Causes of Diseases

Causes of Diseases: Most of the diseases will have many causes, rather than one single cause. These causes of diseases are classified into two types:

Immediate causes: These are the real or primary causes; also called first level of causes. Various microorganisms like bacteria, virus, fungi, protozoans, etc., that can cause infectious diseases are included in this category.

Contributory causes: These are also called intrinsic or internal factors, and do not lead to a disease themselves. These can be of following types:

Poor health due to inadequate diet: It occurs due to deficiency of one or more nutrients, making the person unhealthy or susceptible to diseases, e.g. kwashiorkor, a nutritional deficiency disease occurring due to low protein diet. So, lack of good nourishment becomes second level of cause of disease.

Genetic disorders: These are present since birth; pass down from parents to offsprings, e.g. haemophilia.

Various pollutants present in environment : Pollutants in air, water and soil also contribute in causing diseases, e.g. intensive use of nitrate fertiliser causes methaemoglobinaemia.

Improper functioning of any body organ : Non-communicable diseases (i.e. non-spreadable diseases) like diabetes, blood pressure and heart diseases are due to the malfunctioning of body organs.

Lack of public services or poor economic conditions. It also contributes to the cause of disease. These causes become the third level cause of disease.

Note: The diseases, which are caused when organ and tissues degenerate and do not work well with increasing age are called degenerative diseases. Arthritis, disturbed sight and hearing defects are all degenerative diseases.

Infectious and Non-infectious Causes: Immediate causes of diseases belong to two distinct types.:

One of the group of diseases is caused by infectious agents mainly microorganisms. As the microbe can spread in the community, so the disease caused by it also spreads. Hence, these diseases are known as infectious diseases, e.g. typhoid caused by bacterial infection.

The second group of diseases is not caused by infectious agents. These diseases are restricted only to the persons, who are suffering from them. As they do not spread from infected person to a healthy person, these are called non-infectious diseases or non-communicable diseases, e.g. some cancers are caused by genetic abnormalities or by exposure to certain carcinogenic chemicals and radiations; high blood pressure is caused by excessive weight and lack of exercise, etc. Non-communicable diseases are mainly caused due to:

Lack of essential nutrients/substances in our diet, e.g. proteins, vitamins, minerals, etc.

Uncontrolled growth of tissues in any part of body.

Damage to any part by accident or by other means.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

The disease Filariasis is caused by the worm _________________
A. Wuchereria bancrofti	B. Ancylostoma dodenale	C. Trichinella spirals	D. Enterobius vermicularis
Right Option : A
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Question : 2

Gastroenteritis is caused by ____________________
A. E. coli	B. Amoeba	C. Bacillus bacteria	D. Salmonella typhi
Right Option : C
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Question : 3

Consider the following statements and select your answers from the choices that follow. I: The patient's nerves are damaged in polio. II : Tetanus is caused by virus.
A. Both are correct	B. I alone is correct	C. II alone is correct	D. Both are wrong
Right Option : B
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