In a small minority of cases, an inflammatory reaction occurs within the nervous system that leads to a mild (and rarely serious) case of meningitis.
Coxsackie viral infections are so common and so often occur without symptoms that at any one time there is a large pool of infectious children.
A child is most infectious immediately before and after developing symptoms, but since symptoms don't always occur, a completely healthy looking child can spread coxsackie. Children can become infected multiple times, but reinfections are usually silent.
How is it treated?
Fortunately, children generally do well in handling HFMD. Any fever usually begins to resolve after a few days. Mouth lesions heal in about a week, and lesions elsewhere heal in a week to 10 days.
There isn't a medicine that can specifically eliminate this virus, but the body does a good job of healing itself. As with any illness involving a fever and a small child, a high temperature and loss of appetite create the risk of dehydration. Attention to fluid intake is important. Cool or cold foods (liquids as well as Popsicles, ice cream, and sherbet) are better tolerated than hot ones. Very spicy, salty, or acidic foods (including orange juice and citrus fruits) can sting and should be avoided.
For infants, drinking from a cup may be less uncomfortable than drinking from a bottle (which may put pressure directly on sore areas). Acetominophen (Tylenol) or ibuprofen (Motrin or Advil) are useful in controlling a particularly high fever.
A child with HFMD may return to daycare or resume contact with other children when his/her temperature returns to normal. Although technically still contagious until the rash is gone, this is such a common infection that a policy that keeps children isolated until the rash resolves is impractical and only puts an extra burden on the families of those children. Once healed, lesions do not scar, and children are back to normal (at least until the next childhood virus comes along).