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Background Fear of COVID-19 infection and the response measures have affected sexual behaviours of men who have sex with men (MSM) and access to care for sexually transmitted infections (STI). We investigated whether these changes resulted in increased or decreased STI transmission among MSM. Methods We developed a mathematical transmission model for chlamydia and gonorrhoea among MSM. We accounted for 15–35% reduction in the number of casual partners and 50–80% reduction in STI testing during lockdowns (March-May 2020; October 2020 to February 2021); these reductions were 0–10% and 20–35%, respectively, in periods with less restrictive COVID-19 measures (June-September 2020, March-August 2021). Reductions until August 2020 were estimated from Dutch data; other reductions were based on expert opinion. We assumed no changes after August 2021. Two scenarios were examined: with home-testing (in 25% of cases not tested at healthcare facilities) and without home-testing. We calculated the percentage change in prevalence due to COVID-19 associated changes, compared to prevalence in the same year without changes due to COVID-19. Results From the model, we estimated an increase of 8.4% (interquartile range (IQR), 7.6–9.4%) in chlamydia prevalence and an increase of 7.5% (IQR, 6.0–8.9%) in gonorrhoea prevalence at the end of 2020 without home-testing, compared to the prevalence without COVID-19 associated changes. The increase subsided in 2021, but chlamydia and gonorrhoea prevalence remained higher than without COVID-19 until 2025. With home-testing, the percentage increase in 2020, compared to the scenario without COVID-19, was 5.3% (IQR, 4.6–5.9%) for chlamydia and 3.5% (IQR, 2.6–4.4%) for gonorrhoea prevalence. Conclusion The COVID-19 pandemic may have resulted in an increase in chlamydia and gonorrhoea prevalence in 2020. The increase can be smaller after 2020, if STI testing at healthcare facilities and/or at home increases. The findings emphasize the importance of facilitating STI (self) care in times of crisis.

Background Dutch Sexual Health Clinics (SHCs) had to downscale services during the first coronavirus wave, but continued to provide essential STI/PrEP care including testing for persons at highest risk for (symptomatic) gonorrhoea, infectious syphilis (syphilis) and HIV. We describe STI positivity among SHC attendees between 2011–2020. Methods National SHC surveillance data contained information on demographics, sexual behaviour, STI testing and diagnoses. We split 2020 into periods: 1 January-12 March (pre-lockdown), 13 March-31 May (lockdown) and 1 June-31 August (post-lockdown). Chlamydia, gonorrhoea, syphilis and HIV positivity (n positive/N tested) trends were explored by gender and sexual contact. Results In 2020, weekly numbers of consultations varied between 2,803 and 3,515 pre-lockdown, 564 and 1,298 during lockdown and 1,084 and 1,976 post-lockdown. Relatively more MSM, PrEP users and clients notified for or with symptoms of STI were seen during- and post-lockdown compared to pre-lockdown. Chlamydia positivity was around 18% among heterosexual men and 15% among women from 2016–2019, and increased to 21.1% and 16.6% respectively in 2020. Positivity increased during lockdown, up to 32% among heterosexual men, followed by decreases post-lockdown to pre-lockdown levels. Among MSM, the increase during lockdown was smaller, only slightly affecting overall positivity in 2020. Gonorrhoea positivity also increased during lockdown, causing further increasing trends among heterosexuals from 1.8% in 2011 to 2.2% in 2020 and among MSM from 9.0% to 12.1%. Syphilis positivity among MSM fluctuated between 2.0% and 2.9% in 2011–2020. Positivity peaked (6.7%) during lockdown, while the number of diagnoses was similar to pre-lockdown. In contrast, HIV positivity continued to decrease from 2,0% to 0,3% among MSM in 2011–2020. Conclusion Prioritising persons at highest risk caused decreases in diagnoses, especially chlamydia and gonorrhoea, but increases in positivity. More information is needed to understand transmission dynamics, including testing at GPs, self-testing and sexual behaviour during coronavirus pandemic.

