title: A Stochastic Differential Equation Model for the Spread of HIV amongst People Who Inject Drugs.
abstract: We introduce stochasticity into the deterministic differential equation model for the spread of HIV amongst people who inject drugs (PWIDs) studied by Greenhalgh and Hay (1997). This was based on the original model constructed by Kaplan (1989) which analyses the behaviour of HIV/AIDS amongst a population of PWIDs. We derive a stochastic differential equation (SDE) for the fraction of PWIDs who are infected with HIV at time. The stochasticity is introduced using the well-known standard technique of parameter perturbation. We first prove that the resulting SDE for the fraction of infected PWIDs has a unique solution in (0, 1) provided that some infected PWIDs are initially present and next construct the conditions required for extinction and persistence. Furthermore, we show that there exists a stationary distribution for the persistence case. Simulations using realistic parameter values are then constructed to illustrate and support our theoretical results. Our results provide new insight into the spread of HIV amongst PWIDs. The results show that the introduction of stochastic noise into a model for the spread of HIV amongst PWIDs can cause the disease to die out in scenarios where deterministic models predict disease persistence.
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, UK.
authors.forename: Yanfeng
authors.identifier: 0000-0001-8348-3092
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, UK.
authors.forename: David
authors.identifier: 0000-0001-5380-3307
authors.initials: D
authors.lastname: Greenhalgh
authors.affiliation: Department of Mathematics and Statistics, University of Strathclyde, Glasgow G1 1XH, UK.
authors.forename: Xuerong
authors.initials: X
authors.lastname: Mao
mesh_terms: D000465:Algorithms; D050936:Basic Reproduction Number; D003198:Computer Simulation; D058872:Epidemics; D015658:HIV Infections / Q000150:complications* / Q000453:epidemiology / Q000635:transmission*; D006801:Humans; D015233:Models, Statistical; D011336:Probability; D013269:Stochastic Processes; D015819:Substance Abuse, Intravenous / Q000150:complications* / Q000453:epidemiology