scholarly journals Investigating the effects of accelerated partner therapy (APT) on chlamydia transmission in Britain: a mathematical modelling study

2020 ◽  
Author(s):  
Christian L Althaus ◽  
Catherine H Mercer ◽  
Jackie A Cassell ◽  
Claudia S Estcourt ◽  
Nicola Low
Keyword(s):  
Sexual Activity ◽  
Control Strategies ◽  
Controlled Trial ◽  
Partner Notification ◽  
Cluster Randomised Controlled Trial ◽  
Credible Interval ◽  
Population Based ◽  
Transmission Model ◽  
Transmitted Infection ◽  
Potential Increase

Understanding the effects of partner notification (PN) on the transmission of chlamydia, the most prevalent bacterial sexual transmitted infection worldwide, is critical for implementing optimal control strategies. Accelerated partner therapy (APT) aims to increase the numbers of partners treated and reduce the time to partner treatment. Our objective was to study the effects of APT interventions on partner treatment and chlamydia transmission in order to better understand the results of LUSTRUM, an APT cross-over cluster randomised controlled trial in the UK. We developed a novel deterministic, population-based chlamydia transmission model including the process of PN. We considered a population aged 16-34 years and calibrated the model to sexual behaviour data between people of the opposite-sex and chlamydia prevalence data reported by 3,671 participants in Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3, 2010-2012) using Approximate Bayesian Computation (ABC). We investigated the potential effects of APT on chlamydia transmission by increasing the number of treated partners and reducing the time to partner treatment compared to standard PN. The median prevalence of chlamydia in the model was 1.84% (95% credible interval, CrI: 1.60%-2.62%) in women and 1.78% (95% CrI: 1.13%-2.14%) in men. Chlamydia positivity was highest in partners of symptomatic index cases with low sexual activity. Infected partners were typically asymptomatic and belonged to the high sexual activity group, i.e., are naturally those infected individuals that will contribute most to onward transmission. Reducing the time to partner treatment without achieving higher numbers of partners treated had only minor effects on reducing chlamydia prevalence. In contrast, the model predicts that a potential increase in the number of partners treated from current levels in Britain (0.51, 95% CrI: 0.21-0.80) by 25% would reduce chlamydia prevalence by 18% (95% CrI: 5%-44%) in both women in men within 5 years. These results suggest that APT, through a potential increase in the proportion of partners treated, would be an effective method to reduce ongoing chlamydia transmission in Britain.

Intensified partner notification and repeat testing can improve the effectiveness of screening in reducing Chlamydia trachomatis prevalence: a mathematical modelling study

2021 ◽  
pp. sextrans-2021-055220
Author(s):  
Ben B Hui ◽  
Jane S Hocking ◽  
Sabine Braat ◽  
Basil Donovan ◽  
Christopher K Fairley ◽  
...  
Keyword(s):  
Chlamydia Trachomatis ◽  
Controlled Trial ◽  
Partner Notification ◽  
Population Level ◽  
Cluster Randomised Controlled Trial ◽  
Base Case ◽  
Relative Reduction ◽  
Treatment Rate ◽  
Chlamydia Testing ◽  
Randomised Controlled

BackgroundThe Australian Chlamydia Control Effectiveness Pilot (ACCEPt) was a cluster randomised controlled trial designed to assess the effectiveness of annual chlamydia testing through general practice in Australia. The trial showed that testing rates increased among sexually active men and women aged 16–29 years, but after 3 years the estimated chlamydia prevalence did not differ between intervention and control communities. We developed a mathematical model to estimate the potential longer-term impact of chlamydia testing on prevalence in the general population.MethodsWe developed an individual-based model to simulate the transmission of Chlamydia trachomatis in a heterosexual population, calibrated to ACCEPt data. A proportion of the modelled population were tested for chlamydia and treated annually at coverage achieved in the control and intervention arms of ACCEPt. We estimated the reduction in chlamydia prevalence achieved by increasing retesting and by treating the partners of infected individuals up to 9 years after introduction of the intervention.ResultsIncreasing the testing coverage in the general Australian heterosexual population to the level achieved in the ACCEPt intervention arm resulted in reduction in the population-level prevalence of chlamydia from 4.6% to 2.7% in those aged 16–29 years old after 10 years (a relative reduction of 41%). The prevalence reduces to 2.2% if the proportion retested within 4 months of treatment is doubled from the rate achieved in the ACCEPt intervention arm (a relative reduction of 52%), and to 1.9% if the partner treatment rate is increased from 30%, as assumed in the base case, to 50% (a relative reduction of 59%).ConclusionA reduction in C. trachomatis prevalence could be achieved if the level of testing as observed in the ACCEPt intervention arm can be maintained at a population level. More substantial reductions can be achieved with intensified case management comprising retesting of those treated and treatment of partners of infected individuals.

