Big pharma firms disprove your claim. Although they do much good, I think in many ways they are also both parasites and viruses.

Sarcasm aside, parasites and viruses do have things in common. You writing that they do not does not make it true.

It might be because parasites and viruses have differences that Ivermectin has an spotty success record to date. I'm guessing there are factors not yet understood that lead to great results for some and not great results for others.

In any case, Ivermectin is not a "horse dewormer." Or better said, it is not "JUST" a horse dewormer. It is an unbelievably effective medicine with over 1 billion prescriptions worldwide. The fact that big US pharma firms are paying shittons of money to discourage even looking at using a cheap generic drug like Ivermectin brings me right back to my sarcastic comment at the top.