Nonoxynol-9 use, genital ulcers, and HIV infection in a cohort of sex workers

Abstract

Objectives: To measure the associations between use of nonoxynol-9 (N-9) and incidence of genital ulcers, and incident ulcers and HIV seroconversion.

Methods: In a study of barrier contraceptive use and HIV infection, 273 female sex workers used condoms and 100 mg N-9 suppositories, and recorded sexual activity on coital logs. Genital ulcers were diagnosed clinically at monthly clinic visits. HIV infection was diagnosed by ELISA and Western blot. We calculated ulcer incidence rates by level of N-9 use. A nested matched case-control analysis assessed the effect of ulcers on HIV acquisition.

Results: More frequent N-9 use was not associated with genital ulcers and may have been protective against the lesions. Ulceration was not a strong risk factor for HIV acquisition in this study (odds ratio 1.1; 95% confidence interval 0.3-3.5).

Conclusions: Frequent use of N-9 can cause genital irritation and ulceration. Ulcers, in turn, may be risk factors for HIV acquisition. This study, however, did not find an association between N-9 use and ulcers, nor between ulcers and HIV. There is probably a threshold of N-9 use frequency or dose below which the risk of ulceration is minimal. Ulcers due to infectious causes may have been prevented by N-9 use in this cohort.

PIP: To determine whether nonoxynol-9 produces disruption of the genital epithelium and, in turn, places users of this spermicide at increased risk of human immunodeficiency virus (HIV), 273 seronegative female commercial sex workers in Cameroon were enrolled in a 12-month cohort study. Subjects were instructed to use condoms and 100 mg nonoxynol-9 suppositories at each act of intercourse and to maintain coital logs. The presence or absence of vaginal and cervical ulcers was recorded at monthly gynecologic examinations; HIV testing was performed every three months. Included in the final analysis were the 191 women with no cervical ulcers at baseline. Of these, 77 (40%) were classified as frequent (15 times/month) nonoxynol-9 users, 84 (44%) as intermediate (11-15 times/month) users, and 30 (16%) as infrequent (10 or fewer times/month) users. 40 women had evidence of cervical ulceration during the observation period and 18 developed vaginal ulcerations. Unexpectedly, nonoxynol-9 use was not associated with an increased risk of ulceration. The incidence rates for cervical and vaginal ulcers, respectively, were 2.7% and 0.6% among frequent users, 2.2% and 0.8% among intermediate users, and 9.0% and 3.0% among infrequent users. Of the 17 women who became infected with HIV during the study, 29% had experienced ulceration compared to a rate of 28% for matched controls (odds ratio, 1.1; 95% confidence interval, 0.3-3.5). It is speculated that nonoxynol-9 provides sufficient lubrication during intercourse to prevent epithelial trauma. It is further plausible that any ulcers caused by nonoxynol-9--as opposed to those of infectious etiology--lack the immunologic cell responses required to increase susceptibility to HIV.