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.
Male sexuality problems. In older men, erectile dysfunction usually has a physical cause, such as disease, injury, or side effects of medications. Any disorder that causes injury to the nerves or impairs blood flow to the penis can cause erectile dysfunction. This condition increases with age: about 5 percent of men in their 40s and between 15 and 25 percent of men over 65 experience erectile dysfunction.