Gender Differences in the Risk of HIV Infection among Persons Reporting Abstinence, Monogamy, and Multiple Sexual Partners in Northern Tanzania

BACKGROUND: Monogamy, together with abstinence, partner reduction, and condom use, is widely advocated as a key behavioral strategy to prevent HIV infection in sub-Saharan Africa. We examined the association between the number of sexual partners and the risk of HIV seropositivity among men and women presenting for HIV voluntary counseling and testing (VCT) in northern Tanzania. METHODOLOGY/ PRINCIPAL FINDINGS: Clients presenting for HIV VCT at a community-based AIDS service organization in Moshi, Tanzania were surveyed between November 2003 and December 2007. Data on sociodemographic characteristics, reasons for testing, sexual behaviors, and symptoms were collected. Men and women were categorized by number of lifetime sexual partners, and rates of seropositivity were reported by category. Factors associated with HIV seropositivity among monogamous males and females were identified by a multivariate logistic regression model. Of 6,549 clients, 3,607 (55%) were female, and the median age was 30 years (IQR 24-40). 939 (25%) females and 293 (10%) males (p<0.0001) were HIV seropositive. Among 1,244 (34%) monogamous females and 423 (14%) monogamous males, the risk of HIV infection was 19% and 4%, respectively (p<0.0001). The risk increased monotonically with additional partners up to 45% (p<0.001) and 15% (p<0.001) for women and men, respectively with 5 or more partners. In multivariate analysis, HIV seropositivity among monogamous women was most strongly associated with age (p<0.0001), lower education (p<0.004), and reporting a partner with other partners (p = 0.015). Only age was a significant risk factor for monogamous men (p = 0.0004). INTERPRETATION: Among women presenting for VCT, the number of partners is strongly associated with rates of seropositivity; however, even women reporting lifetime monogamy have a high risk for HIV infection. Partner reduction should be coupled with efforts to place tools in the hands of sexually active women to reduce their risk of contracting HIV

Gender Differences in the Risk of HIV Infection among Persons Reporting Abstinence, Monogamy, and Multiple Sexual Partners in Northern Tanzania

Background: Monogamy, together with abstinence, partner reduction, and condom use, is widely advocated as a key behavioral strategy to prevent HIV infection in sub-Saharan Africa. We examined the association between the number of sexual partners and the risk of HIV seropositivity among men and women presenting for HIV voluntary counseling and testing (VCT) in northern Tanzania. Methodology/ Principal Findings: Clients presenting for HIV VCT at a community-based AIDS service organization in Moshi, Tanzania were surveyed between November 2003 and December 2007. Data on sociodemographic characteristics, reasons for testing, sexual behaviors, and symptoms were collected. Men and women were categorized by number of lifetime sexual partners, and rates of seropositivity were reported by category. Factors associated with HIV seropositivity among monogamous males and females were identified by a multivariate logistic regression model. Of 6,549 clients, 3,607 (55%) were female, and the median age was 30 years (IQR 24–40). 939 (25%) females and 293 (10%) males (p,0.0001) were HIV seropositive. Among 1,244 (34%) monogamous females and 423 (14%) monogamous males, the risk of HIV infection was 19% and 4%, respectively (p,0.0001). The risk increased monotonically with additional partners up to 45% (p,0.001) and 15% (p,0.001) for women and men, respectively with 5 or more partners. In multivariate analysis, HIV seropositivity among monogamous women was most strongly associated with age (p,0.0001), lower education (p,0.004), and reporting a partner with other partners (p = 0.015). Only age was a significant risk factor for monogamous men (p = 0.0004). Interpretation: Among women presenting for VCT, the number of partners is strongly associated with rates of seropositivity; however, even women reporting lifetime monogamy have a high risk for HIV infection. Partner reduction should be coupled with efforts to place tools in the hands of sexually active women to reduce their risk of contracting HIV

Annualized rates of HIV infection among male and female VCT clients in Moshi, Tanzania, 2003–2007.

*<p>Rates of HIV infection per 100 person years at risk</p

HIV seropositivity among women and men presenting for VCT, by number of lifetime partners and age of tester in Moshi, Tanzania, 2003–2007.

<p>Among women, subjects between 30 and 39 years old had the highest risk of seropositivity in each category of lifetime sexual partners (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003075#pone-0003075-g002" target="_blank">Figure 2</a>, Panel A), while subjects 40 years or older had the greatest rise in risk of seropositivity with increasing numbers of sexual partners. The associations were similar but not as strong among men (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003075#pone-0003075-g002" target="_blank">Figure 2</a>, Panel B). Non-parametric trend tests of associations between the number of partners and seropositivity were significant among men in the youngest and two oldest age groups only (p = 0.016; p = 0.035; and p = 0.001, respectively) and among women showed significant effects in all age groups (p<0.0001 to p = 0.006).</p

Absolute risk of HIV seropositivity among women and men presenting for VCT, by number of lifetime sexual partners in Moshi, Tanzania, 2003–2007, N = 6,531.

<p>Absolute risk of HIV seropositivity among women and men presenting for VCT, by number of lifetime sexual partners in Moshi, Tanzania, 2003–2007, N = 6,531.</p

Correlates of HIV infection by gender among 6,104 clients presenting for VCT in Moshi, Tanzania, 2003–2007.

<p>Odds ratios and [95% confidence intervals] from logistic regression models predicting seropositivity. ^*, ^**, and ^*** denote statistical significance at the 0.05, 0.01, and 0.001 levels, respectively. Ref. denotes reference category. Observations with missing covariates were dropped from the analysis. TSH, Tanzania shilling.</p