Note that the organisms are cut in various planes so that you only rarely see a perfect pear shaped organism with 2 nuclei.
As part of this case, I asked the readers to propose a hypothetical scenario on how this infection was acquired. These are some of the answers I received:
1. Young, idealistic univerisity graduate takes the year before medical school to hike from Katahdin to Springer on the Appalachian Trial. Along about early October, somewhere in Blue Ridge of North Carlolina/Tennessee, after testing the limits of "minimalism" and ceasing to filter-sterilize his drinking water, he develops diarrhea so profuse that he's forced to hole up in a remote shelter for several days to regain strength. It is there that he first entertains a notion that the seemingly pristine "mountain streams" probably do serve as primary watershed for the many high-elevation pastures of nearby dairy and beef herds.
2. "Parasite Gal" and husband go hiking in the woods, get thirsty, and drink unfiltered water from a stream. Then, 24 hours later, they wish they were back in London.
I must admit that I am less fond of the second scenario, since it involves me personally!
Thank you for the creative responses.