Motives and barriers to safer sex and regular STI testing among MSM soon after HIV diagnosis.

BACKGROUND: Understanding why some recently with HIV diagnosed men who have sex with men (MSM) choose for safer sex and regular STI testing, whereas others do not, is important for the development of interventions that aim to improve the sexual health of those newly infected. METHODS: To gain insight into motives and barriers to condom use and regular STI testing among MSM soon after HIV diagnosis, 30 HIV-positive MSM participated in semi-structured qualitative interviews on sexual health behaviours in the first year after HIV diagnosis. RESULTS: Typical barriers to condom use soon after diagnosis were emotions such as anger, relief, and feelings of vulnerability. Additional barriers were related to pre-diagnosis patterns of sexual-social behaviour that were difficult to change, communication difficulties, and substance use. Barriers to STI testing revolved around perceptions of low STI risk, faulty beliefs, and burdensome testing procedures. CONCLUSIONS: The great diversity of motives and barriers to condom use and STI testing creates a challenge to accommodate newly infected men with information, motivation, and communication skills to match their personal needs. An adaptive, tailored intervention can be a promising tool of support.

Development and validation of a risk score to assist screening for acute HIV-1 infection among men who have sex with men.

BACKGROUND: Early treatment of acute HIV-1 infection (AHI) is beneficial for patients and could reduce onward transmission. However, guidelines on whom to test for AHI with HIV-1 RNA testing are lacking. METHODS: A risk score for possible AHI based on literature and expert opinion - including symptoms associated with AHI and early HIV-1 - was evaluated using data from the Amsterdam Cohort Studies among men who have sex with men (MSM). Subsequently, we optimized the risk score by constructing two multivariable logistic regression models: one including only symptoms and one combining symptoms with known risk factors for HIV-1 seroconversion, using generalized estimating equations. Several risk scores were generated from these models and the optimal risk score was validated using data from the Multicenter AIDS Cohort Study. RESULTS: Using data from 1562 MSM with 175 HIV-1 seroconversion visits and 17,271 seronegative visits in the Amsterdam Cohort Studies, the optimal risk score included four symptoms (oral thrush, fever, lymphadenopathy, weight loss) and three risk factors (self-reported gonorrhea, receptive condomless anal intercourse, more than five sexual partners, all in the preceding six months) and yielded an AUC of 0.82. Sensitivity was 76.3% and specificity 76.3%. Validation in the Multicenter AIDS Cohort Study resulted in an AUC of 0.78, sensitivity of 56.2% and specificity of 88.8%. CONCLUSIONS: The optimal risk score had good overall performance in the Amsterdam Cohort Studies and performed comparable (but showed lower sensitivity) in the validation study. Screening for AHI with four symptoms and three risk factors would increase the efficiency of AHI testing and potentially enhance early diagnosis and immediate treatment.

Development and validation of the HCV-MOSAIC risk score to assist testing for acute hepatitis C virus (HCV) infection in HIV-infected men who have sex with men (MSM).

Current guidelines recommend hepatitis C virus (HCV) testing for HIV-infected men who have sex with men (MSM) with ongoing risk behaviour, without specifying the type of risk behaviour. We developed and validated the HCV-MOSAIC risk score to assist HCV testing in HIV-infected MSM. The risk score consisted of six self-reported risk factors identified using multivariable logistic regression using data from the Dutch MOSAIC study (n = 213, 2009-2013). Area under the ROC curve (AUC), sensitivity, specificity, post-test-probability-of-disease and diagnostic gain were calculated. The risk score was validated in case-control studies from Belgium (n = 142, 2010-2013) and the United Kingdom (n = 190, 2003-2005) and in cross-sectional surveys at a Dutch sexually transmitted infections clinic (n = 284, 2007-2009). The AUC was 0.82; sensitivity 78.0% and specificity 78.6%. In the validation studies sensitivity ranged from 73.1% to 100% and specificity from 56.2% to 65.6%. The post-test-probability-of-disease ranged from 5.9% to 20.0% given acute HCV prevalence of 1.7% to 6.4%, yielding a diagnostic gain of 4.2% to 13.6%. The HCV-MOSAIC risk score can successfully identify HIV-infected MSM at risk for acute HCV infection. It could be a promising tool to improve HCV testing strategies in various settings.

