Socioeconomic Position and Type 2 Diabetes: The Mediating Role of Psychosocial Work Environment- the Maastricht Study.

Objective: We examined the association between low socioeconomic position (SEP) and Type 2 Diabetes Mellitus (T2DM), and the mediating role of psychosocial work environment by using counterfactual mediation analysis. Methods: Data from 8,090 participants of The Maastricht Study were analysed. SEP indicators (education, income, occupation), self-reported psychosocial work stressors, (pre)diabetes by oral glucose tolerance test were measured at baseline. Incident T2DM was self-reported per annum up to 9 years. Cox regression and causal mediation analyses were performed. Results: 2.8% (N = 172) of the participants without T2DM at baseline reported incident T2DM. People with lower SEP more often had prevalent T2DM (e.g., education OR = 2.49, 95% CI: 2.16-2.87) and incident T2DM (e.g., education HR = 2.21, 95% CI: 1.53-3.20) than higher SEP. Low job control was associated with prevalent T2DM (OR = 1.44 95% CI: 1.25-1.67). Job control partially explained the association between income and prevalent T2DM (7.23%). Job demand suppressed the associations of education and occupation with prevalent T2DM. The mediation models with incident T2DM and social support were not significant. Conclusion: Socioeconomic inequalities in T2DM were present, but only a small part of it was explained by the psychosocial work environment.

Influence of temperature, medium, and storage duration on Chlamydia trachomatis DNA detection by PCR.

We validated the use of stored samples for Chlamydia trachomatis research. C. trachomatis DNA was detected by real-time PCR in clinical (urine and self-taken vaginal swabs) and spiked samples using six different media, five different time points (up to 2 years), and four different temperature conditions. C. trachomatis was detected in all 423 samples, and no clinically relevant degradation impact was detected.

Two decades of hepatitis B infections among drug users in Amsterdam: are they still a high-risk group?

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. HBV genotypes of the anti-HBc seroconverters were determined. Poisson regression was used to test for temporal trends in incidence and to identify risk factors for seroconversion. Of the 598 participants who were anti-HBc negative at entry, 83 seroconverted for anti-HBc. The incidence of HBV declined from 5.9/100 Person Years up to 1993 to 0/100 Person Years in 2002. Of the drug users infected acutely, both injecting and non-injecting, 88% were infected with the same genotype D, serotype ayw3 strain. Multivariate analyses revealed current injecting, age, and calendar year of visit as independent risk factors. The decline in the incidence of HBV among drug users in Amsterdam is probably caused by a decline in injecting behavior. Injecting and non-injecting drug users were infected with the same strain, indicating that drug users infect one another, regardless of their risk behavior. After 2000, no injecting drug users with an acute HBV infection were reported to the Public Health Service Amsterdam and the specific genotype D strain had disappeared. These findings suggest that drug users may no longer be a high-risk group for HBV infection in Amsterdam. However, trends in drug use need to be monitored.

Low HIV-testing rates and awareness of HIV infection among high-risk heterosexual STI clinic attendees in The Netherlands.

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. During each survey period, 1000 consecutive attendees are enrolled voluntary and anonymously for HIV testing and are interviewed on previous HIV testing and outcome. Trends in and predictors for uptake of HIV testing as offered during routine STI consultation were analysed by logistic regression. Trends in awareness of an HIV-positive serostatus as obtained from the anonymous HIV surveys were likewise analysed. RESULTS: The percentage of heterosexual attendees opting for an HIV test during consultation increased from 13% in 1996 to 56% in 2004. However, the proportion of individuals aware of their HIV infection did not change over time and only a minority (19%) of the 108 attendees found HIV-positive in the anonymous surveys were aware of their HIV infection. Persons being or visiting a commercial sex worker, having a non-Dutch ethnicity, lacking health insurance and having an STI diagnosed were less likely to opt for an HIV test. CONCLUSIONS: Although heterosexual attendees increased their uptake of HIV testing during STI consultation over time, uptake of testing by attendees at risk for HIV infection, such as those infected with an STI, remained low. As a result, the percentage of persons aware of their HIV infection remained low, posing a risk for their individual health and for ongoing HIV transmission. Current testing strategies, therefore, misses the group that most needs testing. Based on these results, 'opt-out' HIV testing is now the standard procedure at the Amsterdam STI clinic.

