At least in the US, the medical profession is in denial of the immensity of the parasite issue.
People that go to the doctor with obvious parasite issues are dismissed and diagnosed as having delusional parasitosis which is in itself a scam to sell more drugs.
The truth is the problem is delusional parasitologists because they really are either misled, misguided, or just plain mistaken.
Everyone in the world has at least some parasites. Some of us even take them in intentionally by eating things like yogurt and sauerkraut.
The bacteria that live on your skin are classified as "parasites".
The bacteria and other microbes that live in your intestines are classified as parasites.