Is Group Sex a Higher-Risk Setting for HIV and Other Sexually Transmitted Infections Compared With Dyadic Sex Among Men Who Have Sex With Men?

BACKGROUND: Group sex has been suggested as a potential high-risk setting for HIV and other sexually transmitted infections (STIs) among men who have sex with men (MSM). We investigated whether group sex is associated with lower condom use during anal sex and higher proportions of STIs compared with dyadic sex among HIV-negative MSM between 2009 and 2012. METHODS: Cross-sectional data from 7 data waves of the Amsterdam Cohort Studies were used. The sample consisted of 465 MSM who either reported both group and dyadic sex (at n = 706 visits) or dyadic sex only (at n = 1339 visits) in the preceding 6 months. Logistic regression with generalized estimating equations was used to investigate the association between sexual setting (group vs. dyadic sex), condomless anal sex, and STI. RESULTS: Group sex was reported at 35% (706/2045) of visits. Condomless sex was more often reported during dyadic than group sex (odds ratio, 3.64 95% confidence interval, 2.57-5.16). Men who had group sex were more likely diagnosed as having gonorrhea compared with men with dyadic sex (odds ratio, 1.71; 95% confidence interval, 1.08-2.97), but this effect was not retained in the multivariate model. CONCLUSIONS: Results demonstrate within-person differences in sexual behavior during group and dyadic sex among MSM. Men were more likely to use condoms during group sex than during dyadic sex. Thus, for some, group sex may not necessarily be risky for HIV infection compared with dyadic sex. However, group sex may be a higher-risk setting for acquiring STIs other than HIV, such as gonorrhea. Group sex encounters should be recognized as distinct sexual settings with specific risk characteristics that need to be addressed accordingly.

Does online dating lead to higher sexual risk behaviour? A cross-sectional study among MSM in Amsterdam, the Netherlands.

BACKGROUND: Men having sex with men (MSM) frequently use the Internet to find sex partners. We examined the association between unprotected anal intercourse (UAI) with partners dated online and with partners dated offline (met elsewhere), and examined whether differences can be explained by self-perceived HIV status of the index and knowledge of partnership characteristics. METHODS: MSM were recruited at the Sexually Transmitted Infections Clinic in Amsterdam, in 2008-2009. Participants completed a questionnaire concerning sexual behaviour. Only men reporting both online and offline casual sex partners were included. We assessed the association between online/offline partner dating and UAI, using random-effects logistic regression analysis. RESULTS: Five hundred seventy-seven men (351 HIV-negative, 153 HIV-positive, and 73 HIV-unaware) reported UAI in 26 % of 878 online, and 23 % of 903 offline casual partnerships. The crude OR of online dating for UAI was 1.36 (95 % CI 1.03-1.81). HIV-positive men were more likely to report UAI than HIV-negative men (49 % vs. 28 % of partnerships). Adjusted for demographic characteristics, online dating had no significant effect on UAI among HIV-negative and HIV status-unaware men, but HIV-positive men were more likely to have UAI with online partners (aOR = 1.65 [95 % CI 1.05-2.57]). After correction for partner and partnership characteristics the effect of online/offline dating on UAI among HIV-positive MSM was reduced and no longer significant. CONCLUSIONS: Online dating was not significantly associated with UAI among HIV-negative MSM. HIV-positive MSM were more likely to practise UAI with partners dated online; however, after correction for partner and partnership characteristics, online partnership acquisition was not associated with a significantly increased risk of UAI.

Prevalence and determinants of insufficient work ability in older HIV-positive and HIV-negative workers.

