Diseases- Types of Diseases and Their Symptoms

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A Disease is a condition which is abnormal and negatively affects the structure and functioning of organs or tissues or parts of a living organism. It has to be noted that it is not due to any immediate external injury and disease is a medical condition which has specific signs and symptoms. 

Therefore, it can be stated that a disease is a discomfortable condition that deteriorates the normal functioning of the cells, organs and tissues.

OR

Any risk caused due to divergence from the normal or functional state of an entity can be termed as disease.


Types of Diseases

We have classified various types of diseases based on their nature and the parts of the body they affect in the below tabular form-


Classification of Diseases

Description

Examples

Anatomical

Here, tissue or an organ is affected.

Heart, Kidney, Liver diseases

Topographical 

This kind of disease can be vascular, chest, gastrointestinal and abdominal diseases.

An ENT specialist or a gastroenterologist can help diagnose it.

Physiological

It includes diseases that affect a function or process related to metabolism, respiration or digestion.

Diabetes and Lung problems are the examples.

Pathological

This type of disease that considers the nature of the disease. 

Cancer where uncontrolled cell growth and various inflammatory diseases are the examples.

Epidemiological

It refers to the widespread occurrence of an infectious disease in a community at a particular time; and determines the rate of occurrence, distribution and control of a particular disease in a population. 

Plague and influenza pandemic of the year 1918-1919.


Different Types of Diseases and Their Causes

List of diseases

Causes of Disease (Causative agent)

Plague

Pasteurella Pestis

Chickenpox

Varicella Zoster Virus (VZV)

Meningoencephalitis

Naegleria Fowleri (amoeba)

Cholera

Vibrio Comma (Vibrio cholera)

Anthrax

Bacillus Anthracis

Tetanus

Clostridium Tetani

Whooping Cough

Bordetella Pertussis

Human Papillomavirus infection

Human Papillomavirus

Acquired Immune Deficiency Syndrome (AIDS)

Human Immunodeficiency Virus

Hepatitis

Hepatitis A, Hepatitis B, Hepatitis C, Hepatitis D, Hepatitis E Viruses


Two Classification of Diseases

  1. Infectious Diseases

  2. Non-infectious Diseases

  1. Infectious Diseases

Diseases that can spread from one person to another are called communicable diseases and are caused by microorganisms. The microorganisms that usually cause infectious diseases are called pathogens that include viruses, bacteria, fungi, rickettsia, worms, protozoans. It spreads when the infected person transmits his/her bodily fluids to another person, and the pathogens may exit the host to infect the new person, it takes place during sneezing, coughing, etc. Various examples of this kind of disease are cholera, chickenpox, malaria, COVID-19, etc.

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  1. Non-infectious Diseases

These kinds of diseases are caused due to pathogens as well as other factors that include age, gender of an individual, deficiency in nutrition, unhealthy lifestyle, etc. Some of the examples include hypertension, cancer and diabetes. These are non communicable and do not spread from one person to another. These restrain within a person who contracts them. Some of the examples include cataract, alzheimers, cataract and heart diseases.

Depending on which above categories of Diseases it falls into, diseases can be further Classified as:

  • Degenerative Diseases 

Degenerative diseases are caused due to the malfunctioning of vital body organs as a result of the deterioration of cells over time. One of the best examples is Osteoporosis that causes increased bone weakness with time and it increases the risk of bone fracturing. Another is neurodegenerative disorder when degeneration happens to the cells of the CNS like neurons. In Alzheimers, it often happens due to ageing and bodywear. Some of these diseases are hereditary and because of bad lifestyle choices.

  • Allergies

When the body becomes hypersensitive to certain foreign substances namely allergens, allergic reactions take place. It occurs when the immune system reacts abnormally to any foreign substances which can be harmless. Common allergens are dust, pollen, mites,  animal dander, latex, feathers, and also certain food products like gluten and nuts. Many people face allergies from food substances such as peanuts or other nuts and induce life-threatening conditions. It aggravates difficulty in breathing, swelling of tissues and blocking of airways.

Other common symptoms that are less life-threatening include coughing, running nose, sneezing, itchy and red eyes, skin rashes. Asthma is an example of the allergic disease, others include bee stings, ant bites, etc. 

  • Deficiency Diseases

Deficiency diseases are caused due to the deficiencies of hormones, vitamins, minerals, and nutrients in the body. For example, diabetes occurs due to an inability to produce or utilize insulin, goitre is caused due to iodine deficiency, kwashiorkor is caused due to deficiency of proteins in the diet. Vitamin B1 deficiency results in a disease called beriberi.

  • Goitres

An abnormal enlargement of the thyroid gland that results with blockage of the oesophagus or other organs of the chest and neck is called Goitre. It causes difficulty in breathing and eating.

  • Blood Diseases

Blood disorders result due to the affects in the blood plasma, platelets, white blood cells and red blood cells. For example, Sickle Cell Anaemia is a condition when the red blood cells are destroyed or distorted in the shape of a sickle. It loses the ability to carry oxygen. As a result, it shows symptoms exactly the same as in chronic anaemia that includes shortness of breath and tiredness.

FAQ (Frequently Asked Questions)

1. What is the disease definition in Biology?

Ans. A disease is a disorder of structure or function in a living organism including human, animal, or plant. It causes abnormalities in cells and tissues of the body and produces specific symptoms that may affect a specific location. Disease cannot simply be a direct result of physical injury. Different diseases and their causes may vary, some are infectious and others are non-infectious. Some of the disease examples include hepatitis, cholera, cancer, heart diseases, asthma, etc.

2. What is Diabetes disease and its causes?

Ans. Diabetes is a disease that occurs when the blood glucose in our body, also called blood sugar, is too high. Blood glucose is the main source of energy and is produced when we intake food. A hormone made by the pancreas is insulin that helps glucose from food get into our cells to be used for energy. When insulin is unable to control the levels of sugar or glucose in our blood, a chronic condition namely diabetes takes place. An absence of insulin or an inability of the body to properly use insulin is called insulin resistance and can result in this disease. Diabetes, nowadays, is categorized into type 1 diabetes, type 2 diabetes, prediabetes and gestational diabetes.