Modes of Transmission of Diseases

The spreading of any pathogen from one body to another body is termed as transmission. Moreover, transmission of infections and diseases take place in various ways, like it may get transmitted directly or through means of specific bacteria, protozoa, fungi or virus. However, primarily two modes of disease transmission are there; these include – 


Direct Transmission

When the pathogens are directly transmitted from a person suffering from an infection, it is called direct transmission. For instance, if an open wound somehow contaminates the blood of a person who has Hepatitis B, the person with the injury may get infected with Hepatitis B.

  • Individual to Individual

In this scenario, transmission occurs when an infection-free person gets in touch or interchange bodily fluids with an individual with an infection. For instance, a pregnant woman can transfer infection to her unborn baby through her placenta. Moreover, gonorrhoea is a sexually transferred disease which is an example of direct transmission.

  • Transfer Through Droplets

During sneezing, coughing, or speaking, droplets can come out from mouth and nose and infect a healthy person. Also, infections can spread if an infected person touches another person with his/her hands which are contaminated with the droplets.


Furthermore, these droplets move a small distance as they are very minute. Hence, nearby people are prone to infections.

  • Transmission Through Skin

Here, when the skin of a person suffering from any disease touches another individual, it may infect him/her. For example, conjunctivitis, chickenpox, ringworm and head lice are some infections transmitted by skin.

  • Transfer by Fluids and Blood

As per the phrase, it is understandable that this transmission occurs when blood or body fluids make contact with bloodstream or mucous membrane of a healthy person. Moreover, examples of such mode of transmission are cytomegalovirus, hepatitis, HIV, etc. These infections transfer via urine, semen, saliva, vaginal fluids, breastmilk, etc.


Indirect Transmission

Reversely, when pathogens are not directly transmitted from an individual suffering from an infection, it is called indirect transmission. Here, methods of disease transmission are vectors like flies, ticks, mosquitoes, dogs, etc.

  • Transmission Through Air

Sometimes, few infections stay in the air for a considerable amount of time. As a result, it may affect a person’s immune system who comes in contact with those infections. For instance, if a healthy man/woman goes into a room where a person suffering from measles used to stay, that uninfected man/woman may catch measles.

  • Transmission Through Contaminated Substances

Various objects and usable items can carry pathogens. By touching those infected items which were previously utilised by an infected individual may cause infection in a healthy human being—also, contaminated medical issues and blood transfer infections.

  • Transfer of Disease Through Vector

Various insects and flies can transmit infections. These flies and insects sit and feed on multiple animals, humans, birds and bring along disease-causing agents. Further, when they go and sit on some uninfected person, the infection may get transferred. Lyme and malaria are two examples of vector-borne diseases.

  • Drinking Water and Food

Foods that are not appropriately canned or undercooked are one of the primary sources of disease-causing infections. Moreover, drinking water is also a mode of transmission of infection. Hence, individuals must boil or filter water before drinking and using it for cooking. E.coli gets transmitted via contaminated food items that create stomach issues.

  • Transfer Via Animals

Infection through animals takes place when a diseased animal scratches or bites an individual. Examples of diseases caused by animals are anthrax, plague and rabies.

  • Transmission Through Certain Environmental Factors

Several infectious modes of disease transmission are available in water, plants and soil. They may come in contact with people who can cause diseases. Examples are hookworm and legionnaires’ disease.


Do It Yourself

Which disease is caused by transmission via dog?

(a) Cholera (b) Rabies (c) Anthrax (d) Malaria


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FAQ (Frequently Asked Questions)

1. What are the Different Modes of Disease Transmission of Diseases in Animals?

Ans. The 4 common modes of disease transmission in animals are:

  1. Direct contact

  2. Indirect contact

  3. Droplet

  4. Droplet nuclei

2. What is the Study for Mode of Transmission of Disease Called?

Ans. The study of mode of transmission of diseases is called epidemiology.

3. What is Meant by Modes of Disease Transmission?

Ans. The method or route by which infectious bacteria, viruses and other microorganisms transfer from one location to another is known as modes of transmission.