Background Syphilis rates are increasing globally among men who have sex with men (MSM). Repeat infections within core groups could contribute to ongoing transmission of syphilis. The aim of this study was to measure the frequency and to explore predictors of repeat infectious syphilis infection among MSM attending Sexual Health Centres (SHCs) in the Netherlands. Methods We analysed national SHC surveillance data between July 2014 and December 2019. A unique identifier enabled individual level analysis of repeat consultations and infections. Infectious syphilis (syphilis) included primary, secondary and early latent syphilis diagnoses. Repeat infection was defined as having two syphilis diagnoses during the study period. Multivariable logistic regression analyses were used to explore predictors of repeat syphilis infection. MSM with at least one syphilis diagnosis and one following consultation were included. Age, education level, ethnicity, HIV infection, having symptoms related to syphilis/HIV, being notified for STI, prior STI, condom use and number of partners at first infectious syphilis diagnosis were included in the analysis. Results There were 184,621 consultations registered among 41,210 MSM who tested repeatedly. Among 3,504 MSM, 4,282 syphilis infections were diagnosed. At first syphilis diagnosis median age was 39 (IQR: 29–49), 32.4% was known HIV positive and 41.4% had 10 or more partners in the past 6 months. Repeat infection occurred in 647 MSM (18.5%; median time to repeat infection: 468 days (IQR: 287–808)). Being HIV positive (aOR: 2.02 [95% CI: 1.69–2.42]) and being notified for STI (aOR: 1.21 [95% CI: 1.01–1.46]) were statistically significant predictors of repeat infection. Conclusion This study showed that repeat infection was common and that HIV infection and being notified for STI at first syphilis diagnosis were predictors of repeat infection among MSM who tested repeatedly. Preventive strategies, including adequate partner management, for repeat syphilis are needed, especially for HIV-positive MSM.

Background On 1 January 2014, the minimum age to buy alcohol increased (16–18 years), accompanied by a public awareness campaign (NIX18). Decreases in alcohol consumption are associated with less risky sexual behaviour. This study analyzed the association between the health reforms andChlamydia trachomatis infections (chlamydia) among young heterosexual people. Methods Chlamydia positivity rates, age, and gender from all STI-clinic attendees between 16 and 19 years old in the Netherlands of 2010 to 2016 were obtained. Interrupted time-series assessed immediate and gradual trends in chlamydia rates. Results Among the control group (18–19 year olds) chlamydia rates increased 0.5% each post-ban month (95% Confidence Interval [CI] 1.002–1.008, p = .001). Among 16–17 year olds there was no monthly increase post-ban (Rate Ratio 1.000, 95% CI 0.993–1.007, p = .948). In terms of confounders, only controlling for partner notification dissolved these time trends. Conclusions We found that chlamydia rates after the alcohol ban differed between 16–17 year olds and 18–19 year olds. This demonstrates that the health reforms might have affected this secondary outcome, but obtaining certainty using national surveillance data is difficult. Specific studies should be designed, as now changes in chlamydia over time could be explained by STI-clinic policy changes, by changes on an individual level including reduced alcohol consumption or most likely by the combination of these factors.

Introduction Chlamydia prevalence remains high despite scaled-up control efforts and recurrent infection frequently occurs. Objective We investigated the potential of direct partner treatment for chlamydia related to current practice and attitude of GPs towards partner notification (PN) and partner treatment (PT). Methods Four data-sources were combined: 1) Information on current practice via two short questionnaires at a national GP conference; 2) GPs’ attitudes towards PN/PT were explored in a vignette questionnaire study among GPs in NIVEL Primary Care Database (NIVEL-PCD); 3) Quantitative data on (potential) PT were obtained from prescriptions in electronic patient data of NIVEL-PCD; 4) GP recorded questionnaires related to STI consultations in the sentinel practices of NIVEL-PCD. Results Questionnaires showed that the large majority of GPs (>95%) discuss PN of current and ex-partner(s) with chlamydia-patients. Usually, GPs leave further steps to the patients (83%); partners are rarely treated directly (4%), except when partners are registered in the same practice (16%). In the vignette study, 16-20% of GPs indicated willingness to provide direct PT, depending on patient/partner profile, and 24-45% if possible after patient-initiated PN. Prescription data showed that double dosages of Azithromycin were prescribed in 1-2% of cases. STI consultation data revealed PT in 6/100 cases, via partner prescription or double doses for the index. Conclusions At present, GPs in the Netherlands rarely treat partners of chlamydia cases directly, except for partners registered in the same practice. GPs may be open to options for direct PT, provided there are clear guidelines to arrange this adequately. Key messages: •At present, GPs in the Netherlands rarely treat partners of chlamydia cases directly, except for partners registered in the same practice. •GPs may be open to options for direct PT, provided there are clear guidelines to arrange this legally and practically. (aut. ref.)