Rise in seroprevalence of herpes simplex virus type 1 among highly sexual active homosexual men and an increasing association between herpes simplex virus type 2 and HIV over time (1984-2003).

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. We therefore studied changes in the HSV-1 and HSV-2 prevalence in a large cohort of men who have sex with men (MSM) over a 20-year time period. METHODS: Among 1847 HIV-infected and HIV-uninfected MSM participating in the Amsterdam Cohort Studies, seroprevalence of HSV-1 and HSV-2 was determined and prevalence rate ratios (PRR) and 95% confidence intervals were calculated. RESULTS: Between 1984 and 2003 the HSV-1 and HSV-2 prevalence decreased among HIV-uninfected MSM (P < 0.001), but remained stable among HIV-infected MSM. HSV-1 prevalence increased among men with at least 200 sexual partners over lifetime (PRR: 1.49, P < 0.001). The association between HIV infection and HSV-2 became stronger over time (PRR: 3.45, P < 0.001). CONCLUSIONS: Seroprevalence of HSV-1 and HSV-2 remained high among HIV infected MSM from 1984 to 2003. The association of HIV and HSV-2 increased during the HIV epidemic. Since the proportion of sexual transmission of HSV-1 is rising, it is important to study the potential role of HSV-1 as risk factor for HIV acquisition.

Condom use rather than serosorting explains differences in HIV incidence among men who have sex with men.

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). Moreover, pooled information was collected on anonymous partners. We used logistic regression to test whether sexual behaviors are consistent with serosorting and to test whether risk group is associated with having concordant traceable partners among men reporting unprotected anal intercourse (UAI). RESULTS: We included 513 MSM (54% lower risk and 75% HIV-negative). Lower risk and high-risk MSM with concordant traceable partners were more likely to have UAI than MSM with discordant partners or partners of unknown HIV status (P < 0.001). Risk group was not associated with having concordant UAI. Compared with lower risk MSM, however, high-risk MSM frequently had UAI with nonconcordant traceable partners and with anonymous partners. CONCLUSIONS: Sexual risk behaviors with traceable partners are consistent with serosorting. Nonetheless, the higher level of UAI with anonymous or nonconcordant traceable partners more likely explains the increasing HIV incidence seen among STI Outpatient Clinic attendees than a difference in serosorting behavior.

Characterization of an HIV-1 group M variant that is distinct from the known subtypes.

We identified an HIV-1 variant that belongs to the M group, with limited similarity of short genetic regions (100-200 nt) to subtype K, but the remainder of the genome is unrelated to any established HIV-1 subtype. The isolate was obtained from an HIV-1-positive male, living in the Netherlands, who encountered the virus before 1989, most probably via heterosexual contact in Africa. We describe the full-length genome sequence of four biological clones that were obtained from two samples collected 5 years apart. At both time points all open reading frames were intact. Within the 5-year interval, the person received antiretroviral therapy with zalcitabine and zidovudine for almost 4 years. Evolution of drug-resistant variants is likely given the increase in viral RNA load to +/-10,000 copies/ml during the last year of treatment. Surprisingly, the only regular RT mutation acquired during this period was K70R, which suggests that the genetic background of this variant is perhaps not suitable for the generation of the standard 41L, 67N, and 215Y/F mutations that typically arise during prolonged, nonsuccessful, zidovudine treatment. Awaiting the discovery of at least two additional, epidemiologically unrelated patients with a phylogenetically related HIV-1 variant, we can designate this variant a new HIV-1 subtype, or a distinct branch of subtype K.

