Lead
Every summer, daycares send home notices that hand, foot, and mouth disease (HFMD) is going around. Most children recover within a week, and parents breathe a sigh of relief. And in the majority of cases, that is exactly the right response — HFMD is predominantly a benign, self-limiting illness. But not every outbreak is the same. Coxsackievirus A16 causes the large majority of cases and nearly always stays mild. Enterovirus A71 (EV-A71), responsible for a smaller proportion, has been associated in certain outbreak years with aseptic meningitis and brainstem encephalitis at a reportable rate [1,2]. Holding both things clearly — that HFMD is usually mild, and that some cases warrant prompt medical evaluation — is what leads to useful judgment at home.
The Viruses and the Variability of Outbreaks
HFMD is caused mainly by enteroviruses: a large family of RNA viruses that infect the gastrointestinal tract and can spread to other organs, including the nervous system. Coxsackievirus A16 accounts for roughly 50–60% of cases; EV-A71 for 10–20%, with the proportion varying by region and year [3]. In Japan, the outbreak season peaks in summer (June–August) and affects mainly children under 5; adults can be infected but are often asymptomatic or minimally symptomatic.
Fecal-oral, droplet, and contact routes all transmit the virus. Fecal shedding continues for two to four weeks after symptoms resolve. A child who appears recovered can still be an active source.
The Typical Course
Fever tends to be relatively mild (37–38°C, roughly 98.6–100.4°F), appearing alongside or just before painful oral ulcers on the tongue, cheek mucosa, and gums. A characteristic rash also appears on the palms of the hands, soles of the feet, and buttocks. The combination of these three locations gives the disease its name.
Oral pain often makes eating and drinking unpleasant. When fluid intake falls significantly and stays low, dehydration follows. Monitoring whether the child is drinking is the most important thing to watch during home care. Most cases resolve naturally within seven to ten days.
EV-A71 and Severe Complications
EV-A71 is the causative concern. In EV-A71 infections, aseptic meningitis: inflammation of the brain's protective membranes caused by a virus rather than bacteria, without bacterial growth on culture (headache, vomiting, neck stiffness) can develop as a complication. More rarely, brainstem encephalitis: inflammation of the brainstem, the region controlling breathing, heart rate, and consciousness, which can progress rapidly occurs. Clinical research from large EV-A71 outbreaks in Taiwan and Malaysia documented cases involving myoclonus: sudden, brief, involuntary muscle jerks or twitches (sudden muscle twitching), sleep disturbance, gait disturbance, and rapid neurological deterioration [1,2].
Four warning signs to recognize:
- Persistent high fever of 40°C (104°F) or above
- Vomiting lasting more than two days
- Lethargy, unresponsiveness, or a vacant look
- Seizures, or repeated twitching of the limbs
Any one of these warrants prompt medical evaluation.
Home Care and Infection Control
There is no specific antiviral treatment for HFMD; management is symptomatic. For the pain of oral ulcers, cold foods and drinks — ice cream, gelatin desserts, chilled liquids — provide some relief. Hot, spicy, or acidic foods worsen the pain.
Handwashing is the most effective infection control measure. Priority moments: after diaper changes, before meals, and after any bathroom use. Caregivers are also at real risk of infection and should take the same precautions. Swimming and water activities are generally discouraged during the infectious period.
Exclusion policies for daycare and preschool are not standardized by law in many countries. In Japan, HFMD is not a legally designated exclusion illness, but most facilities request that children stay home at least while fever is present and while blisters are unbroken. Practices vary by institution.
Putting It Into Practice
- If oral pain is preventing the child from drinking, check for dehydration signs (fewer wet diapers, dry mouth, no tears when crying)
- "High fever + vomiting + lethargy" in combination: suspect encephalitis and seek care
- Continue handwashing after symptoms resolve — viral shedding continues in stool
- Adults (including the caregiver) can contract HFMD; make post-diaper-change handwashing automatic
- Logging the date symptoms appeared, where the rash showed up, and the severity of oral ulcers helps with communication at any clinic visit
Summary
The vast majority of HFMD cases are mild and self-resolving. But in years when EV-A71 is circulating, severe neurological complications are a real possibility. Knowing the four warning signs is the one piece of information that changes the quality of home observation — it keeps the baseline approach appropriately relaxed while maintaining the ability to respond quickly when something is actually wrong.
References
- Chang LY, Huang LM, Gau SS, et al. Neurodevelopment and cognition in children after enterovirus 71 infection. N Engl J Med. 2007;356(12):1226–1234. doi:10.1056/NEJMoa065954. PMID: 17377161.
- Huang CC, Liu CC, Chang YC, Chen CY, Wang ST, Yeh TF. Neurologic complications in children with enterovirus 71 infection. N Engl J Med. 1999;341(13):936–942. doi:10.1056/NEJM199909233411302. PMID: 10498488.
- Solomon T, Lewthwaite P, Perera D, Cardosa MJ, McMinn P, Ooi MH. Virology, epidemiology, pathogenesis, and control of enterovirus 71. Lancet Infect Dis. 2010;10(11):778–790. doi:10.1016/S1473-3099(10)70194-8. PMID: 20961813.
- Ooi MH, Wong SC, Lewthwaite P, Cardosa MJ, Solomon T. Clinical features, diagnosis, and management of enterovirus 71. Lancet Neurol. 2010;9(11):1097–1105. doi:10.1016/S1474-4422(10)70209-X. PMID: 20965438.