Hand, foot, and mouth disease (HFMD) is caused by a group of viruses called enteroviruses. The most common culprit in the United States is coxsackievirus A16, though several related viruses can produce the same illness. The disease spreads easily through direct contact with an infected person’s saliva, blister fluid, nasal secretions, or stool.
The Viruses Behind HFMD
Enteroviruses are a large family of viruses, and several members can cause HFMD. Coxsackievirus A16 is responsible for the majority of cases in the U.S. It tends to cause the classic, milder version of the illness: mouth sores, a rash on the hands and feet, and a low fever that resolves within a week or so.
Coxsackievirus A6 is another common cause and often produces more severe symptoms. People infected with this strain may develop larger, more widespread blisters that can appear on the arms, legs, and buttocks in addition to the usual locations. Skin peeling and even temporary nail loss sometimes follow.
A third virus, enterovirus 71 (EV-A71), is more frequently seen in East and Southeast Asia. EV-A71 carries a higher risk of serious complications. In rare cases, it can travel from the gut into the nervous system and cause brain swelling (encephalitis), meningitis, or a polio-like paralysis. Large outbreaks linked to EV-A71 have created significant public health concerns in the Asia-Pacific region.
How the Virus Gets Into Your Body
HFMD viruses enter through the mucous membranes, primarily the mouth and nose. From there, the virus replicates in the lymphatic tissue of the throat and gut. Within a few days it spills into the bloodstream, a phase called viremia, which is how it reaches the skin and mouth lining to produce the characteristic blisters and sores.
In the small number of cases that turn serious, particularly with EV-A71, the virus can travel along nerve fibers using the body’s own transport system for moving molecules along nerve cells. It follows motor nerve pathways into the brainstem and spinal cord. This is why the rare neurological complications tend to affect movement and coordination rather than sensation.
How It Spreads Between People
HFMD is highly contagious. The virus moves from person to person through several routes:
- Close personal contact: Kissing, hugging, or sharing cups and utensils with an infected person.
- Respiratory droplets: Coughing and sneezing release virus-containing droplets that others can inhale or touch.
- Blister fluid: The liquid inside HFMD blisters is packed with virus. Touching a blister or a surface it has contacted can transmit the infection.
- Fecal-oral route: The virus sheds in stool for weeks after symptoms resolve. Diaper changes, shared bathrooms, and inadequate handwashing are common transmission points, especially in daycare settings.
- Contaminated surfaces: Enteroviruses can survive on surfaces for extended periods, anywhere from hours to weeks depending on the material and conditions. Toys, doorknobs, and changing tables in childcare facilities are frequent culprits.
A person with HFMD is most contagious during the first week of illness, but the virus continues shedding in stool for weeks afterward. This means someone can spread the disease even after they feel completely better.
Who Is Most at Risk
Children under five are by far the most commonly affected group. Their immune systems haven’t encountered these viruses before, and the close-contact environments of daycare centers and preschools create ideal conditions for spread. Infants and toddlers are also less likely to wash their hands consistently and more likely to put shared objects in their mouths.
Adults can absolutely get HFMD, though many assume it’s exclusively a childhood illness. Some adults who catch it develop mild or no symptoms at all, but others experience the full range of sores and rashes. Adults can also be silent carriers, spreading the virus without realizing they’re infected. Parents and caregivers of young children with HFMD are at the highest risk of catching it themselves.
Seasonal Patterns
In temperate climates like the U.S., HFMD peaks in summer and early fall. Enteroviruses thrive in warmer weather, and children are often in closer contact at camps and daycare during these months. In tropical regions, cases occur year-round, though outbreaks still tend to cluster.
Why Some Cases Are Worse Than Others
The severity of HFMD depends largely on which virus strain is involved and the age and immune status of the person infected. Most cases caused by coxsackievirus A16 are mild and self-limiting. Coxsackievirus A6 infections can look more alarming, with extensive blistering and peeling skin, but they still typically resolve without lasting harm.
EV-A71 is the strain most associated with dangerous complications. A small percentage of patients, mostly young children, develop neurological problems including aseptic meningitis, acute cerebellar ataxia (a sudden loss of coordination), Guillain-Barré syndrome, or encephalitis. In the most severe cases, these complications can be fatal. This is why large EV-A71 outbreaks in Asia have prompted intensive public health responses and vaccine development efforts.
Children with weakened immune systems and very young infants are also more vulnerable to severe illness regardless of the specific strain involved.
Reducing the Spread
Because no vaccine for HFMD is widely available outside of China, prevention comes down to hygiene. Frequent handwashing with soap and water, especially after diaper changes and before eating, is the single most effective measure. Cleaning and disinfecting shared surfaces matters too. Chlorine-based cleaners and hydrogen peroxide products are the most effective at killing enteroviruses on surfaces, while alcohol-based sanitizers are less reliable against this particular group of viruses.
Keeping sick children home from daycare during the first week of illness helps limit outbreaks, though the extended period of stool shedding means transmission can’t be eliminated entirely. Teaching children to cover coughs and sneezes and to avoid sharing drinks and utensils reduces exposure in group settings.