Hand, Foot, and Mouth Disease (HFMD) is a common viral illness caused by enteroviruses, most frequently Coxsackievirus A16. While typically seen in infants and children under five, the virus is highly contagious. Adults in close contact with infected children often worry about their personal risk, though they generally have a lower rate of symptomatic infection.
Understanding the Risk of Adult Transmission
The risk of adult transmission is determined primarily by prior immunity and the specific viral strain involved. Many adults were exposed to common HFMD strains like Coxsackievirus A16 during childhood, leading to long-lasting immunity against that specific serotype. This existing immunity can prevent symptoms upon re-exposure or significantly lessen the illness’s severity.
However, prior infection with one strain provides little cross-protection against other serotypes, meaning reinfection with a different virus is possible. Novel strains, such as Coxsackievirus A6, have been associated with outbreaks featuring a higher incidence of symptomatic infection in adults. The lack of prior exposure to these circulating strains can leave an adult susceptible.
The virus spreads through multiple routes, making transmission difficult to avoid in a household setting. Transmission occurs via the fecal-oral route, often during diaper changes or assisting with toileting. Infection also spreads through respiratory droplets released when an infected person coughs or sneezes. Direct contact with blister fluid and saliva also allows for viral transmission. The virus is robust and can survive on surfaces like toys and doorknobs for several hours.
The Adult Experience of HFMD Symptoms
When adults contract a symptomatic case of HFMD, the experience is often different and potentially more severe than the typical mild pediatric case. While some adults remain asymptomatic, those who develop the illness may experience more intense discomfort. The illness typically begins with a fever, body aches, and a severe sore throat, often preceding the characteristic rash.
The painful lesions that define the disease can be particularly troublesome for adults. These spots often appear on the palms of the hands and the soles of the feet, but can also affect the face, arms, legs, and trunk. The mouth sores, called herpangina, can be intensely painful and lead to difficulty swallowing, which may pose a risk for dehydration.
In some cases, the infection can lead to a complication known as onychomadesis, which involves the temporary separation and shedding of fingernails or toenails. This happens weeks after the initial infection, typically one to two months later. This phenomenon is more frequently reported in cases caused by the Coxsackievirus A6 strain.
Practical Steps for Exposure Management
Adults caring for an infected individual should focus on hygiene protocols to minimize the risk of transmission. Handwashing is the most effective preventive measure, and hands should be washed frequently with soap and water for at least 20 seconds. This is especially important after changing diapers, assisting with toileting, and before preparing food or eating.
Cleaning and disinfecting frequently touched surfaces is also important. High-touch items like door handles, light switches, toys, and shared electronic devices should be cleaned daily using an appropriate disinfectant, such as a solution of bleach and water. The virus is shed in the stool for several weeks after symptoms resolve, requiring continued vigilance with cleaning long after the infected person feels better.
Adults should seek medical advice if they experience severe symptoms, such as an inability to drink fluids due to painful mouth sores, or signs of dehydration. While HFMD is usually self-limiting and resolves within seven to ten days, professional guidance is important if symptoms do not improve or if there is concern about complications. Isolation is recommended until the fever has been gone for 24 hours without medication and the rash areas are beginning to heal.