This organism lives in the large intestine and causes diarrhoea. Ciliates are widely spread as pathogens and commensals in other animals. One species lives in the gut of termites and aids these animals in digesting wood. There is even a species that lives in the gut of the cockroach. They do not have a set body plan like the other parasitic protozoans we have dealt with, although they are characterised by having complex life-cycles with an alternation of sexual and asexual generations.
Many species are so small that they are parasites within the cells of their host.
This disease was once found all around the world, but is now mostly confined to the tropics. In the human body, malarial parasites mostly infect the red blood cells, although upon initial infection the parasites live in the cells of the liver . In the blood cells, the parasites look like tiny signet rings. They multiply until the host cell bursts, whereupon the parasites find the next cell to infect. These miniature clots may shut off the blood supply to important parts of the body.