Dermatologic Manifestations of Hand-Foot-and-Mouth Disease 

Hand-foot-and-mouth disease (HFMD) is a viral illness with a distinct clinical presentation of oral and characteristic distal extremity lesions. Most commonly, the etiologic agents are coxsackieviruses, members of the Picornaviridae family.

Epidemic hand-foot-and-mouth disease (HFMD) viral infections are usually caused by members of the Enterovirus genus, namely, coxsackievirus A16 or enterovirus 71. In addition, sporadic cases with coxsackievirus types A4-A7, A9, A10, B1-B3, and B5 have been reported. Infections usually occur as isolated events, but epidemics occur regularly. An outbreak of HFMD in China during 2003 was caused by echovirus 19.^[1]

The incubation period averages 3-6 days. Coxsackievirus infection is highly contagious. During epidemics, the virus is spread by horizontal transmission from child to child and from mother to fetus. Transmission occurs by means of direct contact with nasal and/or oral secretions, fecal material, or aerosolized droplets in a fecal-oral or oral-oral route. Initial viral implantation in the buccal and ileal mucosa is followed by spread to lymph nodes within 24 hours. Viremia rapidly ensues, with spread to the oral mucosa and skin. By day 7, neutralizing antibody levels increase and the virus is eliminated.

Frequency

United States

HFMD epidemics tend to occur every 3 years in the United States.

International

Worldwide HFMD occurrences are reported. A seasonal pattern is present in temperate climates, with a peak incidence in late summer and early fall.

Mortality/Morbidity

• Hand-foot-and-mouth disease (HFMD) is more severe in infants and children than adults, but generally, the disease has a mild course.
• Enteroviral infections may also cause myocarditis, pneumonia, meningoencephalitis, and even death.
• Rarely, disease recurs.
• Infection in the first trimester may lead to spontaneous abortion or intrauterine growth retardation.
• A large outbreak of HFMD in Taiwan caused by enterovirus 71 had a high mortality rate of 19.3% in the severe cases; the deaths resulted from pulmonary hemorrhage. During this outbreak, mortality rates were highest in children younger than 3 years.^[2]
• In a large epidermic (138 cases) of HFMD related to enterovirus 71 in Singapore, 7 fatalities occurred, most from interstitial pneumonitis or brainstem encephalitis. The report's conclusions were that in general, HFMD is a benign disease but the presence of unusual physical findings, elevated total white blood cell count, and vomiting and the absence of oral ulcers may signify a patient with higher risk of a fatal outcome.^[3]
• A later study of an HFMD epidermic (14 children) in Australia, again with enterovirus 71, reported that 9 (64%) developed severe neurologic disease in which the host immune response seemed to cause most of the neurologic manifestations.^[4]
• In one study of an outbreak HFMD in Sarawak, Malaysia caused by human enterovirus 71, the authors identified 3 clinical risk factors to help detect children at risk for neurologic complications. Total duration of fever for 3 or more days, peak temperature elevation greater or equal to 38.5°C, and a history of lethargy all were independently associated with cerebrospinal fluid pleocytosis and neurologic disease.^[5]

Race

No racial predilection is recognized for hand-foot-and-mouth disease.

Sex

The male-to-female ratio for hand-foot-and-mouth disease is 1:1.

Age

Most cases of hand-foot-and-mouth disease affect children younger than 10 years, although cases in adults are reported.