Getting rid of parasites is a longer term project than doing a 21 day master cleanse. A lot depends on the type of parasites and the severity of infestation. Many of us believe that it may take up to 2 years to eliminate all parasites. You get rid of one type, only to find another. Some parasites have life cycles of 3-4 months and lay thousands of eggs a DAY.
Best policy is to do one thing at a time.