Parasite cleansing should only be done 2-3 times per year. Some folks who are more at risk for becoming infected cleanse 3 times per year - folks like: teachers, daycare workers, farmers, ranchers, and health care professionals.
Sure you can get reinfected. All parasite eggs are microscopic - BUT regular cleansing keeps the body strong against picking up infections AND it will clen them out before they have time to really take a hold of your body.
Cleansing any closer together that this can create super parasites - which is the same thing as super bugs that come from the over-use of anti-biotics.
During the 90 day or 150 day break from parasite cleansing - I recommend adults take 1/4 teaspoon of each of the following herbs daily: onion, garlic, sage, thyme, ginger, cinnamon and cloves. Just put them into food. Children need half this much and toddlers need about 1/4 of that amount. A good idea is to make a couple of dishes that will incorporate these herbs into your family's food. Just use enough to make it taste good - and you can use the ground ones found in the grocery store.
These herbs are very anti-parasitic in nature and will help keep the body clean - but they are not strong enough to remove all parasites by themselves. They just keep the body "unfriendly" towards parasites. They are also not strong enough to cause resistance.