Why Do We Fall Ill

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Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi or parasites and can spread between individuals. Microorganisms that cause disease are collectively called pathogens.

Pathogens cause disease either by disrupting the bodies normal processes and/or stimulating the immune system to produce a defensive response, resulting in high fever, inflammation and other symptoms.

Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example, a mosquito.

Infectious diseases can be caused by:

1. Bacteria: These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis.
2. Viruses: Even smaller than bacteria, viruses cause a multitude of diseases — ranging from the common cold to AIDS.
3. Fungi: Many skin diseases, such as ringworm and athlete's foot, are caused by fungi. Other types of fungi can infect your lungs or nervous system.
4. Parasites: Malaria is caused by a tiny parasite that is transmitted by a mosquito bite. Other parasites may be transmitted to humans from animal faeces.

Infectious diseases are caused by microorganisms such as viruses, bacteria, fungi or parasites and can spread between individuals. Microorganisms that cause disease are collectively called pathogens.

Pathogens cause disease either by disrupting the bodies normal processes and/or stimulating the immune system to produce a defensive response, resulting in high fever, inflammation and other symptoms.

Infectious diseases can be spread from one person to another, for example through contact with bodily fluids, by aerosols (through coughing and sneezing), or via a vector, for example, a mosquito.

Infectious diseases can be caused by:

1. Bacteria: These one-cell organisms are responsible for illnesses such as strep throat, urinary tract infections and tuberculosis.
2. Viruses: Even smaller than bacteria, viruses cause a multitude of diseases — ranging from the common cold to AIDS.
3. Fungi: Many skin diseases, such as ringworm and athlete's foot, are caused by fungi. Other types of fungi can infect your lungs or nervous system.
4. Parasites: Malaria is caused by a tiny parasite that is transmitted by a mosquito bite. Other parasites may be transmitted to humans from animal faeces.

Means of Spread of Infectious Diseases Infectious diseases spread from an infected person to a healthy person through the air, water, food, vectors, physical contact and sexual contact.

1. Through air: By sneezing and coughing, the microbes spread into air and enter into the body of a healthy person, like the common cold, tuberculosis, pneumonia etc.
2. Through water : The microbes enter into our body by drinking/eating polluted and contaminated water/food, like cholera, amoebic dysentery etc.
3. Vectors : Some organisms like female anopheles mosquito also work as a vector of disease, like malaria, dengue, yellow fever etc.
4. Through sexual contact : Syphilus, AIDS spread by sexual contact with infected person. AIDS virus can also spread through blood transfusion and from the mother to her child during pregnancy and through breast feeding.

AIDS (Acquired Immuno Deficiency Syndrome)

AIDS is caused by a retrovirus called HIV (Human Immuno Deficiency Virus).

Method of transmission of AIDS:  The transmission of AIDS from an infected to a healthy person takes place :

1. through sexual contact
2. blood transfusion
3. use of infected needle or blade etc.
4. This may also get transmitted from infected mother to her foetus.

Prevention :

1. Avoid transfusion of infected blood. This can be done by testing whether the blood is HIV negative or not.
2. Always use disposable needle and syringe.
3. Avoid sexual contact with the unknown person.
4. Avoid the same razor used in the salons.

Disease-causing microbes enter the body by different means and go to different organs and tissues.

1. Microbes which enters through the nose are likely to go to the lungs. ( Bacteria which cause tuberculosis of lungs).
2. Microbes which enter through the mouth are likely to stay in the gut ( Bacteria which causes Typhoid) or liver (Bacteria which causes Jaundice).
3. The virus which causes AIDS enter the body through sexual organs during sexual contact and spreads through the lymph to all parts of the body and damages the immune system.
4. Malaria-causing microbes, entering through a mosquito bite, will go to the liver, and then to the red blood cells.
5. The virus causing Japanese encephalitis, or brain fever, will similarly enter through a mosquito bite goes and infects the brain.

There are two ways of prevention of infectious diseases. They are general ways and specific ways.

General ways of prevention:- Public hygiene is most important for prevention of infectious diseases. Proper and sufficient food for every one will make people healthy to resist infection. Airborne diseases can be prevented by living in conditions that are not crowded. Waterborne diseases can be prevented by providing safe drinking water. Vector-borne diseases can be prevented by providing a clean environment.

Specific ways of prevention:- The specific ways to prevent infectious disease is immunisation by taking vaccines. Vaccines provide immunity from infectious diseases like tetanus, diphtheria, whooping cough, measles, polio etc. Our body has an immune system which fights microbial infection. When this system first sees an infectious microbe, it kills the microbe and remembers it. So if the microbe enters the body the next time, it responds more vigorously. Vaccines mimic the infectious microbe and strengthen our immune system and protect the body from infectious diseases.

The treatment of infectious diseases consists of two steps. They are to reduce the effects of the disease (symptoms) and to kill the microbes which caused the disease.

1. To reduce the effects of the disease:- This can be done by taking medicines to bring down the effects of the disease like fever, pain or loose motions etc. and by taking bed rest to conserve our energy.
2. To kill the microbes:- This can be done by taking suitable antibiotics and drugs which kills the microbes and the disease is cured.