scholarly journals The impact of control strategies and behavioural changes on the elimination of Ebola from Lofa County, Liberia

2017 ◽  
Vol 372 (1721) ◽  
pp. 20160302 ◽  
Author(s):  
Sebastian Funk ◽  
Iza Ciglenecki ◽  
Amanda Tiffany ◽  
Etienne Gignoux ◽  
Anton Camacho ◽  
...  
Keyword(s):  
Reproduction Number ◽  
Control Strategies ◽  
Clinical Intervention ◽  
Credible Interval ◽  
Transmission Model ◽  
Public Health Response ◽  
Healthcare Seeking ◽  
Behavioural Changes ◽  
Treatment Centre ◽  
The Impact

The Ebola epidemic in West Africa was stopped by an enormous concerted effort of local communities and national and international organizations. It is not clear, however, how much the public health response and behavioural changes in affected communities, respectively, contributed to ending the outbreak. Here, we analyse the epidemic in Lofa County, Liberia, lasting from March to November 2014, by reporting a comprehensive time line of events and estimating the time-varying transmission intensity using a mathematical model of Ebola transmission. Model fits to the epidemic show an alternation of peaks and troughs in transmission, consistent with highly heterogeneous spread. This is combined with an overall decline in the reproduction number of Ebola transmission from early August, coinciding with an expansion of the local Ebola treatment centre. We estimate that healthcare seeking approximately doubled over the course of the outbreak, and that isolation of those seeking healthcare reduced their reproduction number by 62% (mean estimate, 95% credible interval (CI) 59–66). Both expansion of bed availability and improved healthcare seeking contributed to ending the epidemic, highlighting the importance of community engagement alongside clinical intervention. This article is part of the themed issue ‘The 2013–2016 West African Ebola epidemic: data, decision-making and disease control’.

scholarly journals Optimal control problem on COVID-19 disease transmission model considering medical mask, disinfectants and media campaign

2020 ◽  
Vol 202 ◽  
pp. 12009
Author(s):  
Dipo Aldila
Keyword(s):  
Optimal Control ◽  
Optimal Control Problem ◽  
Control Problem ◽  
Disease Transmission ◽  
Control Strategies ◽  
Population Based ◽  
Transmission Model ◽  
Media Campaign ◽  
Free Virus ◽  
Final State

In this paper, a system of ordinary differential equation approach is developed to understand the spread of COVID-19. We first formulate the dynamic model by dividing the human population based on their health status, awareness status, and also including the free virus on the environment. We provide a basic analysis of the model regarding the well-posed properties and how the basic reproduction number can be used to determine the final state of COVID-19 in the population. A Pontryagin Maximum’s Principle used to construct the model as an optimal control problem in a purpose to determine the most effective strategies against the spread of COVID-19. Three control strategies involved in the model, such as media campaign to develop an awareness of individuals, medical masks to prevent direct transmission, and use of disinfectant to reduce the number of free virus in the environment. Through numerical simulations, we find that the time-dependent control succeeds in reducing the outbreak of COVID-19. Furthermore, if the intervention should be implemented as a single intervention, then the media campaign gives the most effective cost strategy.

