I'm a person who's got very good insurance and had plenty of normal blood tests, but the only times my blood has been tested for Chagas are the many times I've donated blood, for which I received cookies, juice, movie tickets and once a UCLA blanket but never money. It's also a question on the donation screening, "have you ever tested positive..." but I wasn't aware of the testing until I read the article. If you didn't have a noticeable reaction to the initial infection, you wouldn't think to get tested for it.