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Disease and Its Causes

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Diseases: An Introduction

A disease is a condition that worsens or impairs the normal conditions of organisms. Do you know most people die because of heart disease? And most heart diseases are due to a sedentary lifestyle. These factors are modifiable. Do you know the types of diseases? There are acute and chronic diseases. Acute diseases affect us for a short period, whereas chronic disease affects us for a long period.

There are various causes of disease, such as pathogens or unhealthy lifestyles. You might be surprised to know that fever is not a disease, it is a protective mechanism of the body against pathogens.

Types of Diseases

Diseases are of various types based on their nature.

  • Infectious diseases, also known as communicable diseases

  • Non-infectious diseases, also known as non-communicable diseases

  • Degenerative diseases

  • Allergies

  • Deficiency diseases

Infectious Diseases

Infectious diseases are diseases that spread from one person to another person through some agent. These diseases are caused by microorganisms such as bacteria, viruses, worms, and protozoans. Examples of infectious diseases are the common cold, pneumonia, tuberculosis, etc.

Non-Infectious Diseases

These are diseases that do not transmit from one person to another. These diseases may be caused by some pathogens or factors such as gender, lifestyle, and nutritional deficiency. Examples are hypertension, diabetes, cancer, asthma, etc.

Degenerative Diseases

Degenerative diseases are diseases caused by degenerative changes in cells, tissues, and organs. Examples of degenerative diseases are Alzheimer's disease and osteoporosis.


Allergy is a hypersensitivity type reaction caused because of some substances. Things that cause allergic reactions are called allergens. Dust, mites, pollen, latex, and animal dander are allergens.

Deficiency Diseases

Deficiency diseases are diseases caused due to a decreasing or less amount of hormones, minerals, nutrients, and vitamins in the body. For example, diabetes occurs due to a deficiency of insulin in the blood. Insulin is the hormone produced by the pancreas and converts glucose into glycogen in the liver.

Kwashiorkor or Marasmus are diseases caused due to protein-energy malnutrition, goiter is the disease caused by the deficiency of thyroid hormone.

How are Diseases Caused?

There are various types of causes. Some of the causes are given below:

  • Airborne Diseases - These are diseases caused by pathogens and transmitted through the air. Examples of these diseases are tuberculosis and the common cold.

  • Foodborne Diseases - These are the diseases caused by contaminated food and drinks with pathogens, toxins, and parasites. Examples of these diseases are food poisoning.

  • Lifestyle Diseases - These diseases are caused by a sedentary lifestyle or consumption of unhealthy food or a bad lifestyle. The frequency of these diseases increases with time, especially in developed countries.

  • Communicable Diseases - These diseases are caused by various pathogens. Pathogens include:

  • Bacteria - Microscopic organisms that cause various types of diseases such as Streptococcus, Mycobacterium, etc.

  • Virus - Viral diseases are the common cold, hepatitis, mumps, influenza, and measles. These diseases are caused by rhinovirus, paramyxovirus, etc.

  • Fungus - Fungal infections include athlete's foot, and toenail fungus, fungal infections mostly occur in warm and humid places.

  • Protozoa - Protozoan infections include dysentery, amoebiasis, malaria, etc. Protozoans are Entamoeba histolytica and Plasmodium.

  • Worms - Disease causing worms are guinea worm, giardiasis, etc.

Symptoms of Diseases

Symptoms change according to the nature of the disease. But some of the signs and symptoms are very common and occur in almost every disease. Some of these symptoms are:

  • Headache

  • Pain

  • Vomiting

  • Nausea

  • Nasal congestion

  • Diarrhea

  • Altered urination

  • Redness

  • Swelling or edema

  • Sore throat

  • Chills or sweat

Treatment of Diseases

Treatment of diseases also depends on the nature and causative agent.

  • Antibiotics are drugs used for the treatment of bacterial diseases and infections. Examples of antibiotics are amikacin, penicillin, streptomycin, etc.

