Their hesitancy is understandable. 

The medical community promised them 'A Treatment for Syphilis' when, in fact, the volunteers were shot up with God-knows-what, merely to serve as subjects to be monitored throughout the disease's progression-- lots of White Papers and lectures for academia. 

Now, Medicine is asking them to 'voluntarily' submit to an infusion-treatment protocol with five answers for every question posed.  

It's a sad situation.