Gee, I thought I *had* responded.  There are usually two viral
infections which may present as ulcers in a child's mouth.  One is
Herpes, usually type I.  It tends to be distributed in the front of the
mouth with ulcers on the gums.  It can be quite painful, may last a week
or two.  Like most viral infections, by the time you have symptoms, you
have given the infection to your contacts already.

The other is herpangina, which tends to be a summer infection, and is
caused by Coxsackie virus.  Its ulcers tend to be distributed on the
back of the palate, on the tonsils and on the back of the pharynx.  It
is also most infectious before the symptoms appear.

Jack Newman, MD, FRCPC