PURPOSE: To explore whether the prevalence and determinants of insufficient work ability (WA) of older HIV-positive workers differ from a comparable group of HIV-negative workers. METHODS: Cross-sectional data from 359 HIV-negative and 264 HIV-positive middle-aged individuals (45-65 years) participating in paid labor, collected within the AGEhIV Cohort Study between October 2010-September 2012, were selected. Data were collected by self-administered questionnaires and physical examination. Participants self-rated their current WA, ranging from 0 to 10. WA was dichotomized into insufficient (<6) and sufficient (≥6). Using univariable and multivariable logistic regression, we studied the independent effect of HIV status on insufficient WA and determinants of insufficient WA. RESULTS: Overall, 8% of participants reported insufficient WA (HIV-positive 9 vs. HIV-negative 7%, P = 0.20). Twice as many HIV-positive as HIV-negative individuals were declared partly unfit for work (6 vs. 3%, P = 0.02). HIV status itself was not associated with WA in univariable and multivariable analyses. Multivariable analyses revealed that low educational level, working fewer hours, being partly unfit for work, experiencing a high need for recovery after work, staying home from work ≥2 times in the past 6 months, and reporting depressive symptoms were associated with insufficient WA, independent of HIV status. CONCLUSIONS: HIV-positive individuals aged 45-65 years participating in paid labor seem to function as well at work as HIV-negative individuals. HIV-positive participants were more often formally declared partly unfit for work, but percentages were low in both groups. Knowledge of determinants of insufficient WA may help employers and professionals to optimize WA.

Low bone mineral density in patients with well-suppressed HIV infection: association with body weight, smoking, and prior advanced HIV disease.

BACKGROUND: Human immunodeficiency virus (HIV) and combination antiretroviral therapy (cART) may both contribute to the higher prevalence of osteoporosis and osteopenia in HIV-infected individuals. METHODS: Using dual-energy X-ray absorptiometry, we compared lumbar spine, total hip, and femoral neck bone mineral density (BMD) in 581 HIV-positive (94.7% receiving cART) and 520 HIV-negative participants of the AGEhIV Cohort Study, aged ≥45 years. We used multivariable linear regression to investigate independent associations between HIV, HIV disease characteristics, ART, and BMD. RESULTS: The study population largely consisted of men who have sex with men (MSM). Osteoporosis was significantly more prevalent in those with HIV infection (13.3% vs 6.7%; P<.001). After adjustment for body weight and smoking, being HIV-positive was no longer independently associated with BMD. Low body weight was more strongly negatively associated with BMD in HIV-positive persons with a history of a Centers for Disease Control and Prevention class B or C event. Interestingly, regardless of HIV status, younger MSM had significantly lower BMD than older MSM, heterosexual men, and women. CONCLUSIONS: The observed lower BMD in treated HIV-positive individuals was largely explained by both lower body weight and more smoking. Having experienced symptomatic HIV disease, often associated with weight loss, was another risk factor. The low BMD observed in younger MSM remains unexplained and needs further study.

Repeated STI and HIV testing among HIV-negative men who have sex with men attending a large STI clinic in Amsterdam: a longitudinal study.

OBJECTIVE: In the Netherlands, men who have sex with men (MSM) are advised via informal guidelines to test for STI at least annually. We estimated the proportion of HIV-negative MSM testing repeatedly at 12-month or smaller intervals at a large STI clinic in the Netherlands. In addition, we explored whether repeated testing is related to risk behaviour. DESIGN AND METHODS: Longitudinal data of HIV-negative MSM visiting the Amsterdam STI clinic between 2009 and 2012 were analysed. To estimate the timing of repeated testing, Kaplan-Meier methods were used. Determinants for repeated testing (distinguishing testing at 12-month or smaller intervals and less than 12-monthly testing, with single testers as reference group) were identified using multivariate multinomial logistic regression analyses. RESULTS: In total, 19,479 consultations of 9174 HIV-negative MSM were identified. Of these MSM, 35% (95% CI 33% to 36%) were estimated to return to the STI clinic within 1 year following baseline consultation. Among 1767 men with at least two consultations and at least 2 years between baseline and last consultation, 43% tested repeatedly at 12-month or smaller intervals in those first 2 years. Repeated testers reported higher sexual risk behaviour (ie, only casual or both casual and steady sex partners, higher numbers of sex partners) at baseline compared with single testers. This effect tended to be slightly stronger for men testing repeatedly at 12-month or smaller intervals. CONCLUSIONS: The proportion of MSM testing for STI annually is low. MSM testing repeatedly had higher baseline levels of risk behaviour. Strategies to motivate MSM to test annually should be explored.

