Toxic Shock Syndrome, the frightening new disease which most often seems to strike healthy young women during, or just after, menstrual periods should be cause for concern and care, but not panic.

New outbreaks of the illness, caused by the toxins of a penicillin-resistant bacterium called staphylococcus aureus, almost certainly have been linked to the use of tampons and possibly to one brand in particular, Procter and Gamble's Rely.

And although the safest bet for avoiding this sometimes-fatal systemic infection would be to abandon the use of tampons altogether, this is an unsatisfactory solution for most women -- as the Center for Disease Control has recognized.

Here's what CDC says:

Women can virtuually eliminate the risk of TSS by not using tampons.

Women can reduce the risk by using tampons intermittently -- not all day or all night, for example.

In a meticulously worded follow-up on its research, CDC says this about Rely:

"Until the reasons underlying the increased risk of TSS in users of Rely tampons are more clearly understood, women may choose to use another products." t

In CDC's survey of TSS victims in July and August of this year, all of whom used tampons, it was found that 71 percent had been using Rely tampons. Although it challenged CDC's findings, Procter & Gamble has announced that it will stop producing or selling Rely for the time being, and has asked retailers to remove it from store shelves.

Why Rely should be especially implicated -- or even whether it should be implicated at all -- is unclear. One possibility, investigators speculate, is that the very quality (greater absorbency) that makes it attractive may be facilitating the growth of bacteria in the vaginal cavity by creating the kind of warm, closed environment in which they can flourish.

Or it may be that newer, more absorbent tampons or their applicators inflict some injury on delicate vaginal tissue, or that new tampons ingredients have some unknown effect.

Or TSS may be unrelated directly to new tampons at all. Although it appears certain that there is some role played by tampons use, the critical change may be in the bacteria.

The disease may be caused by a new strain of bacteria with particularly toxic potential, or by an old strain that has acquired the ability to make new toxin.

CDC investigators are considering all of these possibilities. They also are considering the possibility that the women with TSS who used Rely also had something else in common related to the infection -- use of a specific contraceptive, for example.

The illness, although it may occur in a mild form, is regarded by CDC as "severe." There have been 299 cases reported to CDC this year. Of these, 95 percent were women, and there were 25 fatalities.

The symptoms:

Sudden onset -- during or just after a menstrual period -- of a high fever (102 degrees or higher).

Vomiting and/or diarrhea and/or myalgia (muscle pain).

Sunburn-like rash.

Plummeting blood pressure and possible disorientation.

(Around 10 days later there may be peeling of palms and soles, but this symptom is not useful for immediate identification.)

Degree of severity varies, but even with a mild first case, the illness may recur. It is particularly important, say CDC doctors, that women who have had a bout with the disease refrain from using any tampons at all until the staphylococcus aureus has been totally eradicated from the vagina.

If you have any of the TSS symptoms, do NOT panic, but do:

Stop using tampons at once.

Call your doctor -- and be sure to tell him the possible connection to your menstrual period. The disease is not yet well known and misdiagnoses can have tragic results. Don't be squeamish.

"A woman," says Dr. Walter Schlech, a CDC medical epidimiologist, "has to take some responsibility for her own helath."

If cultures confirm a diagnosis of TSS, there are staphyloccus-fighting antibiotics and other measures to help control the disease and prevent a recurrence.