Equilibrium stability regions with fixed untreated chronic phase infectivity.

<p>The untreated chronic phase infectivity is fixed at (a) and (b) Regions represent values of the risk behaviour initiation rate and equilibrium HAART coverage for which both HIV and risk behaviour are endemic, only risk behaviour is endemic, and neither HIV nor risk behaviour are endemic. The red curve separates the HIV-endemic and HIV-free regions. The blue line separates risk behaviour-endemic and risk behaviour-free regions.