Hand-Foot-Mouth Disease

Overview
Pathogen Biology
Transmission & Epidemiology
Symptoms by Phase
Diagnosis
Treatment
Home & Supportive Care
Complications
Prevention
Key Research Papers
Connections
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1. Overview

Hand-foot-mouth disease (HFMD) is a common, highly contagious viral illness primarily affecting infants and children under 5 years of age. It is caused by enteroviruses — most commonly Coxsackievirus A16 (CVA16) and Enterovirus A71 (EV-A71) — and is characterized by a distinctive triad: fever, painful mouth sores (herpangina or oral ulcers), and a rash of flat spots or blisters on the hands, feet, and sometimes the buttocks and genitalia.

HFMD is usually a mild, self-limiting illness lasting 7–10 days. However, EV-A71 in particular is associated with severe neurologic complications — brainstem encephalitis, acute flaccid myelitis, and cardiopulmonary failure — that can be fatal, particularly in children under 3 years. Large HFMD epidemics caused by EV-A71 have occurred across East and Southeast Asia, including outbreaks with thousands of deaths in China.

The disease is highly prevalent in Asia but occurs globally. It is not the same disease as foot-and-mouth disease (also called hoof-and-mouth disease), which is a livestock disease caused by a completely different virus and does not infect humans.

2. Pathogen Biology

HFMD is caused by members of the genus Enterovirus, family Picornaviridae. These are non-enveloped, positive-sense single-stranded RNA viruses approximately 7.4 kb in genome length. The genome encodes a single polyprotein cleaved into structural proteins (VP1–VP4, forming the icosahedral capsid) and nonstructural proteins involved in replication.

Causative Viruses

Coxsackievirus A16 (CVA16): Historically the dominant cause of HFMD worldwide; typically causes mild disease with low rates of neurologic complications. CVA16 has relatively low epidemic potential compared to EV-A71.
Enterovirus A71 (EV-A71): The major cause of severe HFMD and neurologic complications, including fatal brainstem encephalitis. EV-A71 has caused major epidemics in Taiwan (1998), Malaysia (1997, 2000), China (2008–2012), Vietnam (2011–2012), and Cambodia (2012). EV-A71 has three main genogroups (A, B, C) and multiple sub-genotypes.
Other coxsackieviruses: CVA6, CVA10, CVA4, CVA5, CVB1–B5 — all have been reported to cause HFMD; CVA6 has emerged as an important cause of atypical, more severe dermatologic presentations including widespread bullous rash beyond the classic hand/foot/mouth distribution.

Cell Entry and Tropism

EV-A71 uses multiple entry receptors including scavenger receptor class B member 2 (SCARB2) — expressed on neurons, cardiac muscle, and skeletal muscle — and P-selectin glycoprotein ligand-1 (PSGL-1). SCARB2 distribution correlates with EV-A71's neurotropism and cardiac involvement. After gut entry, virus replicates in intestinal lymphoid tissue, disseminates hematogenously (viremia), and can invade the CNS via retrograde axonal transport along peripheral nerves or via hematogenous spread across the blood-brain barrier.

Neurotropism of EV-A71

EV-A71's predilection for the brainstem (especially the medullary and pontine neurons controlling autonomic cardiovascular and respiratory function) explains the life-threatening cardiopulmonary failure seen in severe HFMD. Cytokine storm (IL-6, IL-10, IL-13, IFN-gamma) is central to the pathophysiology of severe EV-A71 disease, contributing to neurogenic pulmonary edema and autonomic dysfunction.

3. Transmission & Epidemiology

HFMD is highly contagious. Transmission occurs via:

Direct contact: Contact with nasal secretions, saliva, blister fluid, or feces of infected individuals. The fecal-oral route is particularly important for prolonged transmission.
Respiratory droplets: Coughing and sneezing spread the virus to close contacts.
Fomite contact: Enteroviruses survive on surfaces for days; contaminated toys, surfaces, and doorknobs are common transmission vectors in child care settings.

Incubation Period

Typically 3–7 days (range 3–10 days). Viral shedding in stool can continue for several weeks after clinical recovery, even after mouth sores and rash have resolved. Adults are frequently asymptomatic or have mild illness despite being infectious.

