Communicable vs Non-communicable Diseases- Definition, 17 Differences, Examples

communicable and non-communicable diseases differences

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Communicable diseases definition

Communicable diseases are the diseases that are caused by infectious agents and can be transmitted from an infected person to other people, animals, or other sources in the environment.

  • Communicable diseases are also called infectious diseases or transmissible diseases.
  • These diseases are transmitted when the infectious agents are transmitted through contact with contaminated surfaces, bodily fluids, blood products, insect bites, or through the air.
  • The spread of infectious diseases might either be direct or indirect.
  • In the direct transmission, the infectious agent is transferred through close physical contact, whereas in indirect transmission, the agent is transferred through air, water, or other vectors.
  • After these agents enter the body of a healthy individual, the organism undergoes a period of time called the incubation period. Once this period is over, the symptoms of the disease begin to appear.
  • In most cases, the immune system of the body tends to destroy infectious agents. However, the disease appears when the organism escapes the immune system.
  • Communicable diseases might be seasonal where certain diseases occur at a certain time of the year. One example of this is malaria, which occurs mostly during the breeding season of the female mosquito.
  • The symptoms of communicable diseases might differ with the nature of the disease; however, the common symptoms are fever, diarrhea, headache, muscle ache, fatigue, etc.
  • Most communicable diseases are acute diseases where the disease and symptoms appear over a short time.
  • Communicable diseases, however, are not considered severe as the treatment for these diseases are available.

Non-communicable diseases definition

Non-communicable diseases are the diseases that are not transferred from an infected person to another via any means and are mostly caused by factors like improper lifestyle and eating habits.

  • Non-communicable diseases are also called non-contagious or non-infectious diseases.
  • Infectious agents like bacteria and viruses do not cause these diseases, and thus these diseases do not spread from an infected person to a healthy individual.
  • Most non-communicable diseases are caused due to an unhealthy diet and lifestyle. However, other causes like mutations, heredity and environmental changes might also trigger some non-communicable diseases.
  • Non-communicable diseases, unlike communicable diseases, are not seasonal and might occur at any time of the year.
  • Diseases like cancer and diabetes might even be hereditary, which are inherited from parents to the offsprings.
  • These diseases are also more chronic as the symptoms appear gradually and thus are difficult to diagnose. Most of the non-communicable diseases pose severe and long-lasting health effects on the patients.
  • Some chronic non-communicable diseases might even have periods of temporary relapse where the disease disappears for a short period of time regularly only to reappear again.
  • Non-communicable diseases are also found to be more severe, responsible for about 70% of all deaths worldwide.
  • There are no specific treatments available for most non-communicable diseases, and the available medicines simply prevent the disease from getting worse. Most non-communicable diseases are not curable.
  • However, maintaining a proper and healthy eating habit and lifestyle with regular check-ups are essential preventive measures against non-communicable diseases.

Key Differences (Communicable vs Non-communicable diseases)

Basis for Comparison

Communicable diseases

Non-communicable diseases

Definition Communicable diseases are the diseases that are caused by infectious agents and can be transmitted from an infected person to other people, animals, or other sources in the environment. Non-communicable diseases are the diseases that are not transferred from an infected person to another via any means and are mostly caused by factors like improper lifestyle and eating habits.
Also called Communicable diseases are also known as infectious diseases. Non-communicable diseases are also known as chronic diseases.
Progression These are more likely to be acute, meaning they appear quickly. These are more likely to be chronic, meaning they last for a longer period of time and progress gradually.
Seasonal Some infectious diseases might be seasonal. Non-communicable diseases are not seasonal and might occur at any time of the year.
Cause Pathogenic microorganisms are the primary cause of communicable diseases. These are caused by nutrition deficiency, hormonal deficiency, or abnormal proliferation of cells.
Inherited Communicable diseases cannot be inherited from one generation to another. Non-communicable diseases might be inherited from one generation to another.
Agents/Vectors Viruses, fungi, and bacteria act as agents/vectors for infection and transmission of such diseases. There are no agents for infection of non-communicable diseases as they primarily depend on the personal diet, allergy, or physical inactivity.
Spread There are many reasons for the spread of communicable diseases. It can spread through the air, by direct contact with a contaminated surface, food, etc. These do not spread from one person to another at all.
Organs affected The most common communicable diseases are those of respiratory tracts, such as common cold, influenza, tuberculosis. Non-communicable diseases are varied, such as cardiovascular disease, diabetes, etc.
Symptoms Symptoms of communicable diseases can be observed as quickly as a day or two from the entry of the pathogen. Symptoms for non-communicable diseases may not be observed until a year or more, which increases the risk of the disease being fatal.
Severity These are less severe, i.e. they develop quickly and pose a short-term threat to the patient. These are more severe, responsible for more deaths worldwide. These diseases also have long-term effects on the life of the patient.
Relapse There are no periods for relapse for infectious diseases. There might be multiple periods of relapse during the diseases.
Diagnosis For many communicable diseases, accurate diagnostic tests are available. Accurate diagnostic tests are not available for most non-communicable diseases.
Treatment These can be treated with a short treatment schedule. These require prolonged treatment.
Curability Almost all communicable diseases can be cured except for HIV/AIDS. Non-communicable diseases such as cancer and diabetes do not have any specific cure.
Prevention These can be prevented by some conventional methods such as maintaining personal hygiene, avoid sharing eating utensils, etc. These need special surgical operations for treatment.
Examples Diseases like typhoid, cholera, malaria, tuberculosis, leprosy are examples of communicable diseases. Diseases like cancer, diabetes, Alzheimer’s diseases, Down’s syndrome, Kwashiorker are examples of non-communicable diseases.

