111 research outputs found

    The Fading of the Mpox Outbreak Among Men Who Have Sex With Men: A Mathematical Modelling Study

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    BACKGROUND: In the Netherlands, the number of mpox cases started declining before mpox vaccination was initiated. Most cases were men who have sex with men (MSM). We investigated whether the decline in mpox could be attributed to infection-induced immunity or behavioural adaptations. METHODS: We developed a transmission model and accounted for possible behavioural adaptations: less casual partners and shorter time until MSM with mpox refrain from sexual contacts. RESULTS: Without behavioural adaptations, the peak in modelled cases matched observations, but the decline was less steep than observed. With behavioural adaptations in the model, we found a decline of 16-18% in numbers of casual partners in June and 13-22% in July 2022. Model results showed a halving of the time before refraining from sex. When mpox vaccination started, 57% of MSM with very high sexual activity in the model had been infected. Model scenarios revealed that the outbreak could have waned by November 2022 even without vaccination. CONCLUSIONS: The limited duration of the mpox outbreak in the Netherlands can be ascribed primarily to infection-induced immunity among MSM with high sexual activity levels. The decline was accelerated by behavioural adaptations. Immunity among those most sexually active is essential to impede mpox resurgence

    The impact of the COVID-19 pandemic on hepatitis B virus vaccination and transmission among men who have sex with men: a mathematical modelling study

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    Background: During the COVID-19 pandemic, the number of hepatitis B virus (HBV) vaccinations among men who have sex with men (MSM) has been considerably lower than before the pandemic. Moreover, a reduction in numbers of sex partners and less frequent HBV testing have been reported. We assessed the impact of these COVID-19-related changes on HBV transmission among MSM in the Netherlands. Methods: We estimated the changes in sexual activity, HBV testing, and HBV vaccination among MSM during the pandemic from Dutch data. We used a deterministic compartmental model and investigated scenarios with small or large decline in sexual activity, testing, and vaccination in periods when no data were available. Also, we examined the increase in HBV vaccinations needed to prevent further increase in HBV incidence. Results: With a decrease in numbers of sex partners of 15-25% during the first lockdown and 5% in the second lockdown, we found a decline of 6.6% in HBV incidence in 2020, despite a >70% reduction in HBV vaccination and testing during the first lockdown. With numbers of sex partners rebounding close to pre-pandemic level in 2021 and a reduction of 15% in testing and 30% in vaccination in 2021, we found an increase of 1.4% in incidence in 2021 and 3.1% in 2026. With these changes, an increase of at least 60% in HBV vaccinations in 2022 would be needed to bring the HBV incidence in 2023 back to the level that it would have had if the pandemic had not occurred. Conclusions: Despite phases of reduction in sexual activity during the COVID-19 pandemic, the decrease in HBV vaccinations can result in a small increase in HBV incidence after 2021, that may persist for years. Considerable efforts are needed to restore the vaccination level and prevent further increase in HBV transmission among MSM

    Estimating HIV Incidence, Time to Diagnosis, and the Undiagnosed HIV Epidemic Using Routine Surveillance Data.

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    BACKGROUND: Estimates of the size of the undiagnosed HIV-infected population are important to understand the HIV epidemic and to plan interventions, including "test-and-treat" strategies. METHODS: We developed a multi-state back-calculation model to estimate HIV incidence, time between infection and diagnosis, and the undiagnosed population by CD4 count strata, using surveillance data on new HIV and AIDS diagnoses. The HIV incidence curve was modelled using cubic splines. The model was tested on simulated data and applied to surveillance data on men who have sex with men in The Netherlands. RESULTS: The number of HIV infections could be estimated accurately using simulated data, with most values within the 95% confidence intervals of model predictions. When applying the model to Dutch surveillance data, 15,400 (95% confidence interval [CI] = 15,000, 16,000) men who have sex with men were estimated to have been infected between 1980 and 2011. HIV incidence showed a bimodal distribution, with peaks around 1985 and 2005 and a decline in recent years. Mean time to diagnosis was 6.1 (95% CI = 5.8, 6.4) years between 1984 and 1995 and decreased to 2.6 (2.3, 3.0) years in 2011. By the end of 2011, 11,500 (11,000, 12,000) men who have sex with men in The Netherlands were estimated to be living with HIV, of whom 1,750 (1,450, 2,200) were still undiagnosed. Of the undiagnosed men who have sex with men, 29% (22, 37) were infected for less than 1 year, and 16% (13, 20) for more than 5 years. CONCLUSIONS: This multi-state back-calculation model will be useful to estimate HIV incidence, time to diagnosis, and the undiagnosed HIV epidemic based on routine surveillance data

    Changing patterns of undiagnosed HIV infection in the Netherlands: Who benefits most from intensified HIV test and treat policies?

