What Causes A Repeated Recurrence Of Typhoid Fever Every Time, After Completing A Course Of Medication?

I got Dengue and Typhoid in Nobember.After Consult with doctor My Dengue was cured but my typhoid was not cured and I have been taking medicine for typhoid since November. But once my medicine end the Typhoid fever came back. Iconsult with many doctors but my typhoid fever is not cured permanently and I have been suffering from it from November.