may include:

• Red, crusted papules
• No blisters or very large ones
• Targetoid lesions
• Involvement of unusual sites such as the ear
• In children with atopic dermatitis, lesions may select skin affected by eczema.

Flat pink patches on the dorsal and palmar surfaces of the hands and feet are soon followed by small elongated greyish blisters. These resolve by peeling off within a week, without leaving scars.  

Usually there are also a few small oral vesicles and ulcers. These are sometimes painful, so the child eats little and frets. There may be a few on the skin around the mouth. In young children a red rash may develop on the buttocks and sometimes on the arms.

Atypical hand foot and mouth disease due to Coxsackie A6 results in a more widespread rash, larger blisters and subsequent skin peeling and/or nail shedding.

How is hand-foot-and-mouth disease diagnosed?

The diagnosis is typically made clinically, due to the characteristic appearance of blisters in typical sites, ie, hands, feet, and mouth. 

In ill children, blood tests may show:

• Raised white cell count
• Atypical lymphocytes
• Raised serum C-reactive protein (CRP)
• Positive serology for causative virus, which may be isolated from swabs of vesicles, mucosal surfaces, or stool specimens, which confirms the infection but is rarely necessary.

Skin biopsy of a blister shows the characteristic histopathologic findings of hand-foot-and-mouth disease.

How is the infection transmitted?

Hand foot and mouth is passed on by direct contact with the skin, nasal and oral secretions of infected individuals, or by faecal contamination.

How is hand-foot-and-mouth disease treated?

Specific treatment is not often necessary. 

• The blisters should not be ruptured, to reduce contagion.
• Keep the blisters clean and apply non-adherent dressings to erosions.
• Maintain adequate fluid intake; if oral intake is poor due to painful erosions, intravenous fluids may be indicated.
• Antiseptic mouthwashes, topical and oral analgesics help relieve pain due to oral ulcers.

Intravenous immunoglobulin and milrinone have shown some efficacy in a few reports. 

No vaccines or specific antiviral medications are available.

Does the child have to stay off school?

As in the vast majority of cases hand foot and mouth disease is a mild illness, there is no need to keep children from school once they are well enough to attend.

The blisters remain infective until they have dried up, which is usually within a few days. The stools are infective for up to a month after the illness. Thorough hand-washing will reduce the spread of the disease.

What are the complications of hand-foot and mouth disease?

Complications are uncommon. They include:

• Dehydration due to inadequate fluid intake
• Fingernail and toenail changes are often noted about 2 months after CVA6 infection:
  • Transverse lines that slowly move outwards
  • Nail shedding (onychomadesis) about 2 months after the illness.
  • Eventually the nails return to normal.

 Serious enteroviral infection can lead to:

• Widespread vesicular rash
• Enteritis (gut infection)
• Myocarditis (heart muscle infection)
• Meningoencephalitis (brain infection)
• Acute flaccid paralysis (spinal cord infection)
• Pulmonary oedema and pneumonia (lung infection)
• In pregnancy, first trimester spontaneous abortion or fetal growth retardation.

Neurological involvement associated with enterovirus 71 infection may include:

• Aseptic meningitis
• Encephalitis
• Encephalomyelitis
• Acute cerebellar ataxia
• Acute transverse myelitis
• Guillain-Barré syndrome
• Opsomyoclonus syndrome
• Benign intracranial hypertension