Background: Chlamydia trachomatis (CT), the most common bacterial sexually transmitted infection (STI) among young women, can result in serious sequelae. Although the course of infection is often asymptomatic, CT may cause pelvic inflammatory disease (PID), leading to severe complications, such as prolonged time to pregnancy, ectopic pregnancy, and tubal factor subfertility. The risk of and risk factors for complications following CT-infection have not been assessed in a long-term prospective cohort study, the preferred design to define infections and complications adequately. Methods: In the Netherlands Chlamydia Cohort Study (NECCST), a cohort of women of reproductive age with and without a history of CT-infection is followed over a minimum of ten years to investigate (CT-related) reproductive tract complications. This study is a follow-up of the Chlamydia Screening Implementation (CSI) study, executed between 2008 and 2011 in the Netherlands. For NECCST, female CSI participants who consented to be approached for follow-up studies (n = 14,685) are invited, and prospectively followed until 2022. Four data collection moments are foreseen every two consecutive years. Questionnaire data and blood samples for CT-Immunoglobulin G (IgG) measurement are obtained as well as host DNA to determine specific genetic biomarkers related to susceptibility and severity of infection. CT-history will be based on CSI test outcomes, self-reported infections and CT-IgG presence. Information on (time to) pregnancies and the potential long-term complications (i.e. PID, ectopic pregnancy and (tubal factor) subfertility), will be acquired by questionnaires. Reported subfertility will be verified in medical registers. Occurrence of these late complications and prolonged time to pregnancy, as a proxy for reduced fertility due to a previous CT-infection, or other risk factors, will be investigated using longitudinal statistical procedures. Discussion: In the proposed study, the occurrence of late complications following CT-infection and its risk factors will be assessed. Ultimately, provided reliable risk factors and/or markers can be identified for such late complications. This will contribute to the development of a prognostic tool to estimate the risk of CT-related complications at an early time point, enabling targeted prevention and care towards women at risk for late complications. Trial registration: Dutch Trial Register NTR-5597. Retrospectively registered 14 February 2016.

Infectious syphilis (syphilis) is diagnosed predominantly among men who have sex with men (MSM) in the Netherlands and is a strong indicator for sexual risk behaviour. Therefore, an increase in syphilis can be an early indicator of resurgence of other STIs, including HIV. National and worldwide outbreaks of syphilis, as well as potential changes in sexual networks were reason to explore syphilis trends and clusters in more depth. National STI/HIV surveillance data were used, containing epidemiological, behavioural and clinical data from STI clinics. We examined syphilis positivity rates stratified by HIV status and year. Additionally, we performed space-time cluster analysis on municipality level between 2007 and 2015, using SaTScan to evaluate whether or not there was a higher than expected syphilis incidence in a certain area and time period, using the maximum likelihood ratio test statistic. Among HIV-positive MSM, the syphilis positivity rate decreased between 2007 (12.3%) and 2011 (4.5%), followed by an increasing trend (2015: 8.0%). Among HIV-negative MSM, the positivity rate decreased between 2007 (2.8%) and 2011 also (1.4%) and started to increase from 2013 onwards (2015: 1.8%). In addition, we identified three geospatial clusters. The first cluster consisted of MSM sex workers in the South of the Netherlands (July 2009-September 2010, n=10, p

