Typically, an infant gets the herpes simplex virus from an adult who has a cold sore.The infant's first such infection (primary herpes) causes general gum inflammation and extensive mouth soreness. Most cases are mild and go unrecognized. Parents often mistake the problem for teething or another illness. Within 2or3days, very small blisters(vesicles) form in the child's mouth.These may not be noticed because they rupture quickly. leaving the mouth raw and sore.The soreness may be anywhere in the mouth but always include the gums. Though the child gets better in a week or so. the herpes virus NEVER leaves the body. and the infection commonly flares up later in life(secondary herpes) People who escape oral herpes in childhood but contract it as adults usually have more severe symptoms.
Unlike the original infection that causes wide-spread mouth soreness, the later flare-ups usually produce cold sores(fever blisters) These flareups are commonly triggered by sunburn on the lips, a cold, fever, food allergy, mouth injury, dental treatment, or anxiety. for a day or two before a blister appears, the person may feel a tingling or discomfort (a prodrome)in the spot where the blister will erupt.
Although merely a painful annoyance for mose people, flare-ups of oral herpes simplex can be life-threatening in people with immune systems compromised by disease(such as AIDS)chemotherapy, radiation therapy,or bone marrow transplants.In such people, large, persisent sores in the mouth can interfere with eating,and the spread of the virus to the brain can be fatal.
