The MSIH program does a marginal (if not horrible) job of their standard MD program - it is unimaginable that they try to do an MPH as well.
It is completely and totally untrue that 1/3 of graduates do MPH's - in the past 5 years, maybe 5 or 6 have done MPH's. Many students find they need to take a year off between 3-4 or after 4th year b/c of problems getting residencies. A handful of the them did MPH's during that year.