Hi Charly, I worked as a pathologist for the coroners department for 6 years, and in that time only saw 1 person that even had liver flukes, let alone an infestation. This guy worked and lived on a cattle station in the tropical north of the state, and ate a great deal of fish caught in the local rivers.
Intestinal parasites are a bit more common, and I'm not surprised your sister had a tape worm. Intestinal parasites can come from a variety of places, but they generally don't become an infestation, unless the person has a very poor immune system, or continually reinfects themselves.
What I have seen of the photos posted on the Liver Flush Forum , are not flukes, and I doubt that they even come from the liver, but are just undigested food from the bowel. (I know what a liver fluke looks like).
It certainly wont hurt to give your intestines a scrub with the DE, or keep your liver healthy with herbs and a good diet.
I'm not a believer in the Conspiracy theory surrounding doctors and the diagnosing of parasites, although, like many diagnostic tests, the tests are not always acurate.
I do believe however, that many people on CZ, that self diagnose, get it wrong also. Doing endless enemas, colonics and flushes, will do more damage to the bowel than a few worms will.
Rather than using the seek and destroy method to kill any parasites, its better to support your body nutritionally, and keep yourself healthy, the parasites will not want to live in a healthy body.