1. What I think is meant is to kill viruses first, followed by bacterium, then parasites. If you have reference saying you should start with smallest parasite to largest please share it.
2. It all depends on whats bugging you. For example a lot of people have heartworms. Go to the doctor for a pill and the source of the problem stays.
So what use is it killing thousands viruses, bacteria etc. ? It does not solve the source problem, if .... for example, you have heartworms.
The best info can be found by owners of a dog, cat, horse, rabbit, bird etc. Scan these and scan yourself and you will see 99,99% similarity in bugs by both. (so treat both otherwise there will be continuous infections).
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