Doctors are seldom trained in parasitic disease or the transmission of immortal animal pathogens. At most, medical students receive thirty hours of training in parasitic disease, at some medical schools. Training in parasites may be a small part of an undergraduate premed class, and training in immortal pathogens as a cause of chronic disease does not exist. Awareness of parasitic disease is growing; however, many doctors remain in denial about parasites and immortal pathogens. Thus, the role of parasites and immortal pathogens are often overlooked in the diagnosis of acute and chronic disease.

Parasitic disease includes intestinal parasites and worms; immortal pathogens that reside in tissue, in interstitial spaces and attached to collagen; and inside cells, including inside immune cells. Once acquired, parasites and immortal pathogens can spread from the initial site of infection over time, and cause chronic disease anywhere in the body.