Hand-foot-and-mouth disease (HFMD) is a very common contagious viral infection in children, characterized by rash on hands and feet, and small sores in the oral cavity. It is most commonly caused by a coxsackievirus.
In most cases, HFMD is a mild and benign disease that disappears spontaneously after a few days without any complications. The biggest concern is usually the risk of dehydration, since the sore throat can make your child unable to drink enough water.
Of all the major causes of fever and rashes, hand-foot-and-mouth disease is one of the easiest to diagnose, due to its typical involvement of the oral mucosa, soles and palms.
What is hand-foot-and-mouth disease
Hand-foot-and-mouth disease is a contagious viral infection, usually caused by, but not limited to, Coxsackievirus A16. Some cases of HFMD can also be caused by other Coxsackievirus serotypes, such as Coxsackievirus A2, A4 to A10, B2, B3 or B5. Other viruses, such as Echovirus 1, 4, 7 or 19, or Enterovirus A71 can also cause the same syndrome, with very similar signs and symptoms.
The clinical course is usually self-limited and short-lived in all serotypes, but hand-foot-mouth syndrome caused by Enterovirus A71 can be more dangerous, as it can be complicated by cases of encephalitis, meningitis or myocarditis (see “complications” below).
Hand-foot-mouth syndrome often occurs in children under 5 years of age, but it can eventually affect adults.
The viruses that cause HFMD can be transmitted by contact with secretions from airways, sores of hands or feet, or feces of infected patients. Therefore, coxsackievirus (and other viruses that cause HFMD) is usually transmitted in the following situations:
- Kissing someone infected.
- Contact with respiratory secretions, usually from coughing or sneezing.
- Drinking contaminated water.
- Shaking hands with someone contaminated.
- Eating foods prepared by an infected person who has not washed his hands properly.
- Contact with toys or objects that may have been contaminated by unwashed hands.
- Contact with contaminated clothing.
- Changing diapers of contaminated children.
Usually, the most contagious stage of hand-foot-and-mouth disease is during the first week of illness. However, even after the cure, the patient may continue to eliminate the virus in the feces, which keeps him contagious for days or even weeks after the symptoms have disappeared.
Most adults who become infected with Coxsackievirus do not develop symptoms, but they may be asymptomatic carriers and transmitters.
The incubation period for HFMD is usually 3 to 6 days. The first symptoms are usually sore throat and low fever, below 38,3°C (101ª F). Malaise and loss of appetite are also common symptoms.
At first, the infection is very similar to any common viral disease. One or two days after the first symptoms, the characteristic lesions of hand-foot-mouth disease begin to emerge.
The oral lesions begin as red spots, which eventually turn into small blisters and later into painful ulcers, similar to common canker sores. These ulcerations usually appear on the tongue and on the inner parts of the lips and cheeks. The palate (roof of the mouth) may also be affected.
One or two days after the onset of oral lesions, a rash on the palms and soles also arises. The exanthem begins as small spots and blisters with a reddish halo around them. The lesions are usually 0.1 to 1 cm in diameter and may rupture, releasing a very contagious fluid. Buttocks, thighs, arms, trunk and face may also present some exanthematous eruption.
It is important to keep in mind that not all people infected with a Coxsackievirus will develop the complete clinical picture. Around 75% of patients present the full syndrome, but the remaining
may only have either oral or skin lesions.
On the other hand, most adults that come into contact with the Coxsackievirus will not develop any symptoms.
HFMD usually lasts for 7 to 10 days and cures spontaneously in most cases without any treatment. The rash generally goes away on its own in about a week.
The most common complication is dehydration. In addition to malaise and loss of appetite, the sore throat is usually very intense, and children often stop accepting food and liquids.
Cases of hand-foot-and-mouth disease caused by Enterovirus A71 also tend to have a benign course, but there is a greater risk of complications, such as:
- Myocarditis (inflammation of the heart muscle).
- Meningitis (inflammation of the membranes surrounding the brain and spinal cord).
- Encephalitis (brain inflammation).
Recent studies show that severe HFMD, with neurologic, respiratory or circulatory complications, was more likely when the patient presents:
- High fever (above 38,3ºC (101ºF).
- Fever for more than 3 days.
- Young age
- Enterovirus A71 infection.
The diagnosis of HFMD usually is made clinically, based upon the typical appearance and location of the rash. In those who present the typical frame of fever, oral ulcers and blistering rash on hands and feet, the diagnosis is easily made without the need for further laboratory research.
In atypical cases, identification of the virus can be obtained through laboratory examination of feces, throat secretions or skin lesions.
There is no specific treatment for hand-foot-and-mouth disease. Nor does it need to, because the disease is usually self-limiting. Management is mainly supportive and no specific antiviral therapy is available.
In general, over-the-counter pain medications, other than aspirin, like acetaminophen (Tylenol) are sufficient to relieve pain and fever. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can be used, although these agents should be avoided in children with signs of dehydration.
It is important to keep the patient well hydrated. Children who are unable to drink sufficiently to maintain hydration should be hospitalized for parenteral fluid therapy.
Infected people should stay at home. Children should not go to daycare or school, and adults should miss work until all symptoms have disappeared. Children are usually most contagious in the first 7 days of disease.
As the virus can still be eliminated in stool even after the symptoms have disappeared, it is important to explain to the patient that he needs to wash his hands frequently, especially after using the toilet and before handling food. In daycare centers it is necessary to be very careful with hand hygiene when changing diapers, so that professionals do not transmit the virus from one child to another.
Surfaces that come in contact with oral secretions or feces, such as common clothes and bedding, should be washed daily. Fomites that may spread the virus should also be cleaned and disinfected frequently.
There is still no vaccine against hand-foot-mouth disease, but there are very advanced and promising studies in progress, including some phase III trials.