Needle exchange programs (NEPs) are designed to prevent human immunodeficiency virus (HIV) transmission among injection drug users. Although most studies report beneficial effects in terms of behavior modification, a direct assessment of the effectiveness of NEPs in preventing HIV infection has been lacking. A cohort study was conducted to assess the association between risk behaviors and HIV seroprevalence and seroincidence among injection drug users in Montreal, Canada. The association between NEP use and HIV infection was examined in three risk assessment scenarios using intensive covariate adjustment for empirical confounders: a cross-sectional analysis of NEP use at entry as a determinant of seroprevalence, a cohort analysis of NEP use at entry as a predictor of subsequent seroconversion, and a nested case-control analysis of NEP participation during follow-up as a predictor of seroconversion. From September 1988 to January 1995, 1,599 subjects were enrolled with a baseline seroprevalence of 10.7%. The mean follow-up period was 21.7 months. The adjusted odds ratio for HIV seroprevalence in injection drug users reporting recent NEP use was 2.2 (95% confidence interval 1.5-3.2). In the cohort study, there were 89 incident cases of HIV infection with a cumulative probability of HIV seroconversion of 33% for NEP users and 13% for nonusers (p < 0.0001). In the nested case-control study, consistent NEP use was associated with HIV seroconversion during follow-up (odds ratio = 10.5, 95% confidence interval 2.7-41.0). Risk elevations for HIV infection associated with NEP attendance were substantial and consistent in all three risk assessment scenarios in our cohort of injection drug users, despite extensive adjustment for confounders. In summary, in Montreal, NEP users appear to have higher seroconversion rates then NEP nonusers.

Summaryobjective To assess the effect on birthweight of antenatal mebendazole plus iron vs. placebo plus iron in a highly hookworm-endemic area.methods Double-blind, randomized controlled trial set in rural and peri-urban communities in the Peruvian Amazon region. A total of 1042 second trimester pregnant women between the ages of 18 and 44 years were recruited from April to November 2003, and followed to July 2004. Women were randomly assigned to receive either mebendazole (500 mg single dose) plus iron supplements (60 mg elemental iron daily) or placebo plus iron supplements. The primary outcome was mean infant birthweight and secondary measures included proportion of low birthweight babies and maternal anaemia.results The prevalence of hookworm infection was 47.5%. There were no differences between intervention groups in mean birthweight (3104 g vs. 3090 g, P ¼ 0.629), proportion of low birthweight (<2500 g; 8.1% vs. 8.7%, P ¼ 0.755) or maternal anaemia in the third trimester [33.0% (158/479) vs. 32.3% (152/471), P ¼ 0.815]. However, the proportion of very low birthweight (<1500 g) was significantly lower in the mebendazole group [0% (0/479) vs. 1.5% (7/471),conclusions This trial provides additional evidence for the use of anthelmintics, over and above iron supplementation, within antenatal care programmes in hookworm-endemic areas. Benefits of de-worming may be higher in countries not having an antenatal iron supplementation programme or where intensity of hookworm infections is higher.

We compared four methods of control selection to assess the effect of using infants with malformations as controls in case-control studies of birth defects. We identified cases and controls using data from the Slone Epidemiology Unit Births Defect Study for the years 1976-1992. Cases were defined as infants with cleft lip and palate and no other malformations (N = 494). Controls (N = 8356) were chosen from infants with other malformations, excluding other oral cleft conditions or syndromes associated with clefts. Maternal smoking during the first 13 weeks of pregnancy was the exposure of interest. We then assessed the measures of association resulting from using controls with varying restrictions. When we excluded all defects potentially associated with maternal smoking (based on reports in the literature), the crude odds ratio for smoking and oral cleft risk was 1.6 (1.3-1.9). When we eliminated all defect groups with a smoking prevalence that was one or more standard deviations above or below the total control group mean, the odds ratio was 1.5 (1.2-1.8); with controls restricted to infants with Mendelian-inherited disorders (with presumably no causal effect of smoking), the odds ratio was 1.6 (1.1-2.7); and when selection was unrestricted, the crude odds ratio was 1.5 (1.2-1.8). When used selectively, infants with malformations other than the anomaly of interest can be a suitable source of controls.