Investigators at Family Health International (FHI), a nonprofit health research organization based in the United States, collaborated with those at the Cameroon Ministry of Public Health to conduct this study with female sex workers in two cities in Cameroon. Of the 1,292 women who enrolled, 941 completed 12 months of follow-up. Volunteers were given contraceptive films to be used before sexual intercourse. The films contained either the spermicide nonoxynol-9 (N-9) or a placebo. The women were supplied with male latex condoms and counseled monthly about reducing their number of partners and other safe sex practices. They also were examined and treated monthly for any STDs.
Preliminary analysis of the results from this recently completed study showed the overall rate of HIV transmission to be 6.7 percent, half the transmission rate that was previously estimated in this population. This rate reduction was the same in both the N-9 film users and the placebo group.
"We are encouraged by the apparent effectiveness of the overall intervention program that included counseling, STD treatment and encouragement of condom use," says Rodney Hoff, Ph.D., chief of the Efficacy Trials Branch in the AIDS Vaccine Research and Prevention Program. "Correct and consistent condom use is highly effective, but women must depend on the willingness of their partners to use male condoms. We and other public health officials are committed to developing an STD/HIV prevention method that can be controlled by a woman. This study is one part of that ongoing effort."
The search for woman-controlled methods has focused on the development of virus- and bacteria-killing products that women can apply intravaginally before having sex. Known collectively as topical microbicides, these products could give women the means to protect themselves from STDs.
"We had hoped that the N-9 film might increase a woman's available options for HIV and STD protection," says Willard Cates, Jr., M.D., M.P.H., FHI's senior vice president for biomedical affairs. "These results show that we must accelerate our research programs dedicated to finding new products and techniques for women to use."
Until safe and effective vaginal microbicides are developed, the Centers for Disease Control and Prevention (CDC) recommends consistent and correct use of male latex condoms, with or without the use of a spermicide, to prevent sexual transmission of HIV and other STDs in high-risk populations. The CDC does not currently recommend the use of spermicides alone. The agency will continue to monitor data from this and other studies of vaginal products with N-9 to determine if their use results in prevention benefits or adverse effects.
N-9 is a detergent-like chemical that has been widely used for more than 30 years in over-the-counter gels, foams, creams and films designed to kill sperm. Researchers have shown that N-9 can kill HIV and other STD microbes in laboratory experiments. Previous studies in small numbers of women suggested that N-9 had some benefit as a topical microbicide, but also prompted some concern that frequent use or use of high doses of N-9 could disrupt the cells that line the genital tract, thereby increasing the chances of HIV infection.
The primary investigators for this study were Ronald E. Roddy, M.P.H., of FHI and Leopold Zekeng, Ph.D., of the Cameroon Ministry of Health. The sex workers volunteered at clinics in Yaounde and Douala between March 1995 and December 1996. To be eligible, participants could not be HIV-positive, pregnant, or allergic to latex or to N-9. Of the eligible volunteers, 941 women were randomized into two groups and completed the study. One group of 478 women were given condoms and contraceptive film containing 70 mg of N-9, and a second group of 463 women were given condoms and film containing placebo (an inert substance). Neither the women nor the study investigators knew which product a woman received.
The rates of HIV and other STD transmission were essentially the same for both groups and were measured in woman-years. For every 100 women using N-9 film and condoms for one year, 6.7 became infected with HIV, 33.3 became infected with gonorrhea and 20.6 with chlamydia. Infection rates for those provided placebo film and condoms were 6.6 for HIV, 31.1 for gonorrhea and 22.2 for chlamydia per 100 woman-years. Women using N-9 film and condoms had 42.2 genital sores per 100 woman-years compared with 33.5 sores in the placebo group. Women in the N-9 film group reported 147,996 acts of sexual intercourse, and those in the placebo film reported 146,942 acts.
Additional funding for this study was provided by the U.S. Agency for International Development and the Mellon Foundation. The N-9 film was provided by Apothecus Pharmaceutical Corp. of Oyster Bay, N.Y.
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