Are viral infections most contagious before or after symptoms appear?

Dear Cecil: My wife and I have been married for five years. She has a mild case of herpes, contracted years before we met and subject to intermittent outbreaks (usually related to stress). But although we take no precautions other than a little restraint occasionally, I have apparently never caught the virus, or at least I have never had an outbreak. Is it really possible that I’m clean? Or could I have herpes and not know it? Or could she not have herpes but something else causing similar manifestations even though it was diagnosed as herpes by two different doctors? Name Withheld, Cave Creek, ArizonaDear Cecil:Is it true that colds and flu and other germ-spread illnesses are most contagious before you get the symptoms rather than after? I have always written this off as a crackpot theory, but now that I have a small child, I’d really like to know. If it’s true, then I don’t need to worry about him being around sick people, or infecting his little friends if he himself is sick. Can you find out for sure? R.B., Monroe, Wisconsin

Cecil replies:

I realize that discussing kiddie sniffles and herpes simplex in the same breath is a bit incongruous, but we’re dealing with the demon Virus here, which makes for strange bedfellows, to say nothing of making bedfellows strange. Starting with the simplest issues and working up: If you look contagious (sneezing, herpes blisters, or whatever), you almost certainly are contagious — that is, you are “shedding virus,” as the clinicians say. On the other hand, it’s quite possible to shed virus without exhibiting any obvious signs of disease. In the initial stage of a viral infection, in herpes called the “prodrome” and in other illnesses called the feeling that you’re coming down with something, the only symptom you feel may be a tingling or aching sensation. Nonetheless, you can readily infect other people and it’s best to lie low — in the case of a cold, staying home and guzzling OJ, and in the case of herpes, keeping yer paws to yourself.

It’s also possible to have a “subclinical” infection, meaning one so mild that it goes from start to finish without the sufferer ever realizing he’s sick. Unfortunately, you can still spread germs to others in this condition. With herpes, in fact, you can become what’s known as an “asymptomatic carrier,” like Typhoid Mary. Maybe that’s the story with you, N.W. For obvious reasons, it’s not known how many asymptomatic carriers there are; I’ve seen estimates ranging from 1 percent to 50 percent of all herpes sufferers. On the other hand, maybe you just lucked out and never contracted herpes at all. The only way to tell for sure is to have tissue cultures taken every couple of months for, say, six months to a year. When herpes is in its inactive, or latent, stage, it’s pretty much undetectable, but if you do have it, chances are it’ll become active sooner or later and show up in the cultures. However, cultures aren’t cheap, and presuming you’re not planning any extramarital forays, knowing won’t do you any good — herpes at present is incurable. It’s possible that what your wife has isn’t herpes but something with similar symptoms. Syphilis, for instance. If you have any doubts on the subject, by all means get a doctor’s opinion.

Cecil Adams

Send questions to Cecil via cecil@straightdope.com.