Sarah, a 28-year-old avid hiker, presents to the clinic with a 10-day history of foul-smelling diarrhea, abdominal cramps, and bloating. She describes her stools as greasy and difficult to flush. She has also experienced nausea and weight loss over the past week. On further questioning, Sarah reports drinking untreated water from a mountain stream during a recent camping trip. Stool analysis reveals pear-shaped trophozoites with two nuclei and a ventral sucking disk. Which of the following best describes the mechanism of this protozoal intestinal infection?
