Thijs J W van de Laar

Gezond Amsterdam, Amsterdamo, North Holland, Netherlands

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Publications (13)58.47 Total impact

  • Journal of Virological Methods. 12/2014;
  • JAIDS Journal of Acquired Immune Deficiency Syndromes 05/2014; · 4.65 Impact Factor
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    ABSTRACT: Background: Since 2000, there is growing evidence that hepatitis C virus (HCV) infection has emerged as a sexually transmitted infection (STI) among HIV-positive MSM. Here, we present a 15-year overview of the HCV epidemic among MSM visiting a large STI-clinic in the Netherlands. Methods: During biannual cross-sectional anonymous surveys (1995–2010), participants were interviewed and tested for HIV and HCV-antibodies. Additional HCV RNA tests were performed in all HIV-positives. Determinants of HCV infection were analysed using logistic regression. Phylogenetic analysis provided evidence for sexual transmission. Results: HCV prevalence among HIV-positive MSM increased from 1995 onwards (5.6%) and peaked in 2008 (20.9%). Prevalent HCV infection was more strongly associated with fisting in 2007–2008 [adjusted odds ratio (aOR) 2.85, 95% confidence interval (CI) 1.19–6.82] than in 2009–2010 (aOR 0.92, 95% CI0.42–2.02). In addition, HCV infection was independently associated with Chlamydia, injecting drug use, unprotected anal intercourse and older age. Phylogenetic analysis revealed a high degree of MSM-specific clustering from 2000 onwards. Identification of a new MSM-specific HCV lineage and the finding of recent HCV infections (0–4%) in established HCV clusters during recent years argue for ongoing transmission of HCV among HIV-positive MSM. HCV prevalence among HIV-negative MSM remained low (2007–2010: 0.5%). Conclusion: HCV prevalence among HIV-positive MSM significantly increased over calendar time but appears to level off in recent years, possibly due to increased awareness, saturation in the population, decreased risk behaviour and earlier HCV screening and treatment. The association with fisting became less strong over time, but our analyses continue to support sexual transmission. Monitoring HIV-positive and HIV-negative MSM for HCV infection remains needed to guide prevention efforts.
    AIDS 01/2014; 28(5):781-790. · 6.41 Impact Factor
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    ABSTRACT: Abstract The largest population of people at risk for HCV-infection is injecting drug users (DU). We hypothesize that recurrent exposure to HCV, by continuing risk behavior, influences the development of an HCV-specific T-cell response. Therefore, we studied the association between repeated exposure to and the height and focus of the HCV-specific T-cell response in HCV antibody-positive injecting DU (n=18) with ongoing risk behavior ('high-risk'), 9 with and 9 without detectable HCV-RNA), and 9 never-injecting DU ('low-risk', HCV-RNA+). Both total HCV-specific T-cell response, as well as the T-cell response against HCV nonstructural proteins, were significantly higher in injecting compared to never-injecting DU. Interestingly, the high-risk HCV-RNA¯ had no measurable CD4(+) T-cell response to Core protein, compared to detectable responses to Core in the HCV-RNA+ group. Thus, both ongoing risk behavior and presence of HCV-RNA affect the HCV-specific T-cell response in both magnitude and specificity, which may have implications for vaccine development.
    Viral immunology 05/2013; · 1.78 Impact Factor
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    ABSTRACT: A population-based anti-hepatitis C virus (HCV) prevalence is important for surveillance purposes and it provides an insight into the burden of disease. In The Netherlands, a recent HCV seroprevalence estimate is not available. This national population-based cross-sectional serosurvey (PIENTER-2) resulted in a weighted national HCV seroprevalence of 0.30% (95% confidence interval 0.05-0.55%). About 70% of the HCV positive individuals found were born in an HCV-endemic country.
    The European Journal of Public Health 03/2012; · 2.52 Impact Factor
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    ABSTRACT: Little is known about the HCV prevalence in non-Western migrant populations. To determine whether targeted HCV screening and prevention programs for migrants are needed, we examined HCV prevalence and determinants among non-Western, Western migrants, and the native Dutch population in the Netherlands. Data were obtained from four surveys: (1) 3895 heterosexual visitors recruited during biannual surveys at the STI-clinic Amsterdam, 2007-2009; (2) random sample of 4563 pregnant women in Amsterdam, 2003; (3) population-based random sample of 1309 inhabitants of Amsterdam, 2004; (4) population-based random sample of 4428 people living in the Netherlands, 2006-2007. Characteristics associated with HCV-positivity were examined and phylogenetic analysis was used to obtain insight in the geographical origin of HCV strains. HCV seroprevalence in the four surveys was low (0.3-0.6%). In total 4860/14,195 (34%) were non-Western and 9329/14,195 (66%) Western participants (including Dutch). First-generation non-Western migrants were more likely to be HCV-positive (0.7-2.3%) than Western participants (0.1-0.4%). Except for survey 3, second-generation non-Western migrants had a lower HCV prevalence than first-generation migrants, comparable to Western migrants and the Dutch population. Phylogenetic analysis showed that the majority of the HCV-positive, first-generation non-Western non-European migrants were infected with endemic strains which are rarely observed in Europe. First-generation non-Western migrants are at increased risk for HCV. Phylogenetic analysis suggests that transmission likely took place in the country of origin, causing introduction but no further transmission of endemic HCV strains in the Netherlands. HCV screening and prevention programs should target first-generation, but not second-generation, non-Western migrants.
