Optimal intervention strategies of staged progression HIV infections through an age-structured model with probabilities of ART drop out

¹ University Cheikh Anta Diop, Department of Mathematics and Informatics, Faculty of Science and Technic, Dakar, Sénégal.
² MIVEGEC, Univ. Montpellier, IRD, CNRS, Montpellier, France.
³ University of Yaounde I, National Advanced School of Engineering, Yaoundé, Cameroon.

^* Corresponding author: ramses.djidjoudemasse@ird.fr

Received: 17 November 2020
Accepted: 22 April 2021

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.