Prospective study of hormonal contraception and women's risk of HIV infection in South Africa

BACKGROUND: Many women using hormonal contraceptives are also at risk of sexually transmitted HIV infection, but data are mixed on whether hormonal contraception increases women's risk of HIV. We investigated associations between HIV incidence and use of combined oral contraceptives (COC), norethindrone enanthate (NET-EN) or depot medroxyprogesterone acetate (DMPA) in a cohort of South African women. METHODS: Participants were 4200 HIV-negative women aged 35-49 years enrolled into a cervical cancer screening trial. At enrollment, women were tested for sexually transmitted infections and reported on their sexual behaviour and contraceptive use. During the 24 months of follow-up, women reported on their sexual behaviours and contraceptive use and underwent repeat HIV testing. RESULTS: During the 5010 person-years of follow-up, 111 incident HIV infections were observed (HIV incidence, 2.2 infections/100 person-years). At enrollment, 21% of women reported using hormonal contraception, primarily DMPA (14% of all women) or NET-EN (5%). After adjusting for sexual risk behaviours and sexually transmitted infections, the incidence of HIV was similar among women using COC, NET-EN or DMPA compared with women not using any hormonal method [incidence rate ratios and 95% confidence intervals, 0.65, 0.16-2.66; 0.79, 0.31-2.02 and 0.96, 0.58-1.59, respectively]. There was also no association between increased duration of DMPA use and HIV incidence (P-value for trend, 0.51). CONCLUSIONS: These findings contribute to the evidence from general population cohorts of women that hormonal contraceptive use is not associated with increased risk of HIV acquisition. Nonetheless, family planning services are an important venue for HIV prevention activities.     

Multivitamin use and colorectal cancer incidence in a US cohort: does timing matter?

Multivitamins contain several nutrients, including folic acid, that are hypothesized to reduce the risk of colorectal cancer. Previous studies suggest that multivitamin use may reduce colorectal cancer risk but only after a long latency period. The authors examined the association between regular multivitamin use (four or more times per week) and colorectal cancer incidence among 145,260 men and women in the Cancer Prevention Study II Nutrition Cohort. Current multivitamin use was reported on a questionnaire at enrollment in 1992-1993. All participants had also reported multivitamin use on a questionnaire completed for a different study approximately 10 years earlier (in 1982). The authors observed 797 incident cases of colorectal cancer during follow-up from 1992 to 1997. After multivariate adjustment, regular multivitamin use at enrollment was not associated with risk of colorectal cancer (rate ratio = 1.04, 95% confidence interval: 0.87, 1.23), whereas regular multivitamin use 10 years before enrollment was associated with reduced risk (rate ratio = 0.71, 95% confidence interval: 0.57, 0.89). Regular multivitamin users 10 years before enrollment were at similarly reduced risk whether they were still regular multivitamin users at enrollment or had stopped. These results are consistent with the hypothesis that past, but not recent, multivitamin use may be associated with modestly reduced risk of colorectal cancer.     

Application of the case-crossover design to reduce unmeasured confounding in studies of condom effectiveness

This analysis examined how unmeasured confounding affects estimates of the effectiveness of condoms in preventing sexually transmitted infections. Data were analyzed from a prospective cohort study of 1,122 female sexually transmitted disease clinic patients in Alabama (1992-1995), wherein participants were evaluated for sexually transmitted infections at six 1-month intervals. Associations between condom use and incident gonorrhea and chlamydia infection were compared between case-crossover and cohort analyses. In a case-crossover analysis of 228 follow-up visits ending in gonorrhea/chlamydia ("case intervals") and 743 self-matched follow-up visits not ending in gonorrhea/chlamydia ("noncase intervals") (183 women), consistent condom use without breakage or slippage was associated with significantly reduced risk of infection relative to nonuse (adjusted risk odds ratio = 0.49, 95% confidence interval: 0.26, 0.92). Conversely, a cohort analysis of 245 case intervals and 3,896 noncase intervals (919 women) revealed no significant reduction in infection risk from consistent use of condoms (adjusted risk odds ratio = 0.79, 95% confidence interval: 0.53, 1.17). Dose-response relations between the number of unprotected sex acts and infection were stronger in the case-crossover analysis (p for trend = 0.009) than in the cohort analysis (p for trend = 0.18). These findings suggest that epidemiologic studies confounded by unmeasured differences between condom users and nonusers underestimate condom effectiveness against these infections. The case-crossover method provides an additional technique for reducing unmeasured confounding in studies of condom effectiveness.     

