<prompt> rK 39 antigen is useful for diagnosis of:DiphtheriaDiphtheria TuberculosisLprosyKala azar  <response>: Antigens used in different tests: Test disease Antigen used Mantoux test PPD Lepromin test Dhamendra antigen Schick test Schick toxin Dipstick test- malaria Histidine rich protein type II Kala azar Rk 39 antigen 