This parasite is most often found in the intestines and rarely causes infections, even in people with compromised immune systems. Less than 5 percent of people in the United States are infected with the organism. Chilomastix makes it into the human body via simple food or water contamination or the fecal-oral route. This means that transmission occurs from the feces of an infected individual to the mouth (by ingestion) of a new host. Even the tiniest amount of fecal matter, like what might be left microscopically on the hand after a visit to the toilet, can get transferred to another person and cause infection.
Chilomastix burrows into the intestinal tract itself, specifically the colon. Although the organism is microscopic and can be found only through a stool sample test, it doesn't have the ability to enter the cells of the intestinal wall, nor is it capable of spreading to other parts of the body (at least, that is what they are saying so far).