On a Two-Sex Model for Gonorrhea Transmission Dynamics Incorporating Treatment and Condom Use

In  this study we  developed a two sex model for gonorrhea transmission dynamics incorporating treatment and condom use as control measures using a system of ordinary differential equations. We further derive an epidemic threshold as the effective reproduction number,  using the next generation method. We established both the disease-free equilibrium and endemic equilibrium states using the linearization method and the manifold theory respectively. From the analysis of the model and results, it was shown that, the disease free equilibrium state is locally and asymptotically stable if  The implication is that gonorrhea can be eliminated fro the population if the effective reproduction number, is less than unity. The endemic equilibrium state is locally and asymptotically stable for  and this implies that gonorrhea disease can spread and there could disease persistence. Key words: Gonorrhea disease, effective reproduction number, equilibrium state, centre manifold theory

Transmission dynamics of Trichomonas vaginalis: A mathematical approach

AbstractDespite the availability of treatment that is effective, Trichomonas vaginalis infections are still high. A deterministic model for transmission dynamics of Trichomonas vaginalis is presented as a system of non-linear differential equations. Analysis of the reproduction number has shown that an increase in the number of straight women (non-lesbians) infected result in an increase in the number of lesbians infected. This suggests that straight women are turning into lesbians already infected. The disease-free equilibrium is shown to be globally asymptotically stable when the corresponding reproduction number is less than unity. Analytical results and numerical simulations both show that treatment is able to control Trichomonas vaginalis infections. This suggests an effective control of trichomoniasis rests in encouraging and persuading sexual partners of those displaying symptoms to seek treatment. Failure for the asymptomatic to seek treatment (mostly males given that the majority of males does not show symptoms) will continue to fuel the infection

Estabilidad de un modelo matemático del VIH/SIDA considerando el tratamiento y el impacto de la cobertura mediática

A mathematical model is proposed to study the dynamics of the spread of HIV/AIDS with treatment considering media coverage. The subpopulations involved in the study are; susceptible individuals, slow-latency infected individuals, fast-latency infected individuals, symptomatic individuals undergoing treatment, and finally individuals with AIDS. We consider a system of ordinary differential equations that let us to understand the dynamics of the spread of HIV/AIDS, taking into account two non-linear incidence rates that show the influence of media coverage as a disease control. We establish conditions for the stability of this model. The result enables us to evaluate the media coverage impact on the dynamics of the disease. Finally, we show a numerical simulation analysis of the model and a sensitivity analysis corresponding to the parameters.Se propone un modelo matemático que estudia la dinámica de la propagación del VIH/SIDA con tratamiento considerando la cobertura mediática. Las subpoblaciones involucradas en el estudio son; los individuos susceptibles, infectados con latencia lenta, infectados con latencia rápida, individuos sintomáticos en tratamiento y por último individuos con SIDA. Consideramos un sistema de ecuaciones diferenciales ordinarias que nos permiten comprender la dinámica de la propagación del VIH/SIDA, teniendo en cuenta dos tasas de incidencias no lineales que muestran la influencia de la cobertura mediática como un control de la enfermedad. Establecemos condiciones para la estabilidad de este modelo. Este resultado nos permite evaluar el impacto de la cobertura mediática sobre la dinámica de la enfermedad. Finalmente, se muestra un análisis de simulación numérica del modelo y otro de sensibilidad correspondiente a los parámetros

Clinical care of HIV-patients: evaluating progress and future challenges

Since the introduction of combination therapy in 1996, Human Immunodeficiency Virus (HIV) treatment has changed substantially. Over twenty new antiretroviral drugs have been licensed for the treatment of HIV-infection and HIV has been transformed into a long-term chronic infection for many patients. Yet it remains unclear how improved efficacy of new antiretrovirals reported in clinical trials has translated to population-level effectiveness in general clinical care. Nor is it clear how the increasingly chronic nature of HIV-infection, characterised by an ageing HIV-population increasingly suffering from age-related non-infectious co-morbidities and drug-drug interactions, will affect HIV care. Such an evaluation is important not just to measure progress, but also to address future challenges for clinical care in order to develop evidence-based changes to clinical guidelines and ensure continued high-quality care. By analysing a dataset that collects data from all HIV-infected patients in clinical care in the Netherlands it was shown that the use of combination antiretroviral therapy (cART) regimens in the Netherlands closely follows changes in guidelines, to the benefit of patients. While there was no significant improvement in mortality, newer drugs with better tolerability and simpler dosing resulted in improved immunological and virological recovery and reduced incidence of switching due to toxicity and virological failure. An individual-based model of the ageing HIV-population in the Netherlands was constructed and used to quantify and evaluate the future challenges posed by an ageing HIV-population. The model showed that the age-structure of HIV-patients in the Netherlands is rapidly shifting to older age. By 2030, almost three quarters of patients will be aged 50 or over. This will result in an increased burden of co-morbidity, polypharmacy and an increasing proportion of patients who will experience potential complications with their HIV-treatment. Cardiovascular disease (CVD) in particular will become a major burden of co-morbid disease. Integrating a smoking cessation programme or changing HIV-treatment guidelines to recommend prescribing a polypill for CVD to all HIV-patients aged 45 or 55 years and over could improve the burden of CVD, improve patient outcome and be cost saving in the long-term.Open Acces