scholarly journals Accelerated partner therapy (APT) partner notification for people withChlamydia trachomatis: protocol for the Limiting Undetected Sexually Transmitted infections to RedUce Morbidity (LUSTRUM) APT cross-over cluster randomised controlled trial

BMJ Open ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. e034806 ◽  
Author(s):  
Claudia S Estcourt ◽  
Alison R Howarth ◽  
Andrew Copas ◽  
Nicola Low ◽  
Fiona Mapp ◽  
...  
Keyword(s):  
Sexually Transmitted Infections ◽  
Primary Outcome ◽  
Controlled Trial ◽  
Partner Notification ◽  
Cluster Randomised Controlled Trial ◽  
Sex Partners ◽  
Sexually Transmitted ◽  
Cluster Randomised ◽  
Heterosexual Women ◽  
Randomised Controlled

IntroductionPartner notification (PN) is a process aiming to identify, test and treat the sex partners of people (index patients) with sexually transmitted infections (STIs). Accelerated partner therapy (APT) is a PN method whereby healthcare professionals assess sex partners, by telephone consultation, before giving the index patient antibiotics and STI self-sampling kits to deliver to their sex partner(s). The Limiting Undetected Sexually Transmitted infections to RedUce Morbidity programme aims to determine the effectiveness of APT in heterosexual women and men with chlamydia and determine whether APT could affectChlamydia trachomatistransmission at population level.Methods and analysisThis protocol describes a cross-over cluster randomised controlled trial of APT, offered as an additional PN method, compared with standard PN. The trial is accompanied by an economic evaluation, transmission dynamic modelling and a qualitative process evaluation involving patients, partners and healthcare professionals. Clusters are 17 sexual health clinics in areas of England and Scotland with contrasting patient demographics. We will recruit 5440 heterosexual women and men with chlamydia, aged ≥16 years.The primary outcome is the proportion of index patients testing positive forC. trachomatis12-16 weeks after the PN consultation. Secondary outcomes include: proportion of sex partners treated; cost effectiveness; model-predicted chlamydia prevalence; experiences of APT.The primary outcome analysis will be by intention-to-treat, fitting random effects logistic regression models that account for clustering of index patients within clinics and trial periods. The transmission dynamic model will be used to predict change in chlamydia prevalence following APT. The economic evaluation will use mathematical modelling outputs, taking a health service perspective. Qualitative data will be analysed using interpretative phenomenological analysis and framework analysis.Ethics and disseminationThis protocol received ethical approval from London—Chelsea Research Ethics Committee (18/LO/0773). Findings will be published with open access licences.Trial registration numberISRCTN15996256.

scholarly journals Per-partnership transmission probabilities for Chlamydia trachomatis infection: evidence synthesis of population-based survey data

2020 ◽  
Author(s):  
Joanna Lewis ◽  
Peter J White ◽  
Malcolm J Price
Keyword(s):  
Evidence Synthesis ◽  
Credible Interval ◽  
Transmission Probability ◽  
Monte Carlo Sampling ◽  
Population Based ◽  
Control Measures ◽  
Chlamydia Infection ◽  
National Study ◽  
Transmitted Infection ◽  
Chlamydia Trachomatis Infection

Abstract Background Chlamydia is the most commonly diagnosed sexually transmitted infection worldwide. Mathematical models used to plan and assess control measures rely on accurate estimates of chlamydia’s natural history, including the probability of transmission within a partnership. Several methods for estimating transmission probability have been proposed, but all have limitations. Methods We have developed a new model for estimating per-partnership chlamydia transmission probabilities from infected to uninfected individuals, using data from population-based surveys. We used data on sexual behaviour and prevalent chlamydia infection from the second UK National Study of Sexual Attitudes and Lifestyles (Natsal-2) and the US National Health and Nutrition Examination Surveys 2009–2014 (NHANES) for Bayesian inference of average transmission probabilities, across all new heterosexual partnerships reported. Posterior distributions were estimated by Markov chain Monte Carlo sampling using the Stan software. Results Posterior median male-to-female transmission probabilities per partnership were 32.1% [95% credible interval (CrI) 18.4–55.9%] (Natsal-2) and 34.9% (95%CrI 22.6–54.9%) (NHANES). Female-to-male transmission probabilities were 21.4% (95%CrI 5.1–67.0%) (Natsal-2) and 4.6% (95%CrI 1.0–13.1%) (NHANES). Posterior predictive checks indicated a well-specified model, although there was some discrepancy between reported and predicted numbers of partners, especially in women. Conclusions The model provides statistically rigorous estimates of per-partnership transmission probability, with associated uncertainty, which is crucial for modelling and understanding chlamydia epidemiology and control. Our estimates incorporate data from several sources, including population-based surveys, and use information contained in the correlation between number of partners and the probability of chlamydia infection. The evidence synthesis approach means that it is easy to include further data as it becomes available.

