I have just received the results of a blood test and have been diagnosed as having herpes-1 antibodies. I guess that means I have herpes-1. Does that mean I'm contagious? Can I kiss my own children ever again? Should I tell any new prospective lovers in my life about it before I have relations with them? Could the results of the test be wrong?

G.M.

I've discussed herpes infections in past columns, but I'll take the opportunity to revisit the issue now to talk a bit more about the kinds of tests used to diagnose herpes infection and what they mean. Herpes simplex viruses (HSV) 1 and 2 cause oral and genital herpes. Most oral herpes cases are caused by HSV-1 and most genital herpes by HSV-2. Both of these viruses remain in the body forever, and in some people, they can cause periodic recurrences of symptoms. When people are first infected with oral herpes, they can be quite ill, developing multiple painful ulcers (sores) in and around the mouth. Fever and headache can also occur during the initial infection. In otherwise healthy people, recurrences of the infection result in the very common cold sore.

Worldwide, 90 percent of all people have been infected with HSV-1 and thus remain chronically (persistently) infected with the virus! In the United States, as many as two-thirds of people are infected. This does not mean that all such people have recurrent cold sores -- as many as 40 percent of chronically infected people never have any symptoms at all.

There are a few different tests for HSV-1. One test involves antibodies, proteins the body makes to fight infection. This antibody test is very accurate, and indicates whether a person is infected with the virus. A single test does not show when the infection occurred, because these antibodies persist for life. If a person has a series of tests that show that the level of antibody rises markedly over a four-week period, however, then it is assumed that the infection was very recent.

Your antibody test was positive. This means that you have been infected with HSV-1 -- just like 90 percent of the world! You have very little to worry about. Sure, you could give the virus to your family, but chances are some or all of them already have it. Even if family members are not already infected and you transmit the virus to them in the future, they are not likely to have a serious infection, and may not have any symptoms at all.

There are other tests for HSV-1. If someone has a sore that is thought to be caused by this virus, several tests can be performed. One of these is a "Tzanck smear," which involves scraping material from the base of the ulcer, placing it on a slide, treating it with a chemical stain, and examining it under a microscope. Certain changes are diagnostic for either HSV or the virus that causes shingles and chickenpox. There is also a rapid test called a direct fluorescent antibody test that can tell within minutes if HSV-1 is present. Finding HSV-1 in a culture grown from a swabbing of the ulcer also conclusively identifies lesions caused by HSV-1, although this process takes a few days. In most cases, however, the diagnosis of herpes can be made clinically, without tests, based on the patient's physical signs and symptoms. Distinguishing HSV-1 from HSV-2 cannot be done clinically -- diagnostic tests are needed to tell the two infections apart -- but is not that important anyway, as treatment is the same for both viruses.