Fear is a wonderful selling point.
As you sit in the waiting room trying your best not to look up at medical-looking posters that warn you about a virtual ten-plagues of disease that you're certain to encounter on your journey, you slowly become oblivious to the ridiculous price of this service.
You become afraid enough that you become convinced that you need these sugar pills.
A few hundred dollars is a relatively small insurance policy to avoid having the skin-melting-off condition or the brain-turning-to-maggot illness or any of the other modern day horrors that apparently exist. You're not going to be the one idiot who tries to prove them wrong.
They seem to know what they're doing.
I didn't get ebola on my trip.
Yet.