Swine workers and swine influenza virus infections

In 2004, 803 rural Iowans from the Agricultural Health Study were enrolled in a 2-year prospective study of zoonotic influenza transmission. Demographic and occupational exposure data from enrollment, 12-month, and 24-month follow-up encounters were examined for association with evidence of previous and incident influenza virus infections. When proportional odds modeling with multivariable adjustment was used, upon enrollment, swine-exposed participants (odds ratio [OR] 54.9, 95% confidence interval [CI] 13.0-232.6) and their nonswine-exposed spouses (OR 28.2, 95% CI 6.1-130.1) were found to have an increased odds of elevated antibody level to swine influenza (H1N1) virus compared with 79 nonexposed University of Iowa personnel. Further evidence of occupational swine influenza virus infections was observed through self-reported influenza-like illness data, comparisons of enrollment and follow-up serum samples, and the isolation of a reassortant swine influenza (H1N1) virus from an ill swine farmer. Study data suggest that swine workers and their nonswine-exposed spouses are at increased risk of zoonotic influenza virus infections.     

Are US populations appropriate for trials of human immunodeficiency virus vaccine? The HIVNET Vaccine Preparedness Study

Questions exist about whether testing of preventive human immunodeficiency virus (HIV)-1 vaccines, which will require rapid recruitment and retention of cohorts with high HIV-1 seroincidence, is feasible in the United States. A prospective cohort study was conducted in 1995-1997 among 4,892 persons at high risk for HIV infection in nine US cities. At 18 months, with an 88% retention rate, 90 incident HIV-1 infections were observed (1.31/100 person-years (PY), 95% confidence interval (CI): 1.06, 1.61). HIV-1 seroincidence rates varied significantly by baseline eligibility criteria--1.55/100 PY among men who had sex with men, 0.38/100 PY among male intravenous drug users, 1.24/100 PY among female intravenous drug users, and 1.13/100 PY among women at heterosexual risk-and by enrollment site, from 0.48/100 PY to 2.18/100 PY. HIV-1 incidence was highest among those men who had sex with men who reported unprotected anal intercourse (2.01/100 PY, 95% CI: 1.54, 2.63), participants who were definitely willing to enroll in an HIV vaccine trial (1.96/100 PY, 95% CI: 1.41, 2.73), and women who used crack cocaine (1.62/100 PY, 95% CI: 0.92, 2.85). Therefore, cohorts with HIV-1 seroincidence rates appropriate for HIV-1 vaccine trials can be recruited, enrolled, and retained.     

Retention of women enrolled in a prospective study of human immunodeficiency virus infection: impact of race, unstable housing, and use of human immunodeficiency virus therapy.

Even though women and people of color represent an increasing proportion of US acquired immunodeficiency syndrome (AIDS) cases, few research studies include adequate representation of these populations. Here the authors describe recruitment and retention of a diverse group of human immunodeficiency virus (HIV)-infected and at risk HIV-uninfected women in a prospective study operating in six sites across the United States. Methods used to minimize loss to follow-up in this cohort are also described. For the first 10 study visits that occurred during a 5-year period between 1994 and 1999, the retention rate of participants was approximately 82%. In adjusted Cox analysis, factors associated with retention among all women were older age, African-American race, stable housing, HIV-infected serostatus, past experience in studies of HIV/AIDS, and site of enrollment. In an adjusted Cox analysis of HIV-infected women, African-American race, past experience in studies of HIV/AIDS, site of enrollment, and reported use of combination or highly active antiretroviral HIV therapy at the last visit were significantly associated with retention. In adjusted Cox analysis of HIV-uninfected study participants, only the site of enrollment was significantly associated with study retention. These results show that women with and at risk for HIV infection, especially African-American women, can be successfully recruited and retained in prospective studies.     

