  In this study initially, we propose an age structured model and calculate the
equilibrium points and basic reproduction number. Later we propose an optimal
control problem to understand the roles of treatment in controlling the
epidemic. From the Stability analysis we see that the infection free
equilibrium remains asymptotically stable whenever $R_0 < 1$ and as $R_0$
crosses unity we have the infected equilibrium to be stable. From the
sensitivity analysis parameters $u_{11}$, $b_1$, $\beta_1$, $d_1$ and $\mu$
were found to be sensitive. Findings from the Optimal Control studies suggests
that the infection among the adult population(age $\geq 30)$ is least
considering the second control $u_{12}$ whereas, when both the controls
$u_{11}$ and $u_{12}$ are considered together the infectives is minimum in case
of young populations(age $ \leq 30$). The cumulative infected population
reduced the maximum when the second control was considered followed by
considering both the controls together. The control $u_{12}$ was effective for
mild epidemic $(R_0 \in(1, 2))$ whereas control $u_{11}$ was found to be highly
effective when epidemic was severe $(R_0 \in(2, 7))$ for the population of age
group $(\leq 30)$. Whereas for age group $(\geq 30)$ the control $u_{12}$ was
highly effective for the entire range of basic reproduction number. The effect
of saturation level in treatment is also explored numerically.
