Xenodiagnosis

I've read some pretty crazy things in the year and a half that I've been in medical schools, but this has to rank somewhere near the top.  On diagnosis of Chagas' disease, caused by the protozoon Trypanosome cruzi:

 

 

"Xenodiagnosis: 40 laboratory-grown reduviid bugs are allowed to feed on a patient, and one month later the bugs' intestinal contents are examined for the parasite" (Clinical Microbiology Made Ridiculously Simple, p. 339).

I'm sorry, but why would you subject patients to being eaten alive by the same bug that may have given them the disease from which they're currently suffering?  Isn't there something ethically and psychologically disturbing about this, especially when you could just as easily (and much less painfully) try to visualize trypomastigotes in a blood sample?  I just can't imagine what it would be like to be "fed on" by 40 bugs at once.

Speaking of things I can't imagine, it's time to go do my first urological and gynecological exams!  WOOHOO!