The majority of women in the United States and Canada have protective levels of antibodies to the bacteria that cause toxic shock syndrome.

A large study shows that most healthy women have antibodies to the toxic shock syndrome toxin-1 (TSST-1) protein, and researchers suggest that colonization with a TSST-1-producing Staphylococcus aureus bacterial strain renders these women immune to getting the disease.

Toxic shock syndrome is a potentially life-threatening disease caused by toxin produced by a strain of S. aureus bacteria. It is most common in menstruating women using high-absorbency tampons, but it has also been reported in other people. Symptoms of the syndrome include sudden high fever, headache, a rash, nausea and diarrhea.

Dr. Paul Modern of Dartmouth-Hitchcock Medical Center in Lebanon, New Hampshire, and colleagues measured serum levels of TSST-1 antibodies from 3,014 women from four US states and the Canadian province of Manitoba.

As he described in a presentation here Monday at the annual meeting of the American Society for Microbiology, the team found that 85% of women had protective levels of TSST-1 antibodies, with only 8% lacking detectable antibody.

The researchers also cultured S. aureus from the vagina, anus, and nose of the women and found that women that were positive in at least one site had a 98% seropositivity rate, meaning that they carried the antibodies.

The team noted that blacks were significantly less likely to have protective antibodies than whites, and that women in Manitoba were significantly more likely than all other states except Arizona to have protective antibodies. The reasons for these findings are not clear, Modern told Reuters.

The high seropositivity rate "is a good thing,'' Modern said. "We assume that's the reason for the higher (antibody) level, because the bacteria was immunizing.''

He said that having a rapid diagnostic test for the presence of antibodies would be helpful, because it would alleviate women's fears of being at risk for the disease.