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.
One thing to bear in mind is that lowering levels of testosterone can cause certain symptoms which can indirectly contribute to erectile dysfunction. Mood swings can create stress and anxiety around sex, while weight gain can lead to the development of diabetes or cardiovascular disease (two common causes of ED).