xen·o·di·ag·no·sis 
(zĕn′ə-dī′əg-nōsĭs, zē′nə-)
(zĕn′ə-dī′əg-nōsĭs, zē′nə-)n. pl. xen·o·di·ag·no·ses (-sēz)
Diagnosis of an infectious disease at an early stage by exposing a presumably infected individual or tissue to a clean, laboratory-bred mosquito, tick, or other vector and then examining the vector for the presence of the infective microorganism.
xen′o·di·ag·nostic (-nŏstĭk) adj.