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    Objectives: To estimate HIV prevalence, the number of people living with HIV/AIDS (PLWHA) and the undiagnosed proportion in the Netherlands for 2012, and to compare these with published 2007 estimates. Design: Synthesis of all available data sources. Methods: Multi-Parameter Evidence Synthesis (MPES) was used to obtain estimates in mutually exclusive key populations at higher risk in three geographical regions (Amsterdam, Rotterdam, rest of the Netherlands). Data sources included HIV prevalence surveys, diagnoses at STI clinics, and registered cases in HIV care. Group specific estimates were reported as Bayesian posterior medians and 95% credible intervals (CrI). Results: The 2012 model estimated 24,350 PLWHA (95% CrI 20,420-31,280) aged 15-70 years; 2,906 (+14%) more than in 2007. The estimated population HIV prevalence was 0.20% (95% CrI 0.17-0.26%). The overall proportion of undiagnosed HIV was lower in 2012 (34%, 95% CrI 22-49%) compared to 2007 (40%, 95% CrI 25-55%). After MSM, migrants from sub-Saharan Africa and the Caribbean formed the largest groups of PLWHA, but proportions of undiagnosed HIV remained high in these groups, 48% and 44% respectively. Amsterdam had lowest proportions undiagnosed for most key populations at higher risk, including MSM and migrants. Conclusions: In 2012, the number of PLWHA was higher compared to 2007, while the proportion of undiagnosed HIV was lower, especially among MSM. Higher HIV testing rates, earlier treatment, and an improved life expectancy may explain these differences. HIV interventions need to be expanded in all key populations at higher risk, with special focus on migrants and key populationsliving outside of Amsterdam. Copyright

    Dietary exposure to polychlorinated biphenyls and dioxins from infancy until adulthood: A comparison between breast-feeding, toddler, and long-term exposure

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    Food is the major source for polychlorinated biphenyl (PCB) and dioxin accumulation in the human body. Therefore, investigating food habits from early ages until reproductive age (25 years) is important in order to assess exposure risk for the next generation. The objective of this study was to assess the PCB/dioxin exposure and the relative contribution of different foods to total exposure during preschool age. Particularly, the importance of lactational PCB/dioxin exposure vs. dietary exposure until adulthood was investigated. A cohort of 207 children was studied from birth until preschool age. Based on 3 planar PCBs and 17 2,3,7,8-substituted dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) measured in breast milk, a model was developed to calculate the cumulative toxic equivalent (TEQ) intake during breast-feeding (0-1 year). In 3. 5-year-old children, daily dietary intake of planar PCB-TEQ and dioxin-TEQ was measured with a validated food questionnaire. Cumulative TEQ intake from 1 to 5 years was estimated using the PCB- and dioxin-TEQ intake measured with the food questionnaire. Cumulative TEQ intake from 6 to 25 years was estimated using national food consumption and contamination data of PCB- and dioxin-TEQ intake. In toddlers, dairy products contributed 43% to PCB-TEQ and 50% to dioxin-TEQ intake. Meat and meat products contributed 14% and 19%, respectively, and processed foods 23% and 15%, respectively. Breast-feeding for 6 months contributed to the cumulative PCB/dioxin TEQ intake until 25 years of age, 12% in boys and 14% in girls. The daily TEQ intake per kilogram body weight is 50 times higher in breast-fed infants and three times higher in toddlers than in adults. Long-term dietary exposure to PCBs and dioxins in men and women is partly due to breast-feeding (12 and 14%, respectively). After weaning, dairy products, processed foods, and meat are major contributors of PCB and dioxin accumulation until reproductive age. Instead of discouraging breast-feeding, maternal transfer of PCBs and dioxins to the next generation must be avoided by enforcement of strict regulations for PCB and dioxin discharge and by reducing consumption of animal products and processed foods in all ages