Objectives: Because most HIV-infected women are of reproductive age, we investigated whether their reproduction planning was affected by their HIV diagnosis. Design: The European women study is a prospective, multicentre cohort of 485 HIV-infected women with a known interval of seroconversion. Methods: The incidence of pregnancy was measured with person-time methods. Generalized estimating equation analysis was used to determine risk factors for pregnancy and pregnancy outcomes. Results: In 449 women, the age-adjusted incidence of pregnancies decreased from 8.6 before HIV diagnosis to 8.2 and 6.0 per 100 person-years in 0-4 and over 4 years after HIV diagnosis, respectively (P = 0.14). The proportion of induced abortions increased from 42% before to 53% after HIV diagnosis (P< 0.05). The risk of spontaneous abortion did not increase as a result of HIV infection. Since 1995, the proportion of births increased (P = 0.009), whereas that of induced abortions decreased (P = 0.01) compared with earlier years. An increased risk of pregnancy after HIV diagnosis was found in northern and central European women compared with southern European women; there was a lower risk in single women than in women with a steady partner. Of all pregnant women, single women, women between 15 and 25 years of age, and women with multiple partners were at increased risk for induced abortion both before and after HIV diagnosis. Conclusion: The incidence of pregnancy decreased with HIV disease progression. Pregnancies after HIV diagnosis appear to be related largely to social and cultural attitudes. The number of induced abortions was high before HIV diagnosis and it significantly increases thereafter.

Objectives: To assess the impact of HIV-related immunodeficiency and antiretroviral treatment on the occurrence and evolution of abnormal Papanicolaou tests. Study design: Cohort of 485 HIV-infected women with a known date of infection, enrolled during May 1993-April 1998 in 23 centres (gynaecology, infectious disease or STD clinics, or drug treatment centres) in 12 European countries; in 21 centres, follow-up was performed every 6 months (median follow-up: 2 years). Methods: Human papillomavirus (HPV) was detected at inclusion by Southern blot and PCR. The prevalence of squamous intraepithelial lesions (SIL), the incidence of SIL and regression from low-grade SIL were studied according to CD4 count after controlling for HPV detection results. Results: Compared with women with CD4 cell counts > 500 × 10 6 /l, women with CD4 cell counts 500 × 10 6 /l, reference), whereas it was less marked and not statistically significant in treated women. Conclusions: Severe HIV-related immunodeficiency strongly increases the risk of occurrence of SIL; antiretroviral treatment may reduce this risk, probably by restoring or at least preserving immune function.

OBJECTIVES To investigate the prevalence and incidence of sexually transmitted infections (STI) in HIV-infected women in relation to time from infection and sexual behaviour. DESIGN The European study on the natural history of HIV infection in women is a prospective cohort study of 487 HIV-infected women with a known interval of seroconversion from 12 European countries. METHODS Incidence was measured with person-time methods. Generalized estimating equations analysis was used to determine risk factors for STI. RESULTS At entry, 15% of the women were diagnosed with at least one acute STI (chlamydial infection, trichomoniasis or gonorrhoea), 10% with at least one other STI (genital warts or genital ulcerations) and 13% with vaginal candidiasis. Although frequently diagnosed during follow-up, the occurrence of acute STI and vaginal candidiasis decreased, whereas the occurrence of other STI increased with ongoing time from HIV infection. Furthermore, women with a history of prostitution [relative risk (RR), 2.00; 95% confidence interval (95% CI), 1.20-3.33] and women with irregular condom use (RR, 7.74; 95% CI, 3.52-17.0) were at higher risk for an acute STI. CONCLUSIONS Although STI diagnoses were frequent, the occurrence of acute STI declined with time from infection which might be explained by changed sexual behaviour over time. The occurrence of other STI increased with time from HIV infection, presumably due to reactivation as a result of immunosuppression.

