Symptoms and Complications of Hand, Foot, and Mouth Disease

Symptoms and Complications

1. Symptoms

The age group that is most susceptible to the disease is under 10 years old, especially under 5 years old. During outbreaks, adolescents and adults who have never had the disease can also become infected through transmission from a family member or from close contact with an infected child. The rate of infection is generally the same across sexes.

The skin rash of hand, foot, and mouth disease is usually 3–7 mm in size and appears on the backs of the hands and feet, but it also commonly appears on the palms, soles, and between the fingers and toes. It usually causes no symptoms, but it may be mildly painful when pressed or accompanied by itching, and it is more common on the hands than on the feet. These rashes initially resemble small, red, common rashes caused by other viruses, but soon turn into blisters. The younger the child, the more likely the rash is to spread widely to the trunk, groin, and buttocks, though rashes in these areas are more often seen as a general rash rather than blisters. However, hand, foot, and mouth disease can also occur with blisters only in the mouth, without a rash on the hands and feet, in as many as 1 in 4 cases. In such cases, it may be difficult to diagnose hand, foot, and mouth disease. Very rarely, the rash may last longer than a week, or disappear and then reappear.

The blisters of hand, foot, and mouth disease usually go away on their own within a week without special treatment. Complications are uncommon, but in infections caused by Coxsackievirus A16, viral meningitis may rarely occur, with symptoms such as fever, headache, vomiting, neck stiffness, and lower back pain, and hospitalization for several days may be necessary. However, if infection is caused by Enterovirus 71, another virus that can cause hand, foot, and mouth disease, more serious neurological complications such as encephalitis or poliomyelitis-like paralysis may occur in addition to typical viral meningitis. This situation occurs more often in young children, and in more severe cases, brainstem encephalitis, neurogenic pulmonary edema, pulmonary hemorrhage, and shock may develop, leading even to sudden death.

2. Diseases that should be distinguished

There are several diseases that need to be distinguished from hand, foot, and mouth disease. These are mainly illnesses that cause blisters or ulcers inside the mouth. In some cases, the distinctive features make them easy to tell apart, but in others it can be difficult. The characteristics of each disease are as follows.

1. Herpangina

The disease called "herpangina" is caused by the same Coxsackievirus or by echovirus, a type of enterovirus that causes hand, foot, and mouth disease. The difference from hand, foot, and mouth disease is that blisters develop in the back of the mouth, that is, the soft palate or the pharyngeal area around the uvula, and then progress to ulcers, without skin rash on the hands and feet. It also tends to cause a higher fever and more discomfort than hand, foot, and mouth disease.

2. Gingivostomatitis caused by herpes virus

There is also gingivostomatitis caused by a "herpes virus," which is different from enteroviruses. This disease also causes blisters and ulcers in the mouth. However, compared with hand, foot, and mouth disease, blisters around the mouth occur more often, and in addition, there is a higher fever, more pain, increased drooling, and a marked decrease in food intake.

3. Herpes labialis

While hand, foot, and mouth disease mainly occurs in children, herpes labialis occurs more often in adolescents and adults. It is a disease in which blisters repeatedly appear on the lips and nearby skin, triggered by stress, overwork, menstruation, and so on. Systemic symptoms such as fever and loss of appetite are usually absent. Before the blisters appear, there may be a tingling, burning sensation, and once the blisters form, pain and itching may occur.

3. Complications

In most cases, the disease recovers naturally without special problems, but complications occur most often in children under 5 years old. If the ulcers in the mouth are severe, painful stomatitis may develop, reducing food intake and causing dehydration, which is the most common complication of hand, foot, and mouth disease. Rarely, aseptic meningitis may also accompany hand, foot, and mouth disease caused by Coxsackievirus. However, in infections caused by Enterovirus 71, neurological complications occur relatively often, including poliomyelitis-like paralysis, aseptic meningitis, encephalitis, encephalomyelitis, acute cerebellar ataxia, acute transverse myelitis, and Guillain-Barré syndrome. These neurological complications arise through immune mechanisms or direct viral damage. In some cases, cardiopulmonary complications such as myocarditis, interstitial pneumonia, and pulmonary edema may also occur rarely.

As mentioned earlier, neurological complications that lead to sequelae are more common in cases caused by Enterovirus 71 than in hand, foot, and mouth disease caused by Coxsackievirus. Since the late 1990s, hand, foot, and mouth disease caused by Enterovirus 71, along with related deaths, has continued to occur in the Western Pacific region, including Taiwan, Malaysia, Vietnam, and China.

In the 1998 outbreak in Taiwan, among cases of hand, foot, and mouth disease caused by Enterovirus 71, 68% had no complications, while complications occurred in the remaining 32%. Of those 32% with complications, 7.3% were aseptic meningitis, 10% encephalitis, 2.3% poliomyelitis-like paralysis, 4.5% encephalomyelitis, and 6.8% fatal pulmonary edema. Among these, 7.9% died and 4% were left with sequelae. In contrast, in hand, foot, and mouth disease caused by Coxsackievirus A16, 94% had no complications, and only 6% developed aseptic meningitis; moreover, there were no deaths or cases with sequelae at all.

In Korea, after a 12-month-old girl became the first domestic fatal case in May 2009 due to neurological complications of hand, foot, and mouth disease caused by Enterovirus 71, cases of hand, foot, and mouth disease caused by Enterovirus 71 have been reported, along with serious neurological complication cases resulting from it.

So far, I have explained the symptoms and complications of hand, foot, and mouth disease.

In the next part, we will look at the diagnosis and prevention of hand, foot, and mouth disease.

Source: Korea Centers for Disease Control and Prevention National Health Information Portal