Association of Chlamydia trachomatis with persistence of high-risk types of human papillomavirus in a cohort of female adolescents

Human papillomavirus (HPV) infection is a necessary but not sufficient cause of cervical cancer. While chlamydia infection has been associated with cervical cancer, the meaning of this association remains unclear. The authors' objective was to investigate this association by evaluating whether concurrent genital tract infections are associated with HPV persistence, a precursor to cervical cancer. Interview data and biologic samples for HPV, Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and bacterial vaginosis testing were collected from female adolescents in an Atlanta, Georgia, longitudinal cohort study at 6-month visits (1999-2003). Associations with persistence (detection of the same HPV type at two sequential visits (visit pair)) were assessed among subjects with 2-5 visits and > or =6 months of follow-up. Associations were evaluated by logistic regression using methods for correlated data. Type-specific persistence of high-risk HPV types was detected in 77 of 181 (43%) analyzed visit pairs. Concurrent infection with C. trachomatis was independently associated with persistence of high-risk HPV types (adjusted odds ratio = 2.1, 95% confidence interval: 1.0, 4.1). Infection with more than one HPV type at the initial visit was also associated with high-risk persistence (adjusted odds ratio = 2.8, 95% confidence interval: 1.6, 4.9). The association between chlamydia infection and cervical cancer may be due to an effect of chlamydia infection on persistence of high-risk HPV.     

Use of mammographic screening by HIV-infected women in the Women's Interagency HIV Study (WIHS)

BACKGROUND: Although HIV-positive women may be less likely than women in general to receive mammography due to socioeconomic disadvantage, HIV diagnosis may increase opportunities for medical interactions which encourage mammography. METHODS: HIV-positive (2,059) and HIV-negative (569) Women's Interagency HIV Study (WIHS) participants reported ever/never history of mammography at baseline (in 1994, 1995) and, at each 6-month follow-up visit, if they had been screened since their last visit. National Health Interview Survey (NHIS) data for 1994 were used to compare WIHS participants to U.S. women. Factors independently related to mammography were determined using logistic regression for baseline data and proportional hazards for follow-up data. Results were adjusted for age. RESULTS: Among women > or =40, fewer WIHS women, regardless of HIV status, reported screening than U.S. women (67% HIV-positive, 62% HIV-negative, 79% NHIS; P < 0.0001). First-time screening while on study was associated with being HIV-positive [rate ratio (95% confidence interval) = 1.6 (1.1, 2.3)]. Factors independently associated with screening were related to health care access and usage. CONCLUSIONS: WIHS women, a disadvantaged population, reported less mammography than the general population. HIV-positive women reported more screening than HIV-negative women, possibly because of greater opportunity to interact with the health care system.     

Self-report of sexually transmitted infections from 1994 to 2010 by adults living in France

BackgroundSince 1994, French population-based knowledge, attitudes, beliefs and practices surveys have enabled researchers to estimate trends in sexual behavioural indicators.MethodsWe estimated trends and prevalence of self-reported sexually transmitted infections during the previous 5 years among 16,095 sexually active adults aged 18–54 through five cross-sectional telephone surveys between 1994 and 2010. We then studied the factors associated with participants’ most recent sexually transmitted infections other than genital candidiasis.ResultsOverall, 2.5% (95% confidence interval: 2.2%–2.9%) of women reported sexually transmitted infections within the previous 5 years, increases being continuously reported between 1998 and 2010. In contrast, men reported lower prevalence of sexually transmitted infections (1.4%; 95% confidence interval: 1.1%–1.7%), which remained stable over time. General practitioners and gynaecologists managed most sexually transmitted infections. Men notified their stable partners about infection less often than women (66% vs. 84%). Self-reported sexually transmitted infections were associated with younger age, multiple sexual partnerships and fear of sexually transmitted infections in both genders, with exclusively homosexual practices in men, and with a high educational level and recent HIV testing in women.ConclusionSelf-reported sexually transmitted infections clearly reflect risky sexual behaviours. The lower prevalence of self-reported sexually transmitted infections among men than among women may reflect less access to screening activities for sexually transmitted infections in men.     

