Abstract

In this paper, we construct a model to describe the transmission of HIV in a homogeneous host population. By considering the specific mechanism of HIV, we derive a model structured in three successive stages: (i) primary infection, (ii) long phase of latency without symptoms, and (iii) AIDS. Each HIV stage is stratified by the duration for which individuals have been in the stage, leading to a continuous age-structure model. In the first part of the paper, we provide a global analysis of the model depending upon the basic reproduction number ℜ0. When ℜ0 ≤ 1, then the disease-free equilibrium is globally asymptotically stable and the infection is cleared in the host population. On the contrary, if ℜ0 > 1, we prove the epidemic’s persistence with the asymptotic stability of the endemic equilibrium. By performing the sensitivity analysis, we then determine the impact of control-related parameters on the outbreak severity. For the second part, the initial model is extended with intervention methods. By taking into account antiretroviral therapy (ART) interventions and the probability of treatment drop out, we discuss optimal intervention methods which minimize the number of AIDS cases.

Highlights

  • human immunodeficiency virus (HIV) weakens your immune system by destroying cells that are essential for fighting diseases and infections

  • The complexity of HIV infection is linked to many elements that involve the specific mechanism of infection [22]

  • In the absence of treatment, the HIV infection goes through three successive stages

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Summary

Introduction

In the absence of treatment, the HIV infection goes through three successive stages. Primary infection: The risk of transmission is high during this phase because of the high viral load at this stage of the infection [21, 40, 51]. This stage is characterized by occurrence of symptoms similar to those of a cold or mild influenza (fever, rashes, fatigue, headaches) which disappear spontaneously after a few weeks [1, 51]. AIDS stage: Because of its constant solicitation, the immune system becomes weaker and weaker until it can no longer defend itself against many pathogen agents and prevent the occurrence of serious or fatal diseases [1, 51]

Waiting time within HIV infection stages
The model
Aims
Preliminaries
Existence of semiflow
Setting model parameters
Transmission rate
Typical epidemic dynamics simulated with the model
Global sensitivity analysis
Optimal intervention strategies
Extended model with intervention methods
Optimal control problem
The necessary optimality condition
Discussion
Performance of control strategies
Effect of intervention only at HIV stage 1 or 2
Combined effect of intervention at both HIV stages
Populations heterogeneity
Conflict of interest
Findings
Technical materials

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