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Infectious and Non-Infectious Diseases

An Overview of Infectious and Non-Infectious Diseases

Last updated date: 24th Mar 2023
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Any abnormal condition that disturbs the regular biological processes and frequently produces symptoms of pain and weakness is referred to as a disease. It frequently comes with signs and warnings. The four main diseases are infectious diseases, deficient diseases, hereditary diseases (genetic and non-genetic hereditary disorders), and physiological diseases. Additionally, diseases can be categorised into two major categories as non-communicable and communicable diseases.

The primary difference between infectious and non-infectious diseases is that infectious disease can spread from person to person since it is contagious. Non-infectious diseases, on the other hand, are not contagious. These diseases are also referred to as non-communicable diseases. They are typically caused by internal body dysfunction.

What is Infection?

Infection is the spread and development of germs inside the body. Bacteria, viruses, yeast, fungi, and other microbes are examples of these germs. Infections can start anywhere in the body and have the potential to spread everywhere. Depending on where in the body it develops, an infection might result in fever and other medical issues. When the immune system of the body is strong, it can frequently fight pathogens and treat infections. Some cancer treatments can weaken the immune system of the body, which increases the risk of infection.

What are Infectious Diseases?

Diseases caused by microorganisms including bacteria, viruses, fungus, and protozoa are referred to as infectious diseases. They are also known as communicable diseases because they can be transmitted from one person to another by means of things like contaminated air, food, water, vectors, etc.

Causes of Infectious Diseases

Microorganisms or pathogens that invade the body are the causes of infectious diseases. For example, a certain virus can cause a viral infection. Pathogens are microscopic organisms that are more likely to result in illnesses. These pathogens are known as infectious agents. These agents are everywhere and come in a variety of shapes and sizes. They could be categorised according to some common traits. Some of these are single-celled organisms like bacteria, viruses, and fungi. It is also known that other multicellular organisms, such as worms, can transmit disease.

These agents can invade our systems in body in a variety of ways, including:

  • By the transfer of body fluids.

  • By inhaling airborne specks or droplets.

  • Skin-to-skin contact.

  • Exposure to waste.

  • Consuming contaminated water or food.

Types of Infectious Diseases

It can be classified based on the infectious agent causing the disease. The primary categories are listed below:

  1. Viral Infections

As the name suggests, viruses are the cause of viral infections. In this particular infection, viruses invade the host's body and release their genetic material before attaching to a cell. After the genetic material is released into the body of the host, the material activates and starts to proliferate. The virus spreads as the cell divides. More viruses are then released from infected cells, where they can infect further cells. Few viruses damage cells instead of changing their structure.

For example, the Epstein-Barr virus, human papillomavirus, triggers unregulated cell reproduction that results in cancer. Other examples include swine flu, polio, dengue fever, HIV, Zika virus, and Ebola virus.

  1. Bacterial Infections

These are caused by bacteria which is a single-celled organisms. Typhoid, cholera, tuberculosis, dysentery, diphtheria, and other conditions are examples of bacterial infections. Bacteria may survive in a variety of harsh conditions, including radioactive waste, severe heat, and extreme cold. Good bacteria prevent disease and kill harmful bacteria, but bad bacteria cause infection. Cholera, TB, diphtheria, and typhoid are a few examples of contagious bacterial diseases. Antibiotics are typically used to treat bacterial infections.

  1. Other Infections

Ectoparasites, helminths, and protozoa can all spread contagious diseases. Contact with faeces is how protozoa are spread. Dysentery is caused by amoebic protozoa. Human infections can also be caused by helminths, which include both flatworms as well as roundworms. Ectoparasites like mites, lice, ticks, and other organisms usually attach to the host's skin and spread illnesses.

What are Non-Infectious Diseases?

Non-infectious diseases are those diseases that do not spread from one organism to another. These diseases are also referred to as non-communicable diseases. They are typically caused by internal body dysfunction. For example diabetes, it is caused by the dysfunction of the cells that produce the hormone insulin, which controls blood sugar levels, causing an imbalance in blood sugar levels. Non-infectious diseases do not spread through direct physical touch or through inhaling infected droplets. Only rare genetics can cause the spread.

