Hand, Foot, and Mouth Disease (HFMD) is a common, highly contagious viral illness often associated with outbreaks in schools and daycare settings. While most frequently observed in infants and young children, the virus can readily infect adolescents and adults. Symptoms in adults can sometimes be mild or even absent, but household exposure poses a real risk for contracting the infection. Many adults wonder if they can catch the illness a second time, especially when continually exposed to young children who are frequent carriers.
The Viral Cause of Hand, Foot, and Mouth Disease
HFMD is caused by a group of non-polio enteroviruses belonging to the Picornaviridae family, not a single pathogen. Historically, the most common culprits in the United States have been Coxsackievirus A16 (CV-A16) and Enterovirus 71 (EV-A71). However, the landscape of HFMD has been shifting due to the emergence of other strains.
Coxsackievirus A6 (CV-A6) is increasingly recognized globally as a significant cause of outbreaks, often associated with more severe symptoms, particularly in adults. The existence of these multiple serotypes is central to understanding reinfection. These viruses are highly contagious, spreading through respiratory droplets, saliva, blister fluid, and fecal matter.
Immunity and the Possibility of Recurrence
Yes, an adult can get HFMD more than once. When a person recovers from an initial infection, their immune system develops a protective response tailored to that specific viral strain or serotype. This makes them immune to being reinfected by the exact same virus.
However, this immune protection is strain-specific, offering little defense against the many other enterovirus serotypes that also cause HFMD. Since at least 23 different enterovirus serotypes have been reported, an individual could potentially contract HFMD multiple times from different strains. Reinfection is possible with the emergence of new circulating strains, such as CV-A6, which can cause illness even in those previously infected with CV-A16. This strain-specific immunity explains why the disease can recur in both adults and children, similar to catching different strains of the common cold.
Clinical Presentation and Severity in Adults
When adults contract HFMD, the symptoms are similar to those seen in children, but the experience can be unexpectedly unpleasant. The illness typically starts with a sudden fever, sore throat, and malaise. This is followed one to two days later by the characteristic rash and painful sores.
The skin lesions usually appear as flat or slightly raised red spots that may blister, most commonly on the palms and soles of the feet. Adults report that the pain and discomfort from these lesions and oral sores are significantly more intense than expected for a generally mild disease. The mouth sores, known as herpangina, can be severe, making swallowing painful and potentially leading to dehydration.
The duration of illness is usually seven to ten days, but recovery can feel protracted. A rare, delayed complication sometimes seen in adults is onychomadesis, the temporary shedding or loss of fingernails or toenails weeks after the initial infection. Though HFMD is rarely serious, some adults, particularly those infected with strains like EV-A71, may face a risk of neurological complications, such as viral meningitis.
Prevention Strategies and Household Management
Preventing the spread of HFMD centers on rigorous hygiene practices, especially in households with young children. The virus is highly contagious and can be shed in the stool for weeks after symptoms disappear, making environmental control necessary. Frequent and thorough handwashing with soap and water for at least 20 seconds is the most effective defense, particularly after using the restroom, changing diapers, or before preparing food.
Disinfection of shared surfaces is a key step in household management. Surfaces like doorknobs, counters, and shared toys should be regularly cleaned with a disinfectant solution to kill lingering virus particles. Adults should avoid close personal contact with an infected individual, including refraining from hugging, kissing, or sharing utensils and cups during the contagious period. Isolating the sick person as much as possible, especially during the first week of illness when contagiousness is highest, helps limit viral transmission.