We examine the electron density profile expected in the lower ionosphere due to a 0.2-s whistler-induced electron precipitation (WEP) burst with experimentally determined properties. The ionization rate in the lower ionosphere due to a single such WEP event has a height variation with a rather broad maximum, leading to additional electron densities of ~5 electrons cm-3 stretching over altitudes of ~75--92 km. For ambient nighttime conditions a single WEP burst with these parameters will lead to a significant electron density changes only for altitudes below ~85 km. We go on to consider the cumulative response of the nighttime D region to a sustained series of WEP bursts observed through Trimpi perturbation activity on one night in the Antarctic. For altitudes >70 km, significant long-term changes in electron densities due to WEP bursts can occur. The additional WEP-produced ionization leads to increases in the high-altitude electron densities, until a new equilibrium level is reached. Peak changes in electron density are ~16 times ambient at 85 km and ~7 times ambient at 90 km, occurring in the ~15-min period during which the WEP rate is at its peak (~4.5 per min). The simulation suggests that electron density levels settle into an new quasi-equilibrium state during the ~3-hour period where the ionization at 85-km altitude is 10--12 times ambient due to WEP bursts occur at ~3 min-1. The ionization changes produced by WEP bursts lead to lower reflection heights for VLF and LF radio waves (in the Earth-ionosphere waveguide). While significant short-term changes in reflection heights are likely, realistic long-term changes in WEP occurrence rates do not appear likely to be able to explain the reported ~2 km decrease in LF reflection heights observed during the last 35 years.