My one-year-old son has developed a case of oral herpes. How does a child get this virus, and how could it have been prevented? Second, his doctor referred to it as gingivostomatitis, and I wondered if you could give me more information about this term. My son is in horrible pain.

S.G.

Gingivostomatitis simply means an infection that involves the gums and mouth. Herpes simplex virus (HSV) is the virus that causes both oral and genital herpes. There are two types, HSV-1 and HSV-2. HSV-1 is the primary cause of oral herpes. This virus is acquired quite easily after contact with infected secretions. Up to 70 percent of adults are infected with HSV-1.

Most primary infections with HSV-1 cause no symptoms. However, if a person does have symptoms, the infection can be severe, with fever, swollen glands, sore throat and painful vesicular (blister-like) lesions that quickly rupture, forming ulcers. The lesions can be anywhere. They can involve the tongue, the inside of the cheeks, the lips and the gums. Adults tend to have a particularly severe sore throat. The pain can be intense, and some patients have to be given intravenous fluids because they cannot swallow at all.

Most cold sores are due to the same herpes virus. However, a cold sore represents a recurrent flare-up of illness. This is typically mild, with no fever or malaise (ill feeling). The lesions mostly occur on the lips. The outbreak typically resolves over four or five days, a considerably shorter time than the duration of the primary episode. Since most primary infections are asymptomatic, a recurrence is often the first manifestation of infection.

Your child could have acquired the virus from almost anyone. Contact with the saliva of family members (remember that about 70 percent of us have the virus) could have transmitted the virus. He was just an unlucky person who had a symptomatic infection. There was no way that the infection could have been prevented.