Low HIV-testing rates among younger high-risk homosexual men in Amsterdam.

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%). Information was matched to the STI registration system. Associations were determined using logistic regression. RESULTS: 817 men reported a negative HIV status, and 384 reported an unknown HIV status. The overall HIV prevalence among the 523 men who tested at new STI consultation was 2.8%. The proportion of men with unknown HIV status was relatively high among those diagnosed with infectious syphilis and those reporting unprotected anal intercourse with a casual partner. Their testing rates at new STI clinic visit were lower. Among men with an unknown HIV status, those aged <30 years and reporting risky sexual behaviour tested the least (OR 0.13, 95% CI 0.03 to 0.61). CONCLUSION: Although HIV testing rates have increased, they are still lower than in other industrialised countries. Moreover, some men still undertake high-risk sex without knowing their own HIV status, which might pose a risk for ongoing HIV transmission. Therefore, more active testing promotion is needed.

HIV incidence and HIV testing behavior in men who have sex with men: using three incidence sources, The Netherlands, 1984-2005.

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. We evaluated calendar trends in HIV incidence, also focusing on age effects. RESULTS: Since the start of the HIV epidemic in the early 1980s, incidence has declined strongly in the ACS. In recent years, an increase was noted among older MSM attending the Amsterdam STI clinic (P = 0.0334). In both cohort studies, HIV incidence was lower and recent time-trends were not statistically significant. Among recently infected men at the STI clinic, only 40% accepted named HIV testing at their STI consultation. CONCLUSIONS: Data suggest that among MSM in the Netherlands, the HIV incidence is between one and four infections per 100 person-years. The epidemic expands among older STI clinic attendees. Prevention should be developed specifically for older men, along with a more efficient HIV testing approach such as routine HIV testing of MSM when they are screened for STI.

No evidence for a sustained increase in sexually transmitted diseases among heterosexuals in Amsterdam, the Netherlands: a 12-year trend analysis at the sexually transmitted disease outpatient clinic, Amsterdam.

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. Additionally, all women are tested for trichomoniasis. STD time trends of heterosexual attendees between 1994 and 2005 were analyzed by logistic regression and generalized linear models with a negative binomial distribution. RESULTS: The number of consultations doubled since 1994. However, no long-term increase was seen in the number of syphilis and gonorrhea infections. Additionally, the trichomonas prevalence declined. However, the number of chlamydia infections increased over time. CONCLUSIONS: Although the number of attendees increased, no evidence for increasing STD incidence was found among heterosexuals. The increase in chlamydia infections can probably be explained by increased screening resulting from increased numbers of attendees.

Impact of a targeted hepatitis B vaccination program in Amsterdam, The Netherlands.

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. Acute HBV remained stable among men having sex with men; given their increased sexual risk behavior, vaccination has probably prevented an increase in their acute infections. Currently, 48-72% of the people who should be included in the program are still susceptible to HBV.

High and persistent excretion of hepatitis A virus in immunocompetent patients.

The duration and level of virus excretion in blood and faeces of patients with hepatitis A virus (HAV) infection were studied in relation to levels of alanine aminotransferase (ALT), disease severity and HAV genotype. Clinical data, blood and faeces were collected from 27 patients with acute hepatitis A (median age: 33 years) for a maximum of 26 weeks. Single blood donations from 55 other patients with acute HAV (median age: 32 years) were also used. Virus loads were quantified by competitive nested RT-PCR. HAV was excreted in faeces for a median period of 81 days after disease onset, with 50% of patients still excreting high levels at Day 36 (2 x 10(6) - 2 x 10(8) copies/ml faeces suspension). Viraemia was detected, but not quantifiable, for a median period of 42 days. In the first 10 days of illness, higher ALT levels were correlated with higher viraemia levels. Comparison of patients infected with genotype 1a with those infected with type 1b did not differ significantly in terms of the duration of HAV excretion or jaundice. In conclusion, faecal excretion of HAV is at a high titre in the first month, perhaps making patients infectious for a longer period than assumed currently. Blood banks should be aware that viraemia may be present for more than 1 month, and genotype did not affect the duration of virus excretion or jaundice.