Examples of Non-Infectious Diseases

  • Cardiovascular Diseases: Heart attacks and strokes

  • Diabetes

  • Cancer

  • Chronic Respiratory Diseases: Asthma

  • Injuries

Difference Between Infectious and Non-Infectious Diseases

Following is the difference between infectious and non-infectious diseases.

Infectious Diseases

Non-Infectious Diseases

1. Infectious diseases are caused by infectious agents such as bacteria, viruses, helminths, etc.

1. Non-infectious diseases are caused by pathogens as well as by ageing, inadequate nutrition, smoking, drinking, and other lifestyle factors.

2. Modes of infection are Fecal-oral, droplets, sexual, direct touch, or vector transfer.

2. Non-infectious diseases are not contagious, several of them might be genetically inherited.

3. Examples include cholera, malaria, AIDS, polio, herpes, chickenpox, tuberculosis, etc.

3. Examples of non-infectious diseases are cancer, asthma, diabetes, colour blindness, etc.

Interesting Facts

  • Infectious diseases are the second-leading cause of death worldwide, killing more than half of those under the age of five.

  • With over half of all infectious disease-related deaths occurring globally, Sub-Saharan Africa will continue to be the area most impacted by the phenomenon of infectious diseases on a global scale.

  • Tuberculosis, which continues to be a major health concern due to drug-resistant TB strains.

  • The primary cause of death from non-communicable diseases is cardiovascular disease.

Important Questions

  1. How are non-infectious diseases controlled?

Ans: By lowering common risk factors like tobacco use, hazardous alcohol use, physical inactivity, and eating unhealthily, many non-infectious diseases can be avoided.

  1. What are the symptoms of non-infectious diseases?

Ans: Symptoms or signs include persistent cough, breathlessness, persistent mucus production, wheezing, chronic chest pain, etc.

  1. What is the most important way to treat an infectious disease?

Ans: Using medicine that kills pathogens is the most important way to treat an infectious disease.


Development and spread of pathogens inside the body is termed as an infection. There are two major types of diseases known: infectious (communicable) disease and non-infectious (non-communicable) disease. Harmful organisms like viruses and bacteria that enter your body from the outside cause infectious diseases. Examples of infectious diseases are swine flu, typhoid, cholera, etc.

Non-infectious diseases are caused by factors such as heredity, anatomical variations, ageing, and environmental factors rather than by harmful organisms. Non-infectious diseases cannot be contracted from other people, such as through a bug bite, or through food. Some examples of non-infectious diseases are asthma, cancer, diabetes, etc.

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FAQs on Infectious and Non-Infectious Diseases

1. What are the causes of infectious disease?

Infectious diseases are caused by bacteria, viruses, fungi, and parasites.

  • Bacteria: UTI, TB, and strep throat are all caused by these one-celled organisms.

  • Viruses: Diseases like the common cold and AIDS are among the many diseases caused by viruses, which are smaller than bacteria.

  • Fungi: Fungi are the root cause of numerous skin conditions, including athlete's foot and ringworm. Your brain system or lungs may contract an infection from different fungi.

  • Parasites: A mosquito bite releases a small parasite that causes malaria. From animal faeces, humans may contract other parasites. 

2. Is COVID-19 an infectious disease?

Those diseases that are caused by organisms, such as bacteria, viruses, fungi, or parasites, and can be passed from one person to another are known as infectious diseases or communicable diseases. COVID-19 is a disease that can spread from individuals who carry the virus. Small droplets from the mouth or nose are released when a person with COVID-19 coughs or exhales, this spreads the disease from one person to another. Thus, COVID-19 is an infectious disease.

3. Is diabetes a communicable disease?

Communicable diseases are those diseases that are caused by pathogens and spread from one person to another person through any form of contact.  Non-infectious diseases are also known as non-communicable diseases and are generally caused by things like heredity, malnutrition, environment, and way of life. Non-infectious diseases cannot be transmitted from one person to another since they are not caused by microorganisms.

One of the four main examples of non-communicable diseases is diabetes, cardiovascular disease, cancer, and chronic respiratory diseases. Diabetes is a chronic disorder that develops when the body cannot properly use the insulin that it makes or does not create enough of it. Thus, diabetes is not a communicable disease, rather it is a non-communicable disease. 

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