Dr. Cahill is also very old. He is probably nearing retirement. It's sad that he's one of the last medical parisitologists out there in the U.S. I actually can't even think of any other doctor that does what he does. His test doesn't find everything tho, after three visits to him he wasn't able to help me and he does minimal blood testing as well. Dr. Cahill is also a little shady ar his office he barely even talks to you for your 300-500 dollar appointment. Dr. Yu on the other hand at least puts some treatment plan together from the first visit.