Enterovirus – hand, foot and mouth disease

Enterovirus family? What family?

Enteroviruses family is a name that includes inside a lot of strains and species. In this family you can also find the poliovirus, for which there is a vaccine. Amongst the enteroviruses there are other subgroups –
– Coxsackievirus type A: with additional division into subgroups.
– Coxsackievirus type B: with additional division into subgroups.
– Echovirus
– Enterovirus with division into subgroups (named with numbers and letters, there are over a 100 strains).
The importance of the different strains and sub-divisions will be explained later ahead.

What does enterovirus do?

A lot of different diseases, in children and adults.
From common infections such as: the common cold, mild pharyngitis and conjunctivitis, and up to central nervous system involvement such as encephalitis. It can also cause infection in the intestines (including vomiting and diarrhea), myocarditis (infection of the cardiac muscle), and life-threatening infections in babies in the first week of life.
In fact, these viruses can be involved and affect every system in our body. Though it can cause severe and dangerous infections, milder forms of infections are far more common.

So what will determine which type of disease will occur?

This is in fact a combination of the virus strain and the degree of immunity the child has against it.
For example, enterovirus #71 is one of the causes for hand, foot and mouth disease. On the other hand, under certain circumstances and some bad luck it can cause a more severe disease with brain involvement.
On the other hand, coxsackievirus type A (strains 6+16) can also cause hand, foot and mouth disease, with a more prominent rash from the one that is caused by the classic enterovirus #71.
Another example is coxsackievirus type a #24 and enterovirus #70, which causes typical conjunctivitis.
Practically, the strain of the virus is not that important (and also not recognizable). The doctor will be satisfied with a general diagnosis of “enterovirus infection”.
Those of you who encountered other strains of enteroviruses in the past will usually have a milder form of the disease, as opposed to those who encounter the virus for the very first time. This explains why most of the patients who contract hand, foot and mouth disease are children, and not adults.
There is too much to say about all the different disease caused by enteroviruses, so I will now focus on hand, foot and mouth disease.

What exactly is hand, foot and mouth disease?

A specific form of enterovirus infection including different strains of the virus. In its classical form there are typical lesions in the oral cavity and a typical rash. In the more severe disease there can be high fever for 4-5 days (in the more mild disease there is no fever). The rash is typical and involves the palms of the feet and hands. The lesions can be anything from small and red to large diffuse blisters (see picture 1+2). Children with dry and atopic skin or children who contracted one of the more violent strains of the disease will have a more significant and diffuse rash.
The oral lesions can cause inconvenience to the child, excessive drooling and pain. Sometimes you will find lesions outside the mouth, causes by virions (the part of the virus that causes the spreading of the virus), in the saliva that drools on the skin around the mouth (picture 3). Sometimes after the healing phase the skin in the tips of the hands and feets will peel off.
It is worth mentioning that in some cases of hand, foot and mouth disease, especially in children who already contracted enterovirus infections in the past and present some immunity against them, the disease can be milder (meaning very few findings in physical examination( if any at all) in the oral cavity and an unidentifiable rash).

Is hand, foot and mouth a contagious disease?

Certainly. When I see an infant with enterovirus infection, I know he will not be the only case in his kindergarten. Outbreaks are common.
The virus passes from one person to another by contracting with secretions from a sick individual to a healthy one. Secretions can be of the respiratory system (saliva for example) or gastrointestinal system (stools). Incubation period is 3-6 days.
When a child is sick, his little brothers and sisters are at risk to contract a similar infection. Contracting the virus from inside the family can be avoided with proper hygiene and preventing touch with secretions.
You should also know that the patient can secret the virus in his respiratory and gastrointestinal system for several weeks after recovering from the virus (1-3 in the respiratory system and 7-11 week in the stools). This is one of the reasons it is hard to control out brakes.