Development of a Multi Sexually Transmitted Infections Modelling Software

Background Human Immunodeficiency Virus (HIV) and other sexually transmitted infections (STIs) do not operate in isolation; people with risk-taking sexual behaviour in particular are more likely to be co-infected. In this complex landscape policy makers are limited by monetary constraints and still need to find optimal coverage solutions. Disease modelling could help in this context but modelling software accessible to decision makers examining various STIs and HIV is rare. Methods I developed an STI modelling software, using the programming language Java, consisting of a model for each STI and a graphical user interface. The models were drafted based on literature reviews and subsequently refined by experts, e.g. STI clinicians and policy makers. Afterwards, all models were internally and externally validated. The user interface was developed with user interface development experts and policy makers. The resulting software was validated using the MenSS trial. Results The software consists of different models, which serve individual purposes. All models are interacting, individual-based discrete event simulations. Separate disease models, which describe the progression of chlamydia, gonorrhoea, HIV, and syphilis, and their corresponding sequelae describe the progression of the respective infections. Sexual network models are used to describe the formation and dissolution of partnerships and thereby the occurrence of sexual contacts. A user can choose from four different network models which are included in the software. Clinical pathway models, which describe interventions, like screening or treatment for all included STIs, reflect the current English setting. All models have been validated using sensitivity analyses and publicly available data sources. The user interface has been validated by policy makers. Conclusion With this modelling software policy makers can compare intervention options, existing and hypothetical, to each other. All parameters, formulas, model structures, and clinical pathways are editable and well documented. The software is not bound to a specific research question but can be fitted for different scenarios to be reused and updated if needed, e.g. if medicinal knowledge changes. For example, by adapting parameters which describe treatment pathways the software can be used in non-English scenarios

Évolution de l'épidémie du VIH en présence d'interventions ciblant le milieu prostitutionnel au Bénin : analyses de tendance et des techniques de collectes de données comportementales

Cette étude à trois volets a été conduite au Bénin et porte sur 1) l’évaluation de la tendance des infections sexuellement transmissibles y compris l’infection à VIH (IST/VIH) et des comportements sexuels associés chez les travailleuses du sexe (TS) de 1993 à 2008 dans un contexte où se développaient des interventions préventives ciblant le milieu prostitutionnel (projet canadien de 1992 à 2006 suivi de l’appropriation des activités par la partie nationale), tout en examinant l’impact du changement dans le modèle d’intervention après le désengagement du projet canadien en 2006, 2) la comparaison des prévalences des IST/VIH et des comportements associés dans la population générale de Cotonou entre 1998 et 2008, 3) la comparaison de la technique d’entrevue individuelle face-à-face (FTFI) à la nouvelle technique d’entrevue de groupe par boîte de votation confidentielle (PBS). De 1993 à 2008, il y a eu une diminution significative dans les prévalences des IST/VIH chez les TS. Ces diminutions étaient très marquées à Cotonou pour le VIH (53,3% à 30,4%; p-ajusté=0,0001) et la gonorrhée (43,2% à 6,4% ; p-ajusté < 0,0001). Par contre, il y a eu une hausse significative dans la prévalence de la gonorrhée entre 2005 et 2008 (rapport de prévalences : RP=1,76 ; Intervalle de confiance à 95% : [1,17-2,65]) après le désengagement du projet canadien. À Cotonou où les interventions ciblées ont connu une intensification entre 2001 et 2006, la prévalence du VIH a diminué significativement de 83% entre 1998 et 2008 (3,0 à 0,5%; p-ajusté=0,002) chez les jeunes hommes de 15 à 29 ans de la population générale. Le PBS a permis d’éliciter une fréquence accrue des comportements sexuels à risque du VIH par rapport au FTFI, et réduirait donc le biais de désirabilité sociale. L’étude met en évidence que dans les pays où l’épidémie du VIH est encore concentrée au sein des TS comme c’est le cas au Bénin, le ciblage préventif du milieu prostitutionnel reste l’intervention la plus efficace pour contrôler l’épidémie. Dans ce contexte où l’exactitude dans la mesure des comportements sexuels est d’importance capitale pour la planification d’interventions efficaces ainsi que leur évaluation, la technique PBS devrait être intégrée aux enquêtes comportementales.This study carried out in Benin had three components associated with the following objectives: 1) to assess the time trends in the prevalence of HIV and other sexually transmitted infections (HIV/STI) and associated sexual behaviors among female sex workers (FSW) from 1993 to 2008, while preventive interventions targeting the sex work milieu were ongoing (developed by the Canadian project from 1992 to 2006 before being taken over by the national authorities) and assess the impact of change in intervention model on trends after the disengagement of the project in 2006, 2) to assess the change in HIV/STI prevalence and associated behaviors in the general population of Cotonou between 1998 and 2008, 3) to compare the method of individual face-to-face interviews (FTFI) to that of polling booth surveys (PBS). From 1993 to 2008, there was a significant decrease in HIV/STI prevalence among FSW and this decrease was very strong in Cotonou for HIV (53.3% to 30.4%, adjusted-p=0.0001) and gonorrhea (43.2 % to 6.4%, adjusted-p < 0.0001). On the other hand, from 2005 to 2008, there was a significant increase in gonorrhea prevalence (prevalence ratio: PR=1.76, 95% confidence interval: [1.17-2.65]) after disengagement of the Canadian project in 2006. In Cotonou, where the targeted interventions were reinforced between 2001 and 2006, HIV prevalence significantly decreased by 83% between 1998 and 2008 (3.0 to 0.5 %, adjusted-p=0.002) among young men of the general population aged 15-29 years. More HIV-related risky sexual behaviors were reported through PBS than through FTFI, thus suggesting that the former reduces social desirability biases. The study shows that in countries where the HIV epidemic is still concentrated among FSW as in Benin, preventive interventions targeting the sex work milieu remain the most effective intervention for a reliable control of the epidemic. Within this context where accurate data on sexual behaviors are of central importance for the design of effective preventive interventions as well as the assessment of their impact, PBS should be integrated into behavioral surveys