Jake, a 25-year-old outdoor enthusiast, presents with a 2-week history of foul-smelling diarrhea, bloating, and abdominal cramps. He denies fever, blood in the stool, or recent foreign travel. On examination, Jake appears mildly dehydrated, and stool analysis confirms the presence of Giardia cysts, leading to a diagnosis of Giardiasis. Which of the following best describes the transmission of Giardiasis?