WordNet (r) 3.0 (2006):

transmittable
    adj 1: (of disease) capable of being transmitted by infection
           [syn: catching, communicable, contagious,
           contractable, transmissible, transmittable]

Moby Thesaurus II by Grady Ward, 1.0:

22 Moby Thesaurus words for "transmittable":
   assignable, communicable, conductive, consignable, contagious,
   conveyable, expressable, impartable, interchangeable, mailable,
   metathetic, movable, portable, portative, removable, transferable,
   transfusable, transmissible, transmissive, transportable,
   transportative, transposable