    An assessment of rates and covariates of mpox diagnosis and vaccination provides evidence to refine eligibility criteria for mpox vaccination among gay, bisexual and other men who have sex with men in the Netherlands

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    Background: The 2022 multicountry mpox outbreaks predominantly affected gay, bisexual and other men who have sex with men (GBMSM) in non-endemic countries. Mpox vaccination is most effective if targeting GBMSM most at risk. It is unknown to what extent eligibility criteria for vaccination align with evidence on risk factors for mpox in GBMSM. Methods: We conducted an online self-report survey among GBMSM in the Netherlands between 29 July and 30 August 30, 2022, corresponding to the first month of the Dutch mpox vaccination campaign. GBMSM were recruited via advertisements on social media and gay dating apps. Participants reported on their sexual behaviour, mpox diagnosis, and/or vaccination since the start of the outbreak. Results: Of the 2,460 participants, 73 (3.0%) were diagnosed with mpox and 485 (19.7%) had been vaccinated. Using population sample weights, we estimated that, of the sexually active GBMSM population aged 18-80 years in the Netherlands, 1.1% had been diagnosed with mpox and 7.8% had been vaccinated. In multivariable logistic regression analyses, we found that current HIV-PrEP use, having 20 sex partners in the past 12 months and having sex in sex venues or at parties in the past two months were independent risk factors for mpox diagnosis. Conclusion: This study provides novel evidence on risk factors for mpox amongst GBMSM in the Netherlands that has guided a refinement of eligibility criteria for mpox vaccination. The dynamics of any future mpox outbreaks are unknown and continued adjustment of vaccination eligibility may be required to achieve sustained elimination

    Web-supported social network testing for HIV among men who have sex with men with a migration background : Protocol for a mixed methods pilot study

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    Acknowledgments The PREVENT project is funded by Aidsfonds (grants P-22603 and P-35609) as a high-risk high-gain project. We also thank the following people for their contributions: from Aidsfonds–Soa Aids Nederland, Suzan Bergh, Hanna Bos, Tatiana Mouhebati, and Marieke van den Borne; from the National Institute for Public Health and the Environment, Birgit van Benthem; from Amsterdam Public Health Service, Anders Boyd and Adriaan Tempert; from Utrecht University, John de Wit; from Maastricht University, Nicole Dukers; from Trial Data Solutions, Gerben Rienk Visser. The time2test website was developed by TjunaPeer reviewedPublisher PD

    Antenatal screening for HIV, hepatitis B and syphilis in the Netherlands is effective

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    Abstract Background A screening programme for pregnant women has been in place since the 1950s in the Netherlands. In 2004 universal HIV screening according to opting out was implemented. Here, we describe the evaluation of the effectiveness of antenatal screening in the Netherlands for 2006-2008 for HIV, hepatitis B virus (HBV) and syphilis in preventing mother-to-child transmission, by using various data sources. Methods The results of antenatal screening (2006-2008) were compared with data from pregnant women and newborns from other data sources. Results Each year, around 185,000 pregnant women were screened for HIV, HBV and syphilis. Refusal rates for the screening tests were low, and were highest (0.2%) for HIV. The estimated annual prevalence of HIV among pregnant women was 0.05%. Prior to the introduction of screening, 5-10 children were born with HIV annually After the introduction of screening in 2004, only 4 children were born with HIV (an average of 1 per year). Two of these mothers had become pregnant prior to 2004; the third mother was HIV negative at screening and probably became infected after screening; the fourth mother's background was unknown. Congenital syphilis was diagnosed in fewer than 5 newborns annually and 5 children were infected with HBV. In 3 of these, the mothers were HBeAg positive (a marker for high infectivity). We estimated that 5-10 HIV, 50-75 HBV and 10 syphilis cases in newborns had been prevented annually as a result of screening. Conclusions The screening programme was effective in detecting HIV, HBV and syphilis in pregnant women and in preventing transmission to the child. Since the introduction of the HIV screening the number of children born with HIV has fallen dramatically. Previous publication [Translation from: 'Prenatale screening op hiv, hepatitis B en syphilis in Nederland effectief', published in 'The Dutch Journal of Medicine ' (NTVG, in Dutch)]</p
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