Seasonal Patterns

HFMD occurs year-round in tropical climates (Southeast Asia) with year-round high humidity favoring enterovirus transmission. In temperate climates (US, Europe), it peaks in summer and fall. Large epidemic cycles occur every 3–5 years in endemic regions, corresponding to shifts in dominant serotype and accumulation of susceptible children born since the prior epidemic.

Age Distribution

Most cases occur in children under 5. Children under 3 are at highest risk for severe disease from EV-A71. Older children and adults can be infected but typically have mild or subclinical illness due to partial immunity from prior enterovirus exposures. Adults with close contact with infected children (parents, teachers, childcare workers) are at risk; pregnant women should exercise particular caution as enterovirus infection during pregnancy can occasionally cause fetal/neonatal illness.

Global Distribution

HFMD is endemic globally but the highest burden — including severe EV-A71 disease — is concentrated in East and Southeast Asia: China, Taiwan, Vietnam, Malaysia, Singapore, Japan, South Korea, and Cambodia. In China alone, more than 1 million HFMD cases are reported annually; a 2008 outbreak caused approximately 126,000 cases and 126 deaths. In the US and Europe, HFMD is common but severe neurologic complications are rare, possibly reflecting differences in circulating serotypes and strains.

4. Symptoms by Phase

Prodromal Phase (Days 1–2)

Fever (typically 38–39°C) with malaise, reduced appetite, and fussiness in young children. Sore throat may be reported. At this stage the diagnosis is not yet apparent.

Enanthem — Oral Lesions (Days 2–3)

Painful mouth sores are the hallmark that drives children off food and creates distress. Sores begin as small red spots or vesicles on the tongue, gums, inner cheeks, and soft palate that quickly ulcerate. These shallow, painful ulcers (aphthous-like) make eating and drinking very painful — refusing food and drooling are classic presentations in toddlers. The oral enanthem pattern in HFMD differs from herpangina (which is caused by different coxsackievirus serotypes and affects the posterior oropharynx/soft palate rather than anterior structures).

Exanthem — Skin Rash (Days 2–5)

Flat red spots or small blisters (vesicles) appear on the palms of the hands and soles of the feet — the classic distribution. Lesions may also appear on the buttocks, genitalia, knees, elbows, and in atypical cases (particularly CVA6), can be widespread and more bullous. The rash is usually not itchy (unlike chickenpox) and typically does not pop easily. Lesions heal without scarring within 7–10 days.

Nail changes (onychomadesis): Shedding of fingernails and toenails may occur 4–8 weeks after HFMD, particularly following CVA6 infection. This resolves spontaneously as new nails grow. While alarming in appearance, nail loss is harmless and temporary.

Recovery Phase

Fever typically resolves by days 3–5. Mouth ulcers heal over 7–10 days; skin lesions resolve within 7–10 days. Children generally feel much better once the fever breaks. Return to daycare or school is appropriate 24–48 hours after fever resolution, when all mouth sores have healed enough that drooling has stopped, and if the child is well enough to participate normally.

5. Diagnosis

HFMD is a clinical diagnosis based on the characteristic triad in the appropriate age group and season. Laboratory confirmation is not routinely required for typical cases but is important for:

Severe illness (neurologic symptoms, cardiopulmonary involvement)
Outbreak investigation and public health surveillance
Atypical presentations
Pregnancy (risk assessment for fetal/neonatal disease)

PCR — Preferred Method

RT-PCR on throat swab, rectal swab, vesicle fluid, or CSF (if neurologic involvement) detects and identifies the specific enterovirus serotype. Highly sensitive and specific; required for EV-A71 confirmation in severe disease and for epidemiologic subtyping.

Viral Culture

Enterovirus culture from throat swab, stool, or vesicle fluid is possible but slow (days to weeks) and less sensitive than PCR. Less useful for clinical management; valuable for public health isolate characterization.

Serology

Acute and convalescent serology (4-fold rise in neutralizing antibody titer) can confirm recent EV-A71 or CVA16 infection retrospectively. Not useful for acute clinical management.