Examples of communicable diseases


  • Diarrhea is a loose, watery, more frequent bowel movement, which is usually short-lived, lasting no more than a few days.
  • Rotavirus is a common cause of diarrhea in children. Other viruses causing diarrhea include Norwalk virus, cytomegalovirus, and viral hepatitis.
  • Moreover, various other factors like some bacteria, medications, lactogen intolerance, etc. can cause diarrhea.
  • Signs and symptoms associated with diarrhea include loose, watery stool, abdominal cramps, and pain, fever, blood and mucus in the blood, etc.
  • Diarrhea can cause dehydration, which can be life-threatening if untreated.
  • Some of the common preventive measures would be washing hands frequently, lathering hands with soap, maintaining healthy hygiene and sanitation.
  • Rotavirus can be cured by administering available vaccines. For traveler’s diarrhea, it is up to the individual by being careful with what they eat and their hygiene.


  • Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition that is caused by the human immunodeficiency virus (HIV).
  • HIV is a sexually transmitted infection that weakens the immune system.
  • If left untreated, HIV will eventually turn into AIDS within 8 to 10 years.
  • It can spread through contact with blood, sexual contact, or from mother to child during pregnancy.
  • Although the symptoms are less severe and phase-specific, most people develop a flu-like illness within two to four weeks of the virus entering into the body.
  • Swollen lymph nodes are considered to be one of the first signs of HIV infection.
  • As the virus progresses, persistent white spots or unusual lesions may be seen on the victim’s mouth.
  • Having unprotected sex, using IV drugs are among the greatest risk factors leading to HIV infection.
  • As HIV weakens the immune system, the body is projected to a number of infections such as pneumocystis pneumonia (PCP), candidiasis, tuberculosis, and many more.
  • HIV doesn’t spread through ordinary contact such as hugging, kissing, or shaking hands. The virus doesn’t spread through air, water or insect bites.
  • There are no vaccines for HIV and no cure for AIDS, but certain antibiotics can significantly slow down its progression.

Examples of Non-communicable diseases


  • Diabetes is a non-communicable chronic condition where the glucose level or sugar level of the blood is higher than normal.
  • Diabetes is of two types;
    • Type 1 diabetes occurs when the body’s immunity system destroys the body’s own healthy cells like the insulin-producing beta cells of the pancreas, mistaking them for foreign invaders.
    • Type 2 diabetes occurs when the body is unable to use the produced insulin effectively, which causes an increase in blood glucose levels.
  • Symptoms of diabetes are not apparent and usually appear gradually over a period of time. By the time the symptoms appear, complications might be seen in the disease.
  • Diabetes is mostly seen in older men and is associated with unhealthy dietary habits.
  • Diabetes might even be heredity where it might transfer from one generation to another.
  • There is no cure for the disease, but medications are available that control the complications of the disease.


  • Cancer is a non-communicable disease that consists of a number of diseases caused due to uncontrolled division of cells with the potential of spreading to different parts of the body.
  • The most common causes of cancer are tobacco use, obesity, poor diet, lack of physical exercise, and intake of alcohol.
  • Some cancer might even be caused due to the genetic condition of the patient.
  • Symptoms like a lump, abnormal bleeding, rapid weight loss, and prolonged cough might appear in many cancers. These symptoms might even have other causes.
  • The most important diagnostic test for cancer is the biopsy, where a part of the tissue is examined for the detection of cancerous cells.
  • As in the case of most chronic diseases, maintaining a proper diet with regular exercise can be employed as preventive measures for cancer.

References and Sources

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About Author

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Anupama Sapkota

Anupama Sapkota has a bachelor’s degree (B.Sc.) in Microbiology from St. Xavier's College, Kathmandu, Nepal. She is particularly interested in studies regarding antibiotic resistance with a focus on drug discovery.

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