Association of HIV Infection With Anal and Penile Low-Risk Human Papillomavirus Infections Among Men Who Have Sex With Men in Amsterdam: The HIV & HPV in MSM Study.

BACKGROUND: This study among men who have sex with men (MSM) aimed to (1) assess prevalence of anogenital low-risk human papillomavirus (lrHPV) infections, (2) evaluate associations with HIV infection, and (3) investigate lrHPV concordance. METHODS: In 2010 to 2011, MSM 18 years or older were recruited in Amsterdam, the Netherlands, and provided anal and penile self-swabs (HIV & HPV in MSM study). Using the HPV SPF10-PCR/DEIA/LiPA25 system, the presence of lrHPV types 6, 11, 34, 40, 42, 43, 44, 53, 54, 66, 68/73, 70, and 74 could be detected. Logistic regression with generalized estimating equations was used to assess the independent effect of HIV on lrHPV infections. The model was repeated for lrHPV subcategories (nononcogenic and weakly oncogenic infections separately). Concordance was defined as detection of the same lrHPV type in both self-swabs of one individual. RESULTS: A total of 778 MSM were included, of whom 317 (41%) were HIV positive (median CD4 count at enrollment, 530 cells/mm). Prevalence of anal lrHPV was 45% (95% confidence interval [CI], 41%-50%) in HIV-negative MSM and 69% (95% CI, 64%-74%) in HIV-positive MSM. Prevalence of penile lrHPV was 20% (95% CI, 16%-24%) and 37% (95% CI, 31%-42%), respectively. In multivariable analysis, HIV infection was independently associated with anal (adjusted odds ratio [aOR], 1.9; 95% CI, 1.5-2.3) and penile lrHPV (aOR, 2.0; 95% CI, 1.4-2.7). Nononcogenic and weakly oncogenic lrHPV subcategories showed a similar pattern of association. Anal lrHPV infections were strongly associated with the presence of a type-concordant penile infection (aOR, 5.8; 95% CI, 4.4-7.5) and vice versa (aOR, 5.7; 95% CI, 4.4-7.5). CONCLUSIONS: Anal and penile infections with lrHPV are common in MSM. HIV infection was an independent determinant for lrHPV infections.

Cross-sectional comparison of the prevalence of age-associated comorbidities and their risk factors between HIV-infected and uninfected individuals: the AGEhIV cohort study.

BACKGROUND: Human immunodeficiency virus (HIV)-infected individuals may be at increased risk of age-associated noncommunicable comorbidities (AANCCs). METHODS: Cross-sectional analyses of AANCC prevalence (including cardiovascular, metabolic, pulmonary, renal, bone, and malignant disease) and risk factors in a prospective cohort study of HIV type 1-infected individuals and HIV-uninfected controls, who were aged ≥45 years and comparable regarding most lifestyle and demographic factors. RESULTS: HIV-infected participants (n = 540) had a significantly higher mean number of AANCCs than controls (n = 524) (1.3 [SD, 1.14] vs 1.0 [SD, 0.95]; P < .001), with significantly more HIV-infected participants having ≥1 AANCC (69.4% vs 61.8%; P = .009). Hypertension, myocardial infarction, peripheral arterial disease, and impaired renal function were significantly more prevalent among HIV-infected participants. Risk of AANCC by ordinal logistic regression was independently associated with age, smoking, positive family history for cardiovascular/metabolic disease, and higher waist-to-hip ratio, but also with HIV infection (odds ratio, 1.58 [95% confidence interval, 1.23-2.03]; P < .001). In those with HIV, longer exposure to CD4 counts <200 cells/µL, and, to a lesser extent, higher levels of high-sensitivity C-reactive protein and soluble CD14, and longer prior use of high-dose ritonavir (≥400 mg/24 hours) were each also associated with a higher risk of AANCCs. CONCLUSIONS: All AANCCs were numerically more prevalent, with peripheral arterial, cardiovascular disease, and impaired renal function significantly so, among HIV-infected participants compared with HIV-uninfected controls. Besides recognized cardiovascular risk factors, HIV infection and longer time spent with severe immunodeficiency increased the risk of a higher composite AANCC burden. There was a less pronounced contribution from residual inflammation, immune activation, and prior high-dose ritonavir use.

