Hand, Foot, and Mouth Disease (HFMD) is a common viral illness which usually affects infants and children under the age of 5. While it can also occur in adults, it is much less common. HFMD can be caused by a number of different enteroviruses. Enteroviruses are members of the Picornaviridae family of viruses, which includes poliovirus, coxsackieviruses, echoviruses, rhinoviruses, and other enteroviruses.

The most common sources of HFMD are enteroviruses species A (HEV-A), particularly enterovirus 71 (EV-71), which is the most common cause of HFMD globally, and several coxsackieviruses including A16 (CVA16), A6 (CVA6), A5 (CVA5), and A10 (CVA10), which are all enteroviruses. CVA16 is the most common cause of HFMD in the US. Most people infected with HFMD recover within 7-10 days without medical treatment and complications are uncommon, but can occur. HFMD infections caused by coxsackieviruses tend to be mild, while cases with severe complications, including death, tend to occur with EV-71 infections.

Hand, Foot, and Mouth Disease is often confused with Foot and Mouth (F&M) disease (also called Hoof and Mouth disease), which is a common disease in cattle, sheep, and swine. However, Foot and Mouth disease is caused by different viruses and the diseases are not believed to be related. Humans do not get the animal disease (F&M) and animals do not get the human disease (HFMD).

Enteroviruses are often detected in the respiratory secretions (mucus, saliva and sputum) and feces of infected people. While historically polio was the most significant enterovirus infection, global vaccination programs against poliovirus have greatly reduced the prevalence of polio. Non-polio enteroviruses have a high mutation rate and there are more than 200 non-polio enteroviruses causing diseases such as the common cold, flaccid paralysis, aseptic meningitis, myocarditis, conjunctivitis, and hand, foot and mouth disease.

The number of cases of HFMD that occur globally each year is not well tracked, but outbreaks occur regularly, indicating that HFMD infections are common. While anyone can become infected with HFMD, infants and children under the age of 5 are most commonly infected.