Epidemiology Table 3 Final multivariate model for factors associated with bacterial vaginosis (BV) infection BV prevalence n/N (%) Adjusted OR* (95% CI) Age (years) 16–19 20–24 25–29 30–35 Facility type Local food handler Restaurant/cafe´/grocery Guesthouse Local brew seller Bar Number of dependents >2 1 None Number of drinks per week 0 1–4 5–9 >10 Sex in past 7 days No Yes Inserting substances for dry sex{ No Yes Menstrual hygiene{ Sanitary pads Cloths/underwear/sponges Cotton wool/toilet paper HIV No Yes Trichomonas vaginalis{ No Yes 51/71 (71.8%) 191/285 (67.0%) 259/418 (62.0%) 306/509 (60.1%) 389/656 (59.3%) 116/196 (59.2%) 101/138 (73.2%) 59/93 (63.4%) 142/200 (71.0%) 466/785 (59.4%) 142/224 (63.4%) 199/274 (72.6%) 347/602 (57.6%) 192/299 (64.2%) 90/137 (65.7%) 178/245 (72.7%) 200/393 (50.9%) 607/890 (68.2%) 777/1220 (63.7%) 29/62 (46.8%) 135/229 (59.0%) 623/988 (63.1%) 39/51 (76.5%) 483/813 (59.4%) 324/470 (68.9%) 530/889 (59.6%) 274/390 (70.3%) p = 0.23 1 0.87 (0.48 to 1.60) 0.66 (0.37 to 1.20) 0.73 (0.40 to 1.33) p = 0.03 1 0.90 (0.64 to 1.28) 1.82 (1.18 to 2.81) 0.92 (0.56 to 1.51) 1.26 (0.85 to 1.86) p = 0.001 1 1.15 (0.82 to 1.60) 1.75 (1.25 to 2.44) p = 0.002 1 1.36 (1.00 to 1.85) 1.44 (0.94 to 2.19) 1.76 (1.22 to 2.55) p,0.001 1 2.03 (1.57 to 2.62) p = 0.003 1 0.44 (0.25,0.75) p = 0.02 1 1.42 (1.02 to 1.95) 2.52 (1.21 to 5.25) p = 0.008 1 1.41 (1.09 to 1.83) p,0.001 1 1.59 (1.22 to 2.09) *Adjusted for all variables in the table; {data for inserting substances for dry sex are missing for 1 woman. Data for menstrual hygiene are missing for 15 women. Results for Trichomonas vaginalis are missing for 4 women. (table 2). In a multivariate model of IVP, adjusted for socio- economic and sexual behavioural factors, BV was significantly lower among women who reported ever inserting substances for dry sex (adjusted OR 0.45; 95% CI 0.26 to 0.78), although there was no association between BV and vaginal drying in the past 24 hours. BV was higher among women using cloths or cotton wool for menstrual hygiene. There was a non-significant trend towards decreased BV prevalence with increased frequency of vaginal cleansing (adjusted p = 0.10), but no evidence of a trend with reported time since last cleansing. Association of BV with biological factors On univariate analysis, BV prevalence was significantly associated with HIV and T vaginalis infection but not with any other STI or with HIV or HSV genital shedding (table 2). After adjusting for socio-economic, behavioural and IVP factors, HIV and T vaginalis remained significantly associated with BV. Final independent risk factors for BV In the final multivariate model, independent risk factors for BV were facility type, having fewer dependents, increasing alcohol 374 consumption, recent sex, using cloths or cotton wool for menstrual hygiene, and prevalent HIV and T vaginalis infection (table 3). BV was inversely associated with ever inserting substances for dry sex. Age was retained in the final model, although it was no longer significantly associated with BV. DISCUSSION We report an extremely high prevalence of BV among Tanzanian HSV-2 seropositive women working in bars, guesthouses and similar facilities, with 63% of women having BV. Other studies in similar populations in sub-Saharan Africa have reported BV prevalence between 20 and 50%.5 6 8 23 24 The higher BV prevalence observed in our study is likely to reflect the fact that our population was HSV-2 seropositive, since a strong association between BV and HSV-2 has been observed in many studies.5 7 23 We found BV prevalence to be independently associated with sex in the past 7 days. Other studies have found BV to be associated with increased sexual activity in both community based settings and among women at high risk of STI.15 16 23 However, a prospective study of rural women in The Gambia found no association between sexual behaviour and BV,25 and BV has also been detected in sexually inexperienced women.19 A recent meta-analysis found the epidemiological data to be consistent with BV having a sexual mode of transmission,15 but additional factors are likely to contribute to its aetiology. Vaginal cleansing was common in our study population as reported in a number of African studies.6 13 23 26 27 IVPs are believed to alter the dominant flora of the vagina and, thus, increase susceptibility to BV.14 27 28 IVP, particularly douching, has been described as a risk factor for BV in industrialised countries.14 28 In sub-Saharan Africa, the association between IVP and BV is inconsistent, perhaps reflecting the heterogeneity of the techni- ques and substances used. In a prospective study of sex workers in Burkino Faso, vaginal cleansing was not associated with BV.23 Among family planning clinic attendees in Zimbabwe and Uganda, vaginal cleansing was not associated with BV although vaginal drying was associated with BV in the univariate analysis.27 Interestingly, we found BV prevalence was significantly lower among women who reported inserting drying substances, although that practice was relatively uncommon. Furthermore, we found a suggestion of a trend towards decreasing BV with increasing frequency of vaginal cleansing. Menstrual hygiene practices have also been suggested as an explanation for the higher prevalence of BV in sub-Saharan Africa. BV prevalence was higher among women in our study who used cloths or cotton wool than in those who used sanitary pads. However, a study in Uganda found no association between BV and using cloths for menstrual hygiene.26 Furthermore, a crossover trial in The Gambia of modern pads and traditional cloths found BV to be slightly more frequent when women used sanitary pads.25 Although not statistically significant, we found some evidence of a protective effect of hormonal contraception on BV, which is consistent with other studies.18 27 The relationship between hormones, contraception and BV is not well- understood. Oestrogen increases vaginal epithelial cell activity, resulting in increased glycogen and a more favourable environ- ment for lactobacilli.17 However, the prevalence of BV among post-menopausal women is low despite low oestrogen levels.17 We found strong independent associations of BV with HIV and T vaginalis. The association between BV and HIV acquisition has been reported in several prospective studies in sub-Saharan Africa.9 11 27 In a similar cohort in Tanzania, women with BV at baseline had a twofold higher risk of HIV Sex Transm Infect 2009;85:370–375. doi:10.1136/sti.2008.035543