What is hand, foot, and mouth disease?
Hand, foot, and mouth disease (HFMD or HFM) is a common,self-limiting, viralinfectionthat causes blisters on the hands, feet, and inside or around the mouth. It mainly affects children under the age of 5 years.
HFMD, also called enteroviralvesicularstomatitis, occurs sporadically worldwide.Epidemicsare most common during warm weather, usually in the late summer or early autumn.
It is important to note that HFMD is NOT related to foot and mouth disease of animals.
Who gets hand, foot, and mouth disease?
HFMD mostly occurs in children under 10 years of age with 95% of the cases occurring in toddlers aged under 5 years. However, it can also affect older children/adolescents. Adults, especially those who areimmunocompromised, may also be affected. However, HFMD only rarely affects healthy adults.
Hand, foot, and mouth disease is very common. The average annualincidenceof HFMD has been reported as 90–2400 cases per 100,000 people in some countries.
What causes hand, foot, and mouth disease?
Enteroviral vesicular stomatitis (HFMD) is usually caused by the Coxsackie virus, most commonly the A16 subtype. It may also be caused by other viruses such as:
- Coxsackie A virus (5, 6, 7, 9, 10)
- 柯萨奇病毒B(2、5)
- Enterovirus 71
- Echoviruses.
Enterovirus 71 infection is associated with more severeinfectionsthat may involve the heart, lungs, and can also causeinflammationof the lining of the brain (meningitis).
Transmission occurs via direct contact with blister fluid or droplets spread from the mouth. It can spread very rapidly among family members or within a school. The virus can be shed in faeces andsalivafor several weeks.
What are the clinical features of hand, foot, and mouth disease?
The illness usually begins with one or all of the following:fever, sore throat, loss of appetite, andlethargy. However, many children remain well in themselves despite therash. The blisters usually appear 1–2 days following the fever.
Theincubationperiod is typically 3–6 days and children remain infectious until the blisters have ruptured and healed (usually 7–10 days).
皮肤findings typically include:
- Blisters on the tops of the hands, feet and/or palms, and soles.Lesionsusually:
- Feel tender
- Evolve over time from flat pinkmaculesto small, elongated, red-greyish blisters
- Are often oval rather than round
- Peel off within a week, without leaving ascar.
- Small blisters (vesicles) andulcersmaydevelopin and/or around the lips and mouth and the back of the throat. These can sometimes be very painful. Oral intake may be significantly impacted, especially in infants and younger children.
- In children witheczema, or past eczema, blisters, flat red macules andpapulesmay develop over other areas of the skin, especially the buttocks and sometimes on the arms, legs, andgenitalskin.
AtypicalHFMD can result in a morewidespreadrash and blistering. Features may include:
- Red,crusted及一个d papules without blistering
- Large blisters (bulla)
- Targetoid(bulls-eye, or target-shaped) lesions
- Nailshedding
- Involvement of atypical or unusual sites such as the ears.
Hand, foot, and mouth disease
How do clinical features vary in differing types of skin?
In children with pre-existing eczema (atopicdermatitis), HFMD lesions may belocalisedineczematousareas (eczema coxsackium).
What are the complications of hand, foot, and mouth disease?
Severe complications are very uncommon in people that are otherwise healthy. They include:
- Dehydration due to inadequate fluid intake. This can cause significant problems in younger children.
- Fingernail and toenail changes are often noted about two months after HFMD infections due to coxsackie A6 infection.
- Transverselines in thenail platethat slowly move outwards
- Onychomadesis(nail shedding) may occur about 2 months after the illness, however, eventually thenailsreturn to normal.
严重enteroviral infection can lead to:
- Widespread blistering
- Enteritis
- 心肌炎
- Inflammation of the brain and or the lining of the brain (meningoencephalitis)
- Loss ofnervefunction in a limb (acuteflaccidparalysis)
- Pulmonaryoedemaand pneumonia
- Haemorrhagicconjunctivitis
- In pregnancy, viruses that cause HFMD can cause first trimester spontaneous miscarriage orintrauterinegrowth restriction
- Meningoencephalitis,thrombocytopenia,disseminatedintravascularcoagulopathy,cardiomyopathyand肝炎in the newborn have rarely been described.
How is hand, foot, and mouth disease diagnosed?
HFMD is usually diagnosed clinically.Cutaneouslesions are typically distributed symmetrically over common sites of the skin such as the hands, feet, and in and around the mouth in a child.
Other diagnostic tools include:
- Polymerase chain reaction(PCR) testing
- ViralDNAmay be detected fromnasopharyngeal, (throat or nose), swabs and stool specimens.
- Analysis of blood, cerebrospinal fluid (CSF), and faeces samples can confirm the diagnosis, but are rarely needed except in atypical or severe cases.
- 皮肤biopsyof a blister
- Very rarely indicated.
- Showsacralskin withlymphocyticinfiltratesat theepidermis.
- Theinfiltrateis associated withkeratinocyteapoptosisin early lesions.
Seehand, foot, and mouth diseasepathologyfor more information.
What is thedifferential diagnosisfor hand, foot, and mouth disease?
- Bacterialinfections: such as Group AStreptococcusandStaphylococcus aureus, may cause similar blistering skin lesions, eg,bullousimpetigo.
- Otherviral infectionssuch as human parechoviruses,herpessimplexvirus, adenoviruses,varicella zoster virus,Epstein-Barr virus, andhuman herpesvirus6 and 7.
- Bullousinsect bite reactionsmay also present on the hands and feet in children.
- Pompholyxeczema.
What is the treatment for hand, foot, and mouth disease?
Specific treatment is not usually required for HFMD, and the focus is symptomatic care. HFMD rarely causes serious complications. Antibiotics do not work and should not be given to children with HFMD.
No vaccines or specificantiviralmedications are available.
General measures
Pain relief
- Simpleanalgesiasuch as paracetamol or ibuprofen as needed.
- Antisepticmouthwashesortopicalsoothing agents (eg, lignocaine) can be used in children with painful oral/palatal ulcers.
- Aspirin should not be used routinely due to the risk of Reyesyndrome.
Hydration
- Constantly offer the child sips of water/juice to prevent dehydration.
- If oral intake is poor, nasogastric or intravenous fluids may be indicated.
Blister care
- Leave blisters to dry naturally.
- Do not pierce/rupture the blisters to reduce contagion.
- Keep the blisters clean and apply non-adherent dressings toerosions.
Should children with hand, foot, and mouth disease stay home from school?
In the vast majority of cases, HFMD is a mild illness and there is no need to keep children from school once they are well enough to attend.
The blisters remain infective until they have dried, which is usually within a few days. However, the virus sheds through faecal stools and these remain infective for up to a month after the illness. Therefore, it is impractical to keep children who are well away from school.
General preventative measures include:
- Thorough hand hygiene especially after coming into contact with one’s bodily fluid.
- This includes touching their blisters, helping them to blow their nose and changing nappies or helping with toileting.
- Minimise sharing personal items such as cutlery, drinking cups, towels, toothbrushes, and clothing.
What is the outcome for hand, foot, and mouth disease?
HFMD infection is usually mild and complete resolution is seen within 7–10 days. Infection often results in long-term immunity to the specific virus, however a second episode can occur following infection with a different member of the enterovirus group.