Towards More Robust Estimates of the Transmissibility of Chlamydia trachomatis

There is a lack of a common concept on how to estimate transmissibility of Chlamydia trachomatis from cross-sectional sexual partnership studies. Using a mathematical model that takes into account the dynamics of chlamydia transmission and sexual partnership formation, we report refined estimates of chlamydia transmissibility in heterosexual partnerships

Frequency and determinants of consistent STI/HIV testing among men who have sex with men testing at STI outpatient clinics in the Netherlands: a longitudinal study.

Men who have sex with men (MSM) are at highest risk for STIs and HIV infections in the Netherlands. However, official guidelines on STI testing among MSM are lacking. They are advised to test for STIs at least every six months, but their testing behaviour is not well known. This study aimed to get insight into the proportion and determinants of consistent 6-monthly STI testing among MSM testing at STI outpatient clinics in the Netherlands

Modelling the impact of tailored behavioural interventions on chlamydia transmission

Peer reviewe

The impact of STI test results and face-to-face consultations on subsequent behavior and psychological characteristics

Acknowledgments The authors would like to thank Maarten Schipper at the Biostatistics Department at the National Institute for Public Health and the Environment, who provided assistance with the statistical analyses. Furthermore, the authors are grateful to the staff at the SHC of Amsterdam, Kennemerland, Hollands Noorden, Twente (especially Karin Westra, Anne de Vries, and Karlijn Kampman) who were involved in the recruitment and data collection of participants at baseline and to Marlous Ratten and Klazien Visser from Soapoli-online, who coordinated the laboratory testing of the home-based test kits at six-month follow-up. The authors would also like to thank the staff at the STI department at the National Institute for Public Health and the Environment, especially Birgit van Benthem.Peer reviewe

Determinants of frequent and infrequent STI testing and STI diagnosis related to test frequency among men who have sex with men in the eastern part of the Netherlands: a 6-year retrospective study.

Men who have sex with men (MSM) remain vulnerable to sexually transmitted infections (STIs) and are advised to be tested at least twice a year. The aim of this study was to assess the determinants of test frequency and their associations with an STI diagnosis

A Measles Epidemic Threshold in a Highly Vaccinated Population

BACKGROUND: Mass vaccination against measles has successfully lowered the incidence of the disease and has changed the epidemic pattern from a roughly biennial cycle to an irregular sequence of outbreaks. A possible explanation for this sequence of outbreaks is that the vaccinated population is protected by solid herd immunity. If so, we would expect to see the fraction of susceptible individuals remaining below an epidemic threshold. An alternative explanation is the occurrence of occasional localised lapses in herd immunity that allow for major outbreaks in areas with a low vaccine coverage. In that case, we would expect the fraction of susceptible individuals to exceed an epidemic threshold before outbreaks occur. These two explanations for the irregular sequence of measles outbreaks can be tested against observations of both the fraction of susceptible individuals and infection attack rates. METHODS AND FINDINGS: We have estimated both the fraction of susceptible individuals at the start of each epidemic year and the infection attack rates for each epidemic year in the Netherlands over a 28-y period. During this period the vaccine coverage averaged 93%, and there was no sustained measles transmission. Several measles outbreaks occurred in communities with low vaccine coverage, and these ended without intervention. We show that there is a clear threshold value for the fraction of susceptible individuals, below which only minor outbreaks occurred, and above which both minor and major outbreaks occurred. A precise, quantitative relationship exists between the fraction of susceptible individuals in excess of this threshold and the infection attack rate during the major outbreaks. CONCLUSION: In populations with a high but heterogeneous vaccine coverage, measles transmission can be interrupted without establishing solid herd immunity. When infection is reintroduced, a major outbreak can occur in the communities with low vaccine coverage. During such a major outbreak, each additional susceptible individual in excess of the threshold is associated with almost two additional infections. This quantitative relationship offers potential for anticipating both the likelihood and size of future major outbreaks when measles transmission has been interrupted

The Effects of Influenza Vaccination of Health Care Workers in Nursing Homes: Insights from a Mathematical Model

Using a mathematical model to simulate influenza transmission in nursing homes, Carline van den Dool and colleagues find that each additional staff member vaccinated further reduces the risk to patients

Study protocol of the iMPaCT project : A longitudinal cohort study assessing psychological determinants, sexual behaviour and chlamydia (re)infections in heterosexual STI clinic visitors

Acknowledgements We are grateful to the staff at the STI clinics of Amsterdam, Kennemerland, Hollands Noorden, Twente, who are involved in the recruitment and data collection of participants, and Marlous Ratten and Klazien Visser from Soapoli-online, who are involved in the coordination of laboratory testing of the home-based sampling kits at six-month follow-up. We also thank the staff at the STI department at the National Institute for Public Health and the Environment, especially Birgit van Benthem. Funding This project is funded by the Strategic Programme (SPR) of the National Institute for Public Health and the Environment (RIVM) (project number S/113004/01/IP). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Availability of data and materials The dataset (anonymised) generated during this study will be made available for interested parties on request.Peer reviewedPublisher PD