  We rewrite abstract delay equations to nonautonomous abstract Cauchy problems
allowing us to introduce a Magnus-type integrator for the former. We prove the
second-order convergence of the obtained Magnus-type integrator. We also show
that if the differential operators involved admit a common invariant set for
their generated semigroups, then the Magnus-type integrator will respect this
invariant set as well, allowing for much weaker assumptions to obtain the
desired convergence. As an illustrative example we consider a space-dependent
epidemic model with latent period and diffusion.