    Journal of Hepatology 04/2011; 55(6):1207-14. · 9.86 Impact Factor
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    ABSTRACT: Hepatitis C Virus (HCV) has recently emerged as sexual transmitted infection among (human immunodeficiency virus) HIV-positive but not HIV-negative men who have sex with men (MSM). We present 4 case reports showing that HIV-infection is not an absolute prerequisite for sexual HCV transmission in MSM. HIV-negative MSM with ulcerative sexual transmitted infection, those who engage in rough sexual practices or report a HCV-positive sexual partner, should be regularly screened for HCV.
    Sexually transmitted diseases 02/2011; 38(2):102-4. · 2.58 Impact Factor
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    Thijs J W van de Laar, Gail V Matthews, Maria Prins, Mark Danta
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    ABSTRACT: Since 2000 outbreaks of acute hepatitis C virus (HCV) among HIV-positive men who have sex with men (MSM) who denied injecting drug use have been reported from Europe, the United States, Canada and Australia. Given the burden of liver disease, in particular HCV, on the morbidity and mortality in HIV patients in the era of combination antiretroviral therapy, the rapid and significant rise in the incidence of HCV in the HIV-infected MSM population in high-income countries is alarming. This relates to a significant change in the epidemiology of HCV that has occurred, with HCV emerging as a sexually transmitted infection within this population. Work to date suggests that this permucosal HCV transmission results from high-risk sexual and noninjecting drug use behaviours, reopening the discussion on the importance of sexual transmission. Given this occurs almost exclusively in HIV-infected MSM, HIV probably has a critical role mediated either through behavioural and/or biological factors. Finally, the management of acute HCV in HIV infection is complicated by concomitant HIV infection and combination antiretroviral therapy. This review will synthesize the most recent epidemiological, immunological and management issues that have emerged as a result of the epidemic of acute HCV among HIV-infected MSM.
    AIDS (London, England) 07/2010; 24(12):1799-812. · 4.91 Impact Factor
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    ABSTRACT: Hepatitis C virus (HCV) genotype 4 (HCV-4) infection is considered to be difficult to treat and has become increasingly prevalent in European countries, including The Netherlands. Using a molecular epidemiological approach, the present study investigates the genetic diversity and evolutionary origin of HCV-4 in Amsterdam, The Netherlands. Phylogenetic analysis of the NS5B sequences (668 bp) obtained from 133 patients newly diagnosed with HCV-4 infection over the period from 1999 to 2008 revealed eight distinct HCV-4 subtypes; the majority of HCV-4 isolates were of subtypes 4d (57%) and 4a (37%). Three distinct monophyletic clusters were identified, with each one having a specific epidemiological profile: (i) Egyptian immigrants infected with HCV-4a (n = 46), (ii) Dutch patients with a history of injecting drug use infected with HCV-4d (n = 44), and (iii) Dutch human immunodeficiency virus (HIV)-positive men who have sex with men (MSM) infected with HCV-4d (n = 26). Subsequent molecular clock analyses confirmed that the emergence of HCV-4 within these three risk groups coincided with (i) the parenteral antischistosomal therapy campaigns in Egypt (1920 to 1960), (ii) the popularity of injecting drug use in The Netherlands (1960 to 1990), and (iii) the rise in high-risk sexual behavior among MSM after the introduction of highly active antiretroviral therapy (1996 onwards). Our data show that in addition to the influx of HCV-4 strains from countries where HCV-4 is endemic, the local spread of HCV-4d affecting injecting drug users and, in recent years, especially HIV-positive MSM will further increase the relative proportion of HCV-4-infected patients in The Netherlands. HCV-4-specific agents are drastically needed to improve treatment response rates and decrease the future burden of HCV-4-related disease.
    Journal of clinical microbiology 09/2009; 47(12):3832-8. · 4.16 Impact Factor
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    ABSTRACT: This study investigates the occurrence of HCV reinfection and superinfection among HCV seroconverters participating in the Amsterdam Cohort Studies among drug users from 1985 through 2005. HCV seroconverters (n=59) were tested for HCV RNA at five different time points: the last visit before seroconversion (t=-1), the first visit after seroconversion (t=1), six months after (t=2) and one year after (t=3) seroconversion, and the last visit prior to November 2005 (t=4). If HCV RNA was present, part of the NS5B region was amplified and sequenced. Additional phylogenetic analysis and cloning was performed to establish HCV reinfection and superinfection. Multiple HCV infections were detected in 23/59 (39%) seroconverters; 7 had HCV reinfections, 14 were superinfected, and 2 had reinfection followed by superinfection. At the moment of HCV reinfection, 7/9 seroconverters were HIV-negative: persistent HCV reinfection developed in both HIV-positive cases but also in 4/7 HIV-negative cases. In total, we identified 93 different HCV infections, varying from 1 to 4 infections per seroconverter. Multiple HCV infections were observed in 10/24 seroconverters with spontaneous HCV clearance (11 reinfections, 3 superinfections) and in 13/35 seroconverters without viral clearance (20 superinfections). HCV reinfection and superinfection are common among actively injecting drug users. This might further complicate the development of an effective HCV vaccine.