Pesticide use and breast cancer risk among farmers' wives in the agricultural health study

The authors examined the association between pesticide use and breast cancer incidence among farmers' wives in a large prospective cohort study in Iowa and North Carolina. Participants were 30,454 women with no history of breast cancer prior to cohort enrollment in 1993-1997. Information on pesticide use and other information was obtained by self-administered questionnaire at enrollment from the women and their husbands. Through 2000, 309 incident breast cancer cases were identified via population-based cancer registries. Rate ratios were calculated for individual pesticides using Poisson regression, controlling for confounding factors. Breast cancer standardized incidence ratios were 0.87 (95% confidence interval: 0.74, 1.02) for women who reported ever applying pesticides and 1.05 (95% confidence interval: 0.89, 1.24) for women who reported never applying pesticides. There was some evidence of increased risk associated with use of 2,4,5-trichloro-phenoxypropionic acid (2,4,5-TP) and possibly use of dieldrin, captan, and 2,4,5-trichlorophenoxyacetic acid (2,4,5-TP), but small numbers of cases among those who had personally used the pesticides precluded firm conclusions. The authors found no clear association of breast cancer risk with farm size or washing of clothes worn during pesticide application, but risk was modestly elevated among women whose homes were closest to areas of pesticide application. Further follow-up of this cohort should help clarify the relation between pesticide exposure and breast cancer risk.     

Smoking and the occurrence of Alzheimer's disease: cross-sectional and longitudinal data in a population-based study

The authors tested the hypothesis that smoking exerts a protective effect on Alzheimer's disease or dementia in a population-based cohort of 668 people aged 75-101 years (Sweden). Smoking was negatively associated with prevalent Alzheimer's disease (adjusted odds ratio = 0.6, 95% confidence interval 0.4-1.1) and dementia (adjusted odds ratio = 0.6, 95% confidence interval 0.4-1.0). Over 3-year follow-up (1989-1992), the hazard ratios of incident Alzheimer's disease and dementia due to smoking were 1.1 (95% confidence interval 0.5-2.4) and 1.4 (95% confidence interval 0.8-2.7). Mortality over 5-year follow-up was greater among smokers in demented (hazard ratio = 3.4) than nondemented (hazard ratio = 0.8) subjects. Smoking does not seem protective against Alzheimer's disease or dementia, and the cross-sectional association might be due to differential mortality.     

Associations between mild-to-moderate anaemia in pregnancy and helminth, malaria and HIV infection in Entebbe, Uganda

It is suggested that helminths, particularly hookworm and schistosomiasis, may be important causes of anaemia in pregnancy. We assessed the associations between mild-to-moderate anaemia (haemoglobin >8.0 g/dl and <11.2 g/dl) and helminths, malaria and HIV among 2507 otherwise healthy pregnant women at enrolment to a trial of deworming in pregnancy in Entebbe, Uganda. The prevalence of anaemia was 39.7%. The prevalence of hookworm was 44.5%, Mansonella perstans 21.3%, Schistosoma mansoni 18.3%, Strongyloides 12.3%, Trichuris 9.1%, Ascaris 2.3%, asymptomatic Plasmodium falciparum parasitaemia 10.9% and HIV 11.9%. Anaemia showed little association with the presence of any helminth, but showed a strong association with malaria (adjusted odds ratio (AOR) 3.22, 95% CI 2.43-4.26) and HIV (AOR 2.46, 95% CI 1.90-3.19). There was a weak association between anaemia and increasing hookworm infection intensity. Thus, although highly prevalent, helminths showed little association with mild-to-moderate anaemia in this population, but HIV and malaria both showed a strong association. This result may relate to relatively good nutrition and low helminth infection intensity. These findings are pertinent to estimating the disease burden of helminths and other infections in pregnancy. [Clinical Trial No. ISRCTN32849447].     