scholarly journals Traditional and Web-Based Technologies to Improve Partner Notification Following Syphilis Diagnosis Among Men Who Have Sex With Men in Lima, Peru: Pilot Randomized Controlled Trial (Preprint)

2018 ◽  
Author(s):  
Jesse L Clark ◽  
Eddy R Segura ◽  
Catherine E Oldenburg ◽  
Hector J Salvatierra ◽  
Jessica Rios ◽  
...  
Keyword(s):  
Randomized Controlled Trial ◽  
Controlled Trial ◽  
Partner Notification ◽  
Secondary Syphilis ◽  
Syphilis Infection ◽  
Transmitted Infection ◽  
Web Based ◽  
Notification System ◽  
Randomized Controlled ◽  
Sex With Men

BACKGROUND Patient-initiated partner notification (PN) following the diagnosis of a sexually transmitted infection is a critical component of disease control in men who have sex with men (MSM) sexual networks. Both printed and internet-based technologies offer potential tools to enhance traditional partner notification approaches among MSM in resource-limited settings. OBJECTIVE This randomized controlled trial aimed to evaluate the effect of 2 different PN technologies on notification outcomes following syphilis diagnosis among MSM in Peru: a Web-based notification system and patient-delivered partner referral cards. METHODS During 2012-2014, we screened 1625 MSM from Lima, Peru, for syphilis infection and enrolled 370 MSM with symptomatic primary or secondary syphilis (n=58) or asymptomatic latent syphilis diagnosed by serology (rapid plasma reagin, RPR, and Microhemagglutination assay for Treponema pallidum antibody; n=312). Prior to enrollment, potential participants used a computer-based self-interviewing system to enumerate their recent sexual partnerships and provide details of their 3 most recent partners. Eligible participants were randomly assigned to one of 4 intervention arms: (1) counseling and patient-initiated Web-based PN (n=95), (2) counseling with Web-based partner notification and partner referral cards (n=84), (3) counseling and partner referral cards (n=97), and (4) simple partner notification counseling (control; n=94). Self-reported partner notification was assessed after 14 days among 354 participants who returned for the follow-up assessment. RESULTS The median age of enrolled participants was 27 (interquartile range, IQR 23-34) years, with a median of 2 partners (IQR 1-5) reported in the past month. Compared with those who received only counseling (arm 4), MSM provided with access to Web-based partner notification (arms 1 and 2) or printed partner referral cards (arms 2 and 3) were more likely to have notified one or more of their sexual partners (odds ratio, OR, 2.18, 95% CI 1.30-3.66; P=.003 and OR 1.68, 95% CI 1.01-2.79; P=.045, respectively). The proportion of partners notified was also higher in both Web-based partner notification (241/421, 57.2%; P<.001) and referral card (240/467, 51.4%; P=.006) arms than in the control arm (82/232, 35.3%). CONCLUSIONS Both new Web-based technologies and traditional printed materials support patient-directed notification and improve self-reported outcomes among MSM with syphilis. Additional research is needed to refine the use of these partner notification tools in specific partnership contexts. CLINICALTRIAL ClinicalTrials.gov NCT01720641; https://clinicaltrials.gov/ct2/show/NCT01720641 (Archived by WebCite at http://www.webcitation.org/70A89rJL4)

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