Differential Diagnosis

Key conditions to distinguish:

Herpangina: Painful vesicles on soft palate/posterior oropharynx only; no skin rash; caused by coxsackievirus groups A and B.
Primary herpetic gingivostomatitis: HSV-1 first infection; involves gums, hard palate, anterior mouth; often more severe; tender lymphadenopathy; tzanck smear/HSV PCR differentiates.
Aphthous ulcers (canker sores): Recurrent, no fever, no skin rash, not contagious.
Varicella (chickenpox): Pruritic widespread vesicular rash; starts on trunk, spreads centrifugally; different oral lesion distribution.
Erythema multiforme: Target lesions; may have mucosal involvement; associated with HSV or drug reactions.

6. Treatment

There is no approved antiviral therapy for HFMD. Intravenous immunoglobulin (IVIG) is used in severe EV-A71 disease with neurologic complications, based on data from several clinical trials showing benefit in reducing the risk of cardiopulmonary failure and death; evidence quality is moderate. Milrinone has been used in EV-A71 autonomic dysfunction complicated by pulmonary edema.

For the vast majority of children with uncomplicated HFMD, treatment is entirely supportive:

Pain management: Paracetamol (acetaminophen) or ibuprofen for fever and mouth pain; ibuprofen may be more effective for pain relief and is appropriate for children over 6 months. Dose by weight.
Topical oral analgesics: Viscous lidocaine is sometimes used in older children but is NOT recommended in children under 2 due to risk of toxicity; antacid-diphenhydramine-lidocaine ("magic mouthwash") mixtures are not proven superior to single analgesics and should not be used in young children.
Hydration: Ensuring adequate fluid intake is the priority; mouth pain can cause children to refuse fluids leading to dehydration.
Oral swish-and-spit: Cold water, diluted salt water, or plain water gargling/rinsing (in older children who can cooperate) can provide temporary relief.
Soft, cold foods: Cold yogurt, ice cream, smoothies, popsicles, apple sauce, and soft foods are better tolerated than acidic, salty, or sharp-textured foods during the painful oral phase.

7. Home & Supportive Care

Most children recover at home. The illness is exhausting for parents as much as children due to the irritability, pain, and feeding refusal:

Keep offering cold fluids frequently. Children may initially refuse but will accept small amounts. Popsicles, cold milk, cold water, and smoothies work well. Set a goal of 1 wet diaper per 6–8 hours in toddlers as a minimum hydration benchmark.
Avoid acidic foods and drinks — orange juice, tomato products, citrus, and vinegar-based foods worsen mouth ulcer pain significantly.
Feed smaller meals more often. Large meals are overwhelming; smaller portions of soft, cold foods every 2–3 hours work better.
Numbing the mouth before meals: Giving a dose of paracetamol or ibuprofen 30 minutes before a meal can reduce mouth pain enough to allow better feeding.
Containment within the home: Keep the child away from newborns, pregnant women, and immunocompromised individuals during the acute illness. Siblings may already have been exposed but can be isolated from other households.
Hand hygiene: Change diapers with gloves (or wash hands immediately and thoroughly), wash hands with soap and water after contact with the child's saliva, nasal secretions, or stool, and after changing diapers.
Signs requiring immediate medical attention: Persistent fever >39°C for 3+ days, inability to take any fluids for 8 hours, lethargy or difficulty waking, stiff neck, severe headache, difficulty breathing, rapid breathing, walking unsteadily, limb weakness or limpness, persistent vomiting, or seizures.

8. Complications

Complications are uncommon in typical HFMD (CVA16) but are a serious concern with EV-A71:

Dehydration: Most common complication in all cases; can require IV fluids if oral intake is severely impaired by mouth pain.
Neurologic complications (primarily EV-A71):
- Aseptic meningitis: Relatively common with EV-A71; generally benign with complete recovery.
- Brainstem encephalitis (rhombencephalitis): Characteristic EV-A71 complication; presents with myoclonic jerks, tremor, ataxia, drowsiness, cranial nerve palsies; can progress rapidly to life-threatening autonomic dysfunction and cardiopulmonary failure.
- Acute flaccid myelitis/paralysis: EV-A71 and CVA24 can cause polio-like lower motor neuron paralysis; usually asymmetric limb weakness; recovery is variable.
Cardiopulmonary failure: The most feared EV-A71 complication — neurogenic pulmonary edema and autonomic cardiac dysfunction leading to rapid deterioration and death. Onset can be rapid, within hours of initial neurologic signs. Warning signs: persistent high fever, vomiting, myoclonic jerks at rest, tachycardia, and elevated blood glucose.
Onychomadesis: Nail shedding 4–8 weeks post-HFMD (particularly CVA6); cosmetically distressing but self-limiting and harmless.
Neonatal enteroviral sepsis: Infants under 2 weeks exposed perinatally to enterovirus can develop severe sepsis-like illness with hepatitis, myocarditis, and encephalitis; high mortality without IVIG.

