The medical system has always been bogged down with bureaucracy, this goes back to the time of Semmelweis who died a broken man because the medical system oppressed & persecuted him over that 'invisible things' could be transmitted to patients that made them sick. http://en.wikipedia.org/wiki/Ignaz_Semmelweis
Another example would be the mental health system who has blindly looked away from alternatives to their pharma therapy. Dr. Carl C. Pfeiffer M.D. and Dr. Abram Hoffer both presented ideas that found problems such as high copper, heavy metals etc that resulted in mental health issues.
Lastly cancer should not be ignored. The germ theory has been presented countless times by credible researchers only to be shot down.
Doctors are typically thought as being the the most trusted, educated and smart people on earth, an authority figure. In my experience I have not found many that are profound, perhaps in small areas but not in overall expertise.
Part of the problem with parasitology is they do not always present recognizable symptoms. parasite species and host immunity will always present different symptomology. Secondly testing is always an issue as there are no clear markers on blood testing that are used for screening for a multitude of diseases. For instance a bacterial infection will present certain markers in the WBC tests. Even if a parasite is suspected (which is doubtful), parasite testing is known for its unreliable outcomes.
Lastly the treatment protocols elicited by the medical system is woefully inadequate. This is in both the correct agents and duration of treatment. Resistance to medicines is another issue.