When is hand, foot, and mouth (HFMD) disease infectious?

When is Hand, Foot, and Mouth Disease Infectious

Hand, foot, and mouth disease (HFMD) is most infectious during the first week of illness, particularly when fever and skin lesions are present, and infected individuals can continue to shed the virus for up to five days in adults and seven days in children after symptom onset. 1, 2

Infectious Period and Viral Shedding

• HFMD has an incubation period of 3-10 days between exposure and the development of symptoms 3
• The disease is most contagious during the acute phase of illness when fever and skin lesions are present 2
• Infected individuals continue to excrete virus for up to five days after symptom onset in adults, and up to seven days in children 1
• The amount of virus shed, and therefore the infection risk, decreases steadily over this period 1

Transmission Routes

• HFMD is transmitted through multiple routes:
  • Fecal-oral contact (primary route) 2
  • Oral-oral contact (e.g., saliva) 2
  • Respiratory droplet contact 2, 1
  • Direct contact with fluid from blisters or vesicles 1
  • Indirect contact via contaminated surfaces and objects (fomites) 1

Signs of Infectiousness

• Fever is typically the first symptom, often accompanied by malaise, sore throat, and irritability in toddlers 4
• The appearance of the characteristic vesicular rash on hands, feet, and in the mouth indicates active infection 2
• Respiratory symptoms such as cough and rhinitis may be present during the infectious period 4
• Gastrointestinal symptoms including nausea, vomiting, and diarrhea may occur during the infectious period 4

Important Clinical Considerations

• Spread from a person before they develop symptoms (pre-symptomatic transmission) has only rarely been recorded, suggesting that most transmission occurs after symptom onset 1
• Children with HFMD should be excluded from swimming pools during the acute illness phase 1
• Vesicle fluid from patients with HFMD should be considered infectious and appropriate precautions should be taken 1
• The virus can remain on surfaces and objects, making hand hygiene and environmental cleaning crucial for prevention 1

Prevention of Transmission

• Hand hygiene (using alcohol-based hand rub or washing with soap and water) is the single most important method of preventing transmission 1
• Disinfection of potentially contaminated surfaces and fomites is essential 2
• Standard precautions should be observed in healthcare settings, including appropriate use of personal protective equipment when examining patients with HFMD 1
• Children should be kept home from school or daycare during the acute phase of illness 2

Return to Normal Activities

• Children can generally return to normal activities once fever resolves and lesions have dried or crusted over 1
• Some guidelines suggest waiting until no new lesions have appeared for 48 hours 1
• Special attention should be paid to hand hygiene even after returning to normal activities, as some viral shedding may continue 1