Molecular epidemiology of Neisseria gonorrhoeae in Amsterdam, The Netherlands, shows distinct heterosexual and homosexual networks.

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. All patients with a completed questionnaire and genotyped isolates were included in the study. We obtained 885 N. gonorrhoeae isolates from 696 patients that revealed 88 clusters and 46 unique genotypes. Patients infected at multiple anatomical sites with one or more strains and patients infected several times during the study period were shown to pursue high-risk sexual behavior and were considered core groups. There were 11 clusters of > or =20 patients; in seven clusters, 81% to 100% of patients were men who have sex with men (MSM), three clusters contained 87 to 100% heterosexual men and women, and one cluster was formed by equal proportions of MSM and heterosexual male and female patients. However, the various clusters differed in characteristics such as types of coinfections, numbers of sexual partners, Internet use to seek sexual partners, and locations of sexual encounters. Molecular epidemiology of gonococcal isolates in Amsterdam revealed core groups and clusters of MSM and heterosexual patients that probably indicate distinct transmission networks.

Association between 'safer sex fatigue' and rectal gonorrhea is mediated by unsafe sex with casual partners among HIV-positive homosexual men.

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. Associations were determined using logistic regression corrected for repeated measurements. RESULTS: The RG infection rate was high among homosexual men who were HIV-positive (16%) compared with those with negative or unknown HIV status. Mediation could be confirmed among HIV-positive men only. Those who experienced higher levels of safer sex fatigue were more likely to be positive for RG. This association was mediated by unprotected anal intercourse (UAI) with casual partners. CONCLUSION: Addressing safer sex fatigue might help prevent UAI with casual partners and possibly also RG among HIV-positive homosexual men.

Low CD4 T cell counts before HIV-1 seroconversion do not affect disease progression in Ethiopian factory workers.

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. To estimate survival times, a continuous-time Markov model was designed on the basis of CD4 T cell counts and World Health Organization clinical staging. By use of a random-effects model, decline in CD4 T cell counts was compared between HIV-1-infected Ethiopian and Dutch individuals. RESULTS: Median survival times were in the range of 9.1-13.7 years, depending on the approach used. This range is similar to that for populations in industrialized countries before the advent of antiretroviral therapy. Ethiopians had a lower annual decline in CD4 T cell counts than did Dutch individuals, which remained when groups with similar CD4 T cell count categories were compared. Moreover, the slower decline in CD4 T cell counts was not due merely to lower HIV-1 RNA loads or an absence of syncytium-inducing/X4 HIV-1 subtype C strains in Ethiopians. CONCLUSIONS: Low baseline CD4 T cell counts do not imply shorter survival times in Ethiopians than in other populations, presumably because of a slower decline in CD4 T cell counts.

Prevalence and incidence of, and risk factors for, HIV-1 infection among factory workers in Ethiopia, 1997-2001.

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). The overall baseline prevalence of HIV was 9.4%-8.5% among males and 12.4% among females. For both the sexes, the factors independently associated with an increased risk of HIV infection were widowhood and having had antibodies against TPHA and HSV-2. The risk factors specific for males were being orthodox Christian, having had a higher lifetime number of sexual partners, and genital discharge in the past five years. The risk factors for females, included low income, one or more rape(s) over lifetime, and casual sex in the last year. The overall incidence of HIV infection was 0.4 per 100 person-years. The highest rate of incidence was observed among young women aged less than 30 years (1 per 100 person-years). The study confirmed that high-risk sexual behaviour and STIs play major roles in the spread of HIV infection in the Ethiopians of both the sexes, but the factors, such as rape and low economic status, make women more vulnerable than men.

Perceived viral load, but not actual HIV-1-RNA load, is associated with sexual risk behaviour among HIV-infected homosexual men.