High awareness of hepatitis C virus (HCV) but limited knowledge of HCV complications among HIV-positive and HIV-negative men who have sex with men.

Hepatitis C virus (HCV) has emerged as a sexually transmitted infection among HIV-positive men who have sex with men (MSM) in high-income countries. Little is reported about HCV awareness among MSM, although this is essential for developing targeted prevention strategies. We, therefore, studied HCV awareness and knowledge among HIV-positive and HIV-negative MSM from the Amsterdam Cohort Studies (ACS). During two visits, 1 year apart and starting in October 2007, MSM from the ACS answered questions regarding HCV awareness, knowledge of HCV transmission (7 items), complications (8 items) and sexual risk behaviour. We examined the percentage of HCV awareness and correctly answered knowledge items, and whether awareness and knowledge improved significantly over time. Using logistic regression, we studied whether HIV status and sexual risk behaviour were associated with awareness. Seventy percent (312/444) of HIV-negative and 80% (74/92) of HIV-positive MSM reported to have ever heard of HCV on the first visit. Overall, awareness increased with 9% between the first and second visit (p < 0.001). In multivariate analysis the association of group sex with HCV awareness was borderline significant (OR 1.49, 95% CI 0.97-2.30). Compared with knowledge of transmission routes, knowledge of complications appeared to be limited. In the ACS, awareness of HCV is high, particularly among those reporting group sex, an important risk factor for HCV transmission. The majority of participants had good knowledge of transmission routes, but limited knowledge of complications of chronic HCV infection. HCV prevention messages could be strengthened, therefore, by further addressing the complications of HCV infection.

Low bone mineral density, regardless of HIV status, in men who have sex with men.

A high prevalence of low bone mineral density (BMD) has been reported among men with primary or chronic human immunodeficiency virus (HIV) infection. To gain further insight into the contribution of HIV infection, we compared the BMD of 41 men who have sex with men (MSM) with primary HIV infection, 106 MSM with chronic HIV infection, and a control group of 30 MSM without HIV infection. Low BMD, defined as a z score of ≥ 2.0 SDs below the mean at the lumbar spine or hip, was highly prevalent in all 3 groups. In the multivariate analyses, HIV infection was not associated with BMD, suggesting that low BMD previously reported in HIV-infected MSM may predate HIV acquisition.

Undetectable viral load and the decision to engage in unprotected anal intercourse among HIV-positive MSM.

We investigated how often HIV-positive MSM (n = 177) decide to engage in unprotected anal intercourse (UAI) because they have an undetectable viral load (UVL). We found that 20-57% of the UAI acts were related to having UVL, varying by partner type and partner HIV status. Among HIV-concordant partners, consideration of UVL before engaging in UAI was more prevalent with sex buddies (55%) than with casual partners (20%), although marginally significant (p = 0.051). Among HIV-discordant partners, no significant difference was found in the frequency of UVL considerations before engaging in UAI: 40% with sex buddies versus 57% with casual partners. Interestingly, while the decision to engage in UAI based on UVL was frequently discussed with HIV-concordant partners (>91%), it was only discussed with HIV-discordant partners in 13-25% of the UAI cases (according to partner type), suggesting that the decision was mostly unilateral.

Serosorting and sexual risk behaviour according to different casual partnership types among MSM: the study of one-night stands and sex buddies.

