The disease is most common among young children. The course is similar to that of herpangina Herpangina Herpangina is a febrile disorder caused by numerous group A coxsackieviruses and occasionally other enteroviruses. Infection causes oropharyngeal, mucosal, vesicular, and ulcerative lesions... read more 
. (See also Overview of Enterovirus Infections Overview of Enterovirus Infections Enteroviruses, along with rhinoviruses (see Common Cold) and human parechoviruses, are a genus of picornaviruses (pico, or small, RNA viruses). All enteroviruses are antigenically heterogeneous... read more .)
Large outbreaks of disease due to enterovirus 71 (EV-71) have occurred in the Asia-Pacific region since 1997. Disease due to EV-71 is more serious than that due to other enteroviruses.
Children have a sore throat or mouth pain and may refuse to eat. Fever is common. Vesicles are distributed over the buccal mucosa and tongue, the palms of the hands and soles of the feet, and, occasionally, the buttocks or genitals; usually, the vesicles of typical HFMD are benign and short-lived.
This photo shows vesicles on the tongue and around the mouth in a patient with hand-foot-and-mouth disease.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
This photo shows oral lesions that appear as various-sized erosions and ulcerations on an erythematous base after vesicles have opened.
© Springer Science+Business Media
This photo shows vesicles on the palm surrounded by erythema.
© Springer Science+Business Media
This photo shows vesicles and erythematous papules on the sole of a patient with hand-foot-and-mouth disease.
SCIENCE PHOTO LIBRARY
This image shows a clear-filled vesicle on the toe of a child with hand-foot-and-mouth disease.
DR P. MARAZZI/SCIENCE PHOTO LIBRARY
Atypical HFMD has 4 distinct presentations:
Widespread vesiculobullous lesions
Eczema coxsackium with lesions concentrated in areas of eczematous skin
Gianotti-Crosti type rash (multiple discrete, erythematous flat-topped papules symmetrically distributed on the face, buttocks, and extensor surface of the extremities)
Purpuric lesions
Onychomadesis (painless nail shedding) is common during convalescence. Aseptic meningitis Aseptic meningitis Enteroviruses, along with rhinoviruses (see Common Cold) and human parechoviruses, are a genus of picornaviruses (pico, or small, RNA viruses). All enteroviruses are antigenically heterogeneous... read more may complicate atypical HFMD, but most patients recover uneventfully.
Infection with EV-71 may be accompanied by severe neurologic manifestations (eg, meningitis Overview of Meningitis Meningitis is inflammation of the meninges and subarachnoid space. It may result from infections, other disorders, or reactions to drugs. Severity and acuity vary. Findings typically include... read more , encephalitis Encephalitis Encephalitis is inflammation of the parenchyma of the brain, resulting from direct viral invasion. Acute disseminated encephalomyelitis is brain and spinal cord inflammation caused by a hypersensitivity... read more , polio-like paralysis). Morbidity and mortality are significantly higher with EV-71 than with coxsackievirus A16 or other enteroviruses. A recent cluster EV-71-associated neurologic disease was noted in the US in 2018 (1 Reference Hand-foot-and-mouth disease (HFMD) is a febrile disorder usually caused by coxsackievirus A16, enterovirus 71, or other enteroviruses. Infection causes a vesicular eruption on the hands, feet... read more 
).
The diagnosis of HFMD is usually made clinically.
Treatment of HFMD is symptomatic. It includes meticulous oral hygiene (using a soft toothbrush and salt-water rinses), a soft diet that does not include acidic or salty foods, and topical measures (see treatment of stomatitis Treatment Oral inflammation and ulcers, known as stomatitis, may be mild and localized or severe and widespread. They are invariably painful. (See also Evaluation of the Dental Patient and Gingivitis... read more 
).
Three inactivated EV-71 vaccines are currently available in China, but none are yet approved for use in the US. Coxsackie A16 vaccines are also in preclinical development.
Reference
1. Messacar K, Burakoff A, Nix WA, et al: Notes from the field: enterovirus A71 neurologic disease in children — Colorado, 2018. MMWR Morb Mortal Wkly Rep 67(36): 1017–1018, 2018. doi: 10.15585/mmwr.mm6736a5