Smoking and time to clearance of human papillomavirus infection in HIV-seropositive and HIV-seronegative women

Persistent human papillomavirus (HPV) infection seems central to cervical carcinogenesis. Smoking is associated with cervical cancer in HPV DNA-positive women, but its association with HPV persistence is unclear, particularly with respect to human immunodeficiency virus (HIV) serostatus. The authors evaluated smoking and HPV clearance by HIV serostatus among 801 women from the HIV Epidemiology Research Study (United States, 1993-2000). Type-specific HPV duration was defined as the interval between initial MY09/11 polymerase chain reaction positivity and the first of two consecutive HPV-negative study visits. Hazard ratios adjusted for study site and risk behaviors (sexual activity or injection drug use) were estimated using Cox regression. This analysis included 522 HIV-seropositive and 279 HIV-seronegative women (median follow-up, 4.4 years). Ever smoking was associated with reduced clearance of high-risk HPV in HIV-seronegative women (hazard ratio (HR) = 0.51, 95% confidence interval (CI): 0.30, 0.88) but not in HIV-seropositive women (HR = 0.96, 95% CI: 0.65, 1.42); similar results were found for current smoking. Current smoking was not associated with clearance of any type-specific HPV in HIV-seropositive (HR = 0.99, 95% CI: 0.82, 1.20) or HIV-seronegative (HR = 0.93, 95% CI: 0.68, 1.26) women. HPV clearance did not appear to vary by amount or duration of smoking. Smoking did not modify overall clearance but was associated with lower high-risk HPV clearance in HIV-seronegative women.     

Modeling the time dependence of the association between human papillomavirus infection and cervical cancer precursor lesions

The authors studied the time-dependent association between human papillomavirus (HPV) infection and squamous intraepithelial lesions (SIL) among women enrolled in a cohort study in Brazil (1993-2002), using repeated Papanicolaou cytologic examination and HPV testing by polymerase chain reaction. Through simulation with conceivable alternative cohort designs, they investigated different regression modeling approaches using time-varying covariates, time-varying hazard ratio functions, and repeated events to assess the effect of delay in lesion detection. Associations between HPV and early SIL were of high magnitude. The age-adjusted hazard ratios for the association between HPV at enrollment and low-grade SIL decreased gradually with time until 72 months for both oncogenic types of HPV (hazard ratio = 3.96, 95% confidence interval (CI): 2.5, 6.4) and nononcogenic types (hazard ratio = 2.37, 95% CI: 1.3, 4.3). The hazard ratio for incident high-grade SIL remained constant, ranging from 7.15 (95% CI: 2.0, 25.1) at 12 months to 6.26 (95% CI: 2.7, 14.5) at 72 months for oncogenic types of HPV. With oncogenic HPV as the time-dependent predictor variable, the hazard ratios for incident SIL and high-grade SIL events were 14.2 (95% CI: 8.7, 23.1) and 32.7 (95% CI: 8.4, 127.3), respectively. Investigators may underestimate the prognostic value of HPV detection using designs that rely on HPV ascertainment at a single time point. The waning in hazard ratios should be considered in the implementation of HPV testing-based screening programs.     

Social and psychological correlates of unprotected anal intercourse among Hispanic-American women: implications for STI/HIV prevention