  • Antivirals are used for the treatment of viral diseases. Examples of antiviral drugs are peramivir and oseltamivir.

  • Antihypertensive drugs are calcium Channel blockers, diuretics, ace inhibitors, beta-blockers, etc.

There are other medications, too given according to diseased conditions.

Preventions of Diseases

It is well said that prevention is better than cure. So to save ourselves from diseases we have to follow certain healthy practices and protective measures. Some of the healthy habits are given below:

  • Wash hands regularly.

  • Always eat cooked food.

  • Exercise daily.

  • Say no to smoking and alcohol.

  • Eat less junk food.

  • Drink more water.

Interesting Facts

  • Laron syndrome is a disease in which the life span of a patient gets increased, and immunity against cancer develops.

  • In 5000 years of human history, humans are only able to eradicate two diseases till now - smallpox and rinderpest.

  • The lack of a toilet in India causes a loss of more than 50 billion dollars per year because of premature deaths and hygiene-related issues.

  • There was a man named James Harrison whose blood contain a rare antigen that can cure rhesus disease.

  • Approximately, 90-95% of cases of cancer are due to environmental conditions.

Important Questions

Q1. What are the most common infectious diseases?

Ans: There are many types of infectious diseases. But the most commonly occurring diseases are - influenza, pneumonia, Staphylococcus aureus infection, E.coli infection, etc.

Q2. What are some deadliest diseases?

Ans: There are many deadliest diseases. Some of the deadliest diseases are given below:

Cancer, heart diseases such as heart attack, HIV, and aids. Some of the diseases do not have any treatment.

Q3. What are the rarest diseases?

Ans: Rarest diseases are the diseases that occur very rarely such as alkaptonuria, encephalitis, Alice In Wonderland Syndrome ( AIWS), and Stoneman syndrome.

Key Features

  • In this article, we discussed disease and what causes disease, causes and prevention of communicable diseases.

  • There are various types of diseases, such as infectious, non-infectious, degenerative diseases, etc.

  • Causes of diseases are various pathogens such as bacteria, viruses, and fungus some lifestyle factors also cause disease.

Practice Questions

Q1. What is black urine disease?

Q2. What is the most common disease in the world?

Q3. What is the most difficult disease to cure?

Q4. Which disease is the silent killer?

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FAQs on Disease and Its Causes

1. What are genetic diseases? Name some genetic diseases 

Genetic diseases are diseases caused by alterations in genetic material. Mostly genetic diseases are inherited. We have 23 pairs of chromosomes. If there is a change in any one of the chromosomes or an increase or decrease in the number of chromosomes due to any factors, it results in genetic disorders. They may be caused by a mutation in the genetic material. Examples of genetic diseases are down syndrome, Klinefelter syndrome, hemophilia, or sickle cell anemia. Cancer may occur due to genetic changes.

2. What is the most common genetic disorder?

Cystic fibrosis is the most common genetic disorder. It is an inherited disorder. It causes damage to those cells which produce mucus, or digestive juices. Mucus or digestive juices become thick and viscous in this disease. They plug the duct and passage and in the lungs cause problems in breathing due to the accumulation of mucus. This condition leads to wheezing sounds from the lungs, and problems in breathing. Weight loss may be there, due to blockage of ducts that carry enzymes, and hence less absorption of food will be there.

3. How can we prevent communicable diseases?

As we know communicable diseases spread from one person to another person, so to prevent the spreading of these diseases, we need to 

  • Maintain hygiene. 

  • Cover mouth and nose while sneezing. 

  • Get vaccinated.

  • Ventilation of home. 

  • Stay at home, if we are sick. 

  • Wash and dry hands regularly. 

  • Do not share personal items. 

  • Do not junk or uncooked food. 

  • Always wash your hands before and after preparing food. 

  • Use safe sex practices. 

  • Sanitise the room and home regularly, if you have any infection.

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