A within host system dynamics model of Hiv/Aids, tuberculosis and malaria treatment policy

Abstract

Simulation and Modelling have a good history of application in numerous decision support health cases where the objective is of a managerial or policy nature. In- formation and Communication Technologies(ICT) in health care decision support with the application of simulation methods is receiving attention as indisputable advantages of these methods are getting widely recognized. Cutting edge eHealth researches have led to signi cant technological achievement, covering an expan- sive range of health services. Understanding the dynamics of disease is of crucial importance particularly in terms of risk assessment and evaluation of intervention policies against a large-scale epidemic outbreak. However most of the information is available after the spread itself, and preemptive assessment is far from vital. Chronic diseases such as HIV, TB and Malaria e.tc. are widely studied and mod- elled. Apparently the researches carried out have been on the pathogenesis of the diseases individually i.e. HIV alone, TB alone and Malaria alone. Others researches have focussed on HIV and TB or HIV and Malaria but none has gone beyond trio infections which is quite common. With the advent of HIV, PLHIV are more prone to cofactors with the resultant of immune activation. Immune ac- tivation leads to the increase of HIV viruses as a result of bursting of resting TH1 cells once they are activated since HIV resides in resting TH1. This research aimed at studying immune activation for people living with HIV when they are attacked by other diseases like TB and Malaria which is quite common. The research was bordering on cells of the immune system that conduct adaptive immunity. Immune system is quite complex to understand even so when the system is attacked by pathogens. As such, System Dynamics Modelling was applied to improve the understanding of immune system behaviour for people living with HIV in light of Malaria and TB. To understand the full range of immune cells and their activities, behaviour of pathogens and communication of immune cells to resist attack, eld studies were carried out. Problems associated with the immune system inability to curb pathogens as a result of immune activation, how the HIV virus takes advantage of activated cells through attack by mycobacterium and merozoites were sought after in the eld studies. The Research presents the overall architecture of the HTM system which constitutes cells, agents of the immune system like interleukins, interferons, natural killer cells as well as information ow. Qualitative research was done using causal loop diagrams as well as simulation through stock and ow diagram to capture the complex and dynamic nature of the immune system. The use of CLD provided deeper understanding of the structure of the cells of the immune system while simulation through stock and ow diagram provided the dynamic behaviour of the same. The results of the study show that activation of the immune system by TB and Malaria for people living with HIV have overwhelming in uence in their health. The study rea rms the need to maintain rested TH1 cells, as wells develop policies

or regimens to deal with synergistic activities of TB and Malaria to PLHIV. The developed HTM system demonstrates the dynamics arising from the complexity, delays and non-linearlity which characterize the immune system. Based on the results of the simulations experiments, the suggested intervention that could im- prove the lives of PLHIV include the following: designing of relevant health IS, strengthening of healthcare system, adoption of ICTs innovations to improve e - ciency and improving literacy levels. The HTM model and the causal loop diagrams presents signi cant knowledge in terms of structure and the understanding of HTM system. The model captures requisite information requirements, key activities of the immune cells which repre- sents the adaptive nature or collapse of the immune system. The model provides tools that tests di erent policies thus making it useful for strategic planning and policy debate.