Publications by authors named "Nicole H Dukers"

In general, little is known about the incidence of hepatitis B virus (HBV) among drug users, especially among non-injecting drug users. Therefore, changes in incidence, risk factors, and circulating genotypes over time were determined among drug users in Amsterdam over an 18-year period (1985-2002). Sera of 1,268 drug users, both injecting and non-injecting, were screened for anti-HBc.

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Objectives: Since 1999, HIV testing is routinely offered to all attendees of the sexually transmitted infections (STI) outpatient clinic in Amsterdam, the Netherlands. This study evaluates whether this more active HIV-testing policy increased uptake of HIV testing and awareness of an HIV-positive serostatus among heterosexual attendees.

Methods: In addition to routine data collected at each STI consultation, data from half-yearly HIV surveys were used from 1994 to 2004.

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Objectives: Herpes simplex virus type 1 and type 2 (HSV-1 and HSV-2) are both highly prevalent. The rate of genital HSV-1 transmission is reportedly increasing over time. HSV-2 is considered to be an important risk factor for HIV transmission.

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Background: HIV incidence is high and increasing among men who have sex with men (MSM) attending the Sexually Transmitted Infection (STI) Outpatient Clinic in Amsterdam but remains low among MSM in the Amsterdam Cohort Studies (ACS). We studied whether sexual behaviors in these 2 groups are consistent with serosorting and if serosorting explains the difference in HIV incidence.

Methods: In 2004 to 2006, a survey of sexual behaviors and HIV status regarding up to 4 traceable partners in the prior 6 months was performed in MSM attending the STI Outpatient Clinic (high-risk) and in MSM in the ACS (lower risk).

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Objective: To investigate HIV-testing behaviour and HIV prevalence among homosexual visitors of a sexually transmitted infection (STI) outpatient clinic, and to investigate determinants of unknown HIV status, and of HIV testing separately for men with unknown and negative HIV status.

Design: Cross-sectional survey conducted from March 2002 to December 2003 among homosexual men with negative or unknown HIV status visiting the Amsterdam STI clinic.

Methods: A convenience sample of 1201 men with negative or unknown HIV status answered a written questionnaire about history of HIV testing, sexual risk behaviour and behavioural determinants (non-response, 35%).

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Background: In The Netherlands, the western part, including Rotterdam and Amsterdam harbors the majority of the known HIV-infected population, of whom men who have sex with men (MSM) comprise the largest transmission category. Given a general rise in sexually transmitted infections (STI) and risky sexual behavior, we examine the HIV incidence among MSM in the Netherlands with data from three different sources.

Methods: To describe the HIV epidemic among MSM we use: a prospective cohort study in Rotterdam (ROHOCO: 1998-2003, n = 265) and another in Amsterdam (ACS: 1984-2005, n = 1498]) plus an anonymous HIV surveillance study (Amsterdam STI clinic: 1991-2004, n = 3733) in which HIV-positive MSM were tested with a less-sensitive HIV assay.

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Objectives: Sexually transmitted diseases (STDs) are on the rise, mainly among men having sex with men (MSM).

Goal: The goal of this study was to evaluate whether STD increases as seen in MSM are also visible among heterosexuals.

Study Design: Attendees of the STD clinic in Amsterdam, The Netherlands, are routinely tested for chlamydia, gonorrhea, and syphilis.

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To evaluate hepatitis B virus (HBV) risk group vaccination in Amsterdam, which started in 1998, we examined 342 reported acute HBV-cases and sequenced 85 DNA isolates. The reported number of cases declined from 214 in 1992-1997 to 128 in 1998-2003, due to a decline in injecting drug users (IDU) and their heterosexual partners. Phylogenetic analyses showed that after 1998, the IDU cluster nearly disappeared, probably due to a decline in injecting.

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Molecular typing, added to epidemiological data, can better identify transmission patterns of gonorrhea in Western countries, where the incidence has recently been rising. From September 2002 to September 2003, patients with a laboratory-confirmed diagnosis of gonorrhea at the Clinic for Sexually Transmitted Infections in Amsterdam, The Netherlands, were subjected to a questionnaire pertaining to sexual risk behavior and sexual partners in the 6 months prior to the diagnosis. The Neisseria gonorrhoeae isolates were all genotyped using PCR-restriction fragment length polymorphism of the porin and opacity genes.