AIMS To determine the prevalence of anaemia among HIV-positive and -negative drug users, estimate the incidence of anaemia among HIV-positive drug users and study risk factors for prevalent anaemia with emphasis on HIV infection, gender and drug use behaviour. DESIGN, SETTING AND PARTICIPANTS Cross-sectional study among HIV-positive and HIV-negative drug users (n = 360) and a longitudinal study among HIV-positive drug users (n = 175, 860 visits) participating in a cohort study of drug users in Amsterdam. MEASUREMENTS Self-reported data on socio-demographics, drug use behaviour and zidovudine and protease inhibitor therapy on regular cohort visits. Laboratory determinations of haemoglobin concentration, CD4(+)-cell counts and HIV-1 RNA. FINDINGS The prevalence of anaemia was 21.1% among participating drug users according to the WHO definition. The incidence of anaemia in HIV-positive individuals was 33.0/100 person-years. The main risk factor for anaemia was high frequency of injecting drugs. A Quetelet body mass index < or = 20 and female gender were also positively and significantly related to anaemia in the cross-sectional study. In the longitudinal study among HIV-positive drug users progression of HIV infection indicated by low CD4(+)-cell count and AIDS diagnosis were predictive of anaemia. CONCLUSION The results indicate that drug users in the Amsterdam cohort study have a high prevalence of anaemia, which can be explained mainly by high frequency of injecting drugs and HIV infection progression. Reduction or cessation of injecting drug use should reduce anaemia.

This cross-sectional study among heterosexual migrant groups in south-eastern Amsterdam, the city area where the largest migrant groups live, provides an insight into HIV testing behaviour in this particular group. Participants were recruited at street locations (May 1997-July 1998) and interviewed using structured questionnaires. They also donated saliva for HIV testing. In total, 705 males and 769 females were included in this study (Afro-Surinamese (45%), Dutch-Antilleans (15%) and West Africans (40%)). Prior HIV testing was reported by 38% of all migrants (556/1479), of which only a minority (28%) had actively requested HIV testing. Multivariate logistic regression showed that not actively requesting HIV testing was more likely among younger (< 23 years) migrants, especially women (ORwomen: 4.79, p < 0.01, ORmen: 1.81, p < 0.05). Furthermore, women without previous STI treatment (OR 2.19, p < 0.05) with Afro-Surinamese ethnicity (OR 2.12, p < 0.05), men without health insurance (OR 2.17, p < 0.05) and with low education (p < 0.01) were also more likely to not actively request HIV testing. Active requests for HIV testing in case of HIV risk should be facilitated by promoting HIV testing and by improving accurate self-assessment of risk for HIV infection, especially among the groups that do not actively request HIV testing. This would increase HIV awareness and provide the opportunity of better medical care earlier in HIV infection.

Summary objective To determine the frequency and determinants of knowledge of dengue infection in three sites in northern Thailand, and to compare prevention measures of people with and without knowledge of dengue. methods In May 2001 we conducted an epidemiological survey among 1650 persons living in three areas in northern Thailand. Knowledge of dengue and the use of prevention measures were measured by means of a structured questionnaire. Differences in knowledge of dengue and the use of prevention measures between risk groups were calculated by chi-square test. Logistic regression was used to identify determinants of knowledge. results Of the 1650 persons, 67% had knowledge of dengue. Fever (81%) and rash (77%) were the most frequently mentioned symptoms. Persons with knowledge of dengue reported a significantly higher use of prevention measures than persons without knowledge of dengue. In multivariate analyses, knowledge of dengue significantly differed by age, sex, occupation and site (P < 0.05). Younger people knew more about dengue than older persons: adjusted odds ratio (aOR) of 6.75 [95% confidence interval (CI): 4.32‐10.6] for the 15‐29 age group compared with people aged 60 and older. In comparison with farmers (reference group), knowledge of dengue was significantly higher among students (aOR: 10.6, 95% CI: 4.27‐26.4), but lower among housewives or unemployed persons (aOR: 0.44, 95% CI: 0.31‐0.64). conclusion The overall knowledge of dengue was high, but housewives, unemployed and old persons had relatively little knowledge of dengue. Therefore, these groups may need special attention in future dengue education programmes. Persons with knowledge of the disease more frequently reported the use of preventive measures, indicating the value of education programmes as a tool in dengue prevention.