9. Prevention

Hygiene Measures

The most effective preventive measures are those that interrupt fecal-oral and respiratory transmission:

Frequent handwashing with soap and water, particularly after diaper changes, after toilet use, and before food preparation.
Disinfect frequently touched surfaces and toys with diluted bleach (1:10 household bleach in water) — alcohol-based disinfectants are less effective against non-enveloped enteroviruses.
Avoid sharing eating utensils, drinking cups, towels, or toothbrushes.
Exclude ill children from childcare and school while they have active fever, mouth sores causing drooling, or open weeping blisters (typically 24–48 hours after fever resolution and when the child is well enough to participate).
Pregnant women should avoid close contact with confirmed HFMD cases.

EV-A71 Vaccines (Asia)

Three inactivated EV-A71 vaccines were licensed in China between 2015 and 2016: CCEEV (Beijing Vigoo Biological), Sinovac EV71 vaccine, and Vero-cell inactivated EV-A71 (CNBG). Phase 3 clinical trials demonstrated 90–97% efficacy against EV-A71-associated HFMD and 80–88% efficacy against EV-A71-associated neurologic disease. These vaccines are used in the EV-A71-endemic countries of East Asia (China, Taiwan, Singapore); none are licensed in the US or Europe as of 2026, where EV-A71 disease severity is lower. Vaccines do not protect against CVA16 or CVA6.

10. Key Research Papers

Xing W, Liao Q, Viboud C, et al. Hand, foot, and mouth disease in China, 2008–12: an epidemiological study. Lancet Infect Dis. 2014;14:308–318. PMID: 24485991.
Ooi MH, Wong SC, Lewthwaite P, et al. Clinical features, diagnosis, and management of enterovirus 71. Lancet Neurol. 2010;9:1097–1105. PMID: 20965438.
Nhan LNT, Khanh TH, Hong NTT, et al. Deaths associated with enterovirus 71 in Vietnam. Emerg Infect Dis. 2012;18:2106–2109. PMID: 23171754.
Zhu FC, Meng FY, Li JX, et al. Efficacy, safety, and immunology of an inactivated alum-adjuvant enterovirus 71 vaccine in children in China. Lancet. 2013;381:2024–2032. PMID: 23726161.
Li J, Klein M, Chugh D, et al. Outcomes of hospitalized patients with hand, foot and mouth disease in the United States, 2014–2021. Pediatr Infect Dis J. 2022;41:e503–e508. PMID: 35839437.
Ang LW, Tay J, Phoon MC, et al. Seroepidemiology of coxsackievirus A6, coxsackievirus A10, and enterovirus 71 infections among children in Singapore. PLoS ONE. 2015;10:e0127999. PMID: 26067714.
Chen SC, Chang HL, Yan TR, et al. An eight-year study of epidemiologic features of enterovirus 71 infection in Taiwan. Am J Trop Med Hyg. 2007;77:188–191. PMID: 17620649.
Ho M, Chen ER, Hsu KH, et al. An epidemic of enterovirus 71 infection in Taiwan (1998). N Engl J Med. 1999;341:929–935. PMID: 10486418.
Li JX, Song YF, Wang L, et al. Two-year efficacy and immunogenicity of Sinovac Enterovirus 71 vaccine against hand, foot and mouth disease in children. Expert Rev Vaccines. 2016;15:129–137. PMID: 26785741.
Huang CC, Liu CC, Chang YC, et al. Neurologic complications in children with enterovirus 71 infection. N Engl J Med. 1999;341:936–942. PMID: 10486419.
Lum LC, Wong KT, Lam SK, et al. Fatal enterovirus 71 encephalomyelitis. J Pediatr. 1998;133:84–89. PMID: 9672516.
Chen KT, Chang HL, Wang ST, et al. Epidemiologic features of hand-foot-mouth disease and herpangina caused by enterovirus 71 in Taiwan, 1998–2005. Pediatrics. 2007;120:e244–e252. PMID: 17606548.

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