HFMD is a highly contagious viral illness common in young children worldwide. It causes a distinctive rash and painful mouth sores. Because of its contagious nature, many caregivers wonder if a person who has recovered can catch it again. The straightforward answer is yes, reinfection is possible. Immunity from one infection does not offer permanent protection against all forms of the illness due to its viral nature.
Understanding Hand, Foot, and Mouth Disease
Hand, Foot, and Mouth Disease is typically a mild infection, primarily affecting infants and children under five, though adults can also contract it. Symptoms usually begin with a fever, reduced appetite, and a general feeling of being unwell, often followed by a sore throat. The telltale signs appear a day or two later: painful, blister-like sores in the mouth and a rash on the palms and soles. This rash may also appear on the buttocks or genitals. The illness typically resolves within seven to ten days. The incubation period is generally three to six days.
The Viral Strains That Allow Reinfection
Reinfection is possible because HFMD is caused by a group of viruses belonging to the Enterovirus family, not a single virus. The most common cause is Coxsackievirus A16, but other strains like Coxsackievirus A6 and Enterovirus 71 (EV-A71) also cause the disease. When the body fights off one of these viruses, it develops serotype-specific immunity. This means the immune system creates antibodies effective only against the exact strain that caused the initial infection.
A person recovered from Coxsackievirus A16, for example, is protected against A16 but remains vulnerable to all other strains. If later exposed to Enterovirus 71 or Coxsackievirus A6, they can develop HFMD a second or third time. The varying strains of enteroviruses circulate within communities. Prior exposure to one strain does not guarantee immunity against the others.
The Course of Subsequent Infections
Subsequent HFMD infections often vary widely, but second occurrences are frequently milder than the first. The body may have partial cross-protection from the prior infection, even if it is not fully immune to the new strain. However, severity depends heavily on the specific viral strain encountered. In rare cases, if the second infection is caused by a strain like Enterovirus 71, which is associated with more serious complications such as aseptic meningitis, the illness can be more severe.
In a typical repeat infection, symptoms follow the expected timeline, lasting approximately one week. The signature rash and mouth sores may still appear, but they might be less widespread or painful than the first time. Regardless of severity, the patient remains contagious during the illness. The virus can be shed in the stool for several weeks after all noticeable symptoms have disappeared.
Reducing the Risk of Transmission
Because HFMD is highly contagious, preventative measures focus on interrupting transmission routes. These include the fecal-oral route, respiratory droplets, and contact with blister fluid.
Hygiene Practices
Frequent and thorough handwashing with soap and water for at least 20 seconds is the most effective intervention to limit spread. This is especially important after changing diapers, using the toilet, and before preparing food.
Environmental Cleaning
Disinfecting frequently touched surfaces and shared objects is important, as the virus can survive for days. Toys, doorknobs, and countertops should be regularly cleaned with a chlorine-based solution. An infected person should avoid close contact and stay home until their fever has resolved and mouth sores have healed.