scholarly journals Comparison of two simulators for individual based models in HIV epidemiology in a population with HSV 2 in Yaoundé (Cameroon)

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Diana M. Hendrickx ◽  
João Dinis Sousa ◽  
Pieter J. K. Libin ◽  
Wim Delva ◽  
Jori Liesenborgs ◽  
...  

AbstractModel comparisons have been widely used to guide intervention strategies to control infectious diseases. Agreement between different models is crucial for providing robust evidence for policy-makers because differences in model properties can influence their predictions. In this study, we compared models implemented by two individual-based model simulators for HIV epidemiology in a heterosexual population with Herpes simplex virus type-2 (HSV-2). For each model simulator, we constructed four models, starting from a simplified basic model and stepwise including more model complexity. For the resulting eight models, the predictions of the impact of behavioural interventions on the HIV epidemic in Yaoundé-Cameroon were compared. The results show that differences in model assumptions and model complexity can influence the size of the predicted impact of the intervention, as well as the predicted qualitative behaviour of the HIV epidemic after the intervention. These differences in predictions of an intervention were also observed for two models that agreed in their predictions of the HIV epidemic in the absence of that intervention. Without additional data, it is impossible to determine which of these two models is the most reliable. These findings highlight the importance of making more data available for the calibration and validation of epidemiological models.

2019 ◽  
Author(s):  
Diana M Hendrickx ◽  
João Dinis Sousa ◽  
Pieter J.K. Libin ◽  
Wim Delva ◽  
Jori Liesenborgs ◽  
...  

ABSTRACTModel comparisons have been widely used to guide intervention strategies to control infectious diseases. Agreement between different models is crucial for providing robust evidence for policy-makers because differences in model properties can influence their predictions. In this study, we compared models implemented by two individual-based model simulators for HIV epidemiology in a population with Herpes simplex virus type 2 (HSV-2). For each model simulator, we constructed four models, starting from a simplified basic model and stepwise including more model complexity. For the resulting eight models, the predictions of the impact of behavioural interventions on the HIV epidemic in Yaoundé (Cameroon) were compared. The results show that differences in model assumptions and model complexity can influence the size of the predicted impact of the intervention, as well as the predicted qualitative behaviour of the HIV epidemic after the intervention. Moreover, two models that agree in their predictions of the HIV epidemic in the absence of intervention can have different outputs when predicting the impact of interventions. Without additional data, it is impossible to determine which of these two models is the most reliable. These findings highlight the importance of making more data available for the calibration and validation of epidemiological models.


2018 ◽  
Author(s):  
Jori Liesenborgs ◽  
Diana M Hendrickx ◽  
Elise Kuylen ◽  
David Niyukuri ◽  
Niel Hens ◽  
...  

ABSTRACTSimpactCyan is an open-source simulator for individual-based models in HIV epidemiology. Its core algorithm is written in C++ for computational efficiency, while the R and Python interfaces aim to make the tool accessible to the fast-growing community of R and Python users. Transmission, treatment and prevention of HIV infections in dynamic sexual networks are simulated by discrete events. A generic “intervention” event allows model parameters to be changed over time, and can be used to model medical and behavioural HIV prevention programmes. First, we describe a more efficient variant of the modified Next Reaction Method that drives our continuous-time simulator. Next, we outline key built-in features and assumptions of individual-based models formulated in SimpactCyan, and provide code snippets for how to formulate, execute and analyse models in SimpactCyan through its R and Python interfaces. Lastly, we give two examples of applications in HIV epidemiology: the first demonstrates how the software can be used to estimate the impact of progressive changes to the eligibility criteria for HIV treatment on HIV incidence. The second example illustrates the use of SimpactCyan as a data-generating tool for assessing the performance of a phylodynamic inference framework.


2015 ◽  
Vol 34 (5) ◽  
pp. 279-283 ◽  
Author(s):  
Magidah Kobty

AbstractOne of the most common sexually transmitted infections is the herpes simplex virus (HSV) Type 2. Although the incidence of newborn infection is not as common as in adults, approximately 1,500 neonates are diagnosed annually with HSV infection. HSV can be detrimental to the life of a newborn, with morbidity and mortality rates of up to 65 percent. This article addresses the maternal and fetal complications of HSV and the impact of HSV on the newborn along with diagnostic evaluation methods. In addition, treatment options and evidence-based practices regarding HSV are defined. Despite growing technology and medical treatment for early identification of HSV, this virus remains challenging and can deeply impact the life of an infant and his or her family. Early diagnosis, treatment, and intervention of an infant with HSV are crucial to ensure the livelihood of the newborn.