Heterosexual anal intercourse is associated with increased risk for HIV and other sexually transmitted infections. Research on the social and psychological risk factors associated with heterosexual unprotected anal intercourse among Hispanic women in the USA is limited. We examined demographic, mental health, relationship power, sexual self-efficacy, self-esteem, acculturation and HIV knowledge as correlates of unprotected anal intercourse among 514 HIV-negative Hispanic women, 18 to 59 years of age, residing in one urban county in southern Florida. In both unadjusted and adjusted results, the likelihood of engaging in unprotected anal intercourse was associated with food insecurity in the past 30 days (adjusted odds ratio [AOR] = 1.57, 95% confidence interval [CI] 1.03, 2.40) and more interpersonal power attributed to the male partner (AOR = 1.63, 95%CI 1.08, 2.45). Not significant, yet of possible importance, were ever having engaged in exchange sex (AOR = 1.96, 95%CI = 0.97, 3.98) and lower HIV knowledge (AOR = 0.80, 95%CI = 0.63, 1.01). Interventions aimed at reducing heterosexual unprotected anal intercourse risk for HIV infection among Hispanic women may benefit by addressing socioeconomic and interpersonal issues, and assessing HIV knowledge and comprehension.     

High risk of human immunodeficiency virus in men who have sex with men with herpes simplex virus type 2 in the EXPLORE study

The relation between herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV) acquisition was evaluated among 4,295 high-risk, HIV-negative men who have sex with men in an intensive behavioral intervention (colloquially referred to as "EXPLORE") study in the United States from 1999 to 2003. Sexual behavior data were obtained by computer-assisted self-interview, and sera were collected semiannually for HIV and HSV-2 serology. HSV-2 infection was classified as "recent incident" (at the first HSV-2 seropositive visit), "remote incident" (within 24 months of the first positive visit), and "prevalent" (for visits >24 months after the first HSV-2 positive visit). Baseline HSV-2 prevalence was 20.3%. HSV-2 incidence was 1.9 (95% confidence interval (CI): 1.6, 2.2) per 100 person-years; significant risk factors were African-American race, unprotected receptive anal intercourse, an HIV-positive male sex partner, and six or more male partners in the prior 6 months. The behavioral intervention did not reduce HSV-2 acquisition (adjusted hazard ratio (HR) = 1.2, 95% CI: 0.9, 1.6). Overall HIV incidence was 1.9 (95% CI: 1.7, 2.2) per 100 person-years. HIV risk was elevated among men who have sex with men with recent incident HSV-2 (adjusted HR = 3.6, 95% CI: 1.7, 7.8), remote incident HSV-2 (adjusted HR = 1.7, 95% CI: 0.8, 3.3), and prevalent HSV-2 (adjusted HR = 1.5, 95% CI: 1.1, 2.1) infection compared with HSV-2 seronegative participants. HIV intervention strategies targeting HSV-2 prevention and suppression among men who have sex with men should be evaluated.     

A large nosocomial outbreak of hepatitis C and hepatitis B among patients receiving pain remediation treatments.

BACKGROUND AND OBJECTIVE: In August 2002, the Oklahoma State Department of Health received a report of six patients with unexplained hepatitis C virus (HCV) infection treated in the same pain remediation clinic. We investigated the outbreak's extent and etiology. DESIGN, SETTING, AND PARTICIPANTS: We conducted a retrospective cohort study of clinic patients, including a serologic survey, interviews of infected patients, and reviews of medical records and staff infection control practices. Patients received outpatient pain remediation treatments one afternoon a week in a clinic within a hospital. Cases were defined as HCV or hepatitis B virus (HBV) infections among patients who reported no prior diagnosis or risk factors for disease or reported previous risk factors but had evidence of acute infection. RESULTS: Of 908 patients, 795 (87.6%) were tested, and 71 HCV-infected patients (8.9%) and 31 HBV-infected patients (3.9%) met the case definition. Multiple HCV genotypes were identified. Significantly higher HCV infection rates were found among individuals treated after an HCV-infected patient during the same visit (adjusted odds ratio [AOR], 6.2; 95% confidence interval [CI95], 2.4-15.8); a similar association was observed for HBV (AOR, 2.9; CI95, 1.3-6.5). Review of staff practices revealed the nurse anesthetist had been using the same syringe-needle to sequentially administer sedation medications to every treated patient each clinic day. CONCLUSIONS: Reuse of needles-syringes was the mechanism for patient-to-patient transmission of HCV and HBV in this large nosocomial outbreak. Further education and stricter oversight of infection control practices may prevent future outbreaks.     

