A 23-year-old female presented to her primary care provider with abdominal pain, cramps, flatulence, and diarrhea five days after returning from a white water rafting trip.
Stool specimens were collected in 10% formalin and zinc polyvinyl alcohol (Zn-PVA) and sent to a reference lab for routine ova-and-parasite (O&P) testing. Figures A-D show what was observed on a trichrome-stain slide of stool preserved in the Zn-PVA. Images were captured at 1000x magnification with oil.
What is your diagnosis? Based on what criteria?