  Highly Pathogenic Avian Influenza A H5N6 is a mutated virus of Influenza A
H5N1 and a new emerging infection that recently caused an outbreak in the
Philippines. The 2017 H5N6 outbreak resulted in a depopulation of 667,184
domestic birds. In this study, we incorporate half-saturated incidence in our
mathematical models and investigate three intervention strategies against H5N6:
isolation with treatment, vaccination and modified culling. We determine the
direction of the bifurcation when $\mathcal{R}_0 = 1$ and show that all the
models exhibit forward bifurcation. We administer optimal control and perform
numerical simulations to compare the consequences and implementation cost of
utilizing different intervention strategies in the poultry population. Despite
the challenges of applying each control strategy, we show that culling both
infected and susceptible birds is a better control strategy in prohibiting an
outbreak and avoiding further recurrence of the infection from the population
compared to confinement and vaccination.
