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.
1 Adequate blood flow is necessary for erection. 2  Because effective blood flow through the arteries and veins is essential to achieve and sustain an erection, any problem that impairs blood flow can cause ED. 3  A number of medical causes associated with erectile dysfunction are problems with the arterial system. HBP damages arteries. 2  There are two root causes of erectile dysfunction (ED): psychological and medical. 3  High blood pressure is a contributing medical factor that leads to ED. 4  HBP damages the entire vascular system. 5  Adequate blood flow is necessary for erection.