How do communicable or infectious diseases spread?

Micro-organism or germs:

There are many different kinds of diseases that afflict the human body. Not all of these are deficiency diseases. We know that deficiency diseases are caused by the lack of a particular nutrient in our diet. There are many diseases that are caused by very small living organisms like bacteria, virus, protozoa and fungi. Deficiency diseases cannot be passed on from one person to another. But some diseases caused by these bacteria and viruses can be passed on from an infected or ill person to a healthy person. Such diseases are called infectious or communicable diseases.

Bacteria, viruses, protozoa and fungi are so small that they cannot be seen with the naked eye. You can see them only with a microscope. This is why they are called micro­organisms or microbes. We commonly refer to them as germs.

How do communicable or infectious diseases spread?

Germs or micro-organisms are all around us. They are present in the water, air, soil, on furniture, on dirty hands, etc. All of these germs do not spread diseases, only particular types do. Typhoid, tuberculosis, and cholera are caused by bacteria and are called bacterial diseases. Diseases that are caused by viruses are called viral diseases. Flu or influenza, common cold, viral fever, smallpox, polio, etc., are viral diseases. Malaria and diarrhea are caused by protozoa and fungi cause diseases like ringworm.

Let us see how some of these germs that cause dangerous diseases like malaria, typhoid, jaundice, tuberculosis, etc., spread.

Through contact with an infected person:

Diseases like ringworm, measles, common cold, chickenpox and tuberculosis are spread by contact with an infected person, his saliva, utensils or clothing.

Through the Air:

We sometimes inhale disease-causing germs present in the air and get infected. Common cold, measles, cough, viral fever spared in this way. These diseases are spread by sneezing, coughing and spitting.

Through infected food and water:

Food and water get infected if they are not kept in the clean place. They can also get infected by germs carried by flies, cockroaches, rats, etc. Or if they are handled with dirty hands. Diseases like cholea, typhoid, diarrhea, jaundice etc. Are spread by eating infected food or by drinking unclean water.

Through bites of insects:

Insects like mosquitoes, bedbugs and fleas spread diseases like malaria, dengue fever and plague. These insects such the blood of a person infected with the disease and become carriers of the germs. When these insects bite a healthy person, they inject these germs into the blood of the healthy person. Dengue fever and malaria are spread by mosquitoes.

Through wounds and cuts:

Our skin protects our body. Germs of disease like tetanus can enter a person’s body through cuts or wound in the skin.

Prevention of communicable diseases:

A few preventive measures can help us protect ourselves from getting an infectious disease. The main objective is to prevent the spread of the micro-organisms or germs of the disease. This can be done in the following ways :

Prevention of diseases spread by contact:

Avoid contact with a patient who is suffering from a disease like measles, chickenpox, tuberculosis etc. The patient should be kept in a separate room. His utensils and clothes should be kept separate and should not be used by any one else. One should not come in contact with his body fluids such as saliva, urine and vomit.

Prevention of diseases spread through the air:

Keeping ourselves and our surroundings clean is very important. Food and water get contaminated, if they are handled with dirty hands or kept in unhygienic conditions. We must only drink water that is safe and stored hygienically. Food exposed to dirt and insects like flies should never be eaten. Eat fresh and hygienically prepared food to prevent yourself from diseases like auundice, typhoid and diarrhea.

Prevention of diseases spread by insects:

Do not allow garbage to collect around your house and keep all dustbins covered to avoid breeding of mosquitoes and flies. Always keep food and water covered to prevent flies from sitting on it. Mosquitoes breed in stagnant water so make sure there is no water stagnant around the house. Spread a thin film of kerosene oil on stagnant water to kill the eggs of mosquitoes that may be in it. Use fumes from burning neem leaves and insecticides in and around your house to kill mosquitoes. Always use mosquito nets and mosquito-nepellents when you sleep. Have fly-proofing nets on doors and windows so that flies and mosquitoes keep out of the house.

Prevention of diseases by immunization:

A vaccine is a preparation containing dead or weak micro­organisms that are introduced into the body of a healthy person orally or through an injection.


1. Deficiency diseases are caused by the lack of a particular nutrient in our diet. These cannot be passed on from one person to another.

2. Diseases that can be passed on from an infected or ill person to a healthy person are called infectious diseases or communicable diseases.

3. Bacteria, virus, protozoa and fungi are four different kinds of micro-organisms.

4. Infectious diseases are caused by these germs or micro-organisms.

5. Infectious or communicable diseases are spread in a number of ways—through food and water, air, direct contact or through insect bites.

6. There are some basic precautions that help in preventing these diseases.

7. One of the best prevention measures against infectious disuses is taking vaccinations to protect ourselves against the disease.