  We investigate the celebrated mathematical SICA model but using fractional
differential equations in order to better describe the dynamics of HIV-AIDS
infection. The infection process is modelled by a general functional response
and the memory effect is described by the Caputo fractional derivative.
Stability and instability of equilibrium points are determined in terms of the
basic reproduction number. Furthermore, a fractional optimal control system is
formulated and the best strategy for minimizing the spread of the disease into
the population is determined through numerical simulations based on the derived
necessary optimality conditions.
