I have been researching for many years and I found few effective products against parasites and have discovered that most of the time there are no such products. You have to look for a product that is suitable for your specific situation and you have to be careful with choosing one of the products.
First of all, the parasite is not feeding on you; the parasite is eating your immune system (immune system cells). If a parasite is feeding on your body, then it would mean that you have a parasitic infection. You would be at risk for getting other parasites, like mites, protozoa, or bacteria, and these parasites would also have the chance to take over your body. However, when parasites are in your body, it means that you are at risk of getting some infections too.
You have to find the parasites, find out whether they are actually living inside your body, and then see whether they are inside your intestines, kidneys, lungs, or any other part of your body. In other words, it's not about just looking at the parasites; you have to look at your body in order to know that the parasites are there.