Hand, Foot, and Mouth Disease (HFMD) is a common, highly contagious viral illness that typically affects infants and young children, though adults can also contract it. The infection is characterized by painful sores in the mouth and a rash, often featuring blisters, on the hands and feet. A person who has recovered from HFMD can be infected with the disease more than once.
The Viral Cause of Reinfection
The possibility of reinfection stems from the fact that HFMD is not caused by a single pathogen, but rather by a group of related viruses within the Enterovirus genus. The most frequent culprits are Coxsackievirus A16 (CV-A16) and Enterovirus 71 (EV-71), though other serotypes like Coxsackievirus A6 (CV-A6) are also common.
An infection triggers an immune response specific only to that particular viral strain. The immune system develops antibodies that recognize and neutralize the specific virus that caused the initial illness. If a person is later exposed to a different viral strain from the Enterovirus group, the existing antibodies offer no protection. This allows the new virus to infect the individual and cause a new episode of Hand, Foot, and Mouth Disease.
Strain-Specific Immunity
The immunity developed after an initial HFMD case is robust and long-lasting, but it is narrowly focused on the specific serotype responsible for that illness. For instance, recovering from Coxsackievirus A16 provides protection against future CV-A16 exposure, but not against strains like Coxsackievirus A6 or Enterovirus 71. Reinfection occurs when a person encounters a circulating viral strain to which they have not yet developed immunity.
The disease is most common in young children who are frequently exposed to different pathogens in group settings, making repeat infections prevalent in daycare centers and households with multiple children. While individuals can experience the illness multiple times, subsequent symptoms may sometimes be less severe. However, the risk of a full-blown illness remains present as long as new serotypes are encountered.
Stopping the Spread
Controlling the spread of the virus relies heavily on rigorous hygiene practices. Hand washing with soap and water for at least 20 seconds is the most effective action in preventing transmission, especially after changing diapers, using the toilet, and before eating.
The virus can survive on surfaces, so environmental cleaning is necessary. Frequently touched objects, such as toys, doorknobs, and countertops, should be regularly cleaned and disinfected. The virus is shed in respiratory droplets and blister fluid, and it can also be shed in the stool for several weeks after symptoms resolve.
To minimize community transmission, children with HFMD should be kept home from school or childcare. Isolation recommendations suggest that a child remain home until their fever has resolved and any open mouth sores have healed. Avoiding close personal contact, such as hugging or sharing utensils, also helps limit the virus’s ability to spread.