Background: Factors that influence shedding of HIV-1 infected cells in cervical and vaginal secretions may be important determinants of sexual and vertical transmission of the virus. We investigated whether hormonal contraceptive use, vitamin A deficiency, and other variables were risk factors for cervical and vaginal shedding of HIV-infected cells.

Methods: Between December, 1994, and April, 1996, women who attended a municipal sexually transmitted diseases (STDs) clinic in Mombasa, Kenya, and had previously tested positive for HIV-1, were invited to take part in our cross-sectional study. Cervical and vaginal secretions from 318 women were evaluated for the presence of HIV-1 infected cells by PCR amplification of gag DNA sequences.

Findings: HIV-1 infected cells were detected in 51% of endocervical and 14% of vaginal-swab specimens. Both cervical and vaginal shedding of HIV-1 infected cells were highly associated with CD4 lymphocyte depletion (p = 0.00001 and p = 0.003, respectively). After adjustment for CD4 count, cervical proviral shedding was significantly associated with use of depot medroxyprogesterone acetate (odds ratio 2.9, 95% CI 1.5-5.7), and with use of low-dose and high-dose oral contraceptive pills (3.8, 1.4-9.9 and 12.3, 1.5-101, respectively). Vitamin A deficiency was highly predictive of vaginal HIV-1 DNA shedding. After adjustment for CD4 count, severe vitamin A deficiency, moderate deficiency, and low normal vitamin A status were associated with 12.9, 8.0, and 4.9-fold increased odds of vaginal shedding, respectively. Gonococcal cervicitis (3.1, 1.1-9.8) and vaginal candidiasis (2.6, 1.2-5.4) were also correlated with significant increases in HIV-1 DNA detection, but Chlamydia trachomatis and Trichomonas vaginalis were not.

Interpretation: Our study documents several novel correlates of HIV-1 shedding in cervical and vaginal secretions, most notably hormonal contraceptive use and vitamin A deficiency. These factors may be important determinants of sexual or vertical transmission of HIV-1 and are of public health importance because they are easily modified by simple interventions.