Objective Young men having sex with men (MSM) are a high-risk group involved in on-going transmission of sexually transmitted infections (STI). To improve our understanding of this epidemic, distribution of STI and testing behaviour in young MSM attending STI clinics in the Netherlands was analysed. Methods National STI surveillance data on young MSM (15–24 years) for 2006–2011 were analysed. STI included were chlamydia, gonorrhoea, infectious syphilis and HIV. Chi-square test for trend was performed to analyse time trends in testing behaviour and STI positivity rates, multivariable logistic regression was used to identify factors associated with STI positivity. Results Number of consultations in young MSM increased from 1161 in 2006 to 3167 in 2011 (+166%). The proportion not aware of their HIV status decreased from 51% in 2006 to 32% in 2011 (p In multivariable analyses, factors significantly associated with an STI were being notified (OR:2.8; 95% CI: 2.5–3.2), multiple sex partners (OR:2.4; 95% CI: 2.0–3.0), previous STI (OR:1.9; 95% CI: 1.6–2.1) and being involved in sex work (OR:1.5; 95% CI: 1.2–1.9). In addition, non-Dutch young MSM were at significantly higher risk for an STI, as were homosexual men compared to bisexual men (OR: 1.3; 95% CI: 1.1–1.4). Conclusions Since the number of consultations and the proportion aware of their HIV status increased over time, awareness for STI seems to be increasing in young MSM. However, gonorrhoea and chlamydia positivity rates are still increasing. Therefore special attention needs to be maintained towards counselling and reaching specific high-risk sub-groups, including young migrant MSM and young MSM involved in sex work to limit on-going transmission of STI.

Background Delay between HIV diagnosis and entry into care may have a negative impact on the individual prognosis and may enable further transmission. Insight into duration and determinants of care-delay is important for public health aimed at reducing ongoing HIV transmission. Methods Prospective data were collected regionally from consenting patients testing HIV positive at the STI clinics in Amsterdam and Rotterdam, from February 2009-December 2011. Logistic regression analyses were performed to assess risk factors for care delay. Delay of entry into care is defined as a time period of 4 weeks or more between confirmed HIV diagnosis and first consultation at the HIV treatment centre. Results In total, 310 participants were included in the study (response 70%). The majority were men who have sex with men. Seventy five percent of the study population was referred directly from STI clinic to treatment centre by a clinician or nurse. Thirty percent of participants were delayed: 15% entered care after 4 weeks and 15% had not entered care yet. Thus, 70% of participants entered care within 4 weeks; median time of entry was 9 days (range 0–739 days). In the multivariate model, age below 25 years (OR = 3.6 95% CI 1.9–6.7) and indirect referral (OR = 3.3 95% CI 1.8–6.5) were independent risk factors for care delay, while people with health insurance were less likely to delay (OR = 0.3 95% CI 0.1–0.9). No association was found between care delay and CD4 cell counts or viral load at diagnosis. Conclusions Younger persons and persons without health insurance are at risk for entering care late after being diagnosed HIV positive. Direct referral from STI clinic to care leads to less delay. Testing of those at risk is not enough to interrupt HIV transmission, entry into care needs to be assured as well. A more active role of the care provider is needed.

Objective To assess the association between chlamydia (CT)-test results and subsequent sexual risk behaviour change in a register based Chlamydia Screening (CSI) programme consisting of four screening rounds. Methods All participants in the CSI programme, who had completed questionnaires and corresponding CT-test results in ≥ 2 rounds, were included. Measurements in round four were excluded, because of low participation rates. Sexual risk behaviour parameters contained the use of condoms, number of partners and having casual, concurrent or new partners. Generalised estimating equations (GEE) were used to assess the influence of the test result on the change in sexual risk behaviour in the subsequent round. Analysis were adjusted for sexual preference, having a steady or casual partner, age and number of rounds participated. Results Of 9360 included participants, 80.5% (n = 7536) and 19.5% (n = 1824) completed CT-testing and questionnaires in respectively two and three rounds. Across all rounds, a significant difference in change of sexual risk behaviour could be found: participants who tested CT-positive in the previous round more often reported reduced risk behaviour (more use of condoms with a casual partner (32.1% vs 24.1%, p = 0.018), less having sex with a casual partner (21.7% vs 15.3%, p = 0.001), lower number of sex partners (38.5% vs 24.7%, p Conclusion Sexual risk behaviour change was associated with previous CT-test results. Participants who tested CT-positive more often positively changed their sexual risk behaviour compared to participants with a negative test result in the previous round.