A few things - there is a Doctor Simon Yu in St Louis that treats parasites infections he does alternative testing though and not scientific so that's one thing to keep in mind.
There are three tests that have potential now -Parawellness, Arizona Parisitology Center and DRG Labs - that one needs a doctor to order it - uses DNA testing rather than ova which can easily miss stuff.
For what it's worth at least in America we can leave reviews of doctors we've seen so if they act like scumbags at least can let other people know too and we can also choose to see a different doctor. It seems like alternative medicine doctors are more aware of the parasite issue than the mainstream doctors. The mainstream doctors are generally useless when it comes to this stuff, they are a joke.