2008 ◽  
Vol 84 (5) ◽  
pp. 356-360 ◽  
Author(s):  
J R Glynn ◽  
A C Crampin ◽  
B M M Ngwira ◽  
R Ndhlovu ◽  
O Mwanyongo ◽  
...  

2014 ◽  
Vol 46 (2) ◽  
pp. 183-206 ◽  
Author(s):  
Judith Clifton ◽  
Daniel Díaz-Fuentes ◽  
Marcos Fernández-Gutiérrez

2000 ◽  
Vol 125 (3) ◽  
pp. 685-692 ◽  
Author(s):  
A. ESKILD ◽  
S. JEANSSON ◽  
J. A. HAGEN ◽  
P. A. JENUM ◽  
A. SKRONDAL

In this study the impact of pregnancy duration on the measured level of HSV-2 antibodies was assessed. The study population comprised 35940 pregnant women in Norway, in 1992–4, followed during pregnancy. A random sample of 960 women was selected. A mean of 2·6 serum samples from each woman were analysed for HSV-2 specific IgG antibodies at different times in pregnancy. Crude and adjusted odds ratios were estimated in logistic regression models taking all observations per women into account. Twenty-seven percent of the pregnant women had antibodies against HSV-2 in the first trimester. The adjusted odds ratio of being HSV-2 antibody positive decreased during the pregnancy and was 0·5 (0·2–0·9, 95% confidence interval) in the 40th as compared to the 10th week of pregnancy. About 50% of initially HSV-2 positive women did not have detecable antibodies by the end of the pregnancy. This may be explained by haemodilution during pregnancy. Our findings have diagnostic implications and should encourage further studies.


2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Jori Liesenborgs ◽  
Diana M. Hendrickx ◽  
Elise Kuylen ◽  
David Niyukuri ◽  
Niel Hens ◽  
...  

AbstractSimpactCyan is an open-source simulator for individual-based models in HIV epidemiology. Its core algorithm is written in C++ for computational efficiency, while the R and Python interfaces aim to make the tool accessible to the fast-growing community of R and Python users. Transmission, treatment and prevention of HIV infections in dynamic sexual networks are simulated by discrete events. A generic “intervention” event allows model parameters to be changed over time, and can be used to model medical and behavioural HIV prevention programmes. First, we describe a more efficient variant of the modified Next Reaction Method that drives our continuous-time simulator. Next, we outline key built-in features and assumptions of individual-based models formulated in SimpactCyan, and provide code snippets for how to formulate, execute and analyse models in SimpactCyan through its R and Python interfaces. Lastly, we give two examples of applications in HIV epidemiology: the first demonstrates how the software can be used to estimate the impact of progressive changes to the eligibility criteria for HIV treatment on HIV incidence. The second example illustrates the use of SimpactCyan as a data-generating tool for assessing the performance of a phylodynamic inference framework.


2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
A. Mhlanga

Herpes simplex virus type 2 (HSV-2) is one of the major sexually transmitted infections in sub-Saharan prisons and the major driver of HIV. In this paper, we propose and analyze a basic mathematical model for the spread of HSV-2 in prisons. We compute the basic reproduction number and demonstrate that it is a sharp threshold for disease dynamics. The impacts of counseling and education of HSV-2-infected individuals are examined. Equilibrium states of the model are determined and their stability is investigated. The basic model is then extended to incorporate a time-dependent intervention strategy. The aim of the control is tied to reducing the number of infectious individuals through early detection, education, and counseling of the infected. The Pontryagin’s Maximum Principle is used to characterize the optimal level of the control, and the resulting optimality system is solved numerically.


2010 ◽  
Vol 87 (1) ◽  
pp. 22-27 ◽  
Author(s):  
A. M. Foss ◽  
P. T. Vickerman ◽  
P. Mayaud ◽  
H. A. Weiss ◽  
B. M. Ramesh ◽  
...  

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