People don't talk much about shingles. But everybody knows somebody who's had it.

About 10 percent of the population will get it eventually, one way or another, some more than once. That rounds out to several hundred thousand cases a year.

The name derives from the Latin word for belt or girdle, describing the typical rash around the victim's torso.

Shingles -- caused by the chickenpox virus -- is a rematch between the person who had chickenpox (perhaps decades before) and the viral survivors of that first bout. Nobody can get shingles who hasn't had chickenpox, but somebody who has never had chickenpox can catch it from somebody who has shingles.

Chickenpox, as a general rule, occurs only once. Shingles, however, can recur over and over in the same individual.

The chickenpox/shingles virus is a so-called "latent" virus. When the body's immune system beats back the chickenpox, some of the viruses -- clever little devils that they are -- find a safe hiding place deep in the nerve cells of the human host, where they are safe from antibodies and other immune-system defenses. When they decide to mount a second invasion, they do it through the nerve fibers.

As a result, the new illness, although generally overcome once again by the body's defenses, is often considerably more serious, painful and longer-lasting than childhood chickenpox. Chickenpox is itchy and uncomfortable. The pain of herpes can be among the worst known to humanity.

Shingles, anybody who has had it will tell you, is no fun.

Dr. John L. Sever, of the National Institute of Neurological and Communicative Disorders and Stroke, NIH, specializes in the so-called "latent" viruses. This group, called herpes, includes the chickenpox/shingles virus as well as those causing cold sores and fever blisters, mononucleosis and the sexually transmitted genital herpes.

Sever lists these misconceptions about shingles:

* If the rash encircles your entire torso, "zap, you're dead."

* It only occurs once.

* It strikes only the severely ill.

* It is only a minor problem.

None of these, says Sever, is the case.

To the normal, healthy individual, shingles is not regarded as life- threatening. It does strike hardest, however, at persons under treatment for conditions in which the immune system is supressed: those who have had an organ transplant, or who have leukemia, Hodgkins disease and various cancers. In these patients, either chickenpox or shingles can be fatal without prompt treatment.

There does not appear to be much risk to the unborn baby of a mother with shingles, although chickenpox itself can be risky in certain rather unusual circumstances.

Most, although not all, shingles victims are over 50, and the older the person, the greater likelihood of occurrence.

It can be little more than a nuisance, but for many it can mean weeks of painful misery -- headaches, blisters, facial neuralgia -- and seems to make other pre-existing conditions worse.

"If you have asthma," says Sever, "it may get worse. People prone to migraines have worse migraines. It's hard to make a case that shingles caused that, but it is not unusual to see."

It can also cause facial paralysis, blindness and an aftermath of pain called "postherpetaic neuralgia" that Sever characterizes as "among the most devastating known to mankind."

The illness itself seems endless, lasting up to five weeks, and the aftermath problems can last for months, occasionally permanently.

However, there is some promising work on drugs. Some have shortened the duration of shingles in experimental cases and may hold promise as well for sufferers of genital herpes. Interferon, the substance that enhances the immune system, also may be useful for shingles. It is still rare and expensive, though, and the available supply goes principally for cancer research.

In a booklet on shingles prepared by Sever and others for NIH, an elderly patient who got shingles 60 years after the chickenpox was quoted as asking bitterly: "Am I only a culture medium for viruses, for heaven's sake?"

It's a sobering thought.

For information on obtaining the booklet, write SHINGLES, 8A06, Building 31, National Institute of Neurological and Communicative Disorders and Stroke, NIH, Bethesda, Md. 20205.