    Journal of Hepatology 07/2009; 51(4):667-74. · 9.86 Impact Factor
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    ABSTRACT: We retrospectively screened 1836 men who have sex with men (MSM) participating in the Amsterdam Cohort Studies (1984-2003) for hepatitis C virus (HCV) antibodies. HCV incidence was 0.18/100 person-years (PY) in human immunodeficiency virus (HIV)-positive MSM (8/4408 PY [95% confidence interval {CI}, 0.08-0.36]) but was 0/100 PY in MSM without HIV (0/7807 PY [95% CI, 0.00-0.05]). After 2000, HCV incidence among HIV-positive men increased 10-fold to 0.87/100 PY (5/572 PY [95% CI, 0.28-2.03]). Additional hospital cases (n=34) showed that MSM in Amsterdam who acquired HCV infection after 2000 reported high rates of ulcerative sexually transmitted infections (59%) and rough sexual techniques (56%), denied injection drug use, and were infected mainly with the difficult-to-treat HCV genotypes 1 (56%) and 4 (36%). Phylogenetic analysis showed 3 monophyletic clusters of MSM-specific HCV strains. The emergence of an MSM-specific transmission network suggests that HIV-positive MSM with high-risk sexual behaviors are at risk for sexually acquired HCV. Targeted prevention and routine HCV screening among HIV-positive MSM is needed to deter the spread of HCV.
    The Journal of Infectious Diseases 08/2007; 196(2):230-8. · 5.85 Impact Factor
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    ABSTRACT: To improve transfusion policy and to increase understanding of the spread of hepatitis C virus (HCV) in the general population, HCV infections among voluntary Dutch blood donors were examined with molecular epidemiologic techniques. During 6 years, 1997 through 2002, confirmed anti-HCV-positive donors were interviewed on HCV-associated risk behavior with a standardized questionnaire. Additionally, HCV isolates were genotyped, partially sequenced, and compared to sequences obtained from Dutch injecting drug users (IDUs). HCV prevalence and incidence rates among Dutch donors were extremely low; the residual risk of transmitting HCV was calculated to be 1 in 30 million donations. Former IDUs (21%), transfusion recipients (30%), and immigrants (>12%) were identified as major HCV risk groups. Cryptogenic transmission caused 18 percent of infections among new donors and all infections among repeat donors. Compared to IDUs, genotype distribution among donors was highly diverse; major subtypes were 3a (27%), 1a (24%), 1b (24%), 2a/b (10%), and 4 (9%). Half of the donors were infected with IDU-related subtypes 1a and 3a, whereas subtype 1b mainly spread via blood transfusion and various other nosocomial modes of transmission in the past. HCV infections acquired in endemic countries could be clearly identified based on genotype. Different modes of transmission are linked to infections with certain HCV subtypes, suggesting separate HCV epidemics, but spillover between different risk groups underlines the value of molecular epidemiologic techniques to gain insight into the origin and dynamics of HCV infections on a population level.
    Transfusion 11/2006; 46(10):1719-28. · 3.53 Impact Factor
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    ABSTRACT: To elucidate the character and magnitude of the hepatitis C virus (HCV) epidemic among drug users in Amsterdam, 197 young drug users from the period 2000 to 2004 were compared with 215 counterparts from 1985 to 1989. Although injection risk behavior and HCV seroprevalence decreased sharply over time, HCV seroprevalence remains high (44%) among young drug users who have ever injected. Phylogenetic analysis shows that current HCV infections originate from diversification of strains already circulating in the past, but also from the recent introduction of new subtypes. HCV subtypes 1a and 3a remain the most prevalent among drug users in Amsterdam, but other subtypes such as 4d and 2b have entered the population. In conclusion, both the unpopularity of injecting drug use and the success of prevention campaigns are likely to be responsible for the decline in the seroprevalence of HCV and increased median time to seroconversion. Treatment of those infected chronically, in combination with the continuation of prevention programs, might decrease future HCV transmission.
    Journal of Medical Virology 01/2006; 77(4):509-18. · 2.37 Impact Factor

Publication Stats

316 Citations
58.47 Total Impact Points

Institutions

  • 2009–2011
    • Gezond Amsterdam
      Amsterdamo, North Holland, Netherlands
    • University of Amsterdam
      • Department of Gastroenterology and Hepatology
      Amsterdam, North Holland, Netherlands
  • 2006–2007
    • GGD Amsterdam
      Amsterdamo, North Holland, Netherlands
    • Municipal Health Service of South Netherlands
      Dordt, South Holland, Netherlands