Outbreak Investigation
Infectious Diseases & Child Health
Key Takeaways
- HFMD is a common viral illness that primarily affects children under 10 years old, caused by enteroviruses (most commonly Coxsackievirus A16 and Enterovirus 71).
- The disease is characterised by fever, painful mouth sores, and a rash with blisters on the hands, feet, and sometimes the buttocks — it is usually mild and resolves within 7 to 10 days.
- While most HFMD cases are self-limiting, Enterovirus 71 (EV71) can rarely cause serious neurological complications including encephalitis, which can be fatal — making outbreak monitoring and early recognition of warning signs essential.
- HFMD spreads easily through direct contact with secretions, saliva, fluid from blisters, and faeces of infected individuals — childcare centres and kindergartens are common outbreak settings due to close contact and developing hygiene practices among young children.
What Is Hand, Foot and Mouth Disease?
Hand, foot and mouth disease (HFMD) is a common viral infection that predominantly affects infants and children under the age of 10, though older children and adults can occasionally be infected as well. Despite its alarming-sounding name and the distress it causes to affected children and their parents, HFMD is usually a mild, self-limiting illness that resolves completely within one to two weeks.
The disease is caused by a group of viruses called enteroviruses. The most common causative agents are Coxsackievirus A16 (which typically causes milder illness) and Enterovirus 71 or EV71 (which is less common but more likely to cause severe complications). Several other coxsackieviruses and enteroviruses can also cause HFMD, which is why a child can get the disease more than once — infection with one virus type does not protect against others.
HFMD is not the same as foot-and-mouth disease (which affects cattle and livestock). Despite the similar name, the two diseases are caused by entirely different viruses and are unrelated.
Recognising the Symptoms
HFMD typically follows a recognisable pattern that develops over several days.
| Stage | Timing | Symptoms |
|---|---|---|
| Incubation period | 3–6 days after exposure | No symptoms — the child appears well but is becoming infectious |
| Early illness | Day 1–2 | Fever (often 38–39°C), sore throat, reduced appetite, general irritability and malaise |
| Mouth sores | Day 1–2 | Painful red spots develop inside the mouth — on the tongue, gums, and inner cheeks. These become small ulcers that make eating and drinking painful |
| Skin rash | Day 1–3 | Small red spots appear on the palms of the hands, soles of the feet, and sometimes the buttocks and groin. These may develop into small blisters |
| Recovery | Day 7–10 | Fever resolves, sores and rash gradually heal. Some children may experience nail shedding several weeks later (harmless and temporary) |
The mouth sores are typically the most troublesome symptom because they cause significant pain during eating and drinking. Young children who cannot articulate their discomfort may simply refuse food and drink, which can lead to dehydration — the most common complication requiring medical attention in otherwise uncomplicated HFMD.
The Hulu Langat Outbreak
The outbreak investigation in Hulu Langat, Selangor documented a cluster of HFMD cases that highlighted the characteristic patterns of HFMD outbreaks in Malaysian communities. Childcare centres and kindergartens were the primary settings for transmission, as they are in HFMD outbreaks worldwide. The close physical contact between young children in group care — sharing toys, touching faces, imperfect hand hygiene, communal eating — creates ideal conditions for enterovirus transmission.
The outbreak investigation involved identifying cases, tracing contacts, collecting samples for viral typing, implementing control measures, and monitoring for any cases of severe disease. Public health authorities worked with affected childcare centres to implement enhanced hygiene measures, isolate symptomatic children, and communicate with parents about recognising symptoms and seeking appropriate care.
When HFMD Becomes Serious
While the vast majority of HFMD cases are mild, it is essential that parents and healthcare providers are aware of the rare but potentially serious complications, particularly those associated with Enterovirus 71 (EV71).
EV71 has a particular affinity for the central nervous system and can, in rare cases, cause encephalitis (inflammation of the brain), aseptic meningitis (inflammation of the membranes surrounding the brain and spinal cord), and acute flaccid paralysis (a polio-like weakness). In the most severe cases, EV71 encephalitis can progress to brainstem involvement with cardiopulmonary failure, which can be rapidly fatal.
Major outbreaks of severe EV71-associated HFMD have occurred across Asia, including in Malaysia (the 1997 Sarawak outbreak was one of the first to draw international attention to EV71), Taiwan, China, Vietnam, and Cambodia. While these severe cases represent a small minority of all HFMD infections, their potential severity makes outbreak surveillance and early recognition of warning signs critically important.
Warning Signs — Seek Immediate Medical Attention If Your Child Has HFMD And:
- Persistent high fever (above 39°C) lasting more than 3 days
- Excessive sleepiness, confusion, or unusual irritability
- Repeated vomiting
- Rapid or difficult breathing
- Weakness or inability to walk
- Sudden jerking movements (myoclonus) — especially during sleep
- Poor urine output (fewer than 3 wet nappies in 24 hours in young children)
- Cold, mottled, or bluish extremities
How HFMD Spreads
Understanding how HFMD spreads is essential for effective prevention. The virus is shed in several body fluids of infected individuals: saliva and nasal secretions (spread by coughing, sneezing, and drooling), fluid from blisters (direct contact with broken blisters), and faeces (the virus is shed in stool for weeks after symptoms resolve, making this the most prolonged route of transmission).
Transmission occurs through direct contact with these fluids, through contaminated surfaces (toys, doorknobs, changing tables), and through respiratory droplets at close range. The virus is remarkably hardy and can survive on surfaces for hours to days, which is why cleaning and disinfection of shared environments is an important control measure.
Importantly, children are most contagious during the first week of illness — but they continue to shed the virus in their stool for weeks after symptoms have resolved. This means that a child who looks and feels completely well may still be infectious to others, which complicates decisions about when to return to school or childcare.
Prevention Guide for Parents and Childcare Providers
- Hand hygiene is the most important preventive measure. Wash your child’s hands (and your own) frequently with soap and water — especially after using the toilet, before eating, and after changing nappies. Alcohol-based hand sanitisers are less effective against enteroviruses than soap and water.
- Clean and disinfect shared surfaces and toys regularly, particularly in childcare settings. Use a dilute bleach solution (1 tablespoon of household bleach per 1 litre of water) or a commercial disinfectant effective against non-enveloped viruses.
- Keep sick children at home until fever has resolved and mouth sores and blisters are healing — typically at least 7 days from symptom onset. Consult your child’s doctor or the childcare centre’s health policy for specific guidance.
- Avoid close contact (kissing, hugging, sharing utensils) with children who have HFMD symptoms.
- Teach children not to share cups, utensils, and towels, particularly during outbreaks.
- If your child has HFMD, focus on hydration. Offer cool, soft foods and plenty of fluids. Cold drinks and ice pops may soothe mouth sores. Avoid acidic or spicy foods that irritate ulcers. Paracetamol can help with fever and pain (follow dosing instructions for your child’s age and weight).
Implications for Malaysian Public Health
HFMD surveillance and outbreak response capacity should be maintained and strengthened, given the recurring nature of outbreaks in Malaysia. Childcare centres and kindergartens should have clear HFMD management protocols, including criteria for exclusion of symptomatic children, enhanced hygiene procedures during outbreaks, and communication templates for notifying parents. Public health messaging during HFMD seasons should emphasise the usually mild nature of the disease (to reduce unnecessary parental anxiety) while clearly communicating the warning signs that warrant urgent medical attention (to ensure severe cases are identified early). Research and development of EV71 vaccines — some of which are already licensed in China — should be monitored for potential applicability to the Malaysian context.