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The study was conducted to determine the prevalence, incidence, and risk factors for HIV infection among factory workers at two sites in Ethiopia. During February 1997-December 2001, a structured questionnaire was used for obtaining information on sociodemographics, sexual behaviour, and reported sexually transmitted infections (STIs) from a cohort of 1679 individuals. Serum samples were screened for antibodies against HIV, Treponema pallidum haemaglutination (TPHA), and herpes simplex virus type 2 (HSV-2).

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Objective: The objective of this study was to investigate whether and what sexual risk behavior is a mediator of associations between rectal gonorrhea (RG) and highly active antiretroviral therapy-related beliefs, safer sex fatigue, or sexual sensation-seeking among homosexual men.

Study Design: This study consisted of a cross-sectional survey between March 2002 and December 2003 among homosexual visitors of the Amsterdam sexually transmitted disease clinic.

Methods: In total, 1568 men answered a written questionnaire.

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Background: Human immunodeficiency virus type 1 (HIV-1)-uninfected Ethiopians have lower CD4 T cell counts than do other populations in Africa and industrialized countries. We studied whether this unique immunological profile results in shorter survival times in HIV-1-infected Ethiopians.

Methods: Data from an open cohort study of 149 HIV-1-infected factory workers in Ethiopia for 1997-2002 were used.

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This study investigates barriers that may pose a threat to a successful implementation of an antiretroviral treatment (ART) program in Ethiopia. As prelude to the provision of ART among factory workers participating in a cohort study on HIV and AIDS in Ethiopia, we measured knowledge and attitudes towards several aspects of ART and provided an educational intervention. The proportion of participants having good knowledge on issues concerning adherence was found reasonably good (67.

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Background: We explored the relevance of simple markers (clinical or laboratory markers not requiring sophisticated laboratories) in the decision of initiation of therapy in resource-poor settings.

Methods: Among HIV-infected Ethiopian cohort participants, simple markers predicting short-term death were examined using time-dependent Cox proportional hazards models. Timing of hypothetical treatment was compared between guidelines using the simple markers (based on presence of at least one marker), guidelines recommended by the United States Department of Health and Human Services (based on CD4 cell count and viral load), and guidelines for resource-limited settings recommended by the World Health Organization (WHO).

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The herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV) epidemics are believed to fuel each other, especially in sub-Saharan countries. In Ethiopia during 1997-2002, a retrospective study was conducted to examine risk factors for infection and transmission of HSV-2, in a cohort of 1612 factory workers. Prevalence of HSV-2 seropositivity at enrollment was 40.

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Background: We explored the relevance of simple markers (clinical or laboratory markers not requiring sophisticated laboratories) in the decision of initiation of therapy in resource-poor settings.

Methods: Among HIV-infected Ethiopian cohort participants, simple markers predicting short-term death were examined using time-dependent Cox proportional hazards models. Timing of hypothetical treatment was compared between guidelines using the simple markers (based on presence of at least one marker), guidelines recommended by the United States Department of Health and Human Services (based on CD4 cell count and viral load), and guidelines for resource-limited settings recommended by the World Health Organization (WHO).

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Objective: Despite readily detectable virus-specific CD8+ T cells in most HIV-infected patients, immune surveillance is eventually lost, leading to progression to AIDS. To investigate the underlying mechanism of this loss of immune control phenotypic analysis of HIV- and Epstein-Barr virus (EBV)-specific CD8+ T cells was performed.

Design: In three clinically distinct groups, long-term asymptomatics, progressors to opportunistic infections and progressors to EBV-associated non-Hodgkin lymphoma's (NHL), both number and phenotype of virus-specific CD8+ T cells was studied longitudinally.

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Objective: Dramatic increases have occurred in sexually transmitted diseases (STD) and in sexual risk behaviour among homosexual men in Amsterdam and internationally. We investigated whether these trends indicate a resurgence of the HIV epidemic.

Methods: HIV incidence was determined among homosexual attendees of an STD clinic in Amsterdam, who had participated in semi-annual anonymous unlinked cross-sectional HIV prevalence studies from 1991 to 2001.

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To elucidate the mode of human herpesvirus 8 (HHV-8) transmission in a population of Amsterdam drug users, HHV-8 seroprevalence and seroincidence were determined in 1179 drug users in the Amsterdam Cohort Studies (1985-1996). Risk factors for HHV-8 infection were examined. Serum samples were screened with an enzyme immunoassay by using HHV-8 lytic capsid (open-reading frame [ORF] 65) and latent nuclear (ORF73) antigens; positive results were confirmed by Western blot and immunofluorescence assay.

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