Studies Link Females to AIDS Spread
The AIDS virus has been isolated for the first time from the genital fluids of women who have evidence of exposure to the virus in their blood, researchers report in two new separate studies.
The findings provide the strongest evidence yet that AIDS can be transmitted from women to men through heterosexual intercourse, although this means of spread has been very infrequent so far in the United States.
The studies, the researchers said, also underscore the importance of safe-sex guidelines, including the use of condoms, which have been shown to prevent transmission of the AIDS virus. The studies will be published Saturday in Lancet, a British medical journal.
“Men and women who have (unprotected) frequent sexual contact with anonymous partners in a sense are playing Russian roulette,” said Dr. Martin S. Hirsch, an infectious disease specialist at Boston’s Massachusetts General Hospital and an author of one of the studies.
In both studies, researchers obtained samples of genital fluids from women who had antibodies to the AIDS virus in their blood, indicating that they have contracted the virus and may be infectious to others. Not everyone who contracts the virus develops the acquired immune deficiency syndrome.
Low Concentration
The AIDS virus was detected in the vagina of four out of eight women studied at the University of California Medical Center at San Francisco and four of 14 women studied in Boston.
The amount of virus in the genital fluids tested was “very low,” according to Dr. Jay A. Levy of UCSF, in whose San Francisco laboratory the study was conducted. The Boston study did not comment on the concentration of virus detected.
The women had been exposed to the AIDS virus either from contaminated intravenous drug needles or by sexual contact with men known to be carriers of the virus--the major routes through which the deadly disease is spread.
As of Monday, 17,781 cases of AIDS, including 1,148 in women, had been reported in the United States and 9,463 patients had died, according to the federal Centers for Disease Control. In 240 cases--197 in women and 43 in men--heterosexual intercourse is thought to have been the means of exposure to the disease.
In Africa, heterosexual spread of AIDS and cases of the disease in women are much more common than in the United States. It is not known what social, economic, medical or other factors are responsible for these differences.
The AIDS virus appears to be present in only small amounts in both male and female genital fluids as compared to higher levels detected in blood or in cerebrospinal fluid, according to Levy.
Because spread of the virus from women to men through vaginal intercourse is a “rare event,” Levy and the other UCSF researchers suggested that other factors are often involved in heterosexual transmission of the disease. These include breaks in the skin of the male or female genital organs that could allow the virus to enter the bloodstream, or venereal diseases that cause increased genital secretions.
The studies did not say whether sex while a woman is menstruating--when blood is in the vagina--increases the risk of spreading the disease.
Levy said that anal intercourse “appeared to be the major source” for men to acquire the AIDS virus from women, but vaginal transmission also occurred at times. “Everything we know about the biology of the AIDS virus suggests that the vagina is a better barrier against the disease than the anal canal.”
Principal author of the the UCSF study was Dr. Constance B. Wofsy and principal author of the one in Boston was Dr. Markus W. Vogt.