BACKGROUND: Increases in sexual risk behaviour and sexually transmitted infections among HIV-infected homosexual men after the introduction of highly active antiretroviral therapy (HAART) confirm the need for innovative prevention activities. The present study focused on time trends in sexual risk behaviour and predictors for unprotected anal intercourse in the HAART era among HIV-infected homosexual men. METHODS: In 2000-2003, 57 HIV-infected homosexual men (mean age 45 years) were interviewed in three serial data waves. Logistic regression, correcting for repeated measurements, was used to assess time trends in risky sex, and the association between HAART-related beliefs, and both the perceived and actual viral load level and CD4 cell counts and subsequent risky sex. RESULTS: Risky sex with casual partners increased from 10.5% in 2000 to 27.8% in 2003 (P < 0.01), and with steady partners of negative or unknown HIV status from 5.3% to 10.7% (P = 0.6). Homosexual men with a favourable perception of their viral load were more likely to engage in subsequent risky sex with steady partners of negative or unknown HIV status than men with a less favourable perception of their viral load; this association was independent of the actual HIV-1-RNA load and CD4 cell counts. CONCLUSION: Risky sex increased in this group of HIV-infected homosexual men. The perceived viral load, but not the actual load, is associated with subsequent risky sex with steady partners of negative or unknown HIV status. Care givers should discuss with patients not only their actual viral load and CD4 cell count but also their perceived viral load.

Transmission of herpes simplex virus Type 2 among factory workers in Ethiopia.

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 40.9%, and incidence of seroconversion was 1.8 seroconversions/100 person-years (PY), which decreased over time. Independent risk factors for seropositivity were having an HSV-2-seropositive partner, female sex, HIV antibodies, positive Treponema pallidum particle agglutination assay result, older age, low education level, and orthodox religion. These same factors were independent risk factors for HSV-2 seroconversion, with the exception of the latter 3. Most HSV-2-infected persons did not report symptoms. Among 41 monogamous HSV-2-serodiscordant heterosexual couples, incidence of HSV-2 seroconversion was 20.75 seroconversions/100 PY for women and 4.93 seroconversions/100 PY for men. The high burden of both HSV-2 and HIV infection in Ethiopia warrants stringent control measures.

Correlates of resistance to HIV-1 infection in homosexual men with high-risk sexual behaviour.

OBJECTIVE: To investigate possible correlates of HIV resistance in participants from the Amsterdam Cohort of Homosexual men who have remained HIV seronegative despite high-risk sexual behaviour. DESIGN/METHODS: We studied in vitro HIV-1 susceptibility and adaptive and innate immunity in 29 high-risk seronegative (HRSN) and 15 HIV-negative pre-seroconversion (pre-SC) homosexual men from the same Amsterdam Cohort Study (ACS) who seroconverted to HIV-1 positive during active follow-up. Host genetics were compared between HRSN and HIV-positive ACS participants. RESULTS: We found lower in vitro susceptibility for a CCR5-using (R5) HIV-1 variant, higher RANTES production levels, but no difference in coreceptor expression in HRSN as compared with pre-SC controls. Reduced R5 in vitro susceptibility of two HRSN tested was restored to normal levels by addition of antibodies against beta-chemokines. A higher proportion of HRSN carried the SDF-1 3'A variant and HLA-A*11, A*31 and Cw*15 alleles. ELIspot analysis with HIV-1 peptide stimulation revealed low frequencies of HIV-1-specific CD8 interferon-gamma producing cytotoxic T cells in both HRSN and pre-SC controls. CONCLUSIONS: Low in vitro R5 susceptibility of cells from the HRSN men was due to beta-chemokine mediated inhibition of virus replication. The presence of HIV-1 specific cytotoxic T cells in both HRSN and pre-SC participants may signify exposure to the virus rather than protection from infection. Host genetic characteristics and other factors affecting innate immunity may contribute to differential resistance to HIV-1 infection among exposed seronegative individuals.