Clustering of Helicobacter pylori infection in couples: differences between high- and low-prevalence population groups

PURPOSE: Several mostly small-scale studies reported clustering of Helicobacter pylori infections as a possible indicator of conjugal transmission, but results have been inconsistent. We assessed clustering of H pylori infections in a large community-based study from Germany that included both high-prevalence and low-prevalence population subgroups. METHODS: Current H pylori infection was determined among 670 couples by means of carbon-13-urea breath test ((13)C-UBT) breath test and a monoclonal antigen immunoassay for H pylori in stool. RESULTS: Prevalences of infection among women were 34.9% (51 of 146 women) if the partner was infected and 14.5% (76 of 524 women) if the partner was not infected. Stratification by nationality showed a strong association of infection for partners with other than German nationality (adjusted odds ratio [OR], 6.05; 95% confidence interval [CI], 1.31-17.96), for whom prevalence of infection was greater than 50%, whereas no association was seen for German partners born in Germany (OR, 1.10; 95% CI, 0.47-2.61), for whom infection prevalence was approximately 10% (p for interaction = 0.048). CONCLUSIONS: Conjugal transmission of infection caused by H pylori is unlikely to be of relevance in low-prevalence population groups. Our results are consistent with the hypothesis of a potential role of conjugal transmission of H pylori infection in high-prevalence population groups.     

Trends in human immunodeficiency virus seroincidence among street-recruited injection drug users in San Francisco, 1987-1998

This paper reports trends in human immunodeficiency virus (HIV) incidence among street-recruited injection drug users (IDUs) in San Francisco, California, from 1987 through 1998, estimated using a sensitive/less sensitive enzyme immunoassay testing strategy. IDUs were enrolled in 23 semiannual cross-sections from three community sites. For identification of recent infections, less sensitive enzyme immunoassay testing was performed on stored specimens that had previously tested positive for HIV antibodies. Annualized incidence rates were calculated and logistic regression models were fitted for assessment of risk factors for recent HIV infection. Among 8,065 susceptible IDUs, 34 had recent infections, for an incidence rate of 1.2% (95% confidence interval: 0.7, 2.0) per person-year. This rate declined from 2.7% in 1987/1988 to approximately 1% per person-year between 1989 and 1998. Two IDU subpopulations were at highest risk for infection: persons under age 30 years (2.8% per person-year) and men who had sex with men (3.0% per person-year). Participants who reported prior HIV test-result counseling were less likely than others to become infected (adjusted odds ratio = 0.43, 95% confidence interval: 0.21, 0.87). Sensitive/less sensitive enzyme immunoassay testing is an effective tool for assessing HIV incidence. HIV incidence among street-recruited IDUs in San Francisco appears to have remained stable and moderate since the late 1980s.     

Pesticide exposure and self-reported Parkinson's disease in the agricultural health study

Previous studies based on limited exposure assessment have suggested that Parkinson's disease (PD) is associated with pesticide exposure. The authors used data obtained from licensed private pesticide applicators and spouses participating in the Agricultural Health Study to evaluate the relation of self-reported PD to pesticide exposure. Cohort members, who were enrolled in 1993-1997, provided detailed information on lifetime pesticide use. At follow-up in 1999-2003, 68% of the cohort was interviewed. Cases were defined as participants who reported physician-diagnosed PD at enrollment (prevalent cases, n = 83) or follow-up (incident cases, n = 78). Cases were compared with cohort members who did not report PD (n = 79,557 at enrollment and n = 55,931 at follow-up). Incident PD was associated with cumulative days of pesticide use at enrollment (for highest quartile vs. lowest, odds ratio (OR) = 2.3, 95% confidence interval: 1.2, 4.5; p-trend = 0.009), with personally applying pesticides more than half the time (OR = 1.9, 95% confidence interval: 0.7, 4.7), and with some specific pesticides (ORs > or = 1.4). Prevalent PD was not associated with overall pesticide use. This study suggests that exposure to certain pesticides may increase PD risk. Findings for specific chemicals may provide fruitful leads for further investigation.