Does your child have sores in the mouth followed by a rash of tiny painful blisters on the hands and feet? Beware of Hand-Foot-Mouth Disease

Hand-Foot-Mouth Disease (Coxsackievirus A16)

Introduction:
A miserable child who has lost interest in eating solids? Perhaps the child has hand-foot-mouth disease.

What is it?
Hand-foot-mouth disease is a common childhood illness featuring mouth sores, fever, and a rash. Similar-sounding “foot-and-mouth disease” is a disease of cattle and is not related to this condition.

Hand-foot-mouth disease is usually caused by a virus called coxsackievirus A16. However, many children with coxsackievirus A16 infections do not have all of the features of hand-foot-mouth disease. Some have no rash, some have no mouth sores, and some even have no fever. A variety of other viruses in the Enterovirus family can also cause hand-foot-mouth disease (the coxsackieviruses are enteroviruses).

Who gets it?
This disease is most common among young children but is seen with some frequency up until puberty. Adults can get it, but this is much less common. Once people have had coxsackievirus A16 they are generally immune, but they could get another case of hand-foot-mouth disease from one of the other, less common viruses. Most infections occur in the summer or early fall, with the peak between August and October in the northern hemisphere.

What are the symptoms?
Children with hand-foot-mouth disease usually start to feel crummy 3 to 7 days after they were exposed. Often, the first thing parents notice is their children’s decreased appetite for solids. Children may also have a fever and a sore throat. A day or two later, many children develop sores in the mouth. They begin as small red spots on the tongue, gums, or mucous membranes. They may blister or form ulcers.

A skin rash may also develop over a day or two, with flat or raised red spots. Unlike with many rashes, the spots are often found on the palms and soles. Also, it is common to have the rash on the buttocks. Often, the red spots will form tender blisters (although not on the buttocks). Unlike with chickenpox, the rash does not itch.

Usually the rash disappears and the child feels better within about 1 week.

How is it diagnosed?
Usually the diagnosis is made based on the history and physical exam. Lab tests are available for the coxsackieviruses and other enteroviruses, but they are not usually necessary. Hand-foot-mouth disease is sometimes confused with strep throat, which can also begin with a fever and sore throat. It is sometimes mistaken for chickenpox because they both have blisters. It might be confused with any of the childhood exanthems. Also, many children with hand-foot-mouth disease are diagnosed with ear infections because the eardrums may appear red.

How is it treated?
Antibiotics do not help with hand-foot-mouth disease. The important issues are pain relief and plenty of fluids. Cold liquids and popsicles can be soothing for a child’s sore throat.

How can it be prevented?
The viruses that cause hand-foot-mouth disease are present both in the stool and in the respiratory secretions. It can spread by fecal–oral transmission, droplet transmission, contact transmission, and by means of fomites. Hand cleansing—especially after diapering/toileting and before eating—can help reduce its spread. Children are often kept out of school or daycare for the first several days of the illness, but it is not clear this prevents others from becoming infected. Other children in the class are probably contagious even though they will never develop symptoms.

Can You Catch Hand-Foot-And-Mouth Disease Twice?

dr Greene: The incredible human body is equipped with an immune system that staggers the imagination. In ages past, explorers charted thrilling new lands. Today, one of the most exciting frontiers of discovery is the wondrous, intricate, complex immune system silently protecting us day and night.

Two types of defense against viruses predominate in the bloodstream: humoral immunity and cellular immunity. The humoral (or one might say 'liquid') immune system attacks viruses when they are loose in the body, either in the bloodstream or in bodily secretions. The cellular immune system attempts to destroy viruses once they have taken up residence inside the body's cells.

The humoral response consists of antibodies made to specific viruses. These antibodies remain present in the circulation and secretions, hopefully eliminating the virus and protecting against future infections. The more water soluble a particular virus is, the more effective the humoral response. A good example of this is the poliovirus. Polio vaccines (and other vaccines) work precisely because they so effectively stimulate specific antibody formation. When a person is re-exposed to polio, the virus is destroyed by antibodies before infection sets in.

The cellular response consists of certain white blood cells, such as cytotoxic lymphocytes or natural killer cells, which attack and destroy our own cells that have been invaded and altered by viruses. Some viruses, such as herpes, are 'sneaky' enough to hide in our cells without changing the way they look to the cellular immune system. These viruses can remain dormant within cells for years, only to re-emerge periodically when our humoral defenses are weak and allow the viruses to get loose in the circulation once again.

Hand-foot-and-mouth syndrome is a distinct viral illness. It produces blisters in the mouth in 90% of infected children and a characteristic rash primarily on the hands, feet, or buttocks in 64% of these children. Most children are cranky, with a sore throat, decreased appetite, and/or fever. The illness typically clears within a week.

Hand-foot-and-mouth syndrome was first reported in 1956, in Australia. As far as we know, it never occurred before that time. For the next 7 years it was reported, only occasionally, in pockets dotting the globe. By 1963, however, it became a common feature of childhood worldwide.

Hand-foot-and-mouth syndrome is caused by several different viruses, including coxsackieviruses A5, A9, A10, A16, B1, B3, enterovirus 71, foot-and-mouth disease virus, and herpes simplex. The vast majority of cases, however, are caused by coxsackievirus A16.

A child with a healthy immune system will form antibodies to whichever virus caused the infection. If your son is re-exposed to the same virus, he will probably not be re-infected. He is still susceptible, in varying degrees, to the other viruses. Since 1963, most children have had one case of hand-foot-and-mouth syndrome, caused by coxsackievirus A16.

There is one other snag. While most children clear their bodies of the virus within one week, coxsackievirus A16 occasionally succeeds in hiding inside children's own cells, like herpes. By eluding the cellular immune system, coxsackievirus A16 can cause chronic or recurring skin lesions. Healthy humoral immunity is able to keep these recurrences from being as severe as the initial episode.

Will your son catch hand-foot-and-mouth syndrome again? Probably not, but there are no guarantees. Who knows? In the next century, enterovirus 71 might become the major cause of hand-foot-and-mouth syndrome. Even so, the human immune system has a remarkable history of adapting to the ever-changing microscopic world around us.

Alan Greene MD FAAP
Source: dr Greene

Group B Coxsackieviruses (Current Topics in Microbiology and Immunology)