A disease is an abnormal condition that affects the function of a part of body or several parts of body. A disease may consists of abnormal changes in structure. Disease is called as a medical condition associated with some symptoms and signs. It may be caused by internal or external factors. External factors like pathogens, bacteria, fungi etc. Internal factors like immunodeficiency, hypersensitivity, allergies and autoimmunity.
They are the one which spreads from one person to another either by physical contact with the person (suffering the disease), or by casual contact with their secretions or objects touched by them or airborne route among other routes. Some examples of transmissible diseases are Tuberclosis, cold and coungh etc.
The disease which do not spreads from one person to another. They are the chronic diseases which lasts for long time and progress slowly. Eg. autoimmune diseases, heart diseases, stroke, cancers, diabetes, chronic kidney disease, osteoporosis, Alzheimer’s disease, cataracts etc.
STDs (Sexually transmitted diseases) are the infections which passes from one person to another by vaginal, anal, and oral intercorse. STDs can be dangerous and most STDs are easily cureable. Eg. Hepatitis B, Herpes, HIV, HPV etc.