Incidence of HIV infection in stable sexual partnerships: a retrospective cohort study of 1802 couples in Mwanza Region, Tanzania.

OBJECTIVE: To describe the dynamics of HIV transmission in stable sexual partnerships in rural Tanzania. DESIGN: Retrospective cohort study nested within community-randomized trial to investigate the impact of a sexually transmitted disease treatment program. METHODS: A cohort of 1802 couples was followed up for 2 years, with the HIV status of each couple assessed at baseline and follow-up. RESULTS: At baseline, 96.7% of couples were concordant-negative, 0.9% were concordant-positive, 1.2% were discordant with the male partner being HIV-positive, and 1.2% were discordant with the female partner being HIV-positive. Individuals living with an HIV-positive partner were more likely to be HIV-positive at baseline (women: odds ratio [OR] = 75.7, 95% confidence interval [CI]: 33.4-172; men: OR = 62.4, CI: 28.5-137). Seroincidence rates in discordant couples were 10 per 100 person-years (py) and 5 per 100 py for women and men, respectively (rate ratio [RR] = 2.0, CI: 0.28-22.1). In concordant-negative couples, seroincidence rates were 0.17 per 100 py in women and 0.45 per 100 py in men (RR = 0.38, CI: 0.12-1.04). Individuals living in discordant couples were at a greatly increased risk of infection compared with individuals in concordant-negative couples (RR = 57.9, CI: 12.0-244 for women; RR = 11.0, CI: 1.2-47.5 for men). CONCLUSION: Men were more likely than women to introduce HIV infection in concordant-negative partnerships. In discordant couples, incidence in HIV-negative women was twice as high as in men. HIV-negative individuals in discordant partnerships are at high risk of infection, and preventive interventions targeted at such individuals are urgently needed.

Syphilis in pregnancy in Tanzania. I. Impact of maternal syphilis on outcome of pregnancy.

To measure the impact of maternal syphilis on pregnancy outcome in the Mwanza Region of Tanzania, 380 previously unscreened pregnant women were recruited into a retrospective cohort at delivery and tested for syphilis. Stillbirth was observed in 18 (25%) of 73 women with high-titer active syphilis (i.e., women with a rapid plasma reagin titer > or = 1 :8 and a positive Treponema pallidum hemagglutination assay or indirect fluorescent treponemal antibody test result), compared with 3 (1%) of 233 uninfected women (risk ratio [RR], 18.1; P<.001). Women with high-titer active syphilis were also at the greatest risk of having low-birth-weight or preterm live births (RR, 3.0 and 6.1, respectively), compared with women with other serological stages of syphilis. Among unscreened women, 51% of stillbirths, 24% of preterm live births, and 17% of all adverse pregnancy outcomes were attributable to maternal syphilis. Syphilis continues to be a major cause of pregnancy loss and adverse pregnancy outcome among women who do not receive antenatal syphilis screening and treatment.

Syphilis in pregnancy in Tanzania. II. The effectiveness of antenatal syphilis screening and single-dose benzathine penicillin treatment for the prevention of adverse pregnancy outcomes.

Treatment for maternal syphilis with single-dose benzathine penicillin (2.4 million units intramuscularly) is being implemented in many parts of sub-Saharan Africa. To examine the effectiveness of this regimen, a prospective cohort of 1688 pregnant women was recruited in Tanzania. Birth outcomes were compared among women treated for high-titer (n=133; rapid plasma reagin [RPR] titer > or = 1:8 and Treponema pallidum hemagglutination assay [TPHA]/fluorescent treponemal antibody [FTA] positive) and low-titer (n=249; RPR titer <1:8 and TPHA/FTA positive) active syphilis and 950 uninfected women. Stillbirth or low-birth-weight live births were observed in 2.3% and 6.3%, respectively, of women treated for high-titer active syphilis and in 2.5% and 9.2%, respectively, of seronegative women. There was no increased risk for adverse pregnancy outcome for women treated for high-titer active syphilis (odds ratio [OR], 0.76; 95% confidence interval [CI], 0.4-1.4) or low-titer active syphilis (OR, 0.95; 95% CI, 0.6-1.5), compared with seronegative women. Single-dose treatment is effective in preventing adverse pregnancy outcomes attributable to maternal syphilis.