Among HIV-negative men who have sex with men (MSM), any incident of unprotected anal intercourse (UAI) between casual partners is usually regarded as risky for HIV transmission. However, men are increasingly using knowledge of their casual partner's HIV-status to reduce HIV risk during UAI (i.e., serosorting). Since familiarity between casual partners may lead to higher levels of UAI and serosorting, we examined how often men have UAI and practice serosorting with three types of casual partnerships that differ in their degree of familiarity. We included 240 HIV-negative men of the Amsterdam Cohort Study among MSM. We distinguished three types of casual partnerships: one-night stand ("met by chance and had sex only once"); multiple-time casual partner ("met and had sex with several times") and the "regular" casual partner ("sex buddy"). Serosorting was defined as UAI with an HIV-concordant partner. Generalised estimating equations analyses were used to examine the association between type of casual partnership and sexual risk behaviour. Analyses revealed that men with a sex buddy were more likely to have UAI than men with a one-night stand (OR [95%CI] 2.39 [1.39-4.09]). However, men with a sex buddy were also more likely to practice serosorting than men with a one-night stand (OR [95%CI] 5.20 [1.20-22.52]). Men with a sex buddy had more UAI but also reported more serosorting than men with a one-night stand. As a result, the proportion of UAI without serosorting is lower for men with a sex buddy, and therefore men might have less UAI at risk for HIV with this partner type. However, the protective value of serosorting with a sex buddy against HIV transmission needs to be further established. At this time, we suggest that a distinction between the one-night stand and the sex buddy should be incorporated in future studies as men behave significantly different with the two partner types.

Low incidence of HIV-1 superinfection even after episodes of unsafe sexual behavior of homosexual men in the Amsterdam Cohort Studies on HIV Infection and AIDS.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) superinfection is infection of an HIV-1 seropositive individual with another HIV-1 strain. The rate at which HIV-1 superinfection occurs might be influenced by sexual behavior. Superinfection might be detected more often by analyzing longitudinal samples collected from time periods of unsafe sexual behavior. METHODS: Envelope C2-C4 and gag sequences were generated from HIV-1 RNA from longitudinal serum samples that were obtained around self-reported sexual risk periods from 15 homosexual therapy-naïve men who participated in the Amsterdam Cohort Studies on HIV Infection and AIDS. Maximum likelihood phylogenetic analysis was used to determine whether HIV-1 superinfection had occurred. RESULTS: We studied a total of 124 serum samples from 15 patients with a median of 8 samples and of 5.8 person-years of follow-up per patient. Phylogenetic analysis on 907 C2-C4 env and 672 gag sequences revealed no case of HIV-1 superinfection, resulting in a superinfection incidence rate of 0 per 100 person-years [95%CI: 0 - -4.2]. CONCLUSIONS: We conclude that HIV-1 superinfection incidence is low in this subgroup of homosexual men who reported unsafe sexual behavior. Additional studies are required to estimate the impact of also other factors, which may determine the risk to acquire HIV-1 superinfection.

Absence of HIV-1 superinfection 1 year after infection between 1985 and 1997 coincides with a reduction in sexual risk behavior in the seroincident Amsterdam cohort of homosexual men.

BACKGROUND: Incidence rates of human immunodeficiency virus type 1 (HIV-1) superinfection differ among cohorts and, as yet, only 2 cohorts of homosexual men have been screened. Here, we investigated the incidence of HIV-1 superinfection during the first year after infection among homosexual participants in the Amsterdam Cohort Studies on HIV infection and AIDS who seroconverted between 1985 and 1997. METHODS: We analyzed env C2-C4 diversity in the serum of therapy-naive participants, using a heteroduplex mobility assay; heteroduplexes were considered to be indicators of potential dual infections, in which case env C2-C4 polymerase chain reaction (PCR) products were cloned and sequenced. Sequences were subjected to phylogenetic analysis. Data on the sexual behavior of participants were collected from 1 year before seroconversion until the end of the investigated period. RESULTS: For 89 seroconverters with a detectable viral load (>1000 copies/mL), env PCR products were generated from serum samples obtained at seroconversion and 1 year later. Heteroduplexes were observed in 68 of the 89 patients; among these 68 patients, a median of 9 molecular clones per time point was sequenced. Phylogenetic analysis did not reveal evidence for superinfection; 1 patient was HIV-1 coinfected. Shortly after diagnosis of HIV infection, the number of sex partners decreased, the frequency of anal intercourse declined, and condom use increased. CONCLUSIONS: The incidence of HIV-1 superinfection soon after seroconversion in this cohort is low. Risk reduction shortly after HIV-1 diagnosis early during the HIV-1 epidemic in the Netherlands may have contributed to the absence of HIV-1 superinfection observed in this study.

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.

Dengue virus infection among long-term travelers from the Netherlands: A prospective study, 2008-2011.

BACKGROUND: Dengue is increasing rapidly in endemic regions. Data on incidence among travelers to these areas are limited. Five prospective studies have been performed thus far, mainly among short-term travelers. OBJECTIVE: To obtain the attack and incidence rate (AR, IR) of dengue virus (DENV) infection among long-term travelers and identify associated risk factors. METHODS: A prospective study was performed among long-term travelers (12-52 weeks) attending the Public Health Service in Amsterdam. Clients planning to travel to (sub)tropical countries were invited to participate. Participants kept a travel diary, recording itinerary, symptoms, and physician visits. Pre- and post-travel blood samples were serologically tested for the presence of Anti-DENV IgG antibodies. Seroconversion was considered suggestive of a primary DENV infection. Anti-DENV IgG present in both corresponding samples in combination with a post-/pre-travel ratio of ≥4:1 was suggestive of a secondary infection. Risk factors for a DENV infection were studied using poisson regression. RESULTS: In total, 600 participants were included; median age was 25 years (IQR: 23-29), 35.5% were male, and median travel duration was 20 weeks (IQR: 15-25). In 39 of 600 participants (AR: 6.5%; 95% CI 4.5-8.5%) anti-DENV IgG test results were suggestive of a recent infection, yielding an IR of 13.9 per 1,000 person-months traveling (95%CI: 9.9-19.1). No secondary infections were found. IR for Asia, Africa, and America were comparable and 13.5, 15.8, and 13.6 per 1,000 person-months respectively. Of participants with a recent DENV infection, 51% did not report dengue-like illness (DLI) or fever, but 10% were hospitalized. In multivariable analysis, travelers who seroconverted were significantly more likely to be vaccinated with ≥2 flavivirus vaccines for the current trip or to have reported DLI in >1 consecutive weeks. CONCLUSIONS: Long-term travelers are at substantial risk of DENV infection. Half of those with a DENV infection reported no symptoms, but 10% were hospitalized, demonstrating the importance of advising anti-mosquito measures during travel.

Usage of purchased self-tests for HIV and sexually transmitted infections in Amsterdam, the Netherlands: results of population-based and serial cross-sectional studies among the general population and sexual risk groups.

OBJECTIVES: There are limited data on the usage of commercially bought self-tests for HIV and other sexually transmitted infections (STIs). Therefore, we studied HIV/STI self-test usage and its determinants among the general population and sexual risk groups between 2007 and 2015 in Amsterdam, the Netherlands. SETTING: Data were collected in four different studies among the general population (S1-2) and sexual risk groups (S3-4). PARTICIPANTS: S1-Amsterdam residents participating in representative population-based surveys (2008 and 2012; n=6044) drawn from the municipality register; S2-Participants of a population-based study stratified by ethnicity drawn from the municipality register of Amsterdam (2011-2015; n=17 603); S3-Men having sex with men (MSM) participating in an HIV observational cohort study (2008 and 2013; n=597) and S4-STI clinic clients participating in a cross-sectional survey (2007-2012; n=5655). PRIMARY AND SECONDARY OUTCOME MEASURES: Prevalence of HIV/STI self-test usage and its determinants. RESULTS: The prevalence of HIV/STI self-test usage in the preceding 6-12 months varied between 1% and 2% across studies. Chlamydia self-tests were most commonly used, except among MSM in S3. Chlamydia and syphilis self-test usage increased over time among the representative sample of Amsterdam residents (S1) and chlamydia self-test usage increased over time among STI clinic clients (S4). Self-test usage was associated with African Surinamese or Ghanaian ethnic origin (S2), being woman or MSM (S1 and 4) and having had a higher number of sexual partners (S1-2). Among those in the general population who tested for HIV/STI in the preceding 12 months, 5-9% used a self-test. CONCLUSIONS: Despite low HIV/STI self-test usage, we observed increases over time in chlamydia and syphilis self-test usage. Furthermore, self-test usage was higher among high-risk individuals in the general population. It is important to continue monitoring self-test usage and informing the public about the unknown quality of available self-tests in the Netherlands and about the pros and cons of self-testing.