  By utilizing a background field effective theory, we compute the collisional
energy loss of a heavy-quark moving through a semi-quark-gluon plasma
characterized by nontrivial holonomy for Polyakov loops. We consider the
elastic scatterings between the incident heavy-quark and the thermal partons
with both hard and soft momentum transfers. As compared to the energy loss
obtained from the perturbation theory, the hard processes get modified through
the thermal distribution functions that depend on the background field, while
the proper treatment of the soft processes strongly relies on the use of the
hard-thermal-loop resummed gluon propagator derived from the background field
effective theory. Our results show that the heavy-quark energy loss is
significantly suppressed in the semi-quark-gluon plasma due to a background
field that is self-consistently generated in the effective theory. On the other
hand, the suppression has a strong dependence on the temperature of the plasma
which becomes negligible above $2\sim 3 $ times the critical temperature. For a
realistic coupling constant, ignoring a relatively weak dependence on the
heavy-quark velocity, the suppression on the collisional energy loss can be
approximated by an overall factor determined solely by the background field.
This simple conclusion is expected to be useful for phenomenological
applications in the heavy flavor physics.
