I want to know the answer to the following question:
What is it difficult to demonstrate the presence of in Chagas disease?
All the background I'm provided with is that "In this case, xenodiagnosis involves the use of the vector of the Chagas agent T. cruzi, an uninfected triatomine bug, which takes a blood meal from a person suspected of having been infected.". Is that enough to answer the question?
Answer: no