the reason may be because certain powerful drugs, especially steroids like prednisone etc, deplete many of the bodies vitamins and minerals.  In this case the B vitamins are depleted.  Studies have shown mosquitos are NOT attracted to those with normal levels of Thiamine or B1 in their blood.  Apparently the B1 is secreted through the skin (us humans cannot smell it) but mosquitos can.  If they detect B1, they are repulsed and go somewhere else.  Just a thought.

-Beth