Pathogens are organisms organisms: living entities-ie animals, plants or microorganisms. that cause disease. They include microorganisms such as bacteria, viruses, fungi and protozoa.ood contaminated with protozoa can cause infections such as amoebic dysentery, of which severe diarrhoea is a symptom. Some protozoa are parasites. These organisms live on, or inside, another organism and cause it harm. Malaria is a disease caused by protozoa that live in the blood.
In most cases, erectile dysfunction is caused by something physical. Common causes include: 1  Heart disease. 2  Clogged blood vessels (atherosclerosis). 3  High cholesterol. 4  High blood pressure. 5  Diabetes.
If this is the case, it is likely the underlying cause of erectile dysfunction is psychological (stress related). If you are unable to get an erection under any circumstances, it is likely that the underlying cause is physical.