Question

List various causes of diseases.

Answer 1

Hint:- A disease is a medical condition which decreases the normal functioning of the organs, cells and tissues. When a person gets a disease, he shows a few signs and symptoms, ranging from normal to serious, depending upon the medical condition.

Complete Answer:-Diseases can be of two types -
A. Non-infectious (non-communicable) diseases;
B. Infectious (communicable) diseases.
The vectors, means of spread or causes of diseases are different :
1. Many of the human diseases are a result of mutations in the genetic complement, in the deoxyribonucleic acid (DNA) of chromosomes.
2. The disease causing pathogens, which are nothing but microorganisms, are transmitted to healthy person(s) from infected person(s), by direct physical contact with the infected individual.
3. Few infectious diseases such as syphilis, gonorrhea, and AIDS are transmitted by sexual contact from one partner to the other.
4. Many animals living with us carry the infecting agents from an infected person to another potential host. These animals act as intermediaries and are termed vectors.
5. Many pathogens can enter the human body from soil through injuries, like - tetanus.
6. Indirect transmissions involve the spreading of pathogens of some of the diseases through some intermediate agents. It occurs through air, food or water.
7. Diseases can also occur due to physical (trauma, heat, cold, etc.), electrical, or chemical (because of some chemicals, drugs, etc.) injuries.
8. Diseases also spread through the animal bites. For example, rabies virus enters the human body by the bite of a rabid dog or monkey.
9. An infected person throws out little droplets on sneezing, coughing or spitting. Anyone close by can breathe in these droplets and, thus, microbes get a chance to start a new infection in this person.

Note:- A Greek physician named Hippocrates was the first one to adopt the concept that disease is not a visitation of the gods but rather is caused by earthly influences.
Vectors are the carriers of